Particle-in-particle morphology for the dispersed phase formed in reactive compatibilization of SAN/EPDM blends

Abstract

Poly(ethylene-co-propylene-co-diene) (EPDM) containing 50 wt% of poly(ethylene-co-propylene) grafted with maleic anhydride (EP-g-MA) has been melt blended with poly(styrene-co-acrylonitrile) (SAN) added with various amounts of reactive SAN, i.e. SAN bearing either primary amine (SAN-NH 2 ) or carbamate groups (SAN-carb). Carbamate groups are precursors of primary amines by thermal thermolysis during melt processing. These reactive systems are good models for studying the effect of the kinetics of the interfacial reaction on the phase morphology. Reaction of maleic anhydride with the primary amine is indeed very fast, at high temperature, in contrast to the reaction with carbamate, which is controlled by the carbamate thermolyis into primary amine. Special attention has been paid to the experimental conditions required for the development of the particle-in-particle morphology for the dispersed phase. Depending on the mixing sequence and the grafting kinetics (NH 2 /MA versus carb/MA), this particular phase morphology can be forced or occurs spontaneously.

Particle-in-particle morphology in reactively compatibilized poly(butylene terephthalate)/epoxide-containing rubber blends

“…In the most recent study, Pagnoulle and Jérôme suggest that such particle-in-particle microstructure results from the coalescence of poorly stabilized rubber particles in the later stages of mixing and is essentially governed by the kinetics of interfacial grafting [10]. The observations reported in this study differ to some extent from this conclusion and allow for better identification of the parameters controlling the formation of particle-inparticle morphology.…”

“…When the minor phase melts prior to the major one, very small particles of the major phase are trapped within the minor phase [9]. In a recent paper, Pagnoulle and Jérô me [10] have demonstrated that, depending on the mixing sequence and on the grafting kinetics, the particle-in-particle morphology can be forced or occurs spontaneously during the compatibilization of modified styrene-co-acrylonitrile copolymers (SAN) with modified ethylene-propylene-diene rubber (EPDM). The authors suggest that, during in situ compatibilization, subinclusions can be spontaneously generated by coalescence of poorly stabilized dispersed particles during the later stages of mixing, i.e.…”

“…In contrast to the previous approach, faster reaction is favorable to the retention of occluded SAN. In this case, to ensure good final properties, the blending sequence must be adjusted to promote interfacial reaction at the interface between the matrix and the dispersed particles [10]. From this latter study, it is clear that the kinetics of interfacial grafting have a large influence on the development of particlein-particle morphology in compatibilized polymer blends.…”

Blendas de poliamida 6/elastômero: propriedades e influência da adição de agente compatibilizante

“…Nestes dois sistemas foi observada a formação de um copolímero na interface entre os domínios e a matriz através do aparecimento da ligação imídica. Pagnoulle e Jérôme também observaram a reação entre o anidrido maleico e a amina primária do copolímero nas blendas de poli(etileno-copropileno-co-dieno)/poli(estireno-co-acrilonitrila) em presença de EPDM enxertado com anidrido maleico [9] .…”

Morphology and thermal behaviour of SAN/EPDM blends

“…To elucidate the extrusion process, reactions and interactions that are established [12][13][14][15][16], the separation of SAN/EPDM blends on its components was carried out by selective solvent extraction and the results are presented in Figure 1. Significant differences in the fractions of graft copolymer (EPDM-g-SAN), SAN polymer, EPDM polymer and gel were observed.…”