Journal articles: 'Copolymers and blends'

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Liu, Jing, Hsiang-Ching Wang, Chean-Cheng Su, and Cheng-Fu Yang. "Chemical Interaction-Induced Evolution of Phase Compatibilization in Blends of Poly(hydroxy ether of bisphenol-A)/Poly(1,4-butylene terephthalate)." Materials 11, no. 9 (September 9, 2018): 1667. http://dx.doi.org/10.3390/ma11091667.

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An immiscible blend of poly(hydroxy ether of bisphenol-A) (phenoxy) and poly(1,4-butylene terephthalate) (PBT) with phase separation was observed in as-blended samples. The compatibilization of phenoxy/PBT blends can be promoted through chemical exchange reactions of phenoxy with PBT upon annealing. The annealed phenoxy/PBT blends had a homogeneous phase with a single Tg that could be enhanced by annealing at 260 °C. Infrared (IR) spectroscopy demonstrated that phase homogenization could be promoted by annealing the phenoxy/PBT blend, where alcoholytic exchange occurred between the dangling hydroxyl group (–OH) in phenoxy and the carbonyl group (C=O) in PBT in the heated blends. The alcoholysis reaction changed the aromatic linkages to aliphatic linkages in the carbonyl groups, which initially led to the formation of a graft copolymer of phenoxy and PBT with an aliphatic/aliphatic carbonyl link. The progressive alcoholysis reaction resulted in the transformation of the initial homopolymers into block copolymers and finally into random copolymers, which promoted phase compatibilization in blends of phenoxy with PBT. As the amount of copolymers increased upon annealing, the crystallization of PBT was inhibited by alcoholytic exchange in the blends.

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Otero Navas, Ivonne, Milad Kamkar, Mohammad Arjmand, and Uttandaraman Sundararaj. "Morphology Evolution, Molecular Simulation, Electrical Properties, and Rheology of Carbon Nanotube/Polypropylene/Polystyrene Blend Nanocomposites: Effect of Molecular Interaction between Styrene-Butadiene Block Copolymer and Carbon Nanotube." Polymers 13, no. 2 (January 11, 2021): 230. http://dx.doi.org/10.3390/polym13020230.

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This work studied the impact of three types of styrene-butadiene (SB and SBS) block copolymers on the morphology, electrical, and rheological properties of immiscible blends of polypropylene:polystyrene (PP:PS)/multi-walled carbon nanotubes (MWCNT) with a fixed blend ratio of 70:30 vol.%. The addition of block copolymers to PP:PS/MWCNT blend nanocomposites produced a decrease in the droplet size. MWCNTs, known to induce co-continuity in PP:PS blends, did not interfere with the copolymer migration to the interface and, thus, there was morphology refinement upon addition of the copolymers. Interestingly, the addition of the block copolymers decreased the electrical resistivity of the PP:PS/1.0 vol.% MWCNT system by 5 orders of magnitude (i.e., increase in electrical conductivity). This improvement was attributed to PS Droplets-PP-Copolymer-Micelle assemblies, which accumulated MWCNTs, and formed an integrated network for electrical conduction. Molecular simulation and solubility parameters were used to predict the MWCNT localization in the immiscible blend. The simulation results showed that diblock copolymers favorably interact with the nanotubes in comparison to the triblock copolymer, PP, and PS. However, the interaction between the copolymers and PP or PS is stronger than the interaction of the copolymers and MWCNTs. Hence, the addition of copolymer also changed the localization of MWCNT from PS to PS–PP–Micelles–Interface, as observed by TEM images. In addition, in the last step of this work, we investigated the effect of the addition of copolymers on inter- and intra-cycle viscoelastic behavior of the MWCNT incorporated polymer blends. It was found that addition of the copolymers not only affects the linear viscoelasticity (e.g., increase in the value of the storage modulus) but also dramatically impacts the nonlinear viscoelastic behavior under large deformations (e.g., higher distortion of Lissajous–Bowditch plots).]

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Otero Navas, Ivonne Otero, Milad Kamkar, Mohammad Arjmand, and Uttandaraman Sundararaj. "Morphology Evolution, Molecular Simulation, Electrical Properties, and Rheology of Carbon Nanotube/Polypropylene/Polystyrene Blend Nanocomposites: Effect of Molecular Interaction between Styrene-Butadiene Block Copolymer and Carbon Nanotube." Polymers 13, no. 2 (January 11, 2021): 230. http://dx.doi.org/10.3390/polym13020230.

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This work studied the impact of three types of styrene-butadiene (SB and SBS) block copolymers on the morphology, electrical, and rheological properties of immiscible blends of polypropylene:polystyrene (PP:PS)/multi-walled carbon nanotubes (MWCNT) with a fixed blend ratio of 70:30 vol.%. The addition of block copolymers to PP:PS/MWCNT blend nanocomposites produced a decrease in the droplet size. MWCNTs, known to induce co-continuity in PP:PS blends, did not interfere with the copolymer migration to the interface and, thus, there was morphology refinement upon addition of the copolymers. Interestingly, the addition of the block copolymers decreased the electrical resistivity of the PP:PS/1.0 vol.% MWCNT system by 5 orders of magnitude (i.e., increase in electrical conductivity). This improvement was attributed to PS Droplets-PP-Copolymer-Micelle assemblies, which accumulated MWCNTs, and formed an integrated network for electrical conduction. Molecular simulation and solubility parameters were used to predict the MWCNT localization in the immiscible blend. The simulation results showed that diblock copolymers favorably interact with the nanotubes in comparison to the triblock copolymer, PP, and PS. However, the interaction between the copolymers and PP or PS is stronger than the interaction of the copolymers and MWCNTs. Hence, the addition of copolymer also changed the localization of MWCNT from PS to PS–PP–Micelles–Interface, as observed by TEM images. In addition, in the last step of this work, we investigated the effect of the addition of copolymers on inter- and intra-cycle viscoelastic behavior of the MWCNT incorporated polymer blends. It was found that addition of the copolymers not only affects the linear viscoelasticity (e.g., increase in the value of the storage modulus) but also dramatically impacts the nonlinear viscoelastic behavior under large deformations (e.g., higher distortion of Lissajous–Bowditch plots).

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Liu, Dongmei, Meiyuan Yang, Danping Wang, Xueying Jing, Ye Lin, Lei Feng, and Xiaozheng Duan. "DPD Study on the Interfacial Properties of PEO/PEO-PPO-PEO/PPO Ternary Blends: Effects of Pluronic Structure and Concentration." Polymers 13, no. 17 (August 26, 2021): 2866. http://dx.doi.org/10.3390/polym13172866.

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Using the method of dissipative particle dynamics (DPD) simulations, we investigated the interfacial properties of PEO/PEO-PPO-PEO/PPO ternary blends composed of the Pluronics L64(EO13PO30EO13), F68(EO76PO29EO76), F88(EO104PO39EO104), or F127(EO106PO70EO106) triblock copolymers. Our simulations show that: (i) The interfacial tensions (γ) of the ternary blends obey the relationship γF68 < γL64 < γF88 < γF127, which indicates that triblock copolymer F68 is most effective in reducing the interfacial tension, compared to L64, F88, and F127; (ii) For the blends of PEO/L64/PPO and the F64 copolymer concentration ranging from ccp = 0.2 to 0.4, the interface exhibits a saturation state, which results in the aggregation and micelle formation of F64 copolymers added to the blends, and a lowered efficiency of the L64 copolymers as a compatibilizer, thus, the interfacial tension decreases slightly; (iii) For the blends of PEO/F68/PPO, elevating the Pluronic copolymer concentration can promote Pluronic copolymer enrichment at the interfaces without forming the micelles, which reduces the interfacial tension significantly. The interfacial properties of the blends contained the PEO-PPO-PEO triblock copolymer compatibilizers are, thus, controlled by the triblock copolymer structure and the concentration. This work provides important insights into the use of the PEO-PPO-PEO triblock copolymer as compatibilizers in the PEO and PPO homopolymer blend systems.

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Smith, S. D., R. J. Spontak, D. H. Melik, S. M. Buehler, K. M. Kerr, and R. J. Roe. "Morphological behavior of compatibilized ternary blends prepared by mechanical mixing." Proceedings, annual meeting, Electron Microscopy Society of America 51 (August 1, 1993): 1200–1201. http://dx.doi.org/10.1017/s0424820100151830.

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When blended together, homopolymers A and B will normally macrophase-separate into relatively large (≫1 μm) A-rich and B-rich phases, between which exists poor interfacial adhesion, due to a low entropy of mixing. The size scale of phase separation in such a blend can be reduced, and the extent of interfacial A-B contact and entanglement enhanced, via addition of an emulsifying agent such as an AB diblock copolymer. Diblock copolymers consist of a long sequence of A monomers covalently bonded to a long sequence of B monomers. These materials are surface-active and decrease interfacial tension between immiscible phases much in the same way as do small-molecule surfactants. Previous studies have clearly demonstrated the utility of block copolymers in compatibilizing homopolymer blends and enhancing blend properties such as fracture toughness. It is now recognized that optimization of emulsified ternary blends relies upon design considerations such as sufficient block penetration into a macrophase (to avoid block slip) and prevention of a copolymer multilayer at the A-B interface (to avoid intralayer failure).

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Liu, Dongmei, Kai Gong, Ye Lin, Tao Liu, Yu Liu, and Xiaozheng Duan. "Dissipative Particle Dynamics Study on Interfacial Properties of Symmetric Ternary Polymeric Blends." Polymers 13, no. 9 (May 8, 2021): 1516. http://dx.doi.org/10.3390/polym13091516.

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We investigated the interfacial properties of symmetric ternary An/AmBm/Bn and An/Am/2BmAm/2/Bn polymeric blends by means of dissipative particle dynamics (DPD) simulations. We systematically analyzed the effects of composition, chain length, and concentration of the copolymers on the interfacial tensions, interfacial widths, and the structures of each polymer component in the blends. Our simulations show that: (i) the efficiency of the copolymers in reducing the interfacial tension is highly dependent on their compositions. The triblock copolymers are more effective in reducing the interfacial tension compared to that of the diblock copolymers at the same chain length and concentration; (ii) the interfacial tension of the blends increases with increases in the triblock copolymer chain length, which indicates that the triblock copolymers with a shorter chain length exhibit a better performance as the compatibilizers compared to that of their counterparts with longer chain lengths; and (iii) elevating the triblock copolymer concentration can promote copolymer enrichment at the center of the interface, which enlarges the width of the phase interfaces and reduces the interfacial tension. These findings illustrate the correlations between the efficiency of copolymer compatibilizers and their detailed molecular parameters.

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Przybysz-Romatowska, Marta, Józef Haponiuk, and Krzysztof Formela. "Poly(ε-Caprolactone)/Poly(Lactic Acid) Blends Compatibilized by Peroxide Initiators: Comparison of Two Strategies." Polymers 12, no. 1 (January 16, 2020): 228. http://dx.doi.org/10.3390/polym12010228.

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Poly(ε-caprolactone) (PCL) and poly(lactic acid) (PLA) blends were compatibilized by reactive blending and by copolymers formed during reaction in the solution. The reactive blending of PCL/PLA was performed using di-(2-tert-butyl-peroxyisopropyl)benzene (BIB) or dicumyl peroxide (DCP) as radical initiator. PCL-g-PLA copolymers were prepared using 1.0 wt. % of DCP or BIB via reaction in solution, which was investigated through a Fourier transform infrared spectrometry (FTIR) and nuclear magnetic resonance (NMR) in order to better understand the occurring mechanisms. The effect of different additions such as PCL-g-PLA copolymers, DCP, or BIB on the properties of PCL/PLA blends was studied. The unmodified PCL/PLA blends showed a sea-island morphology typical of incompatible blends, where PLA droplets were dispersed in the PCL matrix. Application of organic peroxides improved miscibility between PCL and PLA phases. A similar effect was observed for PCL/PLA blend compatibilized by PCL-g-PLA copolymer, where BIB was used as initiator. However, in case of application of the peroxides, the PCL/PLA blends were cross-linked, and it has been confirmed by the gel fraction and melt flow index measurements. The thermal and mechanical properties of the blends were also investigated by means of differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), dynamic mechanical analysis (DMA), and tensile strength.

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Frielinghaus, H., D. Schwahn, K. Mortensen, L. Willner, and K. Almdal. "Pressure and Temperature Effects in Homopolymer Blends and Diblock Copolymers." Journal of Applied Crystallography 30, no. 5 (October 1, 1997): 696–701. http://dx.doi.org/10.1107/s0021889897001404.

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Thermal composition fluctuations in a homogeneous binary polymer blend and in a diblock copolymer were measured by small-angle neutron scattering as a function of temperature and pressure. The experimental data were analyzed with theoretical expressions, including the important effect of thermal fluctuations. Phase boundaries, the Flory–Huggins interaction parameter and the Ginzburg number were obtained. The packing of the molecules changes with pressure. Therefore, the degree of thermal fluctuation as a function of packing and temperature was studied. While in polymer blends packing leads, in some respects, to a universal behaviour, such behaviour is not found in diblock copolymers. It is shown that the Ginzburg number decreases with pressure sensitively in blends, while it is constant in diblock copolymers. The Ginzburg number is an estimation of the transition between the universality classes of the `mean-field' approximation and the three-dimensional Ising model. The phase boundaries in blends increase with pressure, while the phase boundary of the studied block copolymer shows an unusual shape: with increasing pressure it first decreases and then increases. Its origin is an increase of the entropic and of the enthalpic parts, respectively, of the Flory–Huggins interaction parameter.

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Boufflet, Pierre, Sebastian Wood, Jessica Wade, Zhuping Fei, Ji-Seon Kim, and Martin Heeney. "Comparing blends and blocks: Synthesis of partially fluorinated diblock polythiophene copolymers to investigate the thermal stability of optical and morphological properties." Beilstein Journal of Organic Chemistry 12 (October 10, 2016): 2150–63. http://dx.doi.org/10.3762/bjoc.12.205.

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The microstructure of the active blend layer has been shown to be a critically important factor in the performance of organic solar devices. Block copolymers provide a potentially interesting avenue for controlling this active layer microstructure in solar cell blends. Here we explore the impact of backbone fluorination in block copolymers of poly(3-octyl-4-fluorothiophene)s and poly(3-octylthiophene) (F-P3OT-b-P3OT). Two block co-polymers with varying block lengths were prepared via sequential monomer addition under Kumada catalyst transfer polymerisation (KCTP) conditions. We compare the behavior of the block copolymer to that of the corresponding homopolymer blends. In both types of system, we find the fluorinated segments tend to dominate the UV–visible absorption and molecular vibrational spectral features, as well as the thermal behavior. In the block copolymer case, non-fluorinated segments appear to slightly frustrate the aggregation of the more fluorinated block. However, in situ temperature dependent Raman spectroscopy shows that the intramolecular order is more thermally stable in the block copolymer than in the corresponding blend, suggesting that such materials may be interesting for enhanced thermal stability of organic photovoltaic active layers based on similar systems.

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Poulopoulou, Nikki, Nejib Kasmi, Maria Siampani, Zoi Terzopoulou, Dimitrios Bikiaris, Dimitris Achilias, Dimitrios Papageorgiou, and George Papageorgiou. "Exploring Next-Generation Engineering Bioplastics: Poly(alkylene furanoate)/Poly(alkylene terephthalate) (PAF/PAT) Blends." Polymers 11, no. 3 (March 23, 2019): 556. http://dx.doi.org/10.3390/polym11030556.

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Polymers from renewable resources and especially strong engineering partially aromatic biobased polyesters are of special importance for the evolution of bioeconomy. The fabrication of polymer blends is a creative method for the production of tailor-made materials for advanced applications that are able to combine functionalities from both components. In this study, poly(alkylene furanoate)/poly(alkylene terephthalate) blends with different compositions were prepared by solution blending in a mixture of trifluoroacetic acid and chloroform. Three different types of blends were initially prepared, namely, poly(ethylene furanoate)/poly(ethylene terephthalate) (PEF/PET), poly(propylene furanoate)/poly(propylene terephthalate) (PPF/PPT), and poly(1,4-cyclohenedimethylene furanoate)/poly(1,4-cycloxehane terephthalate) (PCHDMF/PCHDMT). These blends’ miscibility characteristics were evaluated by examining the glass transition temperature of each blend. Moreover, reactive blending was utilized for the enhancement of miscibility and dynamic homogeneity and the formation of copolymers through transesterification reactions at high temperatures. PEF–PET and PPF–PPT blends formed a copolymer at relatively low reactive blending times. Finally, poly(ethylene terephthalate-co-ethylene furanoate) (PETF) random copolymers were successfully introduced as compatibilizers for the PEF/PET immiscible blends, which resulted in enhanced miscibility.

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Song, Lixin, Qian Zhang, Yongsheng Hao, Yongchao Li, Weihan Chi, Fei Cong, Ying Shi, and Li-Zhi Liu. "Effect of Different Comonomers Added to Graft Copolymers on the Properties of PLA/PPC/PLA-g-GMA Blends." Polymers 14, no. 19 (September 29, 2022): 4088. http://dx.doi.org/10.3390/polym14194088.

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The melt-free radical grafting of glycidyl methacrylate (GMA) onto poly (lactic acid) (PLA) with styrene (St), α-methylstyrene (AMS), and epoxy resin (EP) as comonomers in a twin-screw extruder was used to prepare PLA-g-GMA graft copolymers. The prepared graft copolymers were then used as compatibilizers to prepare PLA/PPC/PLA-g-GMA blends by melt blending with PLA and polypropylene carbonate (PPC), respectively. The effects of different comonomers in the PLA-g-GMA graft copolymers on the thermal, rheological, optical, and mechanical properties and microstructure of the blends were studied. It was found that the grafting degree of PLA-g-GMA graft copolymers was increased to varying degrees after the introduction of comonomers in the PLA-g-GMA grafting reaction system. When St was used as the comonomer, the grafting degree of the PLA-g-GMA graft copolymer increased most significantly, from 0.8 to 1.6 phr. St as a comonomer also most improved the compatibility between PLA and PPC, and the haze of the blends was reduced while maintaining high transmittance. In addition, the PLA-g-GMA graft copolymer with the introduction of St as a comonomer significantly improved the impact toughness of the blends, while the thermal stability and tensile strength of the blends remained largely unchanged.

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Pavlopoulou, Eleni, Kiriaki Chrissopoulou, Stergios Pispas, Nikos Hadjichristidis, and Spiros H. Anastasiadis. "The Micellization of Well-Defined Single Graft Copolymers in Block Copolymer/Homopolymer Blends." Polymers 13, no. 5 (March 9, 2021): 833. http://dx.doi.org/10.3390/polym13050833.

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A series of well-defined (polyisoprene)2(polystyrene), I2S, single graft copolymers with similar total molecular weights but different compositions, fPS, were blended with a low molecular weight polyisoprene homopolymer matrix at a constant concentration 2 wt%, and the micellar characteristics were studied by small-angle x-ray scattering. To investigate the effect of macromolecular architecture on the formation and characteristics of micelles, the results on the single graft copolymers were compared with those of the corresponding linear polystyrene-b-polyisoprene diblock copolymers, SI. The comparison reveals that the polystyrene core chains are more stretched in the case of graft copolymer micelles. Stretching turned out to be purely a result of the architecture due to the second polyisoprene block in the corona. The micellization of a (polystyrene)2(polyisoprene), S2I, graft copolymer was also studied, and the comparison with the results of the corresponding I2S and SI copolymers emphasizes the need for a critical core volume rather than a critical length of the core-forming block, in order to have stable micelles. Finally, the absence of micellization in the case of the I2S copolymer with the highest polystyrene volume fraction is discussed. For this sample, macrophase separation occurs, with polyisoprene cylinders formed in the copolymer-rich domains of the phase-separated blends.

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Abetz, Volker. "Self-Assembly of Block Copolymers." Polymers 12, no. 4 (April 2, 2020): 794. http://dx.doi.org/10.3390/polym12040794.

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Wang, Chaoyang. "Synthesis of Multiblock Copolymers of Poly(2-vinylpyridine) and Polyoxyethylene and their Application as Compatibilizers for Epichlorohydrin Rubber/Poly(Vinyl Chloride) Blends." Polymers and Polymer Composites 13, no. 2 (February 2005): 191–98. http://dx.doi.org/10.1177/096739110501300208.

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Multiblock copolymers of poly(2-vinylpyridine) (P2-VP) and polyoxyethylene (PEO) were synthesized by condensing telechelic dihydroxy poly(2-vinylpyridine) (THPVP) and PEO with dichloromethane in the presence of potassium hydroxide. The copolymers were purified by extraction with water and toluene successively and characterized by Fourier Transform Infrared Spectroscopy and nuclear magnetic resonance spectroscopy. The block copolymers behave as good compatibilizers for the blending of epichlorohydrin rubber (CHR) with poly(vinyl chloride) (PVC). The addition of approximately 2-3% block copolymer to the blends evidently improves their mechanical properties and causes the two glass transition temperatures ( Tg) to become closer. The blends with a weight ratio PVC/CHR of 4/6 and the addition of 2-4% block copolymer show mechanical properties consistent with those of a thermoplastic elastomer.

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Kofinas, Peter, Peter L. Drzal, and Adel F. Halasa. "Orientation Texture and Gas Transport in Semicrystalline Block Copolymer Blends." Rubber Chemistry and Technology 72, no. 5 (November 1, 1999): 918–28. http://dx.doi.org/10.5254/1.3538842.

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Abstract The shear-induced morphologies produced by plane strain compression, using a channel die, were investigated in semicrystalline ethylene/ethylene-propylene (E/EP/E and E/EP) block copolymers blended with semicrystalline low density polyethylene and amorphous polyisoprene homopolymers. Two dimensional small-angle x-ray scattering (SAXS) was used to determine the lamellar orientation relative to the specimen boundaries. Using a cooling rate of 0.27 °C/s and a load of 9.2 MPa, a normal to the plane of shear microstructure orientation texture was produced in the blends. The E homopolymer chains co-crystallize within the confinement of the oriented microphase separated E block copolymer domains. The long period spacing of the oriented microphase separated E/EP block microstructure remained unchanged, while the spacing associated with the crystallization of the E chains increased with increasing weight percent of E homopolymer in the blend. Gas permeability coefficients for He and CO2 were measured for isotropic and oriented blends. The separation properties of these polymer systems was altered by changing the mechanism of gas transport. A selective solvent was used to develop a uniform porous structure in the oriented blend morphologies. The semicrystalline block copolymer blend structure oriented perpendicular to the direction and normal to the plane of shear presents the opportunity to create a high flux porous structure, while keeping the pores of nanometer dimensions, thus providing some selectivity and retaining mechanical strength.

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Rodak, Agata, Agnieszka Susik, Daria Kowalkowska-Zedler, Łukasz Zedler, and Krzysztof Formela. "Cross-Linking, Morphology, and Physico-Mechanical Properties of GTR/SBS Blends: Dicumyl Peroxide vs. Sulfur System." Materials 16, no. 7 (March 31, 2023): 2807. http://dx.doi.org/10.3390/ma16072807.

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In this work, ground tire rubber and styrene–butadiene block copolymer (GTR/SBS) blends at the ratio of 50/50 wt%, with the application of four different SBS copolymer grades (linear and radial) and two types of cross-linking agent (a sulfur-based system and dicumyl peroxide), were prepared by melt compounding. The rheological and cross-linking behavior, physico-mechanical parameters (i.e., tensile properties, abrasion resistance, hardness, swelling degree, and density), thermal stability, and morphology of the prepared materials were characterized. The results showed that the selected SBS copolymers improved the processability of the GTR/SBS blends without any noticeable effects on their cross-linking behavior—which, in turn, was influenced by the type of cross-linking agent used. On the other hand, it was observed that the tensile strength, elongation at break, and abrasion resistance of the GTR/SBS blends cured with the sulfur system (6.1–8.4 MPa, 184–283%, and 235–303 mm3, respectively) were better than those cross-linked by dicumyl peroxide (4.0–7.8 MPa, 80–165%, and 351–414 mm3, respectively). Furthermore, it was found that the SBS copolymers improved the thermal stability of GTR, while the increasing viscosity of the used SBS copolymer also enhanced the interfacial adhesion between the GTR and SBS copolymers, as confirmed by microstructure evaluation.

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Liu, Dongmei, Kai Gong, Ye Lin, Huifeng Bo, Tao Liu, and Xiaozheng Duan. "Effects of Repulsion Parameter and Chain Length of Homopolymers on Interfacial Properties of An/Ax/2BxAx/2/Bm Blends: A DPD Simulation Study." Polymers 13, no. 14 (July 16, 2021): 2333. http://dx.doi.org/10.3390/polym13142333.

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We explored the effects of the repulsion parameter (aAB) and chain length (NHA or NHB) of homopolymers on the interfacial properties of An/Ax/2BxAx/2/Bm ternary polymeric blends using dissipative particle dynamics (DPD) simulations. Our simulations show that: (i) The ternary blends exhibit the significant segregation at the repulsion parameter (aAB = 40). (ii) Both the interfacial tension and the density of triblock copolymer at the center of the interface increase to a plateau with increasing the homopolymer chain length, which indicates that the triblock copolymers with shorter chain length exhibit better performance as the compatibilizers for stabilizing the blends. (iii) For the case of NHA = 4 (chain length of homopolymers An) and NHB (chain length of homopolymers Bm) ranging from 16 to 64, the blends exhibit larger interfacial widths with a weakened correlation between bead An and Bm of homopolymers, which indicates that the triblock copolymer compatibilizers (Ax/2BxAx/2) show better performance in reducing the interfacial tension. The effectiveness of triblock copolymer compatibilizers is, thus, controlled by the regulation of repulsion parameters and the homopolymer chain length. This work raises important considerations concerning the use of the triblock copolymer as compatibilizers in the immiscible homopolymer blend systems.

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Kresge, E. N. "Polyolefin Thermoplastic Elastomer Blends." Rubber Chemistry and Technology 64, no. 3 (July 1, 1991): 469–80. http://dx.doi.org/10.5254/1.3538564.

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Abstract Thermoplastic elastomers based on blends of polyolefins are an important family of engineering materials. Their importance arises from a combination of rubbery properties along with their thermoplastic nature in contrast to thermoset elastomers. The development of polyolefin thermoplastic elastomer blends follows somewhat that of thermoplastic elastomers based on block copolymers such as styrene-butadiene-styrene triblock copolymer and multisegmented polyurethane thermoplastic elastomers which were instrumental in showing the utility of thermoplastic processing methods. Polyoleflns are based on coordination catalysts that do not easily lend themselves to block or multisegmented copolymer synthesis. However, since polyolefins have many important attributes favorable to useful elastomeric systems, there was considerable incentive to produce thermoplastic elastomers based on simple α-olefins by some means. Low density, chemical stability, weather resistance, and ability to accept compounding ingredients without compromising physical properties are highly desirable. These considerations led to the development of polyolefin thermoplastic elastomer blends, and two types are now widely used: blends of ethylene-propylene rubber (EPM) with polypropylene (PP) and blends of EPDM and PP in which the rubber phase is highly crosslinked. This article reviews the nature of these blends. Both physical and Theological properties are very dependent on the morphology and crosslink density of the blend system. Moreover, the usefulness of practical systems depends extensively on compounding technology based on added plasticizers and fillers.

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Chouliaras, Thanasis, Aristofanis Vollas, Theophilos Ioannides, Valadoula Deimede, and Joannis Kallitsis. "Synthesis of Imidazolium based PILs and Investigation of Their Blend Membranes for Gas Separation." Membranes 9, no. 12 (December 3, 2019): 164. http://dx.doi.org/10.3390/membranes9120164.

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Polymeric (ionic liquid) (PIL) copolymers bearing cationic imidazolium pendants and polar acrylic acid groups (P(VBCImY-co-AAx)), which both favor the interaction with CO2 molecules, have been synthesized and blended with film forming, high glass transition temperature aromatic polyether-based pyridinium PILs (PILPyr). The blend membranes based on the above combination have been prepared and characterized in respect to their thermal and morphological behavior as well as to their gas separation properties. The used copolymers and blends showed a wide range of glass transition temperatures from 32 to 286 °C, while blends exhibited two phase morphology despite the presence of polar groups in the blend components that could participate in specific interactions. Finally, the membranes were studied in terms of their gas separation behavior. It revealed that blend composition, counter anion type and acrylic acid molar percentage affect the gas separation properties. In particular, PILPyr-TFSI/P(VBCImTFSI-co-AA20) blend with 80/20 composition shows CO2 permeability of 7.00 Barrer and quite high selectivity of 103 for the CO2/CH4 gas pair. Even higher CO2/CH4. selectivity of 154 was achieved for PILPyr-BF4/P(VBCImBF4-co-AA10) blend with composition 70/30.

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Ignaczak, Sobolewski, and El Fray. "Bio-Based PBT–DLA Copolyester as an Alternative Compatibilizer of PP/PBT Blends." Polymers 11, no. 9 (August 29, 2019): 1421. http://dx.doi.org/10.3390/polym11091421.

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The aim of this work was to assess whether synthesized random copolyester, poly(butylene terephthalate-r-butylene dilinoleate) (PBT–DLA), containing bio-based components, can effectively compatibilize polypropylene/poly(butylene terephthalate) (PP/PBT) blends. For comparison, a commercial petrochemical triblock copolymer, poly(styrene-b-ethylene/butylene-b-styrene) (SEBS) was used. The chemical structure and block distribution of PBT–DLA was determined using nuclear magnetic resonance spectroscopy and gel permeation chromatography. PP/PBT blends with different mass ratios were prepared via twin-screw extrusion with 5 wt% of each compatibilizer. Thermogravimetric analysis, differential scanning calorimetry, and dynamic mechanical analysis were used to assess changes in phase structure of PP/PBT blends. Static tensile testing demonstrated marked improvement in elongation at break, to ~18% and ~21% for PBT–DLA and SEBS, respectively. Importantly, the morphology of PP/PBT blends compatibilized with PBT–DLA copolymer showed that it is able to act as interphase modifier, being preferentially located at the interface. Therefore, we conclude that by using polycondensation and monomers from renewable resources, it is possible to obtain copolymers that efficiently modify blend miscibility, offering an alternative to widely used, rubber-like petrochemical styrene compatibilizers.

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Fortelný, Ivan, and Josef Jůza. "The Effects of Copolymer Compatibilizers on the Phase Structure Evolution in Polymer Blends—A Review." Materials 14, no. 24 (December 16, 2021): 7786. http://dx.doi.org/10.3390/ma14247786.

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This paper summarizes the results of studies describing the effect of block and graft copolymers on the phase structure formation and evolution in immiscible polymer blends. The main phenomenological rules for prediction of the copolymer compatibilization efficiency are briefly described and compared with selected experimental data. The results of the theories of equilibrium distribution of a copolymer between the blend interface and the bulk phases and its effect on the blend interfacial tension are summarized. The theories of the compatibilizer effect on the droplet breakup in flow are analyzed. The mechanisms of the copolymer effect on the coalescence of droplets in flow are compared and their effect on the droplet size is shown. The problems of reliable description of the effect of a copolymer on the coalescence in quiescent state are presented. Obstacles to derivation of a realistic theory of the copolymer effect on the competition between the droplet breakup and coalescence are discussed. Selected experimental data are compared with the theoretical results.

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Zanzig, David J., Fred L. Magnus, W. L. Hsu, Adel F. Halasa, and Marty E. Testa. "IBR Block Copolymers as Compatibilizers in NR/BR Blends." Rubber Chemistry and Technology 66, no. 4 (September 1, 1993): 538–49. http://dx.doi.org/10.5254/1.3538326.

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Abstract The effect of the addition of 1,4-polyisoprene-1 ,4-polybutadiene (IBR) block copolymers on polymer compatibility and vulcanizate properties of a natural rubber/cis-1,4-polybutadiene rubber blend is studied. Differential scanning calorimetry and transmission electron microscopy are used to determine the degree of polymer compatibility and vulcamzate properties are measured in a sulfur cured, carbon-black filled rubber compound Block copolymer composition, concentration and molecular weight are found to be critical. Improvements in compatibility and vulcamzate properties are observed at low concentrations of IBR block copolymers.

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Seier, Martina, Sascha Stanic, Thomas Koch, and Vasiliki-Maria Archodoulaki. "Effect of Different Compatibilization Systems on the Rheological, Mechanical and Morphological Properties of Polypropylene/Polystyrene Blends." Polymers 12, no. 10 (October 13, 2020): 2335. http://dx.doi.org/10.3390/polym12102335.

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The influence of reactive processing, non reactive and reactive copolymers on immiscible polypropylene (PP)–polystyrene (PS) blends with varying PS concentrations (10 wt.% and 25 wt.%) was evaluated by mechanical (tensile and tensile impact), rheological (melt flow rate, extensional and dynamic rheology) and morphological (scanning electron microscopy) analysis. As an extended framework of the study, the creation of a link to industrial applicable processing conditions as well as an economically efficient use of compatibilzing agent were considered. For radical processed blends, a high improvement in melt strength was observed while non reactive copolymers exhibited a pronounced increase in toughness and ductility correlated with overall best phase homogeneity. Conversely, the influence of the reactive copolymer was quite different for the varied PS concentrations not allowing the assumption of a specific trend for resulting blend properties, but nevertheless in the case of a lower PS concentration the tensile impact strength exceeded the value of virgin PP. Since PS and PP are widely used, the findings of this work could not only be relevant for the generation of more versatile blends compared to virgin components but also for recycling purposes, allowing the enhancement of specific properties facilitating the production of more valuable secondary materials.

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Traxler, Ines, Hannes Kaineder, and Joerg Fischer. "Simultaneous Modification of Properties Relevant to the Processing and Application of Virgin and Post-Consumer Polypropylene." Polymers 15, no. 7 (March 30, 2023): 1717. http://dx.doi.org/10.3390/polym15071717.

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Post-consumer recyclates often have a property profile that results from mixing a variety of products, which are made from different materials, produced by different processing methods, and coming from applications with different lifetimes. This usually leads to a mixture of all these material properties in the recycling process. In contrast, virgin materials are specifically designed for applications and thus offer all the necessary properties for the intended products. In order to be able to use recycled materials for specific and demanding applications, not only the viscosity, which is important for processing and often varies greatly with recyclates, but also the mechanical properties, particularly the tensile modulus and impact strength, must be adjusted. For this purpose, various virgin materials of polypropylene homopolymers, random copolymers, and block copolymers with different flowabilities were mixed in different proportions and their properties were determined. The flowability of homopolymers and random copolymers in the blend behaved very similarly, while block copolymers exhibited a different behavior in some cases. By incorporating homopolymers into blends, the stiffness of the resulting material blend can be very well adjusted. The addition of random copolymers can increase strain at break, and the addition of block copolymers results in a significant increase in impact strength. In numbers, the maximum adjustment range for tensile modulus, yield stress, strain at break, and impact strength are 880 MPa, 14 MPa, 185%, and 6.9 kJ/m2, respectively. While a good and reliable prediction of property profile is possible for polymer blends with different virgin materials, the resulting material properties for polymer blends of virgin and recycled materials are also influenced by impurities. In this work, however, a good prediction was also achieved for recyclate blends.

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Subramanian, P. M. "Polyethylene Terephthalate Blends." International Polymer Processing 3, no. 1 (March 1, 1988): 33–37. http://dx.doi.org/10.1515/ipp-1988-0002.

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Abstract Polymer-Polymer blends containing ethylene-methacrylic copolymers (EMAA) and polyethylene terephthalate (PET) (where PET is the minor component) have been investigated. The permeability properties and the morphology of these blends, when the polyolefin phase is mildly crosslinked with small amounts of an agent that preferentially crosslinks the ethylene copolymer was also studied. The permeability barrier properties of such polymer blends increase as the concentration of the crosslinking agents increase until excessive crosslinking takes place. The morphology of the blends – the size of the dispersed particles – change significantly as more coupling agents are used. These techniques afford us a novel technique to improve the permeability barrier properties by control of the particle size of the barrier polymer.

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Zhang, Yajing, Mingda Wang, Di Zhang, Yibing Wang, Li Wang, Yongjun Qiu, Liquan Wang, Tao Chen, and Liming Zhao. "Crystallization and Performance of Polyamide Blends Comprising Polyamide 4, Polyamide 6, and Their Copolymers." Polymers 15, no. 16 (August 14, 2023): 3399. http://dx.doi.org/10.3390/polym15163399.

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Polyamide 4 (PA4) is a biobased and biodegradable polyamide. The high hydrogen bond density of PA4 bestows it with a high melting point that is close to its thermal decomposition temperature, thereby limiting the melt processing of PA4. In this study, PA4 was blended with polyamide 6 (PA6) and further modified with copolyamide 4/6 (R46). The effects of composition on the crystallization behavior of the blends were studied. The results demonstrated that the binary PA4/PA6 (B46) and ternary PA4/PA6/R46 (B46/R46) blends formed two crystalline phases (PA4- and PA6-rich phases) through crystallization-induced phase separation. With increasing PA6 content, the thermal stability and crystallinity of the B46 blend increased and decreased, respectively, and the contribution of PA6 toward the crystallization of the PA4-rich phase diminished. Molecular dynamics simulations showed the molecular chain orientation of the B46 blends well. The melting points, crystallinities, and grain sizes of the B46/R46 blends were lower than those of the B46 blends. The crystallization of the PA4-rich phase was restrained by the dilution effect of molten-state PA6, and the nucleation and crystallization of the PA6-rich phase were promoted by the presence of crystallized PA4. The B46 blends with 30–40 wt% PA6 had the best mechanical properties.

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Liu, Yongjun, Ming Zhong, Gang Liu, and Shouzhi Pu. "Formation of high-density polyethylene–poly(ethylene-octene) core–shell particles in recycled poly(ethylene terephthalate) by reactive blending." Progress in Rubber, Plastics and Recycling Technology 35, no. 3 (April 21, 2019): 117–37. http://dx.doi.org/10.1177/1477760619843536.

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Recycled poly(ethylene terephthalate) (R-PET)/high-density polyethylene (HDPE)/glycidyl methacrylate grafted poly(ethylene-octene) (mPOE) blends, in which the binary (HDPE/mPOE) dispersed phase was of a HDPE core-mPOE shell structure, were prepared. For this purpose, HDPE-g-mPOE graft copolymers were prepared in HDPE/mPOE blends via reactive extrusion with the presence of the free radical initiator dicumyl peroxide (DCP). Then, R-PET was blended with the HDPE/mPOE blends by melt extrusion. The effect of the DCP and mPOE content in the HDPE/mPOE blends on the phase morphology and mechanical properties of the R-PET/HDPE/mPOE blends were studied systematically. It was found that the blends containing reactive compatibilizer exhibited the encapsulation of the HDPE by the mPOE, forming core–shell particles dispersed phase morphology. The graft chains of HDPE-g-mPOE-g-PET formed by the in situ reaction between R-PET and mPOE phases reduced the interfacial tension. Consequently, the dispersed phase morphology was observed to form smaller diameter core–shell particles. The resultant blends exhibited an effect on both the thermal and mechanical properties. Differential scanning calorimetric analysis showed the dispersed phase particles could act as a nucleating agent in the R-PET matrix to improve the crystallization temperature, while the graft copolymers formed in the compatibilized R-PET/HDPE/mPOE blend decreased the nucleation activity. Notched Charpy impact strength and elongation at break of the R-PET were improved by forming the core–shell particles dispersed phase morphology.

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Spontak, Richard J., Steven D. Smith, and Arman Ashraf. "Molecular-weight factors affecting formation of the OBBD morphology in block copolymer blends." Proceedings, annual meeting, Electron Microscopy Society of America 50, no. 2 (August 1992): 1028–29. http://dx.doi.org/10.1017/s0424820100129772.

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Microphase-separated diblock copolymers have been known since 1970 to exhibit three principal morphologies. These morphologies depend on the composition of the copolymer and include dispersed spheres of the minor component on either a BCC or FCC lattice, dispersed cylinders of the minor component on a hexagonal lattice, or alternating lamellae. Recent microstructural studies of starblock and diblock copolymers have shown that an ordered bicontinuous morphology is observed between the lamellar and cylindrical regimes. This microstructure is currently referred to as the ordered bicontinuous double-diamond (OBDD) morphology and is an example of the Pn3m space group. In poly(styrene-b-isoprene) (SI) diblock copolymers, it exists at approximately 62-66 vol% polystyrene (PS). Efforts aimed at producing this morphology by blending a copolymer with various PS homopolymers have also been successful, when the blend composition is 65-67 vol% PS and the molecular weight of the hompolymer (Mhps) is less than that of the styrene block in the copolymer (Ms). In this work, we have used transmission electron microscopy to elucidate some additional factors responsible for development of the OBDD and other bicontinuous morphologies.

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29

Pandit, Rajesh, Albrecht Berkessel, Ralf Lach, Wolfgang Grellmann, and Rameshwar Adhikari. "Synthesis and Characterization of Nanostructured Blends of Epoxy Resin and Block Copolymers." Nepal Journal of Science and Technology 13, no. 1 (January 21, 2013): 81–88. http://dx.doi.org/10.3126/njst.v13i1.7445.

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Polystyrene–polybutadiene block copolymers having different molecular architectures were epoxidized by using meta-chloroperoxybenzoic acid (MCPBA). Then, the blends with epoxy resin (diglycidyl ether of bisphenol-A; DGEBA) and their nanocomposites with boehmite and layered silicate nanofiller in presence of methylene dianiline (MDA) as a hardener were prepared. The epoxidized copolymers and the composites were characterized by Fourier transform infrared (FTIR) spectroscopy and microindentation technique. In this way, it was possible to tune the morphology of the nanostructured blends of the epoxy resin using the functionalized block copolymer as the template. The presence of nanostructured morphology was attested by the optical transparency of the blends as well as of the composites with nanofiller. The microhardness properties were improved by the incorporation of the nanoparticles, viz. boehmite and layered silicate. Nepal Journal of Science and Technology Vol. 13, No. 1 (2012) 81-88 DOI: http://dx.doi.org/10.3126/njst.v13i1.7445

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Nir, Moira Marx, and Robert E. Cohen. "Mechanical Properties of Blends of Crystallizable Polybutadienes Containing Amorphous Polybutadiene Diblock Copolymers." Rubber Chemistry and Technology 67, no. 2 (May 1, 1994): 342–47. http://dx.doi.org/10.5254/1.3538679.

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Abstract Tensile failure properties of syndiotactic 1,2 polybutadiene/trans 1,4 polybutadiene crystalline blends are improved by addition of 5–10% amorphous 1,2 polybutadiene/1,4 polybutadiene diblock copolymer. The effect of block molecular weight and microphase behavior of the diblock copolymer was investigated. Heterogeneous diblocks enhance blend properties to a greater extent than homogeneous diblocks. In blends with enhanced properties, percent coverage of interfacial surface area by diblock is on the order of 10%.

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31

Moolsin, Supat, Nattawud Saksayamkul, and Adul Na Wichien. "Natural rubber grafted poly(methyl methacrylate) as compatibilizer in 50/50 natural rubber/nitrile rubber blend." Journal of Elastomers & Plastics 49, no. 5 (October 7, 2016): 422–39. http://dx.doi.org/10.1177/0095244316671021.

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The effects of graft copolymers applied as compatibilizers for natural rubber/nitrile rubber (NR/NBR) blends at 50/50 (w/w) on cure characteristics, mechanical properties, thermal properties, oil resistance, and morphology were investigated. The graft copolymers of methyl methacrylate (MMA) onto NR initiated by benzoyl peroxide (NR- g-PMMA<BPO>) and by potassium persulfate (NR- g-PMMA<PPS>) under emulsion polymerization were synthesized and used to compatibilize the blends. The structures of the copolymers were characterized by Fourier transform infrared spectroscopy and proton nuclear magnetic resonance spectroscopy. NR was blended with NBR via a two-roll mill at 70°C under the compatibilizer loading ranging from 0 to 10 parts per hundred of rubber (phr). The results showed that the tensile property and tear strength of the blends increased with the increasing amount of NR- g-PMMA<BPO> as a compatibilizer. Thermal aging determined in terms of tensile properties exhibited the smaller difference between before and after aging in an oven with the increasing compatibilizer loading. The morphology of the compatibilized NR/NBR vulcanizates was investigated by scanning electron microscopy of the tensile fracture surfaces, which exhibited the improvement of interfacial adhesion between the two rubber phases. The thermal properties of compatibilized NR/NBR vulcanizates were reported in terms of a glass transition temperature under differential scanning calorimetry and dynamic mechanical analysis. The incorporation of an appropriate amount of the compatibilizer into the blends apparently improved the oil resistance of NR. Among them, the blend filled with 7.5 phr of NR- g-PMMA<BPO> showed the lowest volume change in IRM 903 oil.

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32

Estagy, Sara, Saeed Ostad Movahed, Soheil Yazdanbakhsh, and Majid Karim Nezhad. "STUDY OF THE FRIEDEL–CRAFT CO-CURING OF ETHYLENE–PROPYLENE–DIENE RUBBER AND STYRENE–BUTADIENE RUBBER." Rubber Chemistry and Technology 89, no. 3 (September 1, 2016): 540–56. http://dx.doi.org/10.5254/rct.16.83801.

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ABSTRACT Polymer blends are mixtures of at least two macromolecular species, polymers, and/or copolymers. A good blend should have strong interphases between different parts of the constituent polymers. To improve adhesion and miscibility of EPDM and SBR in their blends, a Lewis acid, AlCl3, was used to form EPDM-g-SBR copolymer through Friedel–Craft reactions. The effects of blend AlCl3 content, the diene monomer content of the EPDM, the EPDM–SBR weight ratio in the blend, the room temperature aging of the blend, and the type of the oil in the blend on cross-link reactions were studied. The results showed that an increase in AlCl3 content, up to 2 phr in the formulation, was beneficial to ΔTorque (difference between minimum and maximum torque in cure trace) and cross-link density (CLD) values of the compounds. The viscosity of the blends played a key role on AlCl3 curing of the compounds. As a general rule, the ΔTorque and CLD values tended to increase with diene monomer content of the EPDM. A high reduction in ΔTorque values was observed after 3 months of aging at room temperature. The oil incorporation was beneficial to cure parameters in the following order: oleic acid, paraffin oil, no oil, and aromatic oil, respectively. The EPDM–SBR weight ratios of 50:50 and/or 60:40 were demonstrated to be desired blend ratios.

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Chu, J. H., H. K. Tilakaratne, and D. R. Paul. "Blends of tribromostyrene copolymers." Polymer 41, no. 14 (June 2000): 5393–403. http://dx.doi.org/10.1016/s0032-3861(99)00738-7.

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Goldacker, Thorsten, Volker Abetz, and Reimund Stadler †. "Blends of block copolymers." Macromolecular Symposia 149, no. 1 (January 2000): 93–98. http://dx.doi.org/10.1002/1521-3900(200001)149:1<93::aid-masy93>3.0.co;2-w.

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35

Braun, D., D. Yu, L. N. Andradi, B. Löwenhaupt, and G. P. Hellmann. "Polymer blends containing copolymers." Makromolekulare Chemie. Macromolecular Symposia 48-49, no. 1 (August 1991): 55–70. http://dx.doi.org/10.1002/masy.19910480108.

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Khosravi, Tayebeh, and Mohammadreza Omidkhah. "Preparation of CO2-philic polymeric membranes by blending poly(ether-b-amide-6) and PEG/PPG-containing copolymer." RSC Advances 5, no. 17 (2015): 12849–59. http://dx.doi.org/10.1039/c4ra14168g.

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Membranes from the block copolymer poly(ether-b-amide-6) (Pebax® MH 1657) and its blends with PEG-block-PPG-block-PEG and PEG-ran-PPG copolymers were prepared, combining the beneficial properties of PEG (high selectivity) with those of PPG (high permeability, amorphous).

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Fage, J., K. Knoll, N. Niessner, O. Carstensen, T. Schulz, F. Malz, M. Döring, and F. Schönberger. "Poly (Butyl Acrylate)-Graft-Polystyrene Synthesis by Free-Radical Polymerization: Interplay between Structure, Morphology, Mechanical, and Optical Properties." Polymers 11, no. 8 (August 7, 2019): 1317. http://dx.doi.org/10.3390/polym11081317.

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We report a new method of preparation of poly (butyl acrylate)-g-polystyrene/polystyrene blends by free-radical polymerization. Copolymerization of glycidyl (meth)acrylate with butyl acrylate is followed by a polymer analogous reaction of this copolymer with acrylic acid and subsequent copolymerization of the modified backbone with styrene. Investigation on the number of reactive groups per backbone chain and its molecular weight allows grafting efficiencies of about 35% to be reached, as well as low cross-linking. Blends of nanophase-separated copolymers having a backbone with Mn of around 50 kg/mol and 4 reactive groups per chain are transparent, with haze as low as 14%, tensile strength of around 22 MPa, and elongations at the break of around 3%. Correlation between morphology determined by transmission electron microscopy and properties of the blend is established.

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Li, Xiaodan, Fei Zhou, Ting Zheng, Ziqiao Wang, Heng Zhou, Haoran Chen, Lin Xiao, Dongxing Zhang, and Guanhui Wang. "Blends of Cyanate Ester and Phthalonitrile–Polyhedral Oligomeric Silsesquioxane Copolymers: Cure Behavior and Properties." Polymers 11, no. 1 (January 1, 2019): 54. http://dx.doi.org/10.3390/polym11010054.

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Blends of cyanate ester and phthalonitrile–polyhedral oligomeric silsesquioxane copolymers were prepared, and their cure behavior and properties were compared via differential scanning calorimetry (DSC) analysis, thermogravimetric (TG) analysis, dynamic mechanical analysis, Fourier-transform far-infrared (FTIR) spectroscopy, and rheometric studies. The copolymer blends showed high chemical reactivity, low viscosity, and good thermal stability (TG temperatures were above 400 °C). The glass-transition temperature of the blends increased by at least 140 °C compared to cyanate ester resin. The blends are suitable for preparing carbon-fiber-reinforced composite materials via a winding process and a prepreg lay-up process with a molding technique. The FTIR data showed that the polymerization products contained triazine-ring structures that were responsible for the superior thermal properties.

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Sriromreun, P., Mantana Opaprakasit, Atitsa Petchsuk, and Pakorn Opaprakasit. "Synthesis and Characterization of Degradable Poly(Ethylene Terephthalate-co-Lactic Acid) and its Blends." Advanced Materials Research 55-57 (August 2008): 789–92. http://dx.doi.org/10.4028/www.scientific.net/amr.55-57.789.

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Because of their respective advantages, the combination of good material properties of poly(ethylene terephthalate) (PET) and degradability of polylactic acid (PLA) is researched as degradable copolymer for packaging and agricultural applications. Poly(ethylene terephthalate-co-lactic acid) (PET-co-PLA) has been synthesized by employing polycondensation of mixtures of dimethyl terephthalate (DMT), lactic acid (LA) and ethylene glycol (EG), using tin(II) octoate as a catalyst. A chain-extending reagent, hexamethylene diisocyanate (HMDI), was then used in the subsequent step to increase the chain length of the copolymer and improve its mechanical properties for suitable applications. The chemical structure and molecular weight of the copolymers were investigated by FTIR, NMR, and DSC. NMR results indicated the incorporation of lactic acid and PET units in the copolymer chain. Additionally, blends of the resulting copolymer with commercially-available PLA were studied. The blend miscibility was examined by DSC and FTIR spectroscopy.

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Benmouna, A., R. Benmouna, M. R. Bockstaller, and I. F. Hakem. "Self-Organization Schemes towards Thermodynamic Stable Bulk Heterojunction Morphologies: A Perspective on Future Fabrication Strategies of Polymer Photovoltaic Architectures." Advances in Physical Chemistry 2013 (April 16, 2013): 1–8. http://dx.doi.org/10.1155/2013/948189.

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Research efforts to improve our understanding of electronic polymers are developing fast because of their promising advantages over silicon in photovoltaic solar cells. A major challenge in the development of polymer photovoltaic devices is the viable fabrication strategies of stable bulk heterojunction architecture that will retain functionality during the expected lifetime of the device. Block copolymer self-assembly strategies have attracted particular attention as a scalable means toward thermodynamically stable microstructures that combine the ideal geometrical characteristics of a bulk heterojunction with the fortuitous combination of properties of the constituent blocks. Two primary routes that have been proposed in the literature involve the coassembly of block copolymers in which one domain is a hole conductor with the electron-conducting filler (such as fullerene derivatives) or the self-assembly of block copolymers in which the respective blocks function as hole and electron conductor. Either way has proven difficult because of the combination of synthetic challenges as well as the missing understanding of the complex governing parameters that control structure formation in semiconducting block copolymer blends. This paper summarizes important findings relating to structure formation of block copolymer and block copolymer/nanoparticle blend assembly that should provide a foundation for the future design of block copolymer-based photovoltaic systems.

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Reglero, Jose Antonio, Philippe Viot, and Michel Dumon. "Foaming of amorphous polymers and blends in supercritical CO2: Solubility versus block copolymers addition." Journal of Cellular Plastics 47, no. 6 (November 2011): 535–48. http://dx.doi.org/10.1177/0021955x11415925.

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Supercritical CO2 (scCO2) is used as a medium for foaming amorphous polymers. Astudy of the solubility of supercritical CO2 in several amorphous polymers (PS andPMMA) and blends is performed, followed by an investigation of the foaming behavior of the polymer–gas systems. Nano-structuring triblock copolymers (styrene-co- butadiene-co-methylmethacrylate SBM and methylmethacrylate-co-butylacrylate-co- methylmethacrylate MAM) were blended as additives to PS or PMMA by extrusion. The addition of these triblock copolymers results in an important weight gain ratio of gas in a wide range of temperatures (from 25 to 80°C), relating this weight gain ratio to the foaming behavior of the blends (CO2 is preferentially located in the micro or nano-domains issued from the structuration of the block copolymer). Foaming is carried out in a batch one-step scCO2 process, keeping constant the saturation pressure and depressurization rate (300 bar and 60 bar/min, respectively). Influence of saturation temperature (25–85 °C) on the final porous structure is shown. In spite of the influence of the terpolymer on the weight gain ratio, the structuration is believed to provide a good control of microcellular foams in PS and PMMA.

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Cimrová, Věra, Veronika Pokorná, Vagif Dzhabarov, and Drahomír Výprachtický. "Semiconducting Conjugated Copolymer Series for Organic Photonics and Electronics." Materials Science Forum 851 (April 2016): 173–78. http://dx.doi.org/10.4028/www.scientific.net/msf.851.173.

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Donor–acceptor copolymer series containing 4,6-di (thien-2′-yl) thieno [3,4-c][1,2,5] thiadiazole or its derivatives serving as electron-acceptor units and various electron-donor units such as 9,9-bis (alkyl) fluorene, benzene, bithiophene or carbazole derivatives is reported. These copolymers possess narrow optical band gap in the range of 1.0 - 1.5 eV depending on the character of the donor units. They exhibit relatively high electron affinity. Absorption of copolymer thin films covers the whole visible spectral region extended up to NIR for some copolymers. The influence of side chain nature and molecular weight on their photophysical properties is shown. Selected copolymers are used in the blends with fullerene derivative [6,6]-phenyl-C61-butyric acid methyl ester ([60]PCBM) as active layers in bulk heterojunction photovoltaic devices. The results are discussed in relation to the copolymer structure, side chain nature and molecular weight.

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Jinxin, He, Guo Yang, Sun Shulin, and Zhang Huixuan. "Influence of methyl methacrylate-co-glycidyl methacrylate copolymers on the compatibility, morphology and mechanical properties of poly(butylene terephthalate) and polycarbonate blends." Journal of Polymer Engineering 35, no. 3 (April 1, 2015): 247–56. http://dx.doi.org/10.1515/polyeng-2014-0200.

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Abstract Methyl methacrylate-co-glycidyl methacrylate copolymers (MMA-co-GMA) were prepared to compatibilize the poly(butylene terephthalate) (PBT) and polycarbonate (PC) blends. The chemical reactions between the PBT and the epoxy groups and the good miscibility between the PC and the poly(methyl methacrylate) (PMMA) phase were responsible for the excellent compatibilization effect of the MMA-co-GMA copolymers. The MMA-co-GMA copolymers decreased the melting and crystallization temperature of the PBT phase in the PBT/PC blends. Dynamic mechanical analysis result showed that the exchange reactions were inhibited due to the compatibilization reactions owing to the consumption of the carboxyl/hydroxyl end groups of the PBT phase. MMA-co-GMA copolymers decreased the phase domain size of the PBT/PC blends, and with the increase in GMA content in the MMA-co-GMA copolymers, the blends changed from a double continuous phase to a single continuous phase structure. Tensile test indicated that the yield stress, elongation at break and elastic modulus of the PBT/PC blends increased due to the addition of MMA-co-GMA. The impact strength of the blends changed unnoticeably.

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Tzoumani, Ioanna, Zacharoula Iatridi, Athena M. Fidelli, Poppy Krassa, Joannis K. Kallitsis, and Georgios Bokias. "Room-Temperature Self-Healable Blends of Waterborne Polyurethanes with 2-Hydroxyethyl Methacrylate-Based Polymers." International Journal of Molecular Sciences 24, no. 3 (January 29, 2023): 2575. http://dx.doi.org/10.3390/ijms24032575.

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The design of self-healing agents is a topic of important scientific interest for the development of high-performance materials for coating applications. Herein, two series of copolymers of 2-hydroxyethyl methacrylate (HEMA) with either the hydrophilic N,N-dimethylacrylamide (DMAM) or the epoxy group-bearing hydrophobic glycidyl methacrylate were synthesized and studied as potential self-healing agents of waterborne polyurethanes (WPU). The molar percentage of DMAM or GMA units in the P(HEMA-co-DMAMy) and P(HEMA-co-GMAy) copolymers varies from 0% up to 80%. WPU/polymer composites with a 10% w/w or 20% w/w copolymer content were prepared with the facile method of solution mixing. Thanks to the presence of P(HEMA-co-DMAMy) copolymers, WPU/P(HEMA-co-DMAMy) composite films exhibited surface hydrophilicity (water contact angle studies), and tendency for water uptake (water sorption kinetics studies). In contrast, the surfaces of the WPU/P(HEMA-co-GMAy) composites were less hydrophilic compared with the WPU/P(HEMA-co-DMAMy) ones. The room-temperature, water-mediated self-healing ability of these composites was investigated through addition of water drops on the damaged area. Both copolymer series exhibited healing abilities, with the hydrophilic P(HEMA-co-DMAMy) copolymers being more promising. This green healing procedure, in combination with the simple film fabrication process and simple healing triggering, makes these materials attractive for practical applications.

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Stehlíček, Jaroslav, Jana Kovářová, and František Lednický. "Block Copolymers Poly(2,6-dimethyl-1,4-phenylene oxide)-poly(6-hexanelactam). Physical Properties." Collection of Czechoslovak Chemical Communications 58, no. 10 (1993): 2437–43. http://dx.doi.org/10.1135/cccc19932437.

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In powdery poly(2,6-dimethyl-1,4-phenylene oxide)-poly(6-hexanelactam) diblock copolymers, the occurrence of an amorphous interphase consisting of both the blocks was indirectly proved by calorimetric and sorption methods. The copolymer shows a compatibilizing effect in solution-cast films made from the blends of both homocopolymers.

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Khatiwada, Shankar P., Sabu Thomas, Jean Marc Saiter, Ralf Lach, and Rameshwar Adhikari. "Mechanical and thermal properties of triblock copolymer modified epoxy resins." BIBECHANA 16 (November 22, 2018): 196–203. http://dx.doi.org/10.3126/bibechana.v16i0.21651.

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We investigate the ways of improving thermal and mechanical properties of diglycidyl ether of bisphenol-A (DGEBA) based thermoset resin using diaminodiphenylsulphone (DDS) as hardener and using epoxidized polystyrene/polybutadiene-based triblock copolymers as modifier. The epoxidation was performed. The targeted chemical modification using meta-chloroperoxybenzoic acid (m-CPBA) of the copolymer was performed whereby the epoxidation of the butadiene chains mainly took place at 1,4 linkages. The modification copolymer was found to contribute in enhancing the mechanical performance of the blends with epoxy resin. The results indicated the formation of nanostructured morphology in the blends attributable to their enhanced impact strength.BIBECHANA 16 (2019) 196-203

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Liu, Dongmei, Huifeng Bo, Yongchao Jin, Deyang Li, Zhanxin Zhang, Kai Gong, Ye Lin, and Sijia Li. "Effects of concentration and chain length of the sequence copolymer on interfacial properties of homopolymers/sequence copolymers ternary blends: A DPD simulation study." PLOS ONE 17, no. 7 (July 26, 2022): e0270094. http://dx.doi.org/10.1371/journal.pone.0270094.

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The effect of the concentration and chain length of the copolymer AB with sequence length τ = 8 on the interfacial properties of the ternary mixtures A10/AB/B10 are investigated by the dissipative particle dynamics (DPD) simulations. It is found that: i) As the copolymer concentration varies from 0.05 to 0.15, increasing the copolymer enrichment at the center of the interface enlarges the interface width ω and reduces the interfacial tension. However, as the concentration of the sequence copolymers further increases to 0.2, because the interface has formed micelles and the micellization could lower the efficiency of copolymers as a compatibilizer, the interfacial tension exhibits a slightly increase; ii) elevating the copolymer chain length, the copolymer volumes vary from a cylinder shape to a pancake shape. The blends of the copolymer with chain length Ncp = 24 exhibit a wider interfacial width w and a lower interfacial tension γ, which indicates that the sequenced copolymer Ncp = 24 exhibits a better performance as the compatibilizers. This study illustrates the correlations between the reduction in interfacial tension produced by the sequence copolymers and their molecular parameters, which guide a rational design of an efficient compatibilizer.

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Lin, Hu Bin, Chong Min Du, Jian Yi Zhu, and Wen Yao Liang. "Morphology and Mechanical Properties of Compatibilized β Nucleated Polypropylene/Polystyrene Blends." Advanced Materials Research 902 (February 2014): 63–65. http://dx.doi.org/10.4028/www.scientific.net/amr.902.63.

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The β nucleated polypropylene (PP), uncompatibilized β nucleated PP/polystyrene (PS) and compatibilized β nucleated PP/PS blends were prepared on a twinscrew extruder.and then,added into compatibilizers styrene-ethylene-propylene block copolymer (SEP) or twostyrene-ethylene-butylene-styrene block copolymers (SEBS) with different content of styrene.The morphology and mechanical properties of these composites were investigated.

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Wang, Xiong, Sheng Hu, Yi Guo, Guangquan Li, and Renwei Xu. "Toughened High-Flow Polypropylene with Polyolefin-Based Elastomers." Polymers 11, no. 12 (December 1, 2019): 1976. http://dx.doi.org/10.3390/polym11121976.

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Polyolefin is the most widely used and versatile commodity polymer. In this work, three types of polyolefin-based elastomers (PBEs) were adopted to toughen a high-flow polypropylene to improve its overall performance. The chain microstructures of these PBEs, including ethylene/1-octene (E/O) random copolymer from Dow Chemical′s polyolefin elastomer (POE), olefin block copolymers (OBCs) of E/O from Dow, and ethylene/propylene random copolymer from ExxonMobil’s propylene-based elastomer, were elucidated by GPC, 13C NMR, TREF, and DSC techniques. The mechanical, thermal and optical properties, and morphology analysis of the PP/PBE blends were also studied to investigate the toughening mechanism of these PBEs. The results showed that all three types of PBEs can effectively improve the Izod impact strength of the PP/PBE blends by the addition of the rubber compositions, at the cost of the stiffness. PBE-1 and PBE-2 were found to have a great stiffness–toughness balance with about 1700 MPa of flexural modulus, about 110 °C of HDT and 3.6 kJ/m2 of impact strength on the prepared PP/PBE blends by forming separated rubber phase and refined spherulite crystals. As a result, the OBC with alternating hard and soft segments could achieve a similar toughening effect as the E/P random copolymer. Surprisingly, no obvious rubber phase separation was observed in the PP/PBE-4 blend, which might be due to the good compatibility of the E/P random chains with the isotactic PP; therefore, the PP/PBE blend obtains great toughness performance and optical transparency with the highest Izod impact strength of 4.2 kJ/m2 and excellent transparency.

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Tembhekar, Sandeep, Madhuchhanda Maiti, Jinu Jacob George, Anjan Biswas, Anil K. Bhowmick, Madhumita Saroop, and Amit Biswas. "High Strength - Low Hardness Thermoplastic Elastomers from Ethylene-Butene Copolymers and Low Density Polyethylene." Rubber Chemistry and Technology 81, no. 1 (March 1, 2008): 60–76. http://dx.doi.org/10.5254/1.3548198.

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Abstract A thermoplastic elastomer (TPE) is a rubbery material with final properties and functional performance similar to those of a conventional vulcanized rubber at ambient temperature, yet it can be processed as a thermoplastic at elevated temperature. The main objective of the present investigation was to prepare novel olefinic thermoplastic elastomers based on blends of a thermoplastic i.e. low density polyethylene (PE) and new ethylene-butene copolymers (PEB), which would have higher strength and lower hardness compared to the existing TPEs. The 70:30 PEB: PE blend exhibited the best properties. Ethylene vinyl acetate was found to work as compatibilizer at lower loadings in these blends. The resultant blends were of low hardness (60–80 Shore A) and high strength (26–33 MPa). The interaction parameter and the morphology of the blends were the key parameters, which governed the final properties of blends.

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Journal articles on the topic 'Copolymers and blends'

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