Thermal and mechanical properties of polystyrene/poly(acrylonitrile‐g‐(ethylene‐co‐propylene‐co‐diene)‐g‐styrene) (AES) blends prepared by the in situ polymerization of styrene

Abstract

Polystyrene/AES blends formed by the in situ polymerization of styrene in the presence of poly (acrylonitrile-g-(ethylene-co-propylene-co-diene)-g-styrene) (AES) were prepared. AES is a commercial elastomer obtained by the radical copolymerization of styrene and acrylonitrile in the presence of an ethylene-propylene-diene terpolymer (EPDM). The polystyrene/AES blends presented two phases: an EPDM elastomeric phase dispersed in a rigid matrix. The phase behavior was strongly affected by the polymerization temperature. The blends showed higher thermal stability than the polystyrene homopolymer because of the stabilizing effect of EPDM incorporation. The mechanical properties were influenced by the polymerization temperature and blend composition. The blend prepared at 608C with 13.0 wt % AES presented an enhancement of 60% in the impact resistance, whereas the blend prepared at 808C with 21.8 wt % AES presented an enhancement of 150% in the strain at break. Both blends had these properties improved with a small loss in the Young's modulus.

PS/EPDM blends prepared by in situ polymerization of styrene

“…Similar results were observed for PS/EPDM (Keltan 5508)26 and PS/AES31 blends prepared in other work by in situ polymerization. For the blends prepared with Keltan 5508 the temperatures of a 5 wt % loss under an inert atmosphere is 10°C higher than the temperatures observed for the blends prepared in this work.…”

“…The EPDM phase of all blends presents a glass transition temperature at lower temperature than neat EPDM (Table II). This behavior was also observed in earlier works of our research group for PMMA/AES blends,30 PS/EPDM (Keltan 5508),26 and PS/AES blends 31. However, for the blends prepared with Keltan 5508 the shift in the glass transition of the EPDM phase to lower temperatures is smaller than for the blends prepared in this work.…”

Mechanical properties of photoaged in situ polymerized PS/EPDM blends

“…The decrease of the Young's modulus of PS/EPDM is higher in comparison with PS/AES blends with comparable content of elastomer obtained by in situ polymerization, because of the stiffening of PS promoted by the SAN phase of AES. 18 The decrease in modulus with increasing the elastomer content is expected and well reported for rubber toughening of rigid polymers. 8 The Young's modulus is higher for photoaged samples, but the dependence of this property on the blend composition (up to 11 wt % of EPDM) is not affected by aging.…”

Dynamic mechanical and morphological behavior of blends of polystyrene and poly[acrylonitrile‐g‐(ethylene‐co‐propylene‐co‐diene)‐g‐styrene] prepared by in situ polymerization of styrene

“…These blends are immiscible and show complex phase behavior. 18 Furthermore, the morphology of injected specimens is quite different from that of noninjected blends. In this way, the influence of injection molding on the morphology of PS/AES is examined in the current article.…”