Polyolefin blends
Somayeh Rafiei; Davood Soudbar; Minoo Sadri; Fatemeh Shafiei
Abstract
Thermoplastic vulcanizates (TPVs) were prepared based on polypropylene (PP) and polybutadiene rubber (PBR) at different PP/PBR compositions (70/30 and 60/40). PP-grafted-maleic anhydride (PP-g-MA) was introduced into the TPVs at different concentrations (10 and 20%). The compatibilizing effect of PP-g-MA ...
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Thermoplastic vulcanizates (TPVs) were prepared based on polypropylene (PP) and polybutadiene rubber (PBR) at different PP/PBR compositions (70/30 and 60/40). PP-grafted-maleic anhydride (PP-g-MA) was introduced into the TPVs at different concentrations (10 and 20%). The compatibilizing effect of PP-g-MA was demonstrated through cross-sectional morphology. PP-g-MA exhibited a suppressing impact on the coalescence of the rubber domains, leading to a finer and more uniform distribution of the PBR phase. Due to the higher rubber content, the compatibilizing effect was more pronounced for the 60/40 composition, which was on the averge of forming a co-continuous morphology. However, it was found that a higher PP-g-MA content is needed to effectively compatibilize the TPVs. Rheological results revealed opposing effects on the viscoelastic response of the system. However, the elastic response was intensified once higher content of PP-g-MA was used, suggesting its compatibilizing role. Dynamic mechanical analysis results proved the existence of opposing effects and revealed the profound compatibilizing effects of PP-g-MA, especially at higher content (20%). Izod impact strength exhibited moderate and notable enhancements in both TPV compositions by adding 10% and 20% of PP-g-MA, respectively, attributed to the highly increased compatibility of the PP/PBR TPVs, especially at higher levels of PP-g-MA content.
Characterization
Marzie Alidadi-Shamsabadi; Shirin Shokoohi
Abstract
Melt free-radical grafting reactions between ethylene-propylene-dieneterpolymer (EPDM) and glycidyl methacrylate (GMA) were investigated in a batch mixer (170°C, 60rpm). Effect of dicumylperoxide (DCP) initiator and GMA functionalizing monomer concentrations was studied on the grafted EPDM characteristics. ...
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Melt free-radical grafting reactions between ethylene-propylene-dieneterpolymer (EPDM) and glycidyl methacrylate (GMA) were investigated in a batch mixer (170°C, 60rpm). Effect of dicumylperoxide (DCP) initiator and GMA functionalizing monomer concentrations was studied on the grafted EPDM characteristics. Titration results indicated an increase in the graft degree (GD) and gel content (GC) values with increasing DCP concentration as a result of increasing primary free radical concentration and strengthening cross-linking side reaction. FTIR spectrums confirmed that GMA functionalities have been grafted onto EPDM with appearing carbonyl (C=O) peak. After that, the resultant EPDM-g-GMA was used as compatibilizer in PS(polystyrene)/EPDM/PA6 (polyamide6) ternary blends. The effect of rubbery compatibilizer on the blend morphology and mechanical properties was studied. The ATR-FTIR spectra of ternary blends, etched to remove unreacted PA6, demonstrated that the compatibilizing reactions occurred during melt blending. By investigating the SEM micrographs it was revealed that the EPDM-g-GMA compatibilizer at the concentration range of 5 wt.% to 15 wt.% changed the size and type of the blend morphology from separated dispersed to multicore-shell morphology. The finest morphology was achieved by using 7.5 wt.% EPDM-g-GMA. Also, the presence of compatibilizer up to 7.5 wt.% could improve the tensile modulus, yield stress and impact strength, but a decreasing trend was observed at higher concentration of the compatibilizer.
