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1
Binhasan, Mashael, Khaled M. Al-Habeeb, Abdullah S. Almuqbil, Tarik A. Alhaidary, Yasser F. Alfawaz, Imran Farooq, Fahim Vohra e Tariq Abduljabbar. "Assessment of the Physical Properties of an Experimental Adhesive Dentin Bonding Agent with Carbon Nanoparticles". Crystals 12, n. 10 (12 ottobre 2022): 1441. http://dx.doi.org/10.3390/cryst12101441.
Testo completoAbstract (sommario):
The present study was aimed at reinforcing the control adhesive (CA) with two concentrations (2.5% & 5%) of carbon nanoparticles (CNPs) and evaluating the impact of these additions on the adhesive’s properties. Scanning electron microscopy (SEM) and energy dispersive X-Ray (EDX) spectroscopy were utilized to examine the morphological characteristics and elemental mapping of the filler CNPs. To investigate the adhesive’s properties, rheological assessment, shear bond strength (SBS) testing, analysis of the adhesive–dentin interface, degree of conversion (DC) analysis, and failure mode investigations were carried out. The SEM micrographs of CNPs verified roughly hexagonal-shaped cylindrical particles. The EDX plotting established the presence of carbon (C), oxygen (O), and zirconia (Zr). Upon rheological assessment, a gradual reduction in the viscosity was observed for all the adhesives at higher angular frequencies. The SBS testing revealed the highest values for 2.5% CNP adhesive group (25.15 ± 3.08 MPa) followed by 5% CNP adhesive group (24.25 ± 3.05 MPa). Adhesive type interfacial failures were most commonly found in this study. The 5% CNP containing adhesive revealed thicker resin tags and a uniform hybrid layer without any gaps (compared with 2.5% CNP adhesive and CA). The reinforcement of the CA with 2.5% and 5% CNPs augmented the adhesive’s bond strength. Nevertheless, a diminished viscosity (at higher angular frequencies) and reduced DC were observed for the two CNP reinforced adhesives. CNP reinforced dentin adhesives are effective in enhancing the adhesive bond integrity of resin to dentin.
2
Tsujimoto, Akimasa, Nicholas G. Fischer, Wayne W. Barkmeier e Mark A. Latta. "Bond Durability of Two-Step HEMA-Free Universal Adhesive". Journal of Functional Biomaterials 13, n. 3 (29 agosto 2022): 134. http://dx.doi.org/10.3390/jfb13030134.
Testo completoAbstract (sommario):
The purpose of this study is to compare bond durability, in terms of fatigue bond strength, of a two-step HEMA-free universal adhesive and representative adhesives in each systematic category. The adhesives used in this study were OptiBond FL, Prime&Bond NT, Clearfil SE Bond 2, G2-Bond Universal, and Scotchbond Universal Plus Adhesive. Fatigue bond strength testing and scanning electron microscopy analysis of adhesively bonded enamel and dentin interfaces were performed. For the adhesives in etch-and-rinse mode, the enamel fatigue bond strength of the G2-Bond Universal adhesive was significantly higher than those of other adhesives, and the dentin fatigue bond strength of Prime&Bond NT was significantly lower than the others. For adhesives in self-etch mode, the enamel fatigue bond strengths of Clearfil SE Bond 2 and G2-Bond Universal were significantly higher than that of the Scotchbond Universal Plus Adhesive, and the dentin fatigue bond strength of G2-Bond Universal was significantly higher than Clearfil SE Bond 2 and the Scotchbond Universal Plus Adhesive. The two-step HEMA-free universal adhesive showed higher enamel and higher or equal dentin fatigue bond strength than other selected representative adhesive systems in etch-and-rinse mode and higher or equal enamel and higher dentin fatigue bond strength than adhesive systems in self-etch mode.
3
Yoon, S. H., B. J. Kim, K. H. Lee e D. G. Lee. "The Effect of Quartz Nano-Particles on the Damage Monitoring of Adhesive Joint at Cryogenic Temperature". Advanced Materials Research 93-94 (gennaio 2010): 562–65. http://dx.doi.org/10.4028/www.scientific.net/amr.93-94.562.
Testo completoAbstract (sommario):
Recently, a piezoelectric method using piezoelectric characteristics of epoxy adhesives has been successfully developed for the adhesive joints, which can monitor continuously the damage of adhesively bonded structures without producing any defect induced by inserting a sensor. However, due to low piezoelectric properties of epoxy adhesives, the detection of micro crack was impossible. At the cryogenic temperature, the detection of micro crack is important to estimate the fatigue life because the polymeric adhesives become very brittle. Therefore, in this work, the epoxy adhesive was modified by quartz nano-particles which have much higher piezoelectric properties than the epoxy adhesives. To investigate the effects of quartz nano-particles, the static and dynamic tests of the tubular adhesive joints were performed to compare the joint strength and sensitivity of damage monitoring performance. From the experiment result, it was found that the quartz nano-particles not only improved the joint strength but also increased the sensitivity of damage monitoring performance at cryogenic temperature.
4
Zhang, Jun, e Hong Jia. "Performance of Cohesive Zone Models for Brittle and Ductile Adhesives". Advanced Materials Research 941-944 (giugno 2014): 2089–92. http://dx.doi.org/10.4028/www.scientific.net/amr.941-944.2089.
Testo completoAbstract (sommario):
Damage modeling approach is increasingly used to simulate fracture and debonding processes in adhesively bonded joint. In order to understand the relation between the delamination behavior of different types of adhesives and the type of cohesive zone models (CZMs), the pure tension and pure shear experiments were conducted used two distinct adhesives, an epoxy-based adhesive in a brittle manner and VHBTM tape adhesive in a ductile manner. The traction-separation relations of the two adhesives were extracted from the tension and shear experimental results. Three types of cohesive zone models (CZMs) are adopted, including the exponential, bilinear, and trapezoidal models. VUMAT subroutine of CZMs as the adhesive layer is used to simulate the specimen tension and shear debonding procedures. The results demonstrate that (i) the bilinear CZM more suitably describes the brittle adhesive and the exponential CZM suitably describes the ductile adhesive to simulate the tension and shear failure. (ii) cohesive strength and work of separation are the significant affections on the simulation results. and (iii) the shape of CZM is a significant affections on the simulation the pure tension and shear debonding procedure.
5
Kongkon, Paweena, Wiwat Pichayakorn e Sasiwimol Sanohkan. "Novel Deproteinized Natural Rubber Latex Adhesive Used in Extraoral Maxillofacial Prostheses". Sains Malaysiana 50, n. 11 (30 novembre 2021): 3383–94. http://dx.doi.org/10.17576/jsm-2021-5011-22.
Testo completoAbstract (sommario):
This study aimed to develop an adhesive for silicone maxillofacial prostheses and compared the properties with the Daro adhesive hydrobond (Factor II, Inc, Lakeside, AZ, USA). Two adhesives were developed from non-vulcanized natural rubber-based adhesives (Adhesive A) and deproteinized natural rubber latex (DNRL) products (Adhesive B) and stored at 4 °C. The Control group was the commercial Daro adhesive hydrobond (Factor II, Inc, Lakeside, AZ, USA). The physical properties (appearance, viscosity, spreadability, color, and pH) of the adhesives were measured and every week for 12 weeks after storing at 4 °C. The adhesives were characterized under scanning electron microscopy. Mechanical testing done were peel bond strength and biocompatibility testing was done using MTT assay. Physical, surface, and mechanical properties were compared with the commercial adhesive. Data analysis was done using SPSS version 24. Both adhesives were physically and chemically stable at temperature 4 °C and had suitable peel bond strength adhesives as the commercial adhesive. Hence, the adhesives can be used to adhere to the maxillofacial silicone prostheses.
6
Geiss, Paul Ludwig, e Melanie Schumann. "Polymer Interphases in Adhesively Bonded Joints – Origin, Properties and Methods for Characterization". Materials Science Forum 941 (dicembre 2018): 2249–54. http://dx.doi.org/10.4028/www.scientific.net/msf.941.2249.
Testo completoAbstract (sommario):
Chemically curing adhesives are formulations requiring reactions to convert from liquid to solid. Once cured, these adhesives carry the potential to create strong load bearing joints, resisting even severe detrimental service conditions. In adhesively bonded joints with chemically curing adhesives the term "interphase" relates to the adhesive volume adjacent to the surface of the adherent (interface), which generally will exhibit properties different from those of the adhesive bulk polymer. The properties of these interphases play an important role concerning the performance and durability of structural adhesive joints. Therefore localized strain analysis in the cross-section of shear-loaded adhesive joints was performed by combining a high-precision mechanical testing device with digital microscopy and by developing a method for preparing, marking, and digitally tracking the local deformations in micro shear specimen. Non-uniform shear profiles developing in the cross-section of the adhesive joints after exceeding the yield point serve as a sensitive indication for mechanical surface-affected interphase properties and it could be observed, that deranged crosslinking promotes strain softening of the polymer in the interphase. Infrared analysis of the cross-sectional interphase region in adhesively bonded joints was performed with a Bruker Tensor II Fourier Transform Infrared (FTIR) spectrometer equipped with a Hyperion 3000 microscope with a 20x ATR germanium crystal objective and a MCT-Focal-Plane-Array-Detector (FPA), allowing to conduct high resolution chemical imaging and localized chemical analysis.
7
Gültekin, Kürşat, e Mustafa Enes Yazici. "Mechanical properties of aluminum bonded joints reinforced with functionalized boron nitride and boron carbide nanoparticles". Proceedings of the Institution of Mechanical Engineers, Part L: Journal of Materials: Design and Applications 236, n. 1 (10 novembre 2021): 37–49. http://dx.doi.org/10.1177/14644207211056020.
Testo completoAbstract (sommario):
In the presented study, the effect of hexagonal boron nitride and hexagonal boron carbide nanoparticles on the strength of adhesively bonded joints was investigated experimentally. Hexagonal boron nitride nanoparticles were functionalized using 3-(aminopropyl) triethoxysilane to improve adhesion and increase the interaction between epoxy and nanoparticles. Similarly, h-B4C nanoparticles were functionalized by using 3-(glycidyloxypropyl) trimethoxysilane. New structural nano adhesives were produced by reinforcing the functionalized nanoparticles into epoxy at different proportions (0.5 wt.%, 1.0 wt.%, 2 wt.%, 3.0 wt.%, 4.0 wt.%, and 5.0 wt.%). Two different epoxies with different viscosity values (MGS-LR285 and Araldite 2011) were used as adhesives, and aluminum alloy (AA2024-T3) was chosen as an adherend. Tensile test was carried out to determine the failure load of the adhesive joints, and the fracture surface morphology was examined after the test Additionally, Scanning electron microscopy and energy dispersion X-ray spectroscopy (SEM-EDS) analysis was performed to observe the distribution of boron nanoparticles in the adhesives. The experimental results showed that the reinforcement of hexagonal boron nitride and boron carbide nanoparticles to the adhesives increased the joint strength substantially depending on the reinforcement ratio and viscosity of the adhesives. The maximum increase in failure loads was achieved by adding 1 wt.% functionalized boron nitride to high viscosity Araldite 2011 adhesive and 2 wt.% to low viscosity MGS-LR285 adhesive, and the ratio of increase in failure loads is 31% and 63%, respectively. Moreover, by adding 2 wt.% functionalized boron carbide nanoparticles to the Araldite 2011 and MGS-LR285 adhesives, the strength of the joints increased by about 27% and 70%, respectively.
8
Altmann, Alinne Segatto Pires, Fabricio Mezzomo Collares, Gabriela de Souza Balbinot, Vicente Castelo Branco Leitune, Antonio Shigueaki Takimi e Susana Maria Werner Samuel. "Niobium pentoxide phosphate invert glass as a mineralizing agent in an experimental orthodontic adhesive". Angle Orthodontist 87, n. 5 (7 luglio 2017): 759–65. http://dx.doi.org/10.2319/122417-140.1.
Testo completoAbstract (sommario):
ABSTRACT Objective: The aim of this study was to develop an experimental orthodontic adhesive and evaluate how adding phosphate invert glass containing niobium pentoxide (PIG-Nb) affected the adhesive's properties. Material and Methods: PIG-Nb was added at 1, 2.5, and 5 wt% to experimental adhesive (75 wt% bisphenol A methacrylate [BisGMA], 25 wt% triethylene glycol dimethacrylate [TEGDMA], 5 wt% colloidal silica and photoinitiator system). The adhesives were evaluated for mineral deposition, degree of conversion (DC), softening solvent by Knoop microhardness (KNH) variation, pH changes, and shear bond strength (SBS). One-way analysis of variance (ANOVA) (DC and ΔKHN%), two-way ANOVA (SBS), repeated measures ANOVA (pH), and paired test (KNH1 and KNH2) were used at a significance level of P < .05. Results: Adding PIG-Nb to orthodontic adhesives induced deposition on its surface associated with a constant neutral pH. The SBS increased after immersion in artificial saliva, and the PIG-Nb5 exhibited less softening. Conclusion: The addition of PIG-Nb into orthodontic adhesives induced mineral deposition. Experimental orthodontic adhesive containing 5% wt of PIG-Nb exhibited increased mineral deposition and suitable properties for orthodontic applications.
9
Antosik, Adrian Krzysztof, Karolina Mozelewska e Konrad Gziut. "Influence of UV on the self-adhesive properties of silicone pressure-sensitive adhesives". Polimery 68, n. 1 (19 gennaio 2023): 19–24. http://dx.doi.org/10.14314/polimery.2023.1.3.
Testo completoAbstract (sommario):
The paper presents the results of research on the UV radiation influence on the self-adhesive properties of silicone adhesives. The adhesives were obtained by cross-linking commercial resins (PSA 590, Q2-7566) at the temperature of 110°C, using different amounts (0–3 wt%) of bis(2,4-dichlorobenzoyl) peroxide. Self-adhesive properties of adhesives such as adhesion, tack, and durability before and after aging were determined. The adhesives showed stable self-adhesive properties, however, the PSA 590 adhesive had a higher maximum operating temperature than the Q2-7566 adhesive.
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Karpiesiuk, Jacek, e Tadeusz Chyzy. "The effects of various parameters on the strengths of adhesives layer in a lightweight floor system". Open Engineering 10, n. 1 (10 giugno 2020): 443–53. http://dx.doi.org/10.1515/eng-2020-0057.
Testo completoAbstract (sommario):
AbstractThe article presents the results of shear and tensile strength of deformable cement adhesives, reinforced by fiberglass mesh with a different weight in a lightweight floor system without screeds. The substrate under adhesive was EPS and XPS thermal insulation. Tests were carried out in dry, wet conditions as well as during freezing and thawing. On their basis, it can be concluded that the larger contact surface of the EPS thermal insulation with the deformable adhesive C2S1 increases the adhesive’s tensile strength. This surface is not important using C2S2 adhesives or when the substrate is made from rough insulation XPS. It was generally found that the higher weight of the fibreglass mesh in deformable cement adhesives has a more favorable effect on their shear strength. Water absorption does not significantly affect the adhesion of terracotta, and in some configurations of components in this system increases it. The adhesive with the symbol C2S2 compared to C2S1 has a higher tensile and shear strength using the same materials. Frost conditions do not allow for long-term use of this type of floor construction in snow and ice protection systems. This experimental research shows that an economical solution with optimal strength consists of XPS insulation, 205 g/m2 mesh, C2S1 adhesive.
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Ogawa, Yuki, Kimiyoshi Naito, Keisuke Harada e Hiroyuki Oguma. "Proposal of Evaluation Method for Crack Propagation Behaviors of Second-Generation Acrylic Adhesives under Mode I Static Loading". Polymers 15, n. 8 (14 aprile 2023): 1878. http://dx.doi.org/10.3390/polym15081878.
Testo completoAbstract (sommario):
Second-generation acrylic (SGA) adhesives, possessing high strength and toughness, are applicable in automotive body structures. Few studies have considered the fracture toughness of the SGA adhesives. This study entailed a comparative analysis of the critical separation energy for all three SGA adhesives and an examination of the mechanical properties of the bond. Loading-unloading test was performed to evaluate crack propagation behaviors. In the loading–unloading test of the SGA adhesive with high ductility, plastic deformation was observed in the steel adherends; the arrest load dominated the propagation and non-propagation of crack for adhesive. The critical separation energy of this adhesive was assessed by the arrest load. In contrast, for the SGA adhesives with high tensile strength and modulus, the load suddenly decreased during loading, and the steel adherend was not plastically deformed. The critical separation energies of these adhesives were assessed using the inelastic load. The critical separation energies for all the adhesives were higher for thicker adhesive. Particularly, the critical separation energies of the highly ductile adhesives were more affected by the adhesive thickness than highly strength adhesives. The critical separation energy from the analysis using the cohesive zone model agreed with the experimental results.
12
Murray, C. T., R. L. Rudman, M. B. Sabade e A. V. Pocius. "Conductive Adhesives for Electronic Assemblies". MRS Bulletin 28, n. 6 (giugno 2003): 449–54. http://dx.doi.org/10.1557/mrs2003.127.
Testo completoAbstract (sommario):
AbstractA number of different types of adhesives are used in the assembly of electronic components and devices. This article provides an overview of such adhesives that also have another job–they work at conducting electricity or heat. The resins or binders in these adhesives range from thermosetting to pressure-sensitive. Conductivity is obtained by the judicious choice of filler. For electrically conducting adhesives, the fillers range from silver flake to silver-coated fibers. For thermally conducting adhesives, the fillers range from aluminum oxide to boron nitride. We also discuss a specific type of electrically conducting adhesive–the z-axis film adhesive. In these adhesives, particles are oriented in such a fashion that allows conduction in the direction perpendicular to the adhesive, but not in the plane of the adhesive.
13
Zecin-Deren, Anna, Monika Lukomska-Szymanska, Agata Szczesio-Wlodarczyk, Ireneusz Piwonski, Jerzy Sokolowski e Barbara Lapinska. "The Influence of Application Protocol of Simplified and Universal Adhesives on the Dentin Bonding Performance". Applied Sciences 10, n. 1 (23 dicembre 2019): 124. http://dx.doi.org/10.3390/app10010124.
Testo completoAbstract (sommario):
Contemporary adhesives use etch-and-rinse, self-etch, and multimode adhesive strategies. Simplified and universal adhesives present lower bond strength to dentin than conventional, two-bottle etch-and-rinse adhesives. The purpose of this study was to evaluate bonding performance of simplified and universal adhesives to dentin after modifying their application protocol (multiplying applications and extending application time). Adhesive layer thickness (ALT) and shear bond strength (SBS), as well as the correlation between these parameters was calculated. Two universal (Single Bond Universal and Prime & Bond One Select) and two self-etch adhesives (Adper Easy One and Xeno V) were tested. Significant differences in ALT were detected between the adhesives, as well as within the same adhesive between study groups. Tested adhesives presented the thinnest adhesive layer when applied 2 times in 20 s. Single Bond Universal obtained the highest SBS results of all adhesives. Most adhesives (except for Prime & Bond One Select) obtained the highest SBS, when applied two or three times in 40 or 60 s, respectively. No correlation between the ALT and SBS was found. The study showed that increasing the number of applications and extending the application time of self-etch and universal adhesives can be recommended to improve their performance.
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Lee, J. J. W., Y. Wang, I. K. Lloyd e B. R. Lawn. "Joining Veneers to Ceramic Cores and Dentition with Adhesive Interlayers". Journal of Dental Research 86, n. 8 (agosto 2007): 745–48. http://dx.doi.org/10.1177/154405910708600811.
Testo completoAbstract (sommario):
Adhesive joining of veneers to cores offers potential simplicity and economy in the fabrication of all-ceramic crowns. We tested the hypothesis that resin-based adhesives can be used for such fabrication without compromising mechanical integrity of the crown structure. A simple test procedure for quantifying this hypothesis was proposed. A model glass veneer layer 1 mm thick (representative of porcelain), adhesively bonded onto a glass-like core substrate (ceramic or dental enamel), was loaded at its top surface with a hard sphere (occlusal force) until a radial crack initiated at the veneer undersurface. The critical loads for fracture, visually observable in the transparent glass, afforded a measure of the predisposition for the adhesive to cause veneer failure in an occlusal overload. Two adhesives were tested, one a commercial epoxy resin and the other a relatively stiff in-house-developed composite. The results confirmed that stiffer adhesives provide higher resistance to failure.
15
Alsunbul, Hanan, Yasser F. Alfawaz, Eman M. Alhamdan, Imran Farooq, Fahim Vohra e Tariq Abduljabbar. "Influence of carbon and graphene oxide nanoparticle on the adhesive properties of dentin bonding polymer: A SEM, EDX, FTIR study". Journal of Applied Biomaterials & Functional Materials 21 (gennaio 2023): 228080002311592. http://dx.doi.org/10.1177/22808000231159238.
Testo completoAbstract (sommario):
Objective: This study was aimed at including 2.5 wt.% of carbon nanoparticles (CNPs) and graphene oxide NPs (GNPs) in a control adhesive (CA) and then investigate the effect of this inclusion on their mechanical properties and its adhesion to root dentin. Materials and methods: Scanning electron microscopy and energy dispersive X-ray (SEM-EDX) mapping were conducted to investigate the structural features and elemental distribution of CNPs and GNPs, respectively. These NPs were further characterized by Raman spectroscopy. The adhesives were characterized by evaluating their push-out bond strength (PBS), rheological properties, degree of conversion (DC) investigation, and failure type analysis. Results: The SEM micrographs revealed that the CNPs were irregular and hexagonal, whereas the GNPs were flake-shaped. EDX analysis showed that carbon (C), oxygen (O), and zirconia (Zr) were found in the CNPs, while the GNPs were composed of C and O. The Raman spectra for CNPs and GNPs revealed their characteristic bands (CNPs-D band: 1334 cm−1, GNPs-D band: 1341 cm−1, CNPs-G band: 1650 cm−1, and GNPs-G band: 1607 cm−1). The testing verified that the highest bond strength to root dentin were detected for GNP-reinforced adhesive (33.20 ± 3.55 MPa), trailed closely by CNP-reinforced adhesive (30.48 ± 3.10 MPa), while, the CA displayed lowest values (25.11 ± 3.60 MPa). The inter-group comparisons of the NP-reinforced adhesives with the CA revealed statistically significant results ( p < 0.01). Failures of adhesive nature were most common in within the adhesives and root dentin. The rheological assessment results demonstrated a reduced viscosity for all the adhesives observed at advanced angular frequencies. All the adhesives verified suitable dentin interaction shown by hybrid layer and appropriate resin tag development. A reduced DC was perceived for both NP-reinforced adhesives, compared to the CA. Conclusion: The present study’s findings have demonstrated that 2.5% GNP adhesive revealed the highest, suitable root dentin interaction, and acceptable rheological properties. Nevertheless, a reduced DC was observed (matched with the CA). Prospective studies probing the influence of diverse concentrations of filler NPs on the adhesive’s mechanical properties to root dentin are recommended.
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Ruffatto, Donald, Aaron Parness e Matthew Spenko. "Improving controllable adhesion on both rough and smooth surfaces with a hybrid electrostatic/gecko-like adhesive". Journal of The Royal Society Interface 11, n. 93 (6 aprile 2014): 20131089. http://dx.doi.org/10.1098/rsif.2013.1089.
Testo completoAbstract (sommario):
This paper describes a novel, controllable adhesive that combines the benefits of electrostatic adhesives with gecko-like directional dry adhesives. When working in combination, the two technologies create a positive feedback cycle whose adhesion, depending on the surface type, is often greater than the sum of its parts. The directional dry adhesive brings the electrostatic adhesive closer to the surface, increasing its effect. Similarly, the electrostatic adhesion helps engage more of the directional dry adhesive fibrillar structures, particularly on rough surfaces. This paper presents the new hybrid adhesive's manufacturing process and compares its performance to three other adhesive technologies manufactured using a similar process: reinforced PDMS, electrostatic and directional dry adhesion. Tests were performed on a set of ceramic tiles with varying roughness to quantify its effect on shear adhesive force. The relative effectiveness of the hybrid adhesive increases as the surface roughness is increased. Experimental data are also presented for different substrate materials to demonstrate the enhanced performance achieved with the hybrid adhesive. Results show that the hybrid adhesive provides up to 5.1× greater adhesion than the electrostatic adhesive or directional dry adhesive technologies alone.
17
Motlhakudi, I., e A. Jonker. "Fatigue Characterisation of Adhesives Used in Fibre-Reinforced Composites". R&D Journal 39 (2023): 53–79. http://dx.doi.org/10.17159/2309-8988/2023/v39a6.
Testo completoAbstract (sommario):
A review of past investigations into the fatigue behaviour of structural adhesives and bonded joints in fibre-reinforced polymer composites is given. An overview of the structural adhesives used in general bonded joint applications is first provided, followed by an experimental fatigue testing of these bonded components. The aspects that influence fatigue strength and fatigue life for adhesively bonded joints in fibre-reinforced polymer composites are then discussed in terms of the adhesive composition, geometry configuration, surface condition and preparation, and loading conditions. The aspects that relate to fatigue crack initiation and crack propagation in these bonded composite components are discussed in terms of damage modelling, monitoring, and detecting of crack initiation, crack growth rates and crack propagation modelling. The impact of environmental factors such as temperature and humidity on the fatigue performance of these bonded composite joints is also discussed. The paper then concludes by providing guidelines for characterising the fatigue behaviour of adhesively bonded joints and adhesives used in fibre-reinforced polymer composite applications
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Liu, Zhiyong, Zhiguo Song, Benrong Lv e Zumin Qiu. "Rapid Reassembly, Biomass-Derived Adhesive Based on Soybean Oil and Diels–Alder Bonds". Polymers 15, n. 22 (16 novembre 2023): 4428. http://dx.doi.org/10.3390/polym15224428.
Testo completoAbstract (sommario):
Synthetic adhesives play a crucial role in holding together solid materials through interfacial interactions. Thermoplastic and thermosetting adhesives are important types of synthetic adhesives, with thermoplastic adhesives being reassemblable and thermosetting adhesives exhibiting high adhesive strength and creep resistance. However, there is a need to combine the advantages of both types and develop high bonding strength, reassemblable adhesives. Here, epoxidized soybean oil (ESO) was used to prepare adhesive networks and Diels–Alder bonds were incorporated to enhance reassembly ability. The ESO was functionalized with furyl groups and cross-linked via the reaction between furyl and imide groups to involve the Diels–Alder bonds. The resulting adhesive exhibited good solvent resistance and mechanical properties, which could be regulated by adjusting the quantity of cross-linker. The prepared adhesives also demonstrated self-healing capabilities, as the scratch on the surface gradually diminished with heating. Additionally, the adhesives showed the ability to undergo recycling without significant changes in properties. The prepared adhesives exhibited hydrophilicity and the flow characteristics during reassembly were characterized by a decrease in torque. This study provides a promising approach for the development of synthetic adhesives with reassembly ability, which has important implications for the field of bonding.
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Viana, Ana S., e Romana Santos. "Nanoscale characterization of the temporary adhesive of the sea urchin Paracentrotus lividus". Beilstein Journal of Nanotechnology 9 (24 agosto 2018): 2277–86. http://dx.doi.org/10.3762/bjnano.9.212.
Testo completoAbstract (sommario):
Background: Unlike the thin homogeneous films that are typical for adhesives produced by humans, biological adhesives present complex hierarchical micro- and nanostructures. Most studies on marine adhesives have focused on permanent adhesives, whereas the nanostructures of nonpermanent, temporary or reversible adhesives have only been examined in some organisms such as marine flatworms, barnacle cyprids, freshwater cnidaria and echinoderms such as sea cucumbers and sea stars. In this study, the first nanoscale characterization of sea urchin temporary adhesives was performed using atomic force microscopy (AFM). Results: The adhesive topography was similar under dry and native (seawater) conditions, which was comprised of a honeycomb-like meshwork of aggregated globular nanostructures. In terms of adhesion forces, higher values were obtained in dry conditions, reaching up to 50 nN. Under native conditions, lower adhesive forces were obtained (up to 500 pN) but the adhesive seemed to behave like a functional amyloid, as evidenced by the recorded characteristic sawtooth force–extension curves and positive thioflavin-T labelling. Conclusion: Our results confirm that like other temporary adhesives, the sea urchin adhesive footprint nanostructure consists of a meshwork of entangled globular nanostructures. Under native conditions, the adhesive footprints of the sea urchin behaved like a functional amyloid, suggesting that among its proteinaceous constituents there are most likely proteins with amyloid quaternary structures or rich in β-sheets. These results extend our knowledge on sea urchin adhesive composition and mechanical properties essential for the engineering of biomimetic adhesives.
20
Akbarzadeh, P., e Khalil Farhangdoost. "Finite Element Simulation on Failure Assessment of Toughened Epoxy Adhesives". Key Engineering Materials 488-489 (settembre 2011): 537–40. http://dx.doi.org/10.4028/www.scientific.net/kem.488-489.537.
Testo completoAbstract (sommario):
The prediction of the strength of adhesively bonded joints has been investigated using a variety of failure criteria such as maximum stress or strain, and fracture mechanics approaches. Fracture mechanics approaches based on the critical strain energy release rate, for crack propagation are applicable to highly cross-linked structural adhesives and have the advantage of avoiding the explicit consideration of the bi-material singularities inherent in adhesive joints. In the present work, the finite-element simulation of such adhesive joint has been performed and the R-curves of two different rubber-toughened epoxy adhesives were measured using double cantilever beam (DCB) specimens. The FE results are applied to be compared with the experimental results which were reported in the literature.
21
Zecin-Deren, Anna, Jerzy Sokolowski, Agata Szczesio-Wlodarczyk, Ireneusz Piwonski, Monika Lukomska-Szymanska e Barbara Lapinska. "Multi-Layer Application of Self-Etch and Universal Adhesives and the Effect on Dentin Bond Strength". Molecules 24, n. 2 (18 gennaio 2019): 345. http://dx.doi.org/10.3390/molecules24020345.
Testo completoAbstract (sommario):
Contemporary self-etch and multi-mode adhesives were introduced to ensure a fast and reliable bonding procedure. Yet, in terms of bond strength and stability they failed to perform as well as two-bottle, etch-and-rinse adhesives, which remain the gold standard in terms of durability. The purpose of this study was to assess the shear bond strength (SBS) of dental adhesives to dentin with different application protocols. Two self-etch (Adper Easy One and Xeno V) and two multi-mode adhesives (Single Bond Universal and Prime&Bond One Select) were used in the study. The highest SBS was obtained for Single Bond Universal applied in three layers, while the lowest, for Xeno V applied in one layer. Other tested adhesives obtained the highest SBS when applied in three layers. For all tested adhesives, multi-layer application resulted in an increase in adhesive layer thickness, as observed in SEM. The increased thickness of the adhesive layer produced by triple application of unfilled adhesives corresponded with higher SBS values. The present study showed that using triple adhesive layers with simplified adhesive systems can be recommended to improve their performance. Due to differences in the composition of self-etch and universal adhesives, the exact application protocol is product dependent.
22
Huang, Yuheng, Ian A. Kinloch e Cristina Vallés. "Static and Dynamic Mechanical Behavior of Carbon Fiber Reinforced Plastic (CFRP) Single-Lap Shear Joints Joule-Bonded with Conductive Epoxy Nanocomposites". Journal of Composites Science 8, n. 3 (21 marzo 2024): 112. http://dx.doi.org/10.3390/jcs8030112.
Testo completoAbstract (sommario):
The potential of electrically conductive graphene nanoplatelets (GNPs)/epoxy, multi-walled carbon nanotubes (MWNCTs)/epoxy and hybrid GNPs-MWCNTs/epoxy nanocomposites as adhesives for out-of-autoclave (OoA) and in-the-field CFRP repair via Joule heat curing was investigated. Scanning electron microscopy revealed a good dispersion of the nanoparticles in the matrix in all the nanocomposite adhesives above their percolation thresholds, which led to a homogeneous distribution of the heat generated during Joule CFRP repair. The joints bonded with neat epoxy and the nanocomposites showed similar lap shear strengths, with the addition of nanoparticles enhancing the fatigue performance of the adhesively bonded joints relative to when neat epoxy was used as an adhesive and oven-cured. The interfacial and cohesive failure mechanisms were found to coexist in all the cases, with an increasing dominance of the cohesive when nanofillers were embedded into the adhesive. No effect of the specific type of nanofiller incorporated into the epoxy as the conductive component was observed on the mechanical performance of the bonded joints, with the adhesives containing MWCNTs showing similar results to those filled with GNPs at considerably lower loadings due to their lower percolation thresholds. The independence of the properties regardless of the curing method highlights the promise of these Joule-cured adhesives for industrial applications.
23
Szalóki, Melinda, Zsófia Szabó, Renáta Martos, Attila Csík, Gergő József Szőllősi e Csaba Hegedűs. "The Surface Free Energy of Resin-Based Composite in Context of Wetting Ability of Dental Adhesives". Applied Sciences 13, n. 21 (5 novembre 2023): 12061. http://dx.doi.org/10.3390/app132112061.
Testo completoAbstract (sommario):
The surface roughness, surface free energy (SFE) of composites, and composite wettability by dental adhesives are determining factors in achieving a strong and durable adhesion (e.g., composite repair, luting adhesively bonded indirect restorations). In this study, the SFE of one nanohydrid and two bulk-fill composites was investigated in relation to the wetting ability of five different dental adhesives. The profilometry and scanning electron microscopy (SEM) measurement justified that the sandblasting produced a significantly rough surface in which the different filler amounts, filler distribution, and resin-filler ratio participated. The SFE of the tested composite was between 45.65 and 49.07 mJ/m2 regardless of surface treatment. Despite the similarity in SFE, the adhesives wet the surface of the composites in different ways that were between 16.01° and 35.10°. The contact angle of solvent-free dental adhesive was lower due to sandblasting supporting the micromechanical retention. Based on our results, it was found that sandblasting, the most frequently recommended surface treatment, does not change the surface energy but causes a change in the contact angle, which can be explained by the different surface tension of the dental adhesives. It was concluded that the dental adhesive parameters have a more important role in wettability.
24
Vrabič-Brodnjak, Urška. "Bio-Based Adhesives Formulated from Tannic Acid, Chitosan, and Shellac for Packaging Materials". Polymers 15, n. 5 (4 marzo 2023): 1302. http://dx.doi.org/10.3390/polym15051302.
Testo completoAbstract (sommario):
The aim of this study was to develop bio-based adhesives that can be used for various packaging papers. In addition to commercial paper samples, papers produced from harmful plant species in Europe, such as Japanese Knotweed and Canadian Goldenrod, were used. In this research, methods were developed to produce bio-based adhesive solutions in combinations of tannic acid, chitosan, and shellac. The results showed that the viscosity and adhesive strength of the adhesives were best in solutions with added tannic acid and shellac. The tensile strength with adhesives of tannic acid and chitosan was 30% better than with commercial adhesives and 23% for combinations of shellac and chitosan. For paper from Japanese Knotweed and Canadian Goldenrod, the most durable adhesive was pure shellac. Because the surface morphology of the invasive plant papers was more open and had numerous pores compared to the commercial papers, the adhesives penetrated the paper structure and filled the voids. There was less adhesive on the surface and the commercial papers achieved better adhesive properties. As expected, the bio-based adhesives also showed an increase in peel strength and exhibited favorable thermal stability. In summary, these physical properties support the use of bio-based adhesives use in different packaging applications.
25
Al-Saleh, Samar, Abdullah Alateeq, Abdulaziz H. Alshaya, Amal S. Al-Qahtani, Huda I. Tulbah, Mashael Binhasan, Sara Shabib, Imran Farooq, Fahim Vohra e Tariq Abduljabbar. "Influence of TiO2 and ZrO2 Nanoparticles on Adhesive Bond Strength and Viscosity of Dentin Polymer: A Physical and Chemical Evaluation". Polymers 13, n. 21 (2 novembre 2021): 3794. http://dx.doi.org/10.3390/polym13213794.
Testo completoAbstract (sommario):
The present study aimed to formulate an experimental adhesive (EA) and reinforce it with 5 wt.% titanium dioxide (TiO2) or zirconium oxide (ZrO2) to yield 5% TiO2 and 5% ZrO2 adhesives, respectively, and then analyze the impact of this reinforcement on various mechanical properties of the adhesives. The EA contained a blend of monomers such as bisphenol A glycol dimethacrylate (BisGMA), triethylene glycol dimethacrylate (TEGDMA), 2-hydroxyethyl methacrylate (HEMA), and ethyl 4-dimethylamino benzoate and camphorquinone. The EA included ethyl 4-dimethylamino benzoate and camphorquinone photo-initiators, and diphenyliodonium hexafluorophosphate (DPIHP) was also included to act as an electron initiator. The TiO2 and ZrO2 nanoparticles were incorporated into the EA post-synthesis. To characterize the filler nanoparticles, scanning electron microscopy (SEM) and line-energy dispersive X-ray (EDX) spectroscopy were performed. The adhesives were characterized by analyzing their rheological properties, shear-bond strength (SBS), and interfacial failure types. Further, the resin–dentin interface was also analyzed via SEM. The TiO2 nanoparticles were spherically shaped on the SEM micrographs, while the ZrO2 nanoparticles were seen as non-uniformly shaped agglomerates. The EDX mapping demonstrated the presence of Ti and oxygen for TiO2 and Zr and oxygen for the ZrO2 nanoparticles. Both 5% TiO2 and 5% ZrO2 adhesives revealed decreased viscosity as compared with the EA. The 5% TiO2 adhesive demonstrated higher SBS values for both non-thermocycled (NTC) and thermocycled samples (NTC: 25.35 ± 1.53, TC: 23.89 ± 1.95 MPa), followed by the 5% ZrO2 adhesive group (NTC: 23.10 ± 2.22, TC: 20.72 ± 1.32 MPa). The bulk of the failures (>70%) were of adhesive type in all groups. The SEM analysis of the resin–dentin interface revealed the development of a hybrid layer and resin tags (of variable depth) for the EA and 5% TiO2 groups. However, for the 5% ZrO2 group, the hybrid layer and resin tag establishment appeared compromised. Reinforcement of the EA with TiO2 or ZrO2 caused an increase in the adhesive’s SBS (with the 5% TiO2 group demonstrating the highest values) in comparison with the EA (without nanoparticles). However, both nanoparticle-containing adhesives revealed decreased viscosity compared with the EA (without nanoparticles). Further studies investigating the impact of diverse filler concentrations on the properties of adhesives are suggested.
26
Nagura, Y., A. Tsujimoto, NG Fischer, AG Baruth, WW Barkmeier, T. Takamizawa, MA Latta e M. Miyazaki. "Effect of Reduced Universal Adhesive Application Time on Enamel Bond Fatigue and Surface Morphology". Operative Dentistry 44, n. 1 (1 gennaio 2019): 42–53. http://dx.doi.org/10.2341/17-261-l.
Testo completoAbstract (sommario):
SUMMARY Objective: The purpose of this study was to evaluate the effect of reduced application times of universal adhesives on enamel bond fatigue and surface morphology of the treated enamel with constant force atomic force microscopy (AFM). Methods: Four universal adhesives—Adhese Universal (AU), Clearfil Universal Bond Quick (CU), G-Premio Bond (GP), and Scotchbond Universal Adhesive (SU)—were evaluated in a laboratory for their ability to adhesively bond resin composite to enamel. Shear bond strengths were initially determined using 15 specimens per test group for each adhesive. Shear fatigue strengths were then determined using 20 specimens per test group for each the adhesives. The fatigue specimens were loaded using a sine wave at a frequency of 20 Hz for 50,000 cycles or until failure occurred. AFM observations, surface Ra roughness measurements, and geometric surface area evaluations of enamel surface treated with the adhesive agents were also conducted. Results: A strong relationship was found between the initial shear bond strength and shear fatigue strength for enamel surface Ra roughness but not for geometric surface area. The initial shear bond strength and shear fatigue strength of CU and GP were not influenced by different application times, unlike those of AU and SU. While the surface area of enamel treated with the adhesive agents was not significantly influenced by different application times and type of adhesive, surface Ra roughness of the enamel in the AU and SU groups significantly increased with increasing application time, unlike CU and GP. Conclusions: The results of this study suggest that universal adhesives, used with reduced application times, have adequate Ra surface roughness to provide sufficient resistance to enamel bond fatigue at application times from <1 second to 20 seconds, while the geometric surface area of adhesive-treated enamel did not show any significant changes at these different application times.
27
Zikmundová, Markéta, e Martina Eliášová. "Mechanical Properties of Transparent Epoxy Adhesives for Glass Structures". IOP Conference Series: Materials Science and Engineering 1203, n. 3 (1 novembre 2021): 032138. http://dx.doi.org/10.1088/1757-899x/1203/3/032138.
Testo completoAbstract (sommario):
Abstract Adhesive connections are commonly used in many industries as automotive, aerospace, electronics and also in civil engineering. Adhesives in civil engineering are used for non-load bearing structures but nowadays are requirements for using adhesive also for load- bearing structures especially for glass structures. Silicones are mostly used adhesives in civil engineering, they have good resistance to external environment but their lower strength and lower stiffness does not meet requirements for many applications. For this reason, are better semi-rigid or rigid adhesives but there is a lack of information about them. The paper is focused on experimental testing of transparent adhesive connection glass to glass. Four epoxy adhesives were chosen for double lap shear joint. Specimen were exposed to shear test until failure. Shear force and displacement were measured during test. Shear stress, elongation at break, shear modulus and failure mode were obtained from the tests. Only one epoxy adhesive had low adhesion to glass. Specimen with this adhesive had the lowest shear strength. Other three adhesives showed good adhesion to glass and had shear strength 6.5 times higher. Failure mode of specimen with these adhesives was always breaking of the glass.
28
Mozelewska, Karolina, e Adrian Krzysztof Antosik. "Influence of Silicone Additives on the Properties of Pressure-Sensitive Adhesives". Materials 15, n. 16 (19 agosto 2022): 5713. http://dx.doi.org/10.3390/ma15165713.
Testo completoAbstract (sommario):
Research was carried out on the influence of various silicone compounds on the properties of pressure-sensitive adhesives. Silicone-based pressure-sensitive adhesives have good self-adhesive properties and are used in many different industries. However, their thermal resistance is relatively low. In order to improve this property, modifications were made to these adhesives. Compositions were tested, such as viscosity or thermogravimetric analysis, as well as tests of finished products in the form of self-adhesive tapes, i.e., peel adhesion, tack, cohesion at room and elevated temperature, SAFT test (Shear Adhesive Failure Temperature), pot-live (viscosity) and shrinkage. During the tests, an increase in thermal resistance (225 °C), lower shrinkage (0.08%), and lower viscosity was achieved (16.5 Pas), which is a positive phenomenon in the technology of pressure-sensitive adhesives. Thanks to this research, the properties of silicone self-adhesive adhesives have been significantly improved.
29
Kinloch, A. J. "Adhesives in engineering". Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering 211, n. 5 (1 maggio 1997): 307–35. http://dx.doi.org/10.1243/0954410971532703.
Testo completoAbstract (sommario):
When considering methods for joining materials, there are many advantages that engineering adhesives can offer, compared to the more traditional methods of joining such as bolting, brazing, welding, mechanical fasteners, etc. The advantages and disadvantages of using engineering adhesives are discussed and it is shown that it is possible to identify three distinct stages in the formation of an adhesive joint. Firstly, the adhesive initially has to be in a ‘liquid’ form so that it can readily spread over and make intimate molecular contact with the substrates. Secondly, in order for the joint to bear the loads that will be applied to it during its service life, the ‘liquid’ adhesive must now harden. In the case of adhesives used in engineering applications, the adhesive is often initially in the form of a ‘liquid’ monomer which polymerizes to give a high molecular weight polymeric adhesive. Thirdly, it must be appreciated that the load-carrying ability of the joint, and how long it will actually last, are affected by: (a) the design of the joint, (b) the manner in which loads are applied to it and (c) the environment that the joint encounters during its service life. Thus, to understand the science involved and to succeed in further developing the technology, the skills and knowledge from many different disciplines are required. Indeed, the input from surface chemists, polymer chemists and physicists, materials engineers and mechanical engineers are needed. Hence, the science and technology of adhesion and adhesives is a truly multidisciplined subject. These different disciplines have been brought together by developing a fracture mechanics approach to the failure of adhesive joints. The advances that have been made in applying the concepts of fracture mechanics to adhesive joints have enabled a better understanding of the fundamental aspects of adhesion and the more rapid extension of adhesives technology into advanced engineering applications.
30
Horikoshi, Satoshi, Yuhei Arai e Nick Serpone. "In Search of the Driving Factor for the Microwave Curing of Epoxy Adhesives and for the Protection of the Base Substrate against Thermal Damage". Molecules 26, n. 8 (13 aprile 2021): 2240. http://dx.doi.org/10.3390/molecules26082240.
Testo completoAbstract (sommario):
This study used controlled microwaves to elucidate the response of adhesive components to microwaves and examined the advantages of microwave radiation in curing epoxy adhesives. Curing of adhesives with microwaves proceeded very rapidly, even though each component of the adhesive was not efficiently heated by the microwaves. The reason the adhesive cured rapidly is that microwave heating was enhanced by the electrically charged (ionic) intermediates produced by the curing reaction. In contrast, the cured adhesive displayed lower microwave absorption and lower heating efficiency, suggesting that the cured adhesive stopped heating even if it continued to be exposed to microwaves. This is a definite advantage in the curing of adhesives with microwaves, as, for example, adhesives dropped onto polystyrene could be cured using microwave heating without degrading the polystyrene base substrate.
31
Soares, Andreia, e Miguel Pestana. "Polyterpene Resisns: Part I – A Brief Historical Review". Silva Lusitana 28, n. 2 (2020): 181–95. http://dx.doi.org/10.1051/silu/20202802165.
Testo completoAbstract (sommario):
The terpenic resins are polymers of low molecular weight hydrocarbons, obtained by cationic polymerization of terpenes. These products are used in the adhesives, sealants and wax coating industries. Commercial adhesive resins are prepared from monoterpenes -the main ones are α-pinene, β-pinene and dipentene. The softening point and molecular weight of polyterpene resins are critical for their main use (adherence). Its adhesive behavior results from the relationship of the softening point with the molecular weight. At the commercial level, polyterpene resins are produced by polymerization of terpene monomers. Batch and continuous systems are used. The composition of an adhesive requires a wide knowledge of the materials available and the specific requirements of its application. The most common types of adhesives are Pressure Sensitive Adhesives, Hot-melt Adhesives and Structural Adhesives.
32
Bogue, Robert. "Recent innovations in adhesive technology". Assembly Automation 35, n. 3 (3 agosto 2015): 201–5. http://dx.doi.org/10.1108/aa-10-2014-081.
Testo completoAbstract (sommario):
Purpose – This paper aims to provide an insight into recent innovations in adhesive technology by considering a selection of commercial developments and academic research activities. Design/methodology/approach – Following an introduction, this paper first discusses a selection of commercially developed adhesives used in the healthcare, photovoltaics and aerospace industries. It then considers biomimetic adhesive research, specifically dry adhesives which mimic the principles of gecko adhesion and wet adhesives based on the chemistry which underpins mussel adhesion. Finally, brief concluding comments are drawn. Findings – This shows that new adhesives continue to be developed to meet a growing range of industrial requirements, and a major research effort into biologically inspired adhesion mechanisms is poised to yield new families of high-performance adhesives. Originality/value – This provides details of recent commercial and academic developments in adhesive technology.
33
Chersoni, S., G. L. Acquaviva, C. Prati, M. Ferrari, S. Grandini, D. H. Pashley e F. R. Tay. "In vivo Fluid Movement through Dentin Adhesives in Endodontically Treated Teeth". Journal of Dental Research 84, n. 3 (marzo 2005): 223–27. http://dx.doi.org/10.1177/154405910508400303.
Testo completoAbstract (sommario):
Fluid transudation through simplified dentin adhesives can occur in bonded vital crown dentin, since these adhesives behave as permeable membranes after polymerization. The effect of adhesive permeability in endodontically treated teeth is unknown. This study examined the hypothesis that in vivo fluid movement through simplified adhesives occurs when they are applied to root canals. Dowel spaces were prepared in endodontically treated teeth with single root canals. Six adhesives were applied to the intra-radicular dentin of canal walls. Impressions were obtained with polyvinyl siloxane, and replicas were fabricated with the use of polyether impression material. Replica hemisections were gold-coated for SEM examination. Fluid transudation was evident on the adhesive surfaces of all simplified total-etch and self-etch adhesives. Conversely, most of the specimens bonded with the control three-step total-etch adhesive were devoid of fluid droplets. Permeability of simplified adhesives results in water movement, even in root-treated dentin. This may adversely affect the coupling of auto-/dual-cured resin cements.
34
Van Landuyt, K. L., J. Snauwaert, J. De Munck, E. Coutinho, A. Poitevin, Y. Yoshida, K. Suzuki, P. Lambrechts e B. Van Meerbeek. "Origin of Interfacial Droplets with One-step Adhesives". Journal of Dental Research 86, n. 8 (agosto 2007): 739–44. http://dx.doi.org/10.1177/154405910708600810.
Testo completoAbstract (sommario):
Contemporary one-step self-etch adhesives are often documented with interfacial droplets. The objective of this study was to research the origin of these droplets. Two HEMA-rich and one HEMA-free adhesive were applied to enamel and dentin, with the lining composite either immediately cured or cured only after 20 min. All one-step adhesives exhibited droplets at the interface; however, the droplets had two different origins. With the HEMA-free adhesives, droplets were located throughout the adhesive layer and were stable in number over time. With the HEMA-rich adhesives, the droplets were observed exclusively at the adhesive resin/composite interface, and their number increased significantly when the composite was delay-cured. Only the latter droplets caused a significant drop in bond strength after delayed curing. While the droplets in the HEMA-free one-step adhesives should be ascribed to phase separation, those observed with HEMA-rich adhesives resulted from water absorption from dentin through osmosis.
35
Clerc, Gaspard, Thomas Lüthi, Peter Niemz e Jan Willem G. Van de Kuilen. "Reaction kinetics investigation in relation to the influence of humidity on fatigue behavior of wood lap joints". Holzforschung 74, n. 9 (25 settembre 2020): 865–80. http://dx.doi.org/10.1515/hf-2019-0136.
Testo completoAbstract (sommario):
AbstractIt is generally assumed that the properties of wood against fatigue are good, but little is known about the properties of adhesively bonded wood, which represents today most of the wood-based products. Lap-shear samples glued with three common wood adhesives [two ductile one-component polyurethane (1C-PUR) systems and one brittle phenol resorcinol formaldehyde (PRF) adhesive] were tested under cyclical loads at three different climates [20°C, 35% − 50% − 85% relative humidity (RH)]. For the analysis of data, an empirical model based on reaction kinetics was developed. In addition, a probabilistic model was used to estimate the endurance limit and the expected run-out lifetime. Both models were combined to accurately model fatigue at high and low relative stress intensity. It was shown that ductile 1C-PUR adhesives perform better than the brittle adhesive system under dry climates (35%–50% RH). However, for higher RH, the brittle PRF adhesive showed better performance, most probably due to a better wood-adhesive adhesion in wet climate. An average endurance limit for tensile shear stresses between 20% and 48% of the mean tensile shear strength (TSS) was estimated for the tested adhesives. It was shown that the model parameters could be linked to fundamental physical constants through the reaction kinetics approach; however, further research is needed to correlate these parameters to specimen-specific quantities.
36
Avgoulas, Evangelos I., Michael P. F. Sutcliffe, Stephen W. Linderman, Victor Birman, Stavros Thomopoulos e Guy M. Genin. "Adhesive-based tendon-to-bone repair: failure modelling and materials selection". Journal of The Royal Society Interface 16, n. 153 (10 aprile 2019): 20180838. http://dx.doi.org/10.1098/rsif.2018.0838.
Testo completoAbstract (sommario):
Surgical reattachment of tendon to bone is a procedure marked by high failure rates. For example, nearly all rotator cuff repairs performed on elderly patients with massive tears ultimately result in recurrence of tearing. These high failure rates have been attributed to stress concentrations that arise due to the mechanical mismatch between tendon and bone. Although recent studies have identified potential adhesives with mechanical properties tuned to alleviate these stress concentrations, and thereby delay the onset of failure, resistance to the progression of failure has not been studied. Here, we refined the space of adhesive material properties that can improve surgical attachment by considering the fracture process. Using cohesive zone modelling and physiologically relevant values of mode I and mode II adhesive fracture toughnesses, we predicted the maximum displacement and strength at failure of idealized, adhesively bonded tendon-to-bone repairs. Repair failure occurred due to excessive relative displacement of the tendon and bone tissues for strong and compliant adhesives. The failure mechanism shifted to rupture of the entire repair for stiffer adhesives below a critical shear strength. Results identified a narrow range of materials on an Ashby chart that are suitable for adhesive repair of tendon to bone, including a range of elastomers and porous solids.
37
Lototska-Dudyk, U. B., B. P. Kuzminov, N. Ye Chemodurova e V. A. Turkina. "HET-CAM test in evaluation of irritating action of adhesives used in shoe making industry". Medicni perspektivi 28, n. 4 (25 dicembre 2023): 189–99. http://dx.doi.org/10.26641/2307-0404.2023.4.294232.
Testo completoAbstract (sommario):
The global tendency of the contemporary scientific studies is using alternative biologic models as substitutes of experimental animals. HET-CAM (The Hen's Egg Test on the Chorioallantoie Membrane Assay) is an alternative to in vivo tests involving experimental animals. This test is actively used in different biomedical studies. The aim of our work was to study the irritating potential of adhesives used in shoe making industry in experimental setting using the alternative HET-CAM method. Polyurethane, polychloroprene, rubber and styrene-butadiene adhesives that are widely used in shoe-making industry were studied . HET-CAM test was used for the evaluation of the irritating action of the aforementioned adhesives. All adhesives were applied directly onto the chorioallantoic membrane of chick embryos with reactions and changes (hemorrhages, vascular lysis and coagulation) observed and registered in 30, 120 and 300 seconds after the application of the adhesive. Irritating potential of the adhesives was evaluated according to a calculated irritating index. The most pronounced signs of irritating action were caused by polyurethane adhesives, namely hemorrhages and coagulation (30 sec) – two-component adhesive and hemorrhages (30 sec) and coagulation (120-300 sec) – one-component adhesive. Vascular reactions from application of styrene-butadiene adhesives manifested predominantly with lysis and hemorrhages (30 sec), in some samples these reactions were observed at a later time-point (120-300 sec). Irritating action of rubber adhesives manifested mostly with hemorrhages (30 sec), additionally one observation showed some lysis (120 sec). Polychloroprene adhesive caused hemorrhages (30-120 sec) and also lysis (30 sec) in one of the samples. According to the irritating index, polyurethane (one- and two-component) and styrene-butadiene adhesives were estimated to be strong irritants, while rubber and polychloroprene ones of moderate irritating action. НЕТ-САМ test can be used as a component in the evaluation of evidence of irritating action of shoe adhesives.
38
Zhang, Jiahui, Xiaowei Guo, Xiaomeng Zhang, Huimin Wang, Jiufu Zhu, Zuosen Shi, Song Zhu e Zhanchen Cui. "Hydrolysis-resistant and stress-buffering bifunctional polyurethane adhesive for durable dental composite restoration". Royal Society Open Science 7, n. 7 (luglio 2020): 200457. http://dx.doi.org/10.1098/rsos.200457.
Testo completoAbstract (sommario):
A new elastic polyurethane (PU) adhesive was reported in this study to improve the stability and durability of the dental adhesion interface. A polyurethane oligomer was synthesized by the solution polymerization method, and a diluent and solvent were added to prepare PU adhesives. The water sorption, water solubility, contact angle, thermal stability, degree of conversion and mechanical properties of the PU adhesives were evaluated. Experimental applications for tooth restoration (microtensile bond strength and microleakage) were also performed, and cytotoxicity test was carried out. The water sorption and solubility of the PU adhesives were significantly lower than those of three commercial adhesives. The microtensile bond strength of the PU adhesives was improved after thermocycling test, and the extent of microleakage was diminished when compared with that of commercial adhesives. Biocompatibility testing demonstrated that the PU adhesive was non-toxic to L929 fibroblasts. This study shows the ability of PU adhesive to improve the stability and durability of the dental adhesion interface and may refocus the attention of scientists from rigid bonding to flexible bonding for dental adhesion, and it sheds light on a new strategy for the stable and durable bonding interface of dentine adhesives.
39
Valášek, Petr, e Miroslav Müller. "Possibilities of Adhesives Filling With Micro-particle Fillers – Lap-shear Tensile Strength". Acta Universitatis Agriculturae et Silviculturae Mendelianae Brunensis 64, n. 1 (2016): 195–201. http://dx.doi.org/10.11118/actaun201664010195.
Testo completoAbstract (sommario):
An adhesive bonding can be ranged among technologies of materials bonding which are used in all industrial branches. It plays its important role also in an area of the construction of agricultural machines, e.g. tractors, harvestors etc. Utility properties of adhesives can be extended by using various types of fillers. These fillers increase some mechanical characteristics of adhesives and not last they can decrease resultant price. The paper focuses on a possibility to fill the adhesives showing increased lap-shear tensile strength. These adhesives are used e.g. for adhesive bonding of coach bodies in an automotive industry so that is why it is possible to apply them also in the agricultural area. Laboratory experiments describe the lap-shear tensile strength of rigid adherents which were bonded with adhesives with a variable concentration of micro-particle filler – a glass powder. T-test used for a comparison of the shear strength of the bonds created with the adhesives with 5 vol.% of the glass powder did not evidence a statistically significant difference comparing with the unfilled adhesives. This priece of knowledge opens a possible way of a material usage of the glass powder in the area of the adhesive bonding.
40
He, Xiao Cong. "Effect of Adhesive Behavior on Normal Stress Distributions in the Single-Lap Adhesive Joints". Advanced Materials Research 1088 (febbraio 2015): 769–73. http://dx.doi.org/10.4028/www.scientific.net/amr.1088.769.
Testo completoAbstract (sommario):
The effect of adhesives behavior on the normal stress distributions of single-lap adhesive joints is investigated using the three-dimensional finite element technique. Numerical examples are provided to show the influence on the normal stresses of the joints using adhesives of different characteristics which encompass the entire spectrum of elastic stiffness behaviour. finite element analysis solutions of the normal stress distributions in the adhesive layer have been obtained for four typical characteristics of adhesives. The results indicate that Young’s modulus and Poisson’s ratios of adhesives strongly affect the normal stress distributions of the joints.
41
Rosales-Leal, J. I., F. J. de la Torre-Moreno e M. Bravo. "Effect of Pulp Pressure on the Micropermeability and Sealing Ability of Etch & Rinse and Self-etching Adhesives". Operative Dentistry 32, n. 3 (1 maggio 2007): 242–50. http://dx.doi.org/10.2341/06-69.
Testo completoAbstract (sommario):
Clinical Relevance Etch & rinse adhesives are much more micropermeable and affected by pulp fluid compared with self-etching adhesives. Pulp pressure reduces dentin sealing with etch & rinse adhesives but not with self-etching adhesives. Pulp pressure has no effect on enamel sealing, which is lower when self-etching adhesive is used.
42
Ai, Xianbin, Shanghuan Feng, Tao Shui, Himant Kakkar e Chunbao Charles Xu. "Effects of Alcell Lignin Methylolation and Lignin Adding Stage on Lignin-Based Phenolic Adhesives". Molecules 26, n. 22 (9 novembre 2021): 6762. http://dx.doi.org/10.3390/molecules26226762.
Testo completoAbstract (sommario):
To investigate the effects of lignin methylolation and lignin adding stage on the resulted lignin-based phenolic adhesives, Alcell lignin activated with NaOH (AL) or methylolation (ML) was integrated into the phenolic adhesives system by replacing phenol at various adhesive synthesis stages or directly co-polymerizing with phenolic adhesives. Lignin integration into phenolic adhesives greatly increased the viscosity of the resultant adhesives, regardless of lignin methylolation or adding stage. ML introduction at the second stage of adhesive synthesis led to much bigger viscosity than ML or AL introduction into phenolic adhesives at any other stages. Lignin methylolation and lignin adding stage did not affect the thermal stability of lignin based phenolic adhesives, even though lignin-based adhesives were less thermally stable than NPF. Typical three-stage degradation characteristics were also observed on all the lignin-based phenolic adhesives. Three-ply plywoods can be successfully laminated with lignin based adhesives, and it was interesting that after 3 h of cooking in boiling water, the plywoods specimens bonded with lignin-based phenolic adhesives displayed higher bonding strength than the corresponding dry strength obtained after direct conditioning at 20 °C and 65% RH. Compared with NPF, lignin introduction significantly reduced the bonding strength of lignin based phenolic adhesives when applied for plywood lamination. However, no significant variation of bonding strength was detected among the lignin based phenolic adhesives, regardless of lignin methylolation or adding stages.
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Ohgi, H. "Structural adhesives for adhesive bonding". Welding International 1, n. 10 (gennaio 1987): 927–34. http://dx.doi.org/10.1080/09507118709449038.
Testo completo
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Geerts, Sabine, Amandine Bolette, Laurence Seidel e Audrey Guéders. "AnIn VitroEvaluation of Leakage of Two Etch and Rinse and Two Self-Etch Adhesives after Thermocycling". International Journal of Dentistry 2012 (2012): 1–7. http://dx.doi.org/10.1155/2012/852841.
Testo completoAbstract (sommario):
Our experiment evaluated the microleakage in resin composite restorations bonded to dental tissues with different adhesive systems. 40 class V cavities were prepared on the facial and lingual surfaces of each tooth with coronal margins in enamel and apical margins in cementum (root dentin). The teeth were restored with Z100 resin composite bonded with different adhesive systems: Scotchbond Multipurpose (SBMP), a 3-step Etch and Rinse adhesive, Adper Scotchbond 1 XT (SB1), a 2-step Etch and Rinse adhesive, AdheSE One (ADSE-1), a 1-step Self-Etch adhesive, and AdheSE (ADSE), a 2-step Self-Etch adhesive. Teeth were thermocycled and immersed in 50% silver nitrate solution. When both interfaces were considered, SBMP has exhibited significantly less microleakage than other adhesive systems (resp., for SB1, ADSE-1 and ADSE, , and ). When enamel and dentin interfaces were evaluated separately, (1) for the Self-Etch adhesives, microleakage was found greater at enamel than at dentin interfaces (for ADSE, and for ADSE-1, ); (2) for the Etch and Rinse adhesive systems, there was no significant difference between enamel and dentin interfaces; (3) SBMP was found significantly better than other adhesives both at enamel and dentin interfaces. In our experiment Etch and Rinse adhesives remain better than Self-Etch adhesives at enamel interface. In addition, there was no statistical difference between 1-step (ADSE-1) and 2-step (ADSE) Self-Etch adhesives.
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Van Landuyt, K. L., J. De Munck, J. Snauwaert, E. Coutinho, A. Poitevin, Y. Yoshida, S. Inoue et al. "Monomer-Solvent Phase Separation in One-step Self-etch Adhesives". Journal of Dental Research 84, n. 2 (febbraio 2005): 183–88. http://dx.doi.org/10.1177/154405910508400214.
Testo completoAbstract (sommario):
One-step adhesives bond less effectively to enamel/dentin than do their multi-step versions. To investigate whether this might be due to phase separation between adhesive ingredients, we characterized the interaction of 5 experimental and 3 commercial self-etch adhesives with dentin using transmission electron microscopy. All adhesives were examined for homogeneity by light microscopy. Bonding effectiveness to dentin was determined with the use of a micro-tensile bond-strength protocol. The lower bond strength of the one-step adhesives was associated with light-microscopic observation of multiple droplets that disappeared slowly. Interfacial analysis confirmed the entrapment of droplets within the adhesive layer. The prompt disappearance of droplets upon application of a small amount of HEMA (2-hydroxyethyl methacrylate) or a HEMA-containing bonding agent, as well as the absence of droplets at the interface of all HEMA-containing adhesives, strongly suggests that the adhesive monomers separate from water upon evaporation of ethanol/acetone. Upon polymerization, the droplets become entrapped within the adhesive, potentially jeopardizing bond durability. This can be avoided by strong air-drying of the adhesive, thereby removing interfacial water and thus improving bonding effectiveness.
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Ma, Yanfei, Bozhen Zhang, Imri Frenkel, Zhizhi Zhang, Xiaowei Pei, Feng Zhou e Ximin He. "Mussel-Inspired Underwater Adhesives- from Adhesion Mechanisms to Engineering Applications: A Critical Review". Reviews of Adhesion and Adhesives 9, n. 2 (2 giugno 2021): 167–88. http://dx.doi.org/10.7569/raa.2021.097308.
Testo completoAbstract (sommario):
Recent progress in the adhesion mechanism of mussels has led to great excitement in the field of adhesive materials. Although great progress has been made in the mussel adhesion mechanism and underwater adhesives, there are still many unknowns and challenges in this area. Thus, it is highly important to review the recent progress in mechanisms of mussel adhesion and mussel-inspired adhesives and predict trends for the future. In this review, we (1) summarize the research progress in fundamental interaction mechanisms in natural mussels; (2) discuss the application of the mussel interaction mechanism in the biomimetic mussel adhesive materials, from permanent/high-strength adhesives to temporary/smart adhesives; (3) briefly state the potential applications of the mussel-inspired adhesives in multiple fields, such as engineering applications, smart robotics and biomedicine; (4) summarize the future perspectives and unsolved challenges of mussel adhesion mechanisms and mussel-inspired adhesive materials. We envision that this review will provide an insightful perspective in understanding the mussel adhesion mechanism and directions to further explore, and promote the development of novel biomimetic mussel adhesive materials.
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You, Min, Ya Lan Zhao, Jian Li Li e Ying Ying Li. "Numerical Analysis of Multi-Layer on the Stress Distribution in Adhesively Bonded Single Lap Aluminum Joint". Advanced Materials Research 1061-1062 (dicembre 2014): 471–74. http://dx.doi.org/10.4028/www.scientific.net/amr.1061-1062.471.
Testo completoAbstract (sommario):
The effect of dual adhesives to form multi-layer on the stress distributed in adhesively bonded single lap aluminum joint was investigated using elasto-plastic finite element method (FEM). The results from the numerical simulation showed that the values of the peak stress along the bondline are influenced evidently when there is a multi-layer formed by a middle layer with higher elastic modulus adhesive and two layers with lower elastic modulus adhesive.
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Paul, C. W. "Hot-Melt Adhesives". MRS Bulletin 28, n. 6 (giugno 2003): 440–44. http://dx.doi.org/10.1557/mrs2003.125.
Testo completoAbstract (sommario):
AbstractHot-melt adhesives facilitate fast production processes because the adhesives set simply by cooling. Formulations contain polymers to provide strength and hot tack (resistance to separation while adhesive is hot), and tackifiers and/or oils to dilute the polymer entanglement network, adjust the glass-transition temperature, lower the viscosity, and improve wet-out (molecular contact of the adhesive with the substrate over the entire bonding area). Some adhesives also contain waxes to speed setting, lower viscosity, and improve heat resistance. Obtaining adequate strength and heat resistance from nonreactive hot melts requires that some component of the hot melt separate out into a dispersed but interconnected hard-phase network upon cooling. The hard phases are commonly either glassy styrene domains (for adhesives based on styrenic block copolymers) or organic crystallites (for adhesives based on waxes, olefinic copolymers, or ethylene copolymers). This article will describe first the material properties relevant to the processing and performance of hot-melt adhesives, then the chemistry and function of the specific raw materials used in hot melts, and will conclude with illustrative application examples and corresponding formulations.
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Zaharia, Cristian, Roxana Oancea, Alin Gabriel Gabor e Meda-Lavinia Negruțiu. "New Trends in Dental Adhesion—A Systematic Review". Timisoara Medical Journal 2020, n. 1 (26 ottobre 2020): 1. http://dx.doi.org/10.35995/tmj20200107.
Testo completoAbstract (sommario):
Restorative dentistry is based on a continuous development of materials that make the best possible connection with dental tissues. Thus, dental adhesives have been researched with increasing interest. A successful adhesive system depends very much on its chemistry, as well as on the clinical procedures that must be appropriate for that type of dental adhesive. This review presents a retrospective of dental adhesives focusing on research into new types of adhesive systems that involves the use of nanoparticles. Dental adhesive systems are used in most clinical procedures related to restorative dentistry and can be classified into “etch-and-rinse” adhesives and “self-etch” adhesives. Recently, both types of adhesive systems have been modified, being loaded with different types of nanoparticles to try to improve them in terms of the thickness of the adhesive layer, but also to induce other special qualities. Therefore, in order to avoid compromising the restorative procedures by losing the restorations or by affecting the dental pulp due to cytotoxicity, several factors must be considered in choosing the adhesive system.
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He, Xiao Cong. "Influence of Mechanical Behavior of Adhesives on Shear Stress Distributions in the Single-Lap Adhesive Joints". Advanced Materials Research 306-307 (agosto 2011): 1126–29. http://dx.doi.org/10.4028/www.scientific.net/amr.306-307.1126.
Testo completoAbstract (sommario):
This paper deals with the effects of mechanical behavior of adhesives on the shear stress distributions of single-lap adhesive joints under tension using the three-dimensional finite element analysis (FEA) technique. Numerical examples are provided to show the influence on the shear stresses of the joints using adhesives of different characteristics which encompass the entire spectrum of viscoelastic behavior. FEA solutions of the shear stress distributions in the adhesive layer have been obtained for four typical characteristics of adhesives. The results indicate that Young’s modulus and Poisson’s ratios of adhesives strongly affect the shear stress distributions of the joints.