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1
Bahrami, Mohsen, Juana Abenojar e Miguel Angel Martínez. "Comparative Characterization of Hot-Pressed Polyamide 11 and 12: Mechanical, Thermal and Durability Properties". Polymers 13, n. 20 (15 ottobre 2021): 3553. http://dx.doi.org/10.3390/polym13203553.
Testo completoAbstract (sommario):
Chemically speaking, polyamide 11 (PA11) and polyamide 12 (PA12) have a similar backbone, differing only in one carbon. From an origin point of view, PA11 is considered a bioplastic polyamide composed from renewable resources, compared to oil-based PA12. Each of them has a number of advantages over the other, which makes their selection a challenging issue. Depending on the target application, diverse assessments and comparisons are needed to fulfill this mission. The current study addresses this research gap to characterize and compare PA11 and PA12 manufactured by the hot press technique in terms of their mechanical, thermal and durability properties for the first time, demonstrating their potential for future works as matrices in composite materials. In this regard, different characterization techniques are applied to the hot-pressed polymer sheets, including X-ray diffraction (XRD), differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The mechanical performance of the PA11 and PA12 sheets is compared based on tensile tests and shore hardness measurement. The durability behavior of these two polyamides is evaluated in water and relative humidity conditions at different aging times. The experimental results show the ductile behavior of PA12 with respect to the quasi-brittle PA11. Both have a relatively small water and moisture gain: 1.5 wt% and 0.8 wt%, respectively. The higher crystallinity of PA12 (2.1 times more than PA11) with γ-phase is one of the leading parameters to achieve better mechanical and durability properties. The FTIR spectra displayed slight acid hydrolysis. Accordingly, absorbed water or moisture does not cause plasticization; thus, neither hardness nor dimension changes.
2
Lao, S. C., J. H. Koo, T. J. Moon, M. Londa, C. C. Ibeh, G. E. Wissler e L. A. Pilato. "Flame-retardant polyamide 11 nanocomposites: further thermal and flammability studies". Journal of Fire Sciences 29, n. 6 (22 giugno 2011): 479–98. http://dx.doi.org/10.1177/0734904111404658.
Testo completoAbstract (sommario):
Polyamide (nylon) 11 (PA11) were melt-blended by dispersing low concentrations of nanoparticles (NPs), namely nanoclays (NCs) and carbon nanofibers (CNFs) via twin-screw extrusion. To enhance their thermal and flame retardant (FR) properties, an intumescent FR additive was added to the mechanically superior NC and CNF PA11 formulations. For neat and NP-reinforced PA11 as well as for PA11 reinforced by both intumescent FR and select NPs (NC or CNF), decomposition temperatures by TGA, flammability properties by UL 94, and cone calorimetry values were measured. All PA11 polymer systems infused with both NPs and FR additive had higher decomposition temperatures than those infused with solely FR additive. For the PA11/FR/NC polymer blends, Exolit® OP 1312 (FR2) is the preferred FR additive to pass the UL 94 V-0 requirement with 20 wt%. For the PA11/FR/CNF formulations, all Exolit® OP 1311 (FR1), OP 1312 (FR2), and OP 1230 (FR3) FR additives passed the UL 94 V-0 requirement with 20 wt%.
3
Khan, Zahid Iqbal, Zurina Binti Mohamad, Abdul Razak Bin Rahmat, Unsia Habib e Nur Amira Sahirah Binti Abdullah. "A novel recycled polyethylene terephthalate/polyamide 11 (rPET/PA11) thermoplastic blend". Progress in Rubber, Plastics and Recycling Technology 37, n. 3 (15 marzo 2021): 233–44. http://dx.doi.org/10.1177/14777606211001074.
Testo completoAbstract (sommario):
This work explores a novel blend of recycled polyethylene terephthalate/polyamide 11 (rPET/PA11). The blend of rPET/PA11 was introduced to enhance the mechanical properties of rPET at various ratios. The work’s main advantage was to utilize rPET in thermoplastic form for various applications. Three different ratios, i.e. 10, 20 and 30 wt.% of PA11 blend samples, were prepared using a twin-screw extruder and injection moulding machine. The mechanical properties were examined in terms of tensile, flexural and impact strength. The tensile strength of rPET was improved more than 50%, while the increase in tensile strain was observed 42.5% with the addition of 20 wt.% of PA11. The improved properties of the blend were also confirmed by the flexural strength of the blends. The flexural strength was increased from 27.9 MPa to 48 MPa with the addition of 30 wt.% PA11. The flexural strain of rPET was found to be 1.1%. However, with the addition of 10, 20 and 30 wt.% of PA11, the flexural strain was noticed as 1.7, 2.1, and 3.9% respectively. The impact strength of rPET/PA11 at 20 wt.% PA11 was upsurged from 110.53 to 147.12 J/m. Scanning electron microscopy analysis revealed a dispersed PA11 domain in a continuous rPET matrix morphology of the blends. This work practical implication would lead to utilization of rPET in automobile, packaging, and various industries.
4
Wang, Sheng Qin, Mohit Sharma e Yew Wei Leong. "Polyamide 11/Clay Nanocomposite Using Polyhedral Oligomeric Silsesquioxane Surfactants". Advanced Materials Research 1110 (giugno 2015): 65–68. http://dx.doi.org/10.4028/www.scientific.net/amr.1110.65.
Testo completoAbstract (sommario):
This paper reports polyamide 11 (PA11)/layered silicate (clay) nanocomposite using polyhedral oligomeric silsesquioxane (POSS) surfactants. POSS functionalized with amino, ammonium and guanidinium groups were synthesized and used to facilitate the intercalation of polymer chains between silicate layers thereby to improve the dispersion of clay in polymer matrix. Nanocomposites from the blends of POSS-modified clay and PA11 were thus formulated via melting compounding and their mechanical and physical properties were characterized.
5
Lods, Louise, Tutea Richmond, Jany Dandurand, Eric Dantras, Colette Lacabanne, Jean-Michel Durand, Edouard Sherwood, Gilles Hochstetter e Philippe Ponteins. "Continuous Bamboo Fibers/Fire-Retardant Polyamide 11: Dynamic Mechanical Behavior of the Biobased Composite". Polymers 14, n. 2 (12 gennaio 2022): 299. http://dx.doi.org/10.3390/polym14020299.
Testo completoAbstract (sommario):
A biobased composite was generated from bamboo fibers (BF) and a polyamide 11 (PA11) matrix. In order to fulfill security requirements, a PA11 already containing a flame retardant (FR) was chosen: This matrix is referred as PA11-FR. In this work, the effects of flame retardant (melamine cyanurate) on the composite properties were considered. In the calorimetric study, the glass transition and melting temperatures of PA11-FR were the same as those of PA11. The melamine cyanurate (MC) had no influence on these parameters. Thermogravimetric analysis revealed that PA11-FR was less stable than PA11. The presence of MC facilitated thermal decomposition regardless of the analysis atmosphere used. It is important to note that the presence of FR did not influence processing conditions (especially the viscosity parameter) for the biosourced composite. Continuous BF-reinforced PA 11-FR composites, single ply, with 60% of fibers were processed and analyzed using dynamic mechanical analysis. In shear mode, comparative data recorded for BF/PA11-FR composite and the PA11-FR matrix demonstrated that the shear glassy modulus was significantly improved: multiplied by a factor of 1.6 due to the presence of fibers. This result reflected hydrogen bonding between reinforcing fibers and the matrix, resulting in a significant transfer of stress. In tensile mode, the conservative modulus of BF/PA11-FR reached E’ = 8.91 GPa. Upon BF introduction, the matrix tensile modulus was multiplied by 5.7. It can be compared with values of a single bamboo fiber recorded under the same experimental conditions: 31.58 GPa. The difference is partly explained by the elementary fibers’ lack of alignment in the composite.
6
Gunputh, Urvashi F., Gavin Williams, Marzena Pawlik, Yiling Lu e Paul Wood. "Effect of Powder Bed Fusion Laser Sintering on Dimensional Accuracy and Tensile Properties of Reused Polyamide 11". Polymers 15, n. 23 (2 dicembre 2023): 4602. http://dx.doi.org/10.3390/polym15234602.
Testo completoAbstract (sommario):
Polyamide 11 (PA11) is a plant-based nylon made from castor beans. Powder bed fusion laser sintering (PBF-LS) is an additive manufacturing process used for PA11 which allows for the reuse of the unsintered powder. The unsintered powder is mixed with virgin powders at different refresh rates, a process which has been studied extensively for most semi-crystalline polyamides. However, there is lack of information on the effect of using 100% reused PA11 powder and the effect of the number of times it is reused on its own, during powder bed fusion laser sintering. This paper investigates the effect of reusing PA11 powder in PBF-LS and the effect of the number of times it is reused on the dimensional accuracy, density and thermal and tensile properties. From the 100% virgin powder to the third reuse of the powder, there is a decrease in powder wastage, crystallinity and tensile strength. These are associated with the polymerisation and cross-linking process of polymer chains, upon exposure to high temperatures. This results in a higher molecular weight and, hence, a higher density. From the fourth reuse to the tenth reuse, the opposite is observed, which is associated with an increase in high-viscosity unmolten particles, resulting in defects in the PBF-LS parts.
7
Oulmou, F., A. Benhamida, A. Dorigato, A. Sola, M. Messori e A. Pegoretti. "Effect of expandable and expanded graphites on the thermo-mechanical properties of polyamide 11". Journal of Elastomers & Plastics 51, n. 2 (18 giugno 2018): 175–90. http://dx.doi.org/10.1177/0095244318781956.
Testo completoAbstract (sommario):
The preparation and thermo-mechanical characterization of composites based on polyamide 11 (PA11) filled with various amounts of both expandable and expanded graphites are presented. Investigation conducted using X-ray diffraction (XRD), scanning electron microscopy and surface area analyses indicated how graphite expanded under the selected processing conditions. The XRD analysis on PA11/graphite composites revealed no change in the crystal form of the PA11, while the presence of diffraction peaks associated to the graphite-stacked lamellae can be still detected. All the investigated composites showed an improvement of the thermal stability and mechanical properties (elastic and storage moduli).
8
Li, Yongjin, Yuko Iwakura e Hiroshi Shimizu. "Crystal Form and Phase Structure of Poly(vinylidene fluoride)/Polyamide 11/Clay Nanocomposites by High-Shear Processing". Journal of Nanoscience and Nanotechnology 8, n. 4 (1 aprile 2008): 1714–20. http://dx.doi.org/10.1166/jnn.2008.18235.
Testo completoAbstract (sommario):
Polyamide 11 (PA11)/clay, Poly(vinylidene fluoride) (PVDF)/clay and PVDF/PA11/clay nanocomposites were prepared by melt processing using a high shear extruder. Two types of organoclay with different modified alkyl tails and different polarities were used for PA11 and PVDF nanocomposites. PA11 nanocomposites derived from an organoclay having one alkyl tail show a well-exfoliated morphology but no crystal form transformation, whereas those derived from an organoclay having two alkyl tails give a little worse clay dispersion with the clear α to γ crystal form transition with the addition of the clay. In contrast, the PVDF composites derived from the two organoclays result in a poor dispersion. In addition, PVDF/PA11 blend nanocomposites with a novel morphology have been fabricated using the high-shear extruder. It was found that the clay platelets were selectively dispersed in the PA11 phase with the size of larger than 200 nm, while no clay platelets were located in the PVDF phase and in the PA11 nanodomains with the size of smaller than 200 nm. Moreover, the addition of organoclay shows significant effects on the phase structure of PVDF/PA11 blends.
9
Sahnoune, Mohamed, Mustapha Kaci, Aurélie Taguet, Karl Delbé, Samir Mouffok, Said Abdi, José-Marie Lopez-Cuesta e Walter W. Focke. "Tribological and mechanical properties of polyamide-11/halloysite nanotube nanocomposites". Journal of Polymer Engineering 39, n. 1 (19 dicembre 2018): 25–34. http://dx.doi.org/10.1515/polyeng-2018-0131.
Testo completoAbstract (sommario):
AbstractThis article reports some morphological, tribological, and mechanical data on polyamide-11(PA11)/halloysite nanotube (HNT) nanocomposites prepared by melt-compounding. HNTs extracted from the Djebel Debbagh deposit in Algeria were incorporated into the polymer at 1, 3, and 5 wt%. For comparison, commercial HNTs were also used under the same processing conditions. Scanning electron microscopy showed that both HNTs were homogeneously dispersed in the PA11 matrix, despite the presence of few aggregates, in particular at higher filler contents. The tribological properties were significantly improved, resulting in a decrease in the friction coefficient and the wear rate characteristics due to the lubricating effect of HNTs. This is consistent with optical profilometry data, which evidenced the impact of both types of HNTs on the surface topography of the nanocomposite samples, in which the main wear process was plastic deformation. Furthermore, Young’s modulus and tensile strength were observed to increase with the filler content, but to the detriment of elongation at break and impact strength. Regarding the whole data, the raw Algerian halloysite led to interesting results in PA11 nanocomposites, thus revealing its potential in polymer engineering nanotechnology.
10
Tey, Wei Shian, Chao Cai e Kun Zhou. "A Comprehensive Investigation on 3D Printing of Polyamide 11 and Thermoplastic Polyurethane via Multi Jet Fusion". Polymers 13, n. 13 (29 giugno 2021): 2139. http://dx.doi.org/10.3390/polym13132139.
Testo completoAbstract (sommario):
Multi Jet Fusion (MJF) is a recently developed polymeric powder bed fusion (PBF) additive manufacturing technique that has received considerable attention in the industrial and scientific community due to its ability to fabricate functional and complex polymeric parts efficiently. In this work, a systematic characterization of the physicochemical properties of MJF-certified polyamide 11 (PA11) and thermoplastic polyurethane (TPU) powder was conducted. The mechanical performance and print quality of the specimens printed using both powders were then evaluated. Both PA11 and TPU powders showed irregular morphology with sharp features and had broad particle size distribution, but such features did not impair their printability significantly. According to the DSC scans, the PA11 specimen exhibited two endothermic peaks, while the TPU specimen exhibited a broad endothermic peak (116–150 °C). The PA11 specimens possessed the highest tensile strength in the Z orientation, as opposed to the TPU specimens which possessed the lowest tensile strength along the same orientation. The flexural properties of the PA11 and TPU specimens displayed a similar anisotropy where the flexural strength was highest in the Z orientation and lowest in the X orientation. The porosity values of both the PA11 and the TPU specimens were observed to be the lowest in the Z orientation and highest in the X orientation, which was the opposite of the trend observed for the flexural strength of the specimens. The PA11 specimen possessed a low coefficient of friction (COF) of 0.13 and wear rate of 8.68 × 10−5 mm3/Nm as compared to the TPU specimen, which had a COF of 0.55 and wear rate of 0.012 mm3/Nm. The PA11 specimens generally had lower roughness values on their surfaces (Ra < 25 μm), while the TPU specimens had much rougher surfaces (Ra > 40 μm). This investigation aims to uncover and explain phenomena that are unique to the MJF process of PA11 and TPU while also serving as a benchmark against similar polymeric parts printed using other PBF processes.
11
Sergi, Claudia, Libera Vitiello, Pietro Russo, Jacopo Tirillò e Fabrizio Sarasini. "Toughened Bio-Polyamide 11 for Impact-Resistant Intraply Basalt/Flax Hybrid Composites". Macromol 2, n. 2 (6 aprile 2022): 154–67. http://dx.doi.org/10.3390/macromol2020010.
Testo completoAbstract (sommario):
The automotive sector covers almost 40% of polyamide (PA) total demand. A suitable solution to improve the sustainability of this sector is the exploitation of PA matrices sourced from renewable origins, such as PA11, and their reinforcement with natural fibers such as vegetable flax and mineral basalt. A preliminary study on the quasi-static properties of PA11-based composites reinforced with an intraply flax/basalt hybrid fabric demonstrated their feasibility for semi-structural purposes in the transportation field, but their application needs to be validated against dynamic loading. In this regard, this work investigated the low-velocity impact performance of PA11 flax/basalt hybrid composites (10 J, 20 J and 30 J) as a function of temperature (room temperature and +80 °C) and plasticizer addition (butyl-benzene-sulfonamide). The results proved that plasticized PA11 is endowed with a lower glass transition temperature (~15 °C, from DMA) and melting temperature (~10 °C, from DSC), which simplifies manufacturing and processing, but also possesses a higher toughness which delays penetration phenomena and reduces permanent indentation at room temperature between 20.5% and 42.8% depending on impact energy. The occurrence of matrix plasticization at +80 °C caused a more flexible and tougher response from the laminates with a decrease in linear stiffness and a delay in penetration phenomena which made the plasticizer effect less prominent.
12
Zhu, Feichao, Bin Yu, Juanjuan Su e Jian Han. "Study on PLA/PA11 Bio-Based Toughening Melt-Blown Nonwovens". Autex Research Journal 20, n. 1 (1 marzo 2020): 24–31. http://dx.doi.org/10.2478/aut-2019-0002.
Testo completoAbstract (sommario):
AbstractWith aim to improve the mechanical and thermal properties of poly (lactic acid) (PLA) melt-blown nonwovens (MBs), polyamide 11 (PA11) was melt blended with PLA at the weight proportions of PLA/PA11 (95/5, 90/10, 85/15, 80/20), and the corresponding PLA/PA11 MBs were also manufactured. The crystallization, thermal and rheological behaviors of PLA/PA11 blends were investigated. PLA/PA11 MBs were also characterized by morphology and mechanical properties. The results indicated that PA11, as globular dispersed phases, formed confined crystals and could improve the thermal stability of PLA matrix. The viscosity of PLA/PA11 blends was slightly increased but the rheological behaviors of “shear-thinning” kept unchanged in comparison with PLA. The average diameter of PLA/PA11 MB fibers was slightly increased, whereas the toughness of PLA/PA11 MBs including the strength and elongation were efficiently enhanced compared with those of PLA MBs.
13
Do, Van Cong, Vu Giang Nguyen, Huu Trung Tran, Quang Tham Do, Thi Thai Nguyen, Van Tien Mai e Thi Huong Nguyen. "Novel research on polyamide 11 nanocomposites reinforced by Titania nanoparticle deposited jute fibres". Vietnam Journal of Science and Technology 60, n. 6 (30 dicembre 2022): 1032–43. http://dx.doi.org/10.15625/2525-2518/16554.
Testo completoAbstract (sommario):
The combination of jute fibres and polyamide 11 (PA11) to produce full biocomposites is expectance of scientists due to many benefits of both these materials such as high mechanical performances and environmentally friendly behaviors. Unfortunately, there is scarce published research on these bicomposites uptil now. In order to improve the interfacial interaction and adhesion between jute fibres and PA11 resin matrix, an important key in the fabrication of the composites. In this study, a combination of alkaline treatment and Tetraisopropyl orthotitanate (Tip) modification was employed to modify the surface of jute fibres. The deposition or grafting of TiO2 nanoparticles was proved by using Fourier transform infrared (FTIR), scanning electron microscopy (SEM) observations and energy dispersive X-ray spectroscopy (EDS/EDX) analysis. The improvement of the interfacial interaction and adhesion between surface modified jute fibres and PA11 resin as well as high performances (mechanical properties, thermal oxidative and water absorption stability) of obtained biocomposites were also clarified.
14
Hongsriphan, Nattakarn, Kantika Somboon, Chutikan Paujai e Thitichaya Taengto. "Mechanical Enhancement and Thermal Stability of Composites between Polyamide 11 and Functionalized Graphene Nanoplatelets". Key Engineering Materials 858 (agosto 2020): 59–65. http://dx.doi.org/10.4028/www.scientific.net/kem.858.59.
Testo completoAbstract (sommario):
The composites between polyamide 11 (PA11) and functionalized graphene nanoplatelets (GNP) were prepared to compare influence of GNPs content and functionalities; hydroxyl (GO) and carboxylic acid (GC); on mechanical and thermal properties. The composites were melt compounded and injection molded into specimens with the final GNP content of 1, 3, 5, 7 and 9 wt%. It was found in XRD that these plasma-exfoliated GNPs acted as the nucleating agents that changed the crystal form of PA11, but did not have significant influence on crystallinity content. DSC analysis confirmed the nucleating effect of GNPs, which the degree of crystallinity was not affected by the presence of GNPs. The functionalities of GNP did not reduce the degradation temperature of the composites compared to neat PA11. Young's modulus and tensile strength at yield of the composites were higher with respect to the GNP content. This was attributed to stretching restriction of polymer chains by GNPs during the elastic deformation. The composites adding GO had higher tensile properties than those adding GC. In contrast, the composites adding GC showed higher impact strength than those adding GO. SEM micrographs indicated the failure of the composites occurred at the interphase between PA11 matrix and GNPs.
15
Panaitescu, Denis Mihaela, Raluca Augusta Gabor, Adriana Nicoleta Frone e Eugeniu Vasile. "Influence of Thermal Treatment on Mechanical and Morphological Characteristics of Polyamide 11/Cellulose Nanofiber Nanocomposites". Journal of Nanomaterials 2015 (2015): 1–11. http://dx.doi.org/10.1155/2015/136204.
Testo completoAbstract (sommario):
Nanocomposite films were prepared from polyamide 11 (PA11) and cellulose nanofibers (CN) by melt compounding and compression molding. The impact of thermal treatment on the morphology and mechanical behavior of PA11 and nanocomposite films was studied using dynamic mechanical analysis, tensile tests, X-ray diffraction (XRD), and peak force (PF) QNM technique. Slightly higher storage modulus values were obtained for nanocomposites compared to the matrix before the treatment, but a noticeable increase was observed after the treatment. Although CN addition determined increased tensile strength and modulus both before and after the treatment, the increase was much more significant in the case of treated films. The best mechanical properties were shown by treated PA11 films containing 5 wt% CN, with 40% higher Young’s modulus and with 35% higher tensile strength compared to the matrix. Some of the changes pointed out by static and dynamic mechanical tests were explained by the morphological changes determined by the thermal treatment and emphasized by PF QNM and by the increase of XRD crystallinity. A transition from lamellar stack morphology to one involving spherulites was highlighted by AFM. Thermal treatment has proved a valuable method for improving the mechanical properties of PA11/CN composites.
16
Fazli, Ali, e Denis Rodrigue. "Biosourced Poly(lactic acid)/polyamide-11 Blends: Effect of an Elastomer on the Morphology and Mechanical Properties". Molecules 27, n. 20 (12 ottobre 2022): 6819. http://dx.doi.org/10.3390/molecules27206819.
Testo completoAbstract (sommario):
Fully biobased polylactide (PLA)/polyamide-11 (PA11) blends were prepared by melt mixing with an elastomer intermediate phase to address the low elasticity and brittleness of PLA blends. The incorporation of a biobased elastomer made of poly(butylene adipate-co-terephthalate) (PBAT) and polyethylene oxide (PEO) copolymers was found to change the rigid interface between PLA and PA11 into a much more elastic/deformable one as well as promote interfacial compatibility. The interfacial tension of the polymer pairs and spreading coefficients revealed a high tendency of PEO to spread at the PLA/PA11 interface, resulting in a complete wetting regime (interfacial tension of 0.56 mN/m). A fully percolated rubbery phase (PEO) layer at the PLA/PA11 interface with enhanced interfacial interactions and PLA chain mobility contributed to a better distribution of the stress around the dispersed phase, leading to shear yielding of the matrix. The results also show that both the morphological modification and improved compatibility upon PEO addition (up to 20 wt %) contributed to the improved elongation at break (up to 104%) and impact strength (up to 292%) of the ternary PLA/PA11/PEO blends to obtain a super-tough multiphase system.
17
Iz, Muhammet, Jinhyok Lee, Myungchan Choi, Yumi Yun e Jongwoo Bae. "The Effect of Polyamide 11 on the Thermal Stability and Light Transmittance of Silicone-Based Thermoplastic Vulcanizates". Polymers 16, n. 3 (24 gennaio 2024): 324. http://dx.doi.org/10.3390/polym16030324.
Testo completoAbstract (sommario):
The effect of polyamide 11 (PA11) on the thermal stability and light transmittance properties of silicone-based thermoplastic vulcanizates (TPVs) has been investigated. The blends were prepared through a dynamic vulcanization process by adding 15, 30, and 45 wt% PA11 to the silicon-based TPVs, respectively. The effect of PA11 on the dispersion of silicone rubber in the TPVs after dynamic vulcanization was characterized by a scanning electron microscope (SEM), the thermal stability of the compounds was evaluated through the changes in mechanical performance in the thermo-oxidative aging process, and the light transmittance of TPVs was measured by a haze meter. The results showed that adding PA11 to silicone-based TPVs caused a decrease in the size of the silicone rubber particles after dynamic vulcanization, resulting in improved dispersion. Due to this, by increasing the compatibility between the segments through silicone’s effective dispersion, the amount of light absorption was reduced, and the amount of light transmittance was increased. Finally, according to the results of the thermal aging test, it was found that TPVs with 30 and 45 wt% PA11, respectively, showed outstanding thermal resistance after aging at 160 °C and 168 h and did not melt down.
18
Jeziorska, Regina, Agnieszka Szadkowska e Maciej Studzinski. "Morphology and Properties of Poly(2,6-dimethyl-1,4-phenylene oxide)/Polyamide 11 Hybrid Nanocomposites: Effect of Silica Surface Modification". Materials 15, n. 10 (10 maggio 2022): 3421. http://dx.doi.org/10.3390/ma15103421.
Testo completoAbstract (sommario):
Poly(2,6-dimethyl-1,4-phenylene oxide)/polyamide 11 (PPO/PA11 80/20) blend filled with neat (SiO2) or modified silica having amine functional groups (A-SiO2) was melt mixing in a twin-screw extruder. The silica was prepared by the sol–gel process. SEM shows that, with increasing A-SiO2 content from 1 to 5 wt.%, the morphology of PPO/PA11blend changed from droplet matrix to co-continuous with phase inversion. The phase inversion was also observed for 5 wt.% of neat silica, but the droplet-matrix structure was retained. The overall rheological and mechanical properties improvement of the A-SiO2-filled composites in comparison with the unfilled blend and neat silica counterpart was drastic, especially in terms of viscosity and stiffness. A-SiO2 improved PPO and PA11 miscibility and reduced the crystallinity of PA11, without affecting the Tc, owing to the compatibilization effect. On the other hand, neat silica slightly increased the crystallinity of PA11 and decreased the crystallization temperature of PA11 and the glass transition temperature of PPO as a result of its plasticization.
19
Peng, Cun, Hua Yang e Wufei Tang. "Study on the Flammability, Crystal Behaviors and Mechanical Performance of Polyamide 11 Composites by Intercalated Layered Double Hydroxides". International Journal of Molecular Sciences 23, n. 21 (24 ottobre 2022): 12818. http://dx.doi.org/10.3390/ijms232112818.
Testo completoAbstract (sommario):
Sulfamic acid-intercalated MgAl-LDH (SA-LDH) was prepared by an anion exchange method, and its structure was characterized by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). SA-LDH was introduced into polyamide 11 (PA11) by melt blending and to enhance the flame retardancy and mechanical properties. The scanning electron microscope (SEM) and XRD data showed that the lamellar structure of SA-LDH was partly disrupted. The cone calorimeter (CCT) results demonstrated that SA-LDH could effectively decrease the value of heat release rate, which may be ascribed to the better distribution of SA-LDH compared to LHD in the PA11 matrix. The effects of SA-LDH on the crystal behaviors of PA11 were investigated by XRD and differential scanning calorimetry (DSC), indicating that SA-LDH could induce the formation of new crystal forms and served as a heterogeneous nucleating agent. The mechanical progress caused by the incorporation of SA-LDH was correlated with compatibility improvement between SA-LDH and PA11.
20
Lebaupin, Yann, Michaël Chauvin, Thuy-Quynh Truong Hoang, Fabienne Touchard e Alexandre Beigbeder. "Influence of constituents and process parameters on mechanical properties of flax fibre-reinforced polyamide 11 composite". Journal of Thermoplastic Composite Materials 30, n. 11 (21 aprile 2016): 1503–21. http://dx.doi.org/10.1177/0892705716644669.
Testo completoAbstract (sommario):
Flax unidirectional (UD) fabrics and polyamide 11 (PA11) are used to create a 100% bio-sourced composite. The fabrication process is hot press moulding. Different configurations are studied by varying process parameters and composite constituents. Three temperature values (190°C, 200°C and 210°C) are combined with three pressure levels (35, 65 and 100 bars). In addition, two types of flax fabric (A and B) are tested and two types of PA11 (in the form of powder or film) are used. The two forms of PA11 are characterized using differential scanning calorimetry and rheological methods. Ten different composites are then manufactured. They are compared by means of tensile tests and dynamic mechanical analysis (DMA). Results are correlated with microstructural study: measurements of porosity degree and scanning electron microscopic observations are also performed. Finally, an optimum configuration is determined: the composite flax B/PA11 film manufactured with a temperature value of 210°C and using gradual levels of pressure (25 bars during 2 min, 40 bars during 2 min and 65 bars until the end of cycle). This configuration leads to a Young’s modulus value of 36 GPa and a tensile strength of 174 MPa, with the highest storage modulus and the lowest damping factor values measured by DMA.
21
Zhu, Feichao, Juanjuan Su, Mingjun Wang, Munir Hussain, Bin Yu e Jian Han. "Study on dual-monomer melt-grafted poly(lactic acid) compatibilized poly(lactic acid)/polyamide 11 blends and toughened melt-blown nonwovens". Journal of Industrial Textiles 49, n. 6 (31 agosto 2018): 748–72. http://dx.doi.org/10.1177/1528083718795913.
Testo completoAbstract (sommario):
With increasing demands on the high-performance and environmental-friendly melt-blown nonwovens (MBs) for separation and filtration, herein, we reported a poly(lactic acid)/polyamide 11 (PLA/PA11) 100% bio-based MBs in situ compatibilized by dual-monomer glycidyl methacrylate–styrene melt-grafted poly(lactic acid) (PLA-g-(St-co-GMA)). The morphology, crystallization, thermal and rheological behaviors of reactive extruded PLA/PA11/PLA-g-(St-co-GMA) melt blends were investigated, and the structure and filtration performance of corresponding MBs were fully characterized. The results indicated that the interface between PLA and PA11 were effectively improved due to the compatibilizer of PLA-g-(St-co-GMA). PA11 promoted the cold crystallization and enhanced the thermal stability of PLA matrix. The reactive blends displayed a higher viscosity with unchanged rheological behaviors compared with PLA. In comparison with PLA MBs, the average fiber diameter and pore size of PLA/PA11/PLA-g-(St-co-GMA) MBs were slightly increased, whereas the strength and toughness were significantly improved. All the PLA/PA11/PLA-g-(St-co-GMA) MBs presented high air permeability and low filtration resistance. High filtration efficiency (>99.8%) could also be obtained especially for the target particles with diameters larger than 2.5 µm.
22
Dintcheva, N. Tz, G. Filippone, R. Arrigo e F. P. La Mantia. "Low-Density Polyethylene/Polyamide/Clay Blend Nanocomposites: Effect of Morphology of Clay on Their Photooxidation Resistance". Journal of Nanomaterials 2017 (2017): 1–9. http://dx.doi.org/10.1155/2017/3549475.
Testo completoAbstract (sommario):
The photooxidation behaviour of low-density polyethylene (LDPE)/polyamide (PA) blends, containing polyamide 11 (PA11) or polyamide 6 (PA6), has been investigated in the absence and presence of a small amount of commercial organomodified clay (OMMT). The polymer blends LDPE/PA11 and LDPE/PA6 at 75/25 wt./wt.%, with and without OMMT, have been prepared by a two-step procedure: extrusion and sheet formulation. The formulated complex systems have been subjected to accurate morphological analysis in order to evaluate the effect of the OMMT presence on the refinement of the blend morphology. Furthermore, the produced sheets have been subjected to arterial UVB exposure and the variations of the mechanical properties and chemical structure of all the investigated samples have been monitored as a function of the exposure time. Finally, the rate of the photodegradation of the complex systems has been related to the morphological changes of these systems upon OMMT addition.
23
Li, Rui, Bin Xue e Jianzhong Pei. "Enhancement of the dielectric performance of PA11/PVDF blends by a solution method with dimethyl sulfoxide". e-Polymers 15, n. 6 (1 novembre 2015): 439–45. http://dx.doi.org/10.1515/epoly-2015-0131.
Testo completoAbstract (sommario):
AbstractIn this study, the solution method was used to prepare polyamide 11/polyvinylidene difluoride (PA11/PVDF) blend films. The crystal phase compositions and microstructures of the blends were studied by Fourier transform infrared spectroscopy, X-ray diffraction and scanning electron microscopy analysis. Additionally, the dielectric properties of the PA11/PVDF blends, with different ratios and concentrations, were tested. The results indicated that the solution method is more propitious in forming β crystals during the preparation of the PA11/PVDF blend films compared with the melt blending method. The amount of β crystals present in PVDF was dependent on the ratio of dimethyl sulfoxide (DMSO) and H2O. Specifically, for the 5:95 ratio of DMSO/H2O precipitants, the PA11/PVDF (80:20) blend films prepared by the solution method had a high dielectric constant of 188.1 and a dielectric loss of 1.37.
24
Huynh, Mai Duc. "PREPARATION OF POLYAMIDE11/BAMBOO FLOUR POLYMER COMPOSITE USING POLYVINYL ALCOHOL AS COMPATIBILIZER". Vietnam Journal of Science and Technology 56, n. 2A (21 giugno 2018): 209–16. http://dx.doi.org/10.15625/2525-2518/56/2a/12688.
Testo completoAbstract (sommario):
In this work, the effects of bamboo flour (BF) and polyvinyl alcohol (PVA) contents on the tensile strength, impact strength, thermogravimetric analysis (TGA) and dynamic mechanical thermal analysis (DMTA) of polyamide 11/BF composites were studied in detail. The PVA was added into PA11/BF composites by two methods: (i) melt mixing with the other components in Haake mixer (one-step method); (ii) dispersing on the surface of BF in ethanol solution before mixing with PA11 in the melted state (two-step method). The investigation of mechanical properties showed the tensile strength of composites prepared by two-step method was higher than that of one-step method, while the trend for impact strength was opposite. On the other hand, DMTA analyses exhibited the enhacement of the compatibility of PA11/BF sample by observing the shift of peaks at the b relaxation around -80 oC due to the presence of PVA. This led to the increase of thermal stability of PA11/PVA/BF composites in comparison with PA11/BF composites.
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Puglisi, Roberta, Andrea Antonino Scamporrino, Nadka Tzankova Dintcheva, Giovanni Filippone, Elena Bruno, Paola Scarfato, Pierfrancesco Cerruti e Sabrina Carola Carroccio. "Photo- and Water-Degradation Phenomena of ZnO Bio-Blend Based on Poly(lactic acid) and Polyamide 11". Polymers 15, n. 6 (14 marzo 2023): 1434. http://dx.doi.org/10.3390/polym15061434.
Testo completoAbstract (sommario):
The goal of this work was to investigate the morphological and chemical–physical changes induced by adding ZnO nanoparticles to bio-based polymeric materials based on polylactic acid (PLA) and polyamide 11 (PA11). Precisely, the photo- and water-degradation phenomena of nanocomposite materials were monitored. For this purpose, the formulation and characterization of novel bio-nanocomposite blends based on PLA and PA11 at a ratio of 70/30 wt.% filled with zinc oxide (ZnO) nanostructures at different percentages were performed. The effect of ZnO nanoparticles (≤2 wt.%) within the blends was thoroughly explored by employing thermogravimetry (TGA), size exclusion chromatography (SEC), matrix-assisted laser desorption ionization–time-of-flight mass spectrometry (MALDI-TOF MS) and scanning and transmission electron microscopy (SEM and TEM). Adding up to 1% wt. of ZnO resulted in a higher thermal stability of the PA11/PLA blends, with a decrement lower than 8% in terms of molar masses (MMs) values being obtained during blend processing at 200 °C. ZnO promoted trans-ester-amide reactions between the two polymers, leading to the formation of PLA/PA11 copolymers. These species could work as compatibilisers at the polymer interface, improving thermal and mechanical properties. However, the addition of higher quantities of ZnO affected such properties, influencing the photo-oxidative behaviour and thus thwarting the material’s application for packaging use. The PLA and blend formulations were subjected to natural aging in seawater for two weeks under natural light exposure. The 0.5% wt. ZnO sample induced polymer degradation with a decrease of 34% in the MMs compared to the neat samples.
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Mandlekar, Neeraj, Aurélie Cayla, François Rault, Stéphane Giraud, Fabien Salaün e Jinping Guan. "Valorization of Industrial Lignin as Biobased Carbon Source in Fire Retardant System for Polyamide 11 Blends". Polymers 11, n. 1 (21 gennaio 2019): 180. http://dx.doi.org/10.3390/polym11010180.
Testo completoAbstract (sommario):
In this study, two different types of industrial lignin (i.e., lignosulphonate lignin (LL) and kraft lignin (DL)) were exploited as charring agents with phosphorus-based flame retardants for polyamide 11 (PA11). The effect of lignins on the thermal stability and fire behavior of PA11 combined with phosphinate additives (namely, aluminum phosphinate (AlP) and zinc phosphinate (ZnP)) has been studied by thermogravimetric analysis (TGA), UL 94 vertical flame spread, and cone calorimetry tests. Various blends of flame retarded PA11 were prepared by melt process using a twin-screw extruder. Thermogravimetric analyses showed that the LL containing ternary blends are able to provide higher thermal stability, as well as a developed char residue. The decomposition of the phosphinates led to the formation of phosphate compounds in the condensed phase, which promotes the formation of a stable char. Flammability tests showed that LL/ZnP ternary blends were able to achieve self-extinction and V-1 classification; the other formulations showed a strong melt dripping and higher burning. In addition to this, cone calorimetry results showed that the most enhanced behavior was found when 10 wt % of LL and AlP were combined, which strongly reduced PHRR (−74%) and THR (−22%), due to the interaction between LL and AlP, which not only promotes char formation but also confers the stability to char in the condensed phase.
27
Jaouadi, Nour, Mohamed Jaziri, Abderrahim Maazouz e Khalid Lamnawar. "Biosourced Multiphase Systems Based on Poly(Lactic Acid) and Polyamide 11 from Blends to Multi-Micro/Nanolayer Polymers Fabricated with Forced-Assembly Multilayer Coextrusion". International Journal of Molecular Sciences 24, n. 23 (24 novembre 2023): 16737. http://dx.doi.org/10.3390/ijms242316737.
Testo completoAbstract (sommario):
The objective of the present study was to investigate multiphase systems based on polylactic acid (PLA) and polyamide 11 (PA11) from blends to multilayers. Firstly, PLA/PA11 blends compatibilized with a multifunctionalized epoxide, Joncryl, were obtained through reactive extrusion, and the thermal, morphological, rheological, and mechanical behaviors of these materials were investigated. The role of Joncryl as a compatibilizer for the PLA/PA11 system was demonstrated by the significant decrease in particle size and interfacial tension as well as by the tensile properties exhibiting a ductile behavior. Based on these findings, we were able to further clarify the effects of interdiffusion and diffuse interphase formation on the structure, rheology, and mechanics of compatible multilayered systems fabricated with forced-assembly multilayer coextrusion. The results presented herein aim to provide a deeper understanding of the interfacial properties, including the rheological, mechanical, and morphological behaviors, towards the control of the interface and confinement in multilayer polymers resulting from coextrusion, and also to permit their use in advanced applications.
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Dobrosielska, Marta, Renata Dobrucka, Paulina Kozera, Rafał Kozera, Marta Kołodziejczak, Ewa Gabriel, Julia Głowacka, Marek Jałbrzykowski, Krzysztof J. Kurzydłowski e Robert E. Przekop. "Biocomposites Based on Polyamide 11/Diatoms with Different Sized Frustules". Polymers 14, n. 15 (2 agosto 2022): 3153. http://dx.doi.org/10.3390/polym14153153.
Testo completoAbstract (sommario):
Amorphous diatomite containing approx. 80% silicon dioxide SiO2 was used as a filler for a thermoplastic polymer of polyamide 11 obtained from natural sources. The diatomite particles of different sizes were previously fractionated by sedimentation to obtain powders with varying particle size distribution, including powders with or without frustule particles, crushed, uncrushed or agglomerated. Biocomposites containing 2.5, 5, 10 and 20% filler were tested for their mechanical properties, including tensile strength, flexural strength and impact strength. In addition, a particle size analysis (by Dynamic Light Scattering, DLS) was performed and the dispersion of the filler in the polymer matrix (Scanning Electron Microscopy, SEM), thermal parameters (Differential Scanning Calorimetry, DSC, and Dynamic Mechanical Analysis, DMA) were determined. Testing showed that biocomposites modified with diatomaceous earth have a higher mechanical strength than the reference system, especially with larger amounts of the filler (10 and 20%), e.g., the tensile strength of pure PA11 is about 46 MPa, while 20OB and 20OF 47.5 and 47 MPa, respectively, while an increase in max. flexural strength and flexural modulus is also observed compared to pure PA11 by a maximum of 63 and 54%, respectively Diatomaceous earth can be obtained in various ways—it is commercially available or it is possible to breed diatoms in laboratory conditions, while the use of commercially available diatomite, which contains diatoms of different sizes, eliminates the possibility of controlling mechanical parameters by filling biocomposites with a filler with the desired particle size distribution, and diatom breeding is not possible on an industrial scale. Our proposed biocomposite based on fractionated diatomaceous earth using a sedimentation process addresses the current need to produce biocomposite materials from natural sources, and moreover, the nature of the process, due to its simplicity, can be successfully used on an industrial scale.
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Dobrosielska, Marta, Renata Dobrucka, Dariusz Brząkalski, Paulina Kozera, Agnieszka Martyła, Ewa Gabriel, Krzysztof J. Kurzydłowski e Robert E. Przekop. "Polyamide 11 Composites Reinforced with Diatomite Biofiller—Mechanical, Rheological and Crystallization Properties". Polymers 15, n. 6 (21 marzo 2023): 1563. http://dx.doi.org/10.3390/polym15061563.
Testo completoAbstract (sommario):
Amorphic diatomaceous earth is derived from natural sources, and polyamide 11 (PA11) is produced from materials of natural origin. Both of these materials show a low harmfulness to the environment and a reduced carbon footprint. This is why the combination of these two constituents is beneficial not only to improve the physicochemical and mechanical properties of polyamide 11 but also to produce a biocomposite. For the purpose of this paper, the test biocomposite was produced by combining polyamide 11, as well as basic and pre-fractionated diatomaceous earth, which had been subjected to silanization. The produced composites were used to carry out rheological (melt flow rate-MFR), mechanical (tensile strength, bending strength, impact strength), crystallographic (X-ray Diffraction-XRD), thermal and thermo-mechanical (differential scanning calorimetry–DSC, dynamic mechanical thermal analysis–DMTA) analyses, as well as a study of hydrophobic–hydrophilic properties of the material surface (wetting angle) and imaging of the surface of the composites and the fractured specimens. The tests showed that the additive 3-aminopropyltriethoxysilane (APTES) acted as an agent that improved the elasticity of composites and the melt flow rate. In addition, the produced composites showed a hydrophilic surface profile compared to pure polylactide and polyamide 11.
30
Rasselet, Damien, Anne-Sophie Caro-Bretelle, Aurélie Taguet e José-Marie Lopez-Cuesta. "Reactive Compatibilization of PLA/PA11 Blends and Their Application in Additive Manufacturing". Materials 12, n. 3 (5 febbraio 2019): 485. http://dx.doi.org/10.3390/ma12030485.
Testo completoAbstract (sommario):
The aim of this work was to study the properties of polylatic acid/polyamide 11 (PLA/PA11) blends compatibilized with a multifunctionalized epoxide, Joncryl®, and to evaluate the performance of such blends processed by Fused Deposition Modeling (FDM) 3D printing, compared to those produced by injection molding method. Blends containing different Joncryl contents from 0.5 to 3 wt% were prepared by twin-screw extrusion. Evaluation of thermal, rheological and mechanical properties of such blends proved that Joncryl acted as a compatibilizer. Results showed that Joncryl effects on blends properties were improved with increasing its content. A significant reduction of PA11 dispersed phases diameter and an improvement of tensile properties with a ductile behavior were achieved for the highest Joncryl contents. A significant elongation of PA11 dispersed phases was observed into FDM filaments and dog bone shaped specimens produced thereafter. Despite this peculiar morphology, FDM printed samples exhibited only enhanced stiffness but poor reinforcement and elongation at break in comparison with injected ones.
31
Zheng, Xiaofang, Yongzhong Huang, Shaodi Zheng, Zhengying Liu e Mingbo Yang. "Improved dielectric properties of polymer-based composites with carboxylic functionalized multiwalled carbon nanotubes". Journal of Thermoplastic Composite Materials 32, n. 4 (12 marzo 2018): 473–86. http://dx.doi.org/10.1177/0892705718762614.
Testo completoAbstract (sommario):
The biggest issues in the preparation of carbon nanotube (CNT)-reinforced composites reside in efficient dispersion of CNT into polymer matrix. In our work, a simple acid treatment method was adopted to obtain carboxylic functionalized multiwalled nanotubes (MWNTs), thus improving the dispersion of CNT and interaction between particles and polymer matrix. X-ray photoelectron spectroscopy and Fourier transform infrared showed that the carboxylic groups were introduced onto the surface of MWNTs. The Raman spectroscopy showed that the amorphous carbon materials and impurities decreased after acid treatment. The electrical and dielectric properties of the Polyamide-11 (PA11)-based composites filled with pristine multiwalled nanotubes (p-MWNTs) and carboxylic functionalized multiwalled nanotubes (c-MWNTs) were investigated. The biggest dielectric constant of PA11/c-MWNTs composites, which was about twice as high as that of PA11/p-MWNTs composites at room temperature and 103 Hz (345–610), was obtained, accompanied by a lower dielectric loss. The formation of abundant microcapacitors and improved interfacial polarization effect by improving the dispersion of MWNTs in the composites via carboxylic functionalization was the main reason for the excellent dielectric properties of PA11/c-MWNTs composites.
32
Sillani, Francesco, Ramis Schiegg, Manfred Schmid, Eric MacDonald e Konrad Wegener. "Powder Surface Roughness as Proxy for Bed Density in Powder Bed Fusion of Polymers". Polymers 14, n. 1 (26 dicembre 2021): 81. http://dx.doi.org/10.3390/polym14010081.
Testo completoAbstract (sommario):
Powder bed fusion of polymers is becoming increasingly adopted by a variety of industries to tailor the strength, weight and functionality of end-use products. To meet the high standards of the modern manufacturing industry, parts built with powder bed fusion require consistent properties and to be free of defects, which is intrinsically connected to the quality of the powder bed prior to melting. The hypothesis of this work is that the roughness of the top surface of an unmelted powder bed can serve as a proxy for the powder bed density, which is known to correlate with final part density. In this study, a laser line scan profilometer is integrated onto the recoater arm of a custom powder test bench, which is able to automatically create layers of powder. A diverse group of polymers was investigated including polyamide 12 (PA12), polyamide 11 (PA11), polypropylene (PP), and a thermoplastic elastomer (TPU) under different recoating speed in order to increase the variance of the dataset. Data analytics were employed to compare roughness to measured powder bed density and a statically significant correlation was established between them.
33
Morici, Elisabetta, Giulia Infurna e Nadka Tz Dintcheva. "Ecofriendly Biopolymer-Based Nanocomposite Films with Improved Photo-Oxidative Resistance". Materials 15, n. 16 (21 agosto 2022): 5778. http://dx.doi.org/10.3390/ma15165778.
Testo completoAbstract (sommario):
The interest towards high performance biopolymer-based materials increases continuously and, to guarantee appropriately industrial applications, the photo-oxidative resistance and stability of these materials must be adequately addressed. In this study, innovative biopolymer-based nanocomposites, i.e., Polyamide 11 (PA11), containing ad-hoc modified Layered Double Hydroxides (LDH), were successfully formulated and characterized. Particularly, LDH were considered carriers for hindered amine light stabilizing molecules, so two different hindered amine moieties (HALS1 and HALS2) were anchored on LDH layered internal structures and/or outer surfaces. The presence of HALS1 and HALS2 in LDH were confirmed by X-ray diffraction, spectroscopy, and thermogravimetric analysis. Then, the novel LDH-HALS nanofillers (here named LDH-HALS1 and LDH-HALS2) were introduced into a PA11 matrix by melt mixing at 5 wt.%; the produced nanocomposites were characterized by differential scanning calorimetry, rheological, and morphological analysis. All obtained results suggest that the LDH-HALS1/HALS2 nanofillers were very well dispersed into the PA11 matrix. Additionally, the photo-oxidative resistance of the PA11-based nanocomposite films was evaluated by subjecting thin films to UVB exposure and the degradation process was monitored by spectroscopic analysis over time. The photo-oxidative resistance of the PA11/LDH-HALS1/HALS2 was compared to that of PA11-based nanocomposites containing unmodified LDH and the commercial hindered amine UV-stabilizer (Cyasorb® UV-3853). It was established that by anchoring the hindered amine moieties to the LDH, the PA11 nanocomposites were successfully protected against UVB exposure. This was because the hindered amine light stabilizing molecules were available to act at the critical zone where the degradation phenomena occur, which is at the interface between the matrix and the inorganic particles.
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Fernández-Álvarez, Maria, Francisco Velasco, Asuncion Bautista, Flavia Cristina M. Lobo, Emanuel M. Fernandes e Rui L. Reis. "Manufacturing and Characterization of Coatings from Polyamide Powders Functionalized with Nanosilica". Polymers 12, n. 10 (8 ottobre 2020): 2298. http://dx.doi.org/10.3390/polym12102298.
Testo completoAbstract (sommario):
Polyamide coatings are thermoplastics with great advantages such as a good corrosion protection of the base metal and wear resistance. Their application as powder coatings is an environmentally friendly option that is currently attracting growing interest. However, during their life service, they can sometimes be exposed to conditions that they are unable to stand. In this work, a polyamide 11 (PA11) powder was reinforced with different percentages of silica nanoparticles (1–3 wt. %). Powder mixtures were prepared through extrusion followed by compression molding processes to manufacture coatings. For the coatings under study, the effect of 500 h xenon exposure was studied in order to know their ultraviolet (UV) resistance. Attenuated total reflection-Fourier transform infrared spectroscopy (FTIR-ATR) and differential scanning calorimetry (DSC) tests were performed to study changes in polymer structure and if they are affected by nanoparticles. The effect of nanoadditions and xenon exposure on hardness and stiffness were also evaluated. Furthermore, reciprocal wear tests were performed before and after irradiation, and the wear tracks were analyzed using optoelectronic microscopy and scanning electron microscopy (SEM). Finally, the aesthetic properties were measured. The results reveal improvements in mechanical and wear properties when 1% nanosilica is added to the PA11, which then become more relevant after xenon radiation exposure.
35
Dong, Chufeng, Yitao Liu, Jiepu Li, Guangfu Bin, Chilou Zhou, Wulin Han e Xiang Li. "Hydrogen Permeability of Polyamide 6 Used as Liner Material for Type IV On-Board Hydrogen Storage Cylinders". Polymers 15, n. 18 (10 settembre 2023): 3715. http://dx.doi.org/10.3390/polym15183715.
Testo completoAbstract (sommario):
As a commonly used liner material for fully reinforced, carbon-fiber-composite hydrogen storage cylinders, polyamide 6 (PA6) needs to meet the required hydrogen permeation index during use; otherwise, it may adversely affect the safe use of hydrogen storage cylinders. The hydrogen permeability of PA6 under different temperatures and pressures was tested, and the variations in its hydrogen permeability were investigated. Additionally, the hydrogen permeability of PA6, polyamide 11 (PA11), and high-density polyethylene (HDPE) at a temperature of 288 K and a pressure of 70 MPa was tested, and the differences in hydrogen permeability among these commonly used liner materials for type IV on-board hydrogen storage cylinders were studied. The results reported herein indicate that both the hydrogen permeability and diffusion coefficient of PA6 increase with rising test temperature but decrease with increasing pressure. The solubility coefficient of PA6 shows no significant change with varying test temperatures and pressures. At a test temperature of 288 K and a pressure of 70 MPa, among the three materials, PA6 has slightly stronger hydrogen permeation resistance than PA11, while HDPE has the least resistance. These research findings can serve as valuable reference data for evaluating the hydrogen permeability of liner materials.
36
Ussia, Martina, Giusy Curcuruto, Daniela Zampino, Nadka Tzankova Dintcheva, Giovanni Filippone, Raniero Mendichi e Sabrina Carola Carroccio. "Role of Organo-Modifier and Metal Impurities of Commercial Nanoclays in the Photo- and Thermo-Oxidation of Polyamide 11 Nanocomposites". Polymers 12, n. 5 (2 maggio 2020): 1034. http://dx.doi.org/10.3390/polym12051034.
Testo completoAbstract (sommario):
The photo-oxidative degradation processes of bio-based PA11 nanocomposites containing montmorillonite (MMT) and the organo-modified Cloisite®30B were investigated to discriminate the influence of organo-modified components on the polymer durability. Indeed, despite the extensive studies reported, there are still ambiguous points to be clarified from the chemical point of view. To this aim, UV-aged materials were analyzed by Size Exclusion Chromatography (SEC), Inductively Coupled Plasma–Mass Spectrometry (ICP-MS) and Matrix-Assisted Laser Desorption Ionization Time-of-Flight Mass Spectrometry (MALDI-TOF MS). This enabled determining changes in both chemical structure and Molar Masses (MMs) induced by light, heat and oxygen exposure. The addition of organo-modified nanoclays strongly affected the PA11 light durability, triggering the macromolecular chains scission due to the typical αH, Norrish I and II mechanisms. However, the main contribution in boosting the photo-oxidative degradation is induced by iron impurities contained into the clays. Conversely, thermo-oxidation process performed at 215 °C was unambiguously affected by the presence of the organo-modifiers, whose presence determined an enhancement of crosslinking reactions.
37
Morici, Elisabetta, Giuseppe Pecoraro, Sabrina Carola Carroccio, Elena Bruno, Paola Scarfato, Giovanni Filippone e Nadka Tz Dintcheva. "Understanding the Effects of Adding Metal Oxides to Polylactic Acid and Polylactic Acid Blends on Mechanical and Rheological Behaviour, Wettability, and Photo-Oxidation Resistance". Polymers 16, n. 7 (27 marzo 2024): 922. http://dx.doi.org/10.3390/polym16070922.
Testo completoAbstract (sommario):
Biopolymers are of growing interest, but to improve some of their poor properties and performance, the formulation of bio-based blends and/or adding of nanoparticles is required. For this purpose, in this work, two different metal oxides, namely zinc oxide (ZnO) and titanium dioxide (TiO2), at different concentrations (0.5, 1, and 2%wt.) were added in polylactic acid (PLA) and polylactic acid/polyamide 11 (PLA/PA11) blends to establish their effects on solid-state properties, morphology, melt behaviour, and photo-oxidation resistance. It seems that the addition of ZnO in PLA leads to a significant reduction in its rigidity, probably due to an inefficient dispersion in the melt state, while the addition of TiO2 does not penalize PLA rigidity. Interestingly, the addition of both ZnO and TiO2 in the PLA/PA11 blend has a positive effect on the rigidity because of blend morphology refinement and leads to a slight increase in film hydrophobicity. The photo-oxidation resistance of the neat PLA and PLA/PA11 blend is significantly reduced due to the presence of both metal oxides, and this must be considered when designing potential applications. The last results suggest that both metal oxides could be considered photo-sensitive degradant agents for biopolymer and biopolymer blends.
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Mandlekar, Neeraj, Aurélie Cayla, François Rault, Stéphane Giraud, Fabien Salaün e Jinping Guan. "Development of Novel Polyamide 11 Multifilaments and Fabric Structures Based on Industrial Lignin and Zinc Phosphinate as Flame Retardants". Molecules 25, n. 21 (27 ottobre 2020): 4963. http://dx.doi.org/10.3390/molecules25214963.
Testo completoAbstract (sommario):
Biobased lignin represents one of the possible materials for next-generation flame retardant additives due to its sustainability, environmental benefits and comparable efficiency to other flame retardant (FR) additives. In this context, this study presents the development of FR polyamide 11 (PA11) multifilament yarns and fabric structures containing different industrial lignins (i.e., lignosulfonate lignin (LL), and Kraft lignin (KL)) and zinc phosphinate (ZnP). The combination of ZnP and lignin (KL or LL) at different weight ratios were used to prepare flame retarded PA11 blends by melt mixing using a twin-screw extruder. These blends were transformed into continuous multifilament yarns by the melt-spinning process even at a high concentration of additives as 20 wt%. The mechanical test results showed that the combination of KL and ZnP achieved higher strength and filaments showed regularity in structure as compared to the LL and ZnP filaments. Thermogravimetric (TG) analysis showed the incorporation of lignin induces the initial decomposition (T5%) at a lower temperature; at the same time, maximum decomposition (Tmax) shifts to a higher temperature region and a higher amount of char residue is reported at the end of the test. Further, the TGA-FTIR study revealed that the ternary blends (i.e., the combination of LL or KL, ZnP, and PA11) released mainly the phosphinate compound, hydrocarbon species, and a small amount of phosphinic acid during the initial decomposition stage (T5%), while hydrocarbons, carbonyls, and phenolic compounds along with CO2 are released during main decomposition stage (Tmax). The analysis of decomposition products suggests the stronger bonds formation in the condensed phase and the obtainment of a stable char layer. Cone calorimetry exploited to study the fire behavior on sheet samples (polymer bulk) showed an improvement in flame retardant properties with increasing lignin content in blends and most enhanced results were found when 10 wt% of LL and ZnP were combined such as a reduction in heat release rate (HRR) up to 64% and total heat release (THR) up to 22%. Besides, tests carried out on knitted fabric structure showed less influence on HRR and THR but the noticeable effect on postponing the time to ignition (TTI) and reduction in the maximum average rate of heat emission (MARHE) value during combustion.
39
Khan, Z. I., U. Habib, Z. B. Mohamad e A. M. Raji. "Enhanced mechanical properties of a novel compatibilized recycled polyethylene terephthalate/polyamide 11 (rPET/PA11) blends". Express Polymer Letters 15, n. 12 (2021): 1206–15. http://dx.doi.org/10.3144/expresspolymlett.2021.96.
Testo completo
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Sergi, Claudia, Libera Vitiello, Patrick Dang, Pietro Russo, Jacopo Tirillò e Fabrizio Sarasini. "Low Molecular Weight Bio-Polyamide 11 Composites Reinforced with Flax and Intraply Flax/Basalt Hybrid Fabrics for Eco-Friendlier Transportation Components". Polymers 14, n. 22 (21 novembre 2022): 5053. http://dx.doi.org/10.3390/polym14225053.
Testo completoAbstract (sommario):
The transportation sector is striving to meet the more severe European legislation which encourages all industrial fields to embrace more eco-friendly policies by exploiting constituents from renewable resources. In this framework, the present work assessed the potential of a bio-based, low molecular weight PA11 matrix reinforced with flax and intraply flax/basalt hybrid fabrics. To this aim, both quasi-static and impact performance were addressed through three-point bending and low-velocity impact tests, respectively. For hybrid composites, the effect of stacking sequence, i.e., [0/0] and [0/90], and fiber orientation were considered, while the effect of temperature, i.e., −40 °C, room temperature and +45 °C, was investigated for laminates’ impact response. The mechanical experimental campaign was supported by thermal and morphological analyses. The results disclosed an improved processability of the low molecular weight PA11, which ensured a manufacturing temperature of 200 °C, which is fundamental to minimize flax fibers’ thermal degradation. Both quasi-static and impact properties demonstrated that hybridization is a good solution for obtaining good mechanical properties while preserving laminates’ lightness and biodegradability. The [0/90] configuration proved to be the best solution, providing satisfying flexural performance, with an increase between 62% and 83% in stiffness and between 19.6% and 37.6% in strength compared to flax-based laminates, and the best impact performance, with a reduction in permanent indentation and back crack extent.
41
Russo, Pietro, Giorgio Simeoli, Libera Vitiello e Giovanni Filippone. "Bio-Polyamide 11 Hybrid Composites Reinforced with Basalt/Flax Interwoven Fibers: A Tough Green Composite for Semi-Structural Applications". Fibers 7, n. 5 (6 maggio 2019): 41. http://dx.doi.org/10.3390/fib7050041.
Testo completoAbstract (sommario):
Intraply hybrid green composites were prepared by film stacking and hot-pressing of bio-based polyamide 11 (PA11) sheets and commercial hybrid fabrics made by interweaving flax and basalt fibers (2/2 twill structure). Two matrices were considered, one of them containing a plasticizing agent. After preliminary thermal and rheological characterizations of the neat matrices, the laminates were studied in terms of flexural properties at low and high deformation rates, and the results were interpreted in the light of morphological analyses (scanning electron and optical microscopy). Despite the poor interfacial adhesion detected for all investigated composite samples, the latter exhibited a good combination of flexural strength, modulus, and impact resistance. Such well-balanced mechanical properties make the studied samples potential candidates for semi-structural applications, e.g., in the transportation sector.
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Wu, Hao, Rogelio Ortiz e Joseph H. Koo. "Rubber toughened flame retardant (FR) polyamide 11 nanocomposites Part 1: the effect of SEBS-g-MA elastomer and nanoclay". Flame Retardancy and Thermal Stability of Materials 1, n. 1 (25 luglio 2018): 25–38. http://dx.doi.org/10.1515/flret-2018-0003.
Testo completoAbstract (sommario):
Abstract The objective of this research is to develop a multifunctional polyamide 11 (PA11) with balanced thermal, mechanical, and flammability properties for SLS. In this study, two sets of formulations were prepared by twin-screw extrusion: the first set examined the effect of maleic anhydride modified elastomers on flammability and the mechanical properties, whereas the second set added various amount of nanoclay and discussed thermal stability, flammability and mechanical properties. The addition of 20 wt.% elastomer brought the elongation at break up to 40%. Reduction in heat release capacity as high as 49% was achieved, all nanocomposite samples passed UL 94 V-1 rating. The addition of nanoclay improved the tensile modulus by up to 78%, the elongation at break for all the formulations were negatively affected by the addition of flame retardant and nanoclay.
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Yu, Muhuo, Liangliang Qi, Lele Cheng, Wei Min, Zhonghao Mei, Ruize Gao e Zeyu Sun. "The Effect of Cooling Rates on Thermal, Crystallization, Mechanical and Barrier Properties of Rotational Molding Polyamide 11 as the Liner Material for High-Capacity High-Pressure Vessels". Molecules 28, n. 6 (7 marzo 2023): 2425. http://dx.doi.org/10.3390/molecules28062425.
Testo completoAbstract (sommario):
The rapid development of hydrogen fuel cells has been paralleled by increased demand for lightweight type IV hydrogen storage vessels with high hydrogen storage density, which raises the performance requirements of internal plastic liners. An appropriate manufacturing process is important to improve the quality of polymer liners. In this paper, DSC, WAXD, a universal testing machine and a differential pressure gas permeameter were used to investigate the effect of the cooling rate of the rotational molding polyamide 11 on the thermal, crystallization, mechanical and barrier properties. The cooling rate is formulated according to the cooling rate that can be achieved in actual production. The results suggest that two PA11 liner materials initially exhibited two-dimensional (circular) growth under non-isothermal crystallization conditions and shifted to one-dimensional space growth due to spherulite collision and crowding during the secondary crystallization stage. The slower the cooling process, the greater the crystallinity of the specimen. The increase in crystallinity significantly improved the barrier properties of the two PA11 liner materials, and the gas permeability coefficient was 2-3-fold higher than at low crystallinity. Moreover, the tensile strength, the tensile modulus, the flexural strength, and the flexural modulus increased, and the elongation at break decreased as the crystallinity increased.
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Baron, Marc, Mamy-Daniel Rakotorinina, Mohamed Ihab El Assil, Yohann Guillaneuf, Didier Gigmes, Didier Siri, Anouk Gaudel-Siri et al. "Melt radical grafting of diethylmaleate and maleic anhydride onto oligoamide-11 (OA11) and polyamide-11 (PA11) in presence of acyloxyimide derivatives: Toward the compatibilization of PA11/EVOH blends". Materials Today Communications 19 (giugno 2019): 271–76. http://dx.doi.org/10.1016/j.mtcomm.2019.02.003.
Testo completo
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Sharma, Mohit, Sheng Qin Wang e Yew Wei Leong. "Wear Resistance Properties of Nylon-SiC Hybrids Composites". Advanced Materials Research 1110 (giugno 2015): 88–91. http://dx.doi.org/10.4028/www.scientific.net/amr.1110.88.
Testo completoAbstract (sommario):
For marine and offshore applications, the materials specific strength is vital parameter in improvisation of flexible riser parts for deep sea exploration. Nylon is prospective materials for riser application due to its good degree of flexibility and excellent barrier properties, but with the disadvantage of limited working temperature and low wear resistance. The incorporation of fibrous and/or particulate reinforcement is significant to investigate polymers utility for extreme environment condition, such as; elevated temperature and high applied load. Previously it has been reported on the utilization of fibrous(carbon/glass/Aramid) and particulate fillers to improve thermoplastics properties but at the cost of detrimental flexibility. Ceramics in the form of whiskers (high modulus and rigid unbreakable rods) are the potential fillers/reinforcements for polymer due to their excellent properties, such as; high toughness, wear resistance, remarkable thermal and dimensional stability. Present work is aimed to utilize the silicon carbide (SiC) whiskers as reinforcement for Polyamide 11 (PA11) to improve its mechanical, thermal and wear resistance properties. The SiC whisker filled polymer has shown significant improvement in properties of PA11 to employ it as potential materials for flexible riser applications.
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Dzienniak, Damian. "The Influence of the Material Type and the Placement in the Print Chamber on the Roughness of MJF-Printed 3D Objects". Machines 10, n. 1 (9 gennaio 2022): 49. http://dx.doi.org/10.3390/machines10010049.
Testo completoAbstract (sommario):
This paper describes a surface-roughness study performed on samples manufactured additively using the Multi Jet Fusion (MJF) technology. The samples were divided into three groups based on the material used in the process: polypropylene (PP), thermoplastic polyurethane (TPU), and polyamide 11 (PA11). Subsequently, they were tested by means of a roughness-measuring system, which made it possible to determine the typical surface roughness parameters (Ra, Rq, Rz). The tests were designed to examine whether the placement and orientation of 3D objects while printing, in connection with the material used, can significantly influence the surface quality of MJF-printed objects. The results show that the TPU samples have a surface roughness much higher than the PP and PA11 ones, which exhibit roughness levels very similar to each other. It can also be concluded that surfaces printed vertically (along the Z-axis) tend to be less smooth—similarly to the surfaces of objects made of TPU located in the central zones of the print chamber during printing. This information may be of value in cases where low surface roughness is preferred (e.g., manufacturing patient-specific orthoses), although this particular study does not focus on one specific application.
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Tonello, Riccardo, Knut Conradsen, David Bue Pedersen e Jeppe Revall Frisvad. "Surface Roughness and Grain Size Variation When 3D Printing Polyamide 11 Parts Using Selective Laser Sintering". Polymers 15, n. 13 (6 luglio 2023): 2967. http://dx.doi.org/10.3390/polym15132967.
Testo completoAbstract (sommario):
Selective laser sintering (SLS) is a well-established technology that is used for additive manufacturing. Significant efforts have been made to improve SLS by optimizing the powder deposition, laser beam parameters, and temperature settings. The purpose is to ensure homogeneous sintering and prevent geometric and appearance inaccuracies in the manufactured objects. We evaluated the differences in the surface roughness and grain size of curved objects manufactured by using upcoming SLS technology that features two CO laser sources. Our analysis was carried out on polyamide 11 (PA11), which is a sustainable biobased polymer that has been gaining popularity due to its high-performance properties: its low melting point, high viscosity, and excellent mechanical properties. By using a Taguchi experimental design and analysis of variance (ANOVA), we examined the influence on the surface roughness and grain size of the build setup, the presence of thin walls, and the position of the sample on the powder bed. We found significant differences in some surface roughness and grain size measurements when these parameters were changed.
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Vande Ryse, Ruben, Michiel Van Osta, Mounia Gruyaert, Maarten Oosterlinck, Ádám Kalácska, Mariya Edeleva, Frederik Pille, Dagmar R. D’hooge, Ludwig Cardon e Patrick De Baets. "Playing with Low Amounts of Expanded Graphite for Melt-Processed Polyamide and Copolyester Nanocomposites to Achieve Control of Mechanical, Tribological, Thermal and Dielectric Properties". Nanomaterials 14, n. 7 (29 marzo 2024): 606. http://dx.doi.org/10.3390/nano14070606.
Testo completoAbstract (sommario):
Polyamide 11 (PA11) and copolyester (TPC-E) were compounded through melt extrusion with low levels (below 10%) of expanded graphite (EG), aiming at the manufacturing of a thermally and electrically conductive composite resistant to friction and with acceptable mechanical properties. Thermal characterisation showed that the EG presence had no influence on the onset degradation temperature or melting temperature. While the specific density of the produced composite materials increased linearly with increasing levels of EG, the tensile modulus and flexural modulus showed a significant increase already at the introduction of 1 wt% EG. However, the elongation at break decreased significantly for higher loadings, which is typical for composite materials. We observed the increase in the dielectric and thermal conductivity, and the dissipated power displayed a much larger increase where high frequencies (e.g., 10 GHz) were taken into account. The tribological results showed significant changes at 4 wt% for the PA11 composite and 6 wt% for the TPC-E composite. Morphological analysis of the wear surfaces indicated that the main wear mechanism changed from abrasive wear to adhesive wear, which contributes to the enhanced wear resistance of the developed materials. Overall, we manufactured new composite materials with enhanced dielectric properties and superior wear resistance while maintaining good processability, specifically upon using 4–6 wt% of EG.
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Barczewski, Mateusz, Aleksander Hejna, Jacek Andrzejewski, Joanna Aniśko, Adam Piasecki, Adrian Mróz, Zaida Ortega, Daria Rutkowska e Kamila Sałasińska. "The Recyclability of Fire-Retarded Biobased Polyamide 11 (PA11) Composites Reinforced with Basalt Fibers (BFs): The Influence of Reprocessing on Structure, Properties, and Fire Behavior". Molecules 29, n. 13 (8 luglio 2024): 3233. http://dx.doi.org/10.3390/molecules29133233.
Testo completoAbstract (sommario):
The growing requirements regarding the safety of using polymers and their composites are related to the emergence of more effective, sustainable, and hazardous-limited fire retardants (FRs). Significant amounts of FRs are usually required to effectively affect a polymer’s burning behavior, while the knowledge of their recycling potential is still insufficient. At the same time, concerns are related not only to the reduced effectiveness of flame retardancy but also, above all, to the potential deterioration of mechanical properties caused by the degradation of temperature-affected additives under processing conditions. This study describes the impact of the four-time reprocessing of bio-based polyamide 11 (PA11) modified with an intumescent flame-retardant (IFR) system composed of ammonium polyphosphate (APP), melamine cyanurate (MC), and pentaerythritol (PER) and its composites containing additional short basalt fibers (BFs). Composites manufactured via twin-screw extrusion were subjected to four reprocessing cycles using injection molding. A comprehensive analysis of their structural, mechanical, and fire behavior changes in each cycle was conducted. The obtained results confirmed the safety of using the proposed fire-retarded polyamide and its composites while reprocessing under the recommended process parameters without the risk of significant changes in the structure. The partial increase in flammability of reprocessed PA-based materials caused mainly by polymer degradation has been described.
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Wu, Hao, Rogelio Ortiz e Joseph H. Koo. "Rubber toughened flame retardant (FR) polyamide 11 nanocomposites Part 2: synergy between multi-walled carbon nanotube (MWNT) and MMT nanoclay". Flame Retardancy and Thermal Stability of Materials 2, n. 1 (1 gennaio 2019): 19–29. http://dx.doi.org/10.1515/flret-2019-0003.
Testo completoAbstract (sommario):
AbstractIn the previous study, flame retardant (FR) polyamide 11 (PA11) nanocomposites formulations designed for selective laser sintering (SLS)were prepared and characterized. The SEBS-g-MA elastomer successfully improved the material’s ductility. Although the nonhalogenated FR additives and montmorillonite (MMT) nanoclay successfully decreased the heat release capacity (HRC) and peak heat release rate (pHRR) as characterized by microscale combustion calorimeter (MCC). None of the rubber toughened formulations achieved UL 94 V0 rating, which is a bench mark for many FR polymer applications. As part two of this study, we explored the synergism between two nanoparticles, nanoclay and multi-walled carbon nanotubes (MWNTs), to see whether better FR properties can be achieved. TEM micrographs indicate that both nanoclay and MWNTs achieved high level of dispersion. Flammability results showed that all formulations achieved UL 94 V0 rating, which is a significant improvement from the previous formulations without MWNTs. Char morphology characterization indicated that a solid carbonaceous char layer was reinforced by nanoclay and MWNTs.