Dynamic mechanical properties and morphological structure of PS/EPDM blends prepared by in situ‐polymerization of styrene

Abstract

PS/EPDM blends prepared by in situ-polymerization of styrene in the presence of EPDM are immiscible and show two phases. Furthermore, the dynamic mechanical behavior of injected specimens is quite different from that of noninjected blends. This is attributed to the differences in morphology before and after injection molding. The morphology of the noninjected blends consists of PS spherical domains covered by a thin layer of EPDM, whereas the injected blends show elastomeric dispersed phase morphology in a rigid matrix. SEM analysis was important to elucidate the changes in the dynamic mechanical behavior of PS/EPDM blends, but TEM analysis is more precise for morphological characterization and yielded the real average diameter of EPDM particles. Comparing the average diameters for the PS/EPDM blends obtained from SEM and TEM analyses, the diameters obtained from the SEM analysis are wider than those of TEM which is due to the solvent extraction effect on the blend morphology.

Natural Compounds against Alzheimer’s Disease: Molecular Recognition of Aβ1–42 Peptide by Salvia sclareoides Extract and its Major Component, Rosmarinic Acid, as Investigated by NMR

“…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

“…Micrographs of the blend 11.8EPDM‐T‐A, Figure 3, suggest that the elastomer phase is surrounding the glassy polymer phases. This kind of morphology was previously reported in our research group for PS/AES blends also obtained by in situ polymerization in the absence of stirring 12…”

“…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.…”

“…Another blends obtained by in situ polymerization have been studied such as PMMA and poly(ethylene‐ co ‐vinyl acetate) (EVA),9 poly(styrene) (PS) and AES,10 PS and poly(styrene‐ b ‐butadiene‐ b ‐styrene) (SBS),7 PMMA and poly(styrene‐ co ‐acrylonitrile) (SAN),11 and PS and poly(ethylene‐ co ‐propylene‐ co ‐diene) (EPDM) 12, 13. Cheng and Chen9 investigated the influence of the initiator on the morphology of PMMA/EVA blends and observed that the formed graft copolymer results in finely dispersed EVA particles in the PMMA matrix.…”

Toughened polystyrene with improved photoresistance: Effects of the compatibilizers

“…The toughening mechanism is quite complex, and a minimum rubber volume fraction with adequate particle sizes are required for efficient toughening 3. However, the use of PB in HIPS imparts some limitations to outdoor applications because this rubber presents a relatively low stability to photodegradation 4. To overcome this problem, PB can be replaced by saturated or at least less unsaturated rubbers, such as ethylene–propylene–diene terpolymer (EPDM).…”