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Toughening of polyamide 6 (PA6) can be achieved by appropriate addition of an elastomeric matrix phase; however, this leads to a loss of rigidity and mechanical strength. As a result, much research has been directed at obtaining an optimal balance between toughness and rigidity for these thermoplastics. The approach explored here is the formation of nanocomposites from PA6/acrylonitrile-butadiene-styrene (ABS) blends prepared by melt mixing with a modified montmorillonite (Cloisite 1 30B) and styrene/maleic anhydride copolymer as a compatibilizer. The effect of the mixing sequence of the components on the morphology and properties is a primary focus. The morphology and mechanical properties of the materials were characterized by X-ray diffraction, electron microscopy, and tensile and impact testing. Incorporation of the compatibilizer in the PA6/ABS blend increased toughness but decreased rigidity. A significant increase of modulus was observed for the nanocomposite blend compared with the blend or the matrix. This increase was attributed to the exfoliation of organoclay layers in the PA6 matrix phase. It was also observed that the morphology of the ABS dispersed phase was considerably influenced by the mixture sequence.

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de três sequências de mistura na microestrutura e propriedades das blendas foi estudado. A morfologia e as propriedades mecânicas dos materiais foram caracterizadas por microscopia eletrônica de transmissão (MET) e testes de resistência ao impacto e módulo de elasticidade, respectivamente. Os resultados mostraram que a morfologia e propriedades mecânicas das blendas ternárias foram bastante diferentes e dependem da sequência de mistura. A blenda preparada pela mistura simultânea de todos os componentes, em uma única extrusão, apresentou melhor tenacidade. Por outro lado, quando o ABS e o SMA foram misturados juntos em uma primeira extrusão, antes da incorporação da PA6 em uma segunda extrusão, o valor da resistência ao impacto encontrado foi menor que o da matriz PA6 e da blenda sem compatibilizante PA6/ABS. Evidências de reações químicas entre o compatibilizante SMA e a matriz PA6 também foram investigadas através de reometria de torque. Palavras-chave: Blendas, poliamida 6, tenacidade, sequência de mistura. Effect from the Blending Sequence on the Properties of PA6/ABS Blends Compatibilized with SMA CopolymerAbstract: Blends of polyamide 6 (PA6) with acrylonitrile-butadiene-estyrene (ABS) were prepared in a twin-screw extruder, using the styrene-maleic anhydride (SMA) copolymer containing 7% of maleic anhydride as compatibilizer. The effects from three blending sequences on the microstructure and properties of the blends were investigated. The morphology and mechanical properties of the materials were characterized by transmission electron microscopy and tensile and impact tests. The results showed that the morphology and mechanical properties of ternary blends depend on the sequence of blend preparation. The blend prepared using the mixture of all components in a single-pass extrusion showed the more significant improvement in the material toughness. However, when the ABS and SMA were melt mixed together in a first extrusion step prior to incorporating PA6 in a second extrusion, the impact strength is lower than that of the blend without compatibilizer PA6/ABS and PA6 matrix. Evidence of chemical reactions between the compatibilizer SMA and PA6 was also obtained using a torque rheometer. Keywords: Blends, polyamide 6, toughness, blend sequence. IntroduçãoAs poliamidas pertencem a uma classe de polímeros atraente para aplicações em engenharia devido à combinação de propriedades como: baixa viscosidade no estado fundido, boa resistência ao impacto sem entalhe e excelente resistência química. Por outro lado, as poliamidas são altamente higroscópicas e sensíveis ao entalhe, isto é, são dúcteis quando não entalhados, mas fraturam de maneira frágil quando entalhados, devido a sua baixa resistência à propagação da trinca. Em adição, poliamidas tendem a ser frágeis em temperaturas subambientes e carregamento sob condições severas. Essas deficiências podem ser melhoradas pela mistura destes polímeros com outros plásticos como poli(óxido de fenileno) (PPO), poli(acrilonitrila-butadieno-estireno) (ABS), poliolefinas, en...

This paper investigates the use of an aqueous dispersion of polyethylene copolymer with a relatively high content of acrylic acid as a compatibilizer and as an alternative medium to obtain polyethylene CNF nanocomposites. The CNF content was varied from 1 to 90wt% and the appearance, optical, thermal, mechanical and rheological properties, as well the morphology of the films were evaluated. The PE/CNF films are transparent up to 20wt% of NFC indicating a good dispersion of CNF, but a poor distribution, with PE-rich and CNF-rich regions observed by SEM. Improved mechanical properties were achieved, with a 100% and 15,900% increase in the Young's modulus with 1wt% and 90wt% NFC, respectively. The rheological behavior indicated good melt processability. According to these results, aqueous polyolefin dispersions seem to be a promising, easy and relatively fast route for obtaining cellulose/polyolefins nanocomposites with low to high contents of cellulose nanofibrils.

Blends of poly(butylene terephthalate) (PBT) with 30 wt % acrylonitrile–ethylene–propylene–diene–styrene (AES) were prepared with methyl methacrylate (MMA)/glycidyl methacrylate (GMA)/ethyl acrylate (EA) terpolymers (MGEs) as compatibilizing agents. These acrylic terpolymers were miscible with the styrene–acrylonitrile (SAN) phase of AES, whereas the epoxide groups of GMA could react with the PBT end groups; this could lead to the formation of grafted copolymers (PBT‐g‐MGE) at the PBT/AES interface during the melt processing of the blends if at least a fraction of this interface was formed between the PBT and SAN phases. This study found evidence of the aforementioned interfacial structure through the effectiveness of the MGE terpolymers in promoting the compatibilization, as evaluated by dynamical mechanical analysis, through the increase in the viscosity of the blends, and through the reduction of the AES particle size dispersed in the PBT matrix. These effects became more intense with an increase in the overall concentration of GMA in the blends and with a reduction of the molecular weight of MGE. Another effect promoted by the compatibilization was a remarkable reduction of the brittle–ductile transition temperatures of the blends, which was correlated with the reduction of the AES particle size. However, this correlation between the brittle–ductile transition temperatures and particle size did not hold for the blend with the lowest AES particle size, which showed a high ductile–brittle transition temperature. These mechanical behaviors were examined on the basis of the current theory of the toughening of thermoplastics, which takes into account the importance of the rubber interparticle distance and the cavitation process of these particles. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 1244–1259, 2005

Poly(butylene terephthalate) (PBT)/styrene-acrylonitrile copolymer (SAN) blends were investigated with respect to their phase morphology. The SAN component was kept as dispersed phase and PBT as matrix phase and the PBT/SAN viscosity ratio was changed by using different PBT molecular weights. PBT/SAN blends were also compatibilized by adding methyl methacrylate-co-glycidyl methacrylate-co-ethyl acrylate terpolymer, MGE, which is an in situ reactive compatibilizer for melt blending. In noncompatibilized blends, the dispersed phase particle size increased with SAN concentration due to coalescence effects. Static coalescence experiments showed evidence of greater coalescence in blends with higher viscosity ratios. For noncompatibilized PBT/SAN/MGE blends with high molecular weight PBT as matrix phase, the average particle size of SAN phase does not depend on the SAN concentration in the blends. However noncompatibilized blends with low molecular weight PBT showed a significant increase in SAN particle size with the SAN concentration. The effect of MGE epoxy content and MGE molecular weight on the morphology of the PBT/SAN blend was also investigated. As the MGE epoxy content increased, the average particle size of SAN initially decreased with both high and low molecular weight PBT phase, thereafter leveling off with a critical content of epoxy groups in the blend. This critical content was higher in the blends containing low molecular weight PBT than in those with high molecular weight PBT. At a fixed MGE epoxy content, a decrease in MGE molecular weight yielded PBT/SAN blends with dispersed nanoparticles with an average size of about 40 nm.