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

Abstract

PS/AES blends were prepared by in situ polymerization of styrene in the presence of AES elastomer, a grafting copolymer of poly(styrene-co-acrylonitrile) -SAN and poly(ethylene-co-propylene-co-diene)-EPDM chains. These blends are immiscible and present complex phase behavior. Selective extraction of the blends' components showed that some fraction of the material is crosslinked and a grafting of PS onto AES is possible. The morphology of the noninjected blends consists of spherical PS domains covered by a thin layer of AES. After injection molding, the blends show morphology of disperse elastomeric phase morphology in a rigid matrix. Two factors could contribute to the change of morphology: (1) the stationary polymerization conditions did not allow the mixture to reach the equilibrium morphology; (2) the grafting degree between PS and AES was not high enough to ensure the morphological stability against changes during processing in the melting state. The drastic change of EPDM morphology from continuous to disperse phase has as consequence a decrease in the intensity of the loss modulus peaks corresponding to the EPDM glass transition. However, the storage modulus at temperatures between the glass transition of EPDM and PS/SAN phases does not change significantly. This effect was attributed to the presence of the SAN rigid chains in the AES.

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“…The EPDM phases of all blends present a glass transition temperature at lower temperatures than the EPDM phase of AES (Figure 6(b)). This behavior was also observed in earlier work of our research group for polyhydroxybutyrate/AES blends,32 PMMA/AES blends 15, in situ polymerized polystyrene (PS)/AES 33 and PS/EPDM 34. This shift to lower temperatures is attributed to the phase inversion of the EPDM phase of AES due to AES dissolution in methyl methacrylate monomer and its in situ polymerization.…”

Effect of in situ polymerization conditions of methyl methacrylate on the structural and morphological properties of poly(methyl methacrylate)/poly(acrylonitrile‐g‐(ethylene‐co‐propylene‐co‐diene)‐g‐styrene) PMMA/AES Blends

“…The shift of the glass transition of the elastomer phase to lower temperatures was also observed in earlier work of our research group for polyhydroxybutyrate/AES blends,37 PMMA/AES blends,38 in situ polymerized polystyrene (PS)/AES39 and PS/EPDM 12. This behavior in blends of a rubbery phase dispersed in glassy material is common and attributed to hydrostatic dilatational thermal stresses generated within the rubber particles because of the differences in the thermal expansion between the rubber and the glass matrix.…”

Zn‐salt poly(styrene–ran–cinnamic acid) ionomer as a polystyrene with improved impact toughness, heat resistance, and minimally compromised processability

“…Whereas blending PS, in situ during polymerization, with ethylene-propylene-diene terpolymer (EPDM) and poly [acrylonitrile-g-(ethylene-co-propylene-co-diene)-g-styrene] (AES) increased the impact strength of PS by 210% and reduced the tensile strength by 30% when the former contains 17 wt.% EPDM, while the latter contains 13.0 wt.% AES, it increases the impact strength by 60% and improves the heat resistance of PS/EPDM. [10][11][12] Melt filling PS with different fractions (3-15 wt.%) of nano-TiO 2 and nano-Ca 3 (PO 4 ) 2 increased the vicat softening temperature (VST) of PS but decreased the tensile strength or impact toughness, 13,14 presumably due to weak PSinorganic interfacial interactions. Similarly, solution filling PS with montmorillonite resulted in an increase of the thermal decomposition temperature by about 10 C. 15 Anžlovar et al 16 filled cellulose nanocrystals (CNCs) surface-modified with benzoic anhydride with PS, the addition of 5 wt.% modified CNCs to the PS matrix resulted in a 30% improvement in tensile strength and a 23% increase in Young's modulus because of the strong entanglement of PS chains with the modified CNCs.…”