The effects of morphological changes on the thermal expansion, toughness and heat resistance of polyamide-6 (PA)/styrene–ethylene–butylene–styrene (SEBS)/polyphenylene ether (PPE) blends were investigated. Compared with the typical ‘sea (PA matrix)–island (PPE domain)–lake (SEBS in PPE domain)’ morphology, an injection-molded ternary blend with a preferential distribution of SEBS component at the interface between PA and PPE exhibited a low coefficient of linear thermal expansion (CLTE) in the flow direction. This low CLTE was ascribed to the deformation of SEBS and PA into a co-continuous microlayer network structure during injection molding. Consequently, the expansion preferentially occurred towards the thickness direction. Further CLTE reduction either by a change in PA viscosity or by the selective location of an inorganic filler was examined, and its influences on impact strength and heat resistance are discussed based on transmission electron microscopy observations. © 2015 Society of Chemical Industry

Nanocomposite microspheres containing styrene–acrylate resin, wax, and carbon black (CB) with desired CB dispersion were prepared through heterocoagulation. The CB surface was modified using conventional anionic emulsifier and anionic dispersants with different lengths of nonionic chains and reactivities or through polymer encapsulation via emulsion polymerization to regulate the dispersion and concentration of CB in the microspheres. Experimental results showed that anionic dispersants with long nonionic chains effectively dispersed and stabilized CB particles. Polystyrene (PS) was then encapsulated on the CB surface by using a reactive dispersant and a water-soluble initiator of polymerization. The CB particles exhibited comparable pH stability with other heterocoagulation components. Overall, encapsulation through emulsion polymerization can be used to obtain not only high CB content but also improved CB distribution in the resulting microspheres. High coagulation efficiency can also be achieved using polystyrene-encapsulated dispersed CB because of its high affinity to emulsifiers and reactive dispersants during dispersion. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43516.

Fine regulation of the microstructure of rubber/polypropylene (PP) alloys could remarkably reduce the coefficient of linear thermal expansion (CLTE) while retaining the mechanical properties similar to those of thermoplastic elastomers. Rubber/PP elastomers with different morphologies were successfully prepared by controlling the appropriate rubber type, viscosity ratio, and processing method. The CLTE of the polymer alloy parallel to the microlayer directions was considerably reduced when the rubber domains were deformed into microlayers and co-continuous with plastic domains. The thickness of the PP layers played a crucial role on CLTE reduction. The CLTE considerably decreased with reduced thickness of the PP layer. The sample with a co-continuous microlayer structure exhibited good flexibility, high elongation, low hardness, and permanent deformation. Thus, low-thermal-expansion elastomer materials may have wide applications. Stress relaxation and strain recovery of the ethylene–propylene–diene terpolymer/PP (70/30 wt %) blend were investigated to further clarify the influence of co-continuous microlayer structure on mechanical properties. Anisotropic mechanical properties were consistent with the morphology. Results of the stress relaxation behavior test would provide further support to the mechanism of the low thermal expansion of blends with co-continuous microlayer structure. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43902.

An ethylene–propylene–diene terpolymer/isotactic polypropylene blend with a structure of co-continuous microlayers was fabricated by injection molding and was then investigated. The blend exhibited an extremely low coefficient of linear thermal expansion (CLTE) in the directions of the length and the width. As the thickness of the oriented portion increased, the CLTE was further reduced. The morphology of the co-continuous microlayers and the thermal expansion behavior varied with the sampling positions on the injection-molded sheets. To study the relationship between the morphology and the melt flow, the melt flow behavior during injection molding was simulated using Moldflow. Orientation of the microlayers was determined using shear flow. When the shear rate increased, the orientation state increased and the CLTE decreased. © 2015 Society of Chemical Industry

The hydrogen bonding interactions between poly(n-butyl methacrylate) and a series of low molecular weight phenols containing two to four hydroxyl groups with different steric effects were investigated by differential scanning calorimetry and Fourier-transform infrared spectroscopy. Results showed that the hydrogen bonding strength between the two components varies greatly according to the steric effects of the phenolic hydroxyl group. As the size of the group beside the hydroxyl increases, the hydrogen bond strength weakens. The glass transition temperature of binary hybrid systems was put into relation with the corresponding hydrogen bonding interaction strength. Strong hydrogen bonding strength increased T_g to higher values than that predicted by the linear additivity rule; by contrast, T_g of hybrid systems with weak hydrogen bonds showed linear changes. All of the samples showed linear variations at low concentrations of small molecules. The damping properties of five systems were analyzed by dynamic mechanical analysis. Either the loss factor or area of tan δ peak of the five systems increased compared with that of the pure polymer, thereby showing great improvements in the damping properties of the poly(n-butyl methacrylate)/small molecule hybrid material. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41954.

Poly(styrene-co-ethyl acrylate) [P(St-co-EA)] with different ratios of St/EA was mixed with the small molecule 4,4′-thio-bis(6-tert-butyl-m-methyl phenol) (AO300) to investigate the influence of hydrogen bonding strength on the glass transition behavior. The glass transition temperature (T_g) linearly increased after adding AO300, and the slope value decreased with increased St/EA ratio. All lines could be extended to 62 °C, demonstrating that T_g of the small molecule in situ detected by the polymer chain was much higher than that by small molecule itself (29 °C). Fourier transform infrared spectroscopy analysis showed that the small molecules began to be self-associated at a concentration where the hydrogen bonded carbonyl ratio of the bulk polymer was approximately 0.5 and irrespective of the St/EA ratio. Above the critical loading, the mixture's T_g negatively deviated from the linearly extended lines because of self-association of the small molecules. The apparent T_g of AO300 was found to strongly depend on intermolecular hydrogen bonding number and strength. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015, 53, 400–408

In this study, poly (lactic acid) (PLA) blended with various rubber components, i.e., poly (ethylene-glycidyl methacrylate) (EGMA), maleic anhydride grafted poly(styrene-ethylene/butylene-styrene) triblock elastomer (m-SEBS), and poly(ethylene-co-octene) (EOR), was investigated. It was observed that EGMA is highly compatible due to its reaction with PLA. m-SEBS is less compatible with PLA and EOR is incompatible with PLA. Electron microscopy (SEM and TEM) revealed that a fine co-continuous microlayer structure is formed in the injection-molded PLA/EGMA blends. This leads to polymer blends with high toughness and very low linear thermal expansion both in the flow direction and in the transverse direction. The microlayer thickness of rubber in PLA blends was found to play key roles in reducing the linear thermal expansion and achieving high toughness of the blends. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

Electrically conductive polymer composites for bipolar plate were fabricated by two-step compression molding technique. Raw materials consisted of natural graphite flakes (G), expanded graphite (EG), carbon black (CB), and phenol resin (PF). The G/EG/CB/PF composites were first compressed at a temperature lower than curing point (100°C) and then cured at a high temperature above curing point (150°C) and high pressure (10 MPa). Results showed that G and EG are oriented in the direction parallel to the composite plate surface. CB is dispersed not only in the phenol resin matrix but also in the packing and porous space of G and EG. The addition of EG and CB significantly increases number of the electrical channels and thus enhances the electrical conductivity of the composite. Under optimal conditions, electrical conductivity and flexural strength of the composite were 2.80 × 10⁴ S/m and 55 MPa, respectively, suggesting that the dipolar plates prepared by two-step compression molding technique are adequate to meet the requirement of proton exchange membrane fuel cells. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 2296–2302, 2013

The effect of organoclay on phase morphology development of PA6/SEBS alloys had been investigated. PA6/SEBS blends of various compositions, with and without the presence of exfoliated organoclay in the PA6 phase, were prepared and the morphology and thermal expansion of these blends were examined. The results suggested that at compositions where PA6 remains as the matrix domain, the presence of the organoclay had little or no effect upon the blends morphology, PA6/SEBS alloy with SEBS as the matrix could evolve from sea-island to cocontinuous structure after 5 phr organoclay were added. Significant reduction in the coefficient of linear thermal expansion (CLTE) along theflow direction and furthermore improving the heat distortion temperature of the injection-molded PA6/SEBS/organoclay ternary nanocomposites was observed due to the formation of a total stable and fine cocontinuous nanolayer structure. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers

A novel method for preparation of polymer-based magnetic microspheres was proposed by utilizing melt reactive blending, which was based on selective location of Fe₃O₄ nanoparticles in PA6 domain of polystyrene (PS)/polyamide 6 (PA6) immiscible blends. The results showed that most of Fe₃O₄ was located in the PA6 microspheres. Magnetization data revealed the magnetite content of PA6/Fe₃O₄ microsphere could be up to 54 wt % with strong magnetic responsibility and high saturation magnetization. Carboxyl functional group, bonded with PA6/Fe₃O₄ microsphere by copolymerization of acrylic acid with PA6 chain in different concentration ethanoic acid (HAc) solution, was used as a ligand for protein adsorption. The amount of adsorbed bovine serum albumin (BSA) was optimized by changing the medium pH and the initial concentrations of BSA. The results denoted that the adsorption capacity of BSA reaches 215 mg/g microspheres, showing potentials to promising applications in bioseparation and biomedical fields. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011.