ABSTRACT:The optical transparency, thermal resistance, intermolecular interaction, and mechanical properties of poly(styrene-block-butadiene-block-styrene) (SBS), which were modified by blending with crystalline polypropylene (PP) or amorphous polystyrene (PS), were analyzed. The dynamic mechanical test indicated that the PP exhibited an intermolecular interaction with SBS and PS was compatible with SBS. The optical properties indicated that the direction of the light was changed due to the difference between the refractive indices of SBS and the added modifiers. Additionally, refraction and reflection occurred at the interface, reducing the transparency of SBS. The thermal resistance of SBS clearly improved upon modification by the addition of crystalline PP polymer. The thermal treatment increased the tensile strength and the elongation at breakage of modified SBS by reducing the internal stress, which was generated during the blending process.
In this study, polypropylene/ethylene-octene copolymer (PP/POE) blends, PP/talc, and PP/POE/micro-talc (MT) composites were fabricated using a twin screw. To estimate the performances of the PP/POE blends, PP/talc, and PP/POE/MT composites, mechanical properties, heat deflection temperature (HDT), thermomechanical analysis, and isothermal crystallization characterization were conducted. Incorporating talc particles increased the tensile strength, flexural properties, and HDT of the PP matrix, but reduced the elongation at break and notched impact strength. The inclusion of POE elastomers in the PP matrix yielded the opposite effect on PP/talc composites. PP/POE/MT composites provide a compromise that improves both the flexural properties and notched impact strength. Moreover, the inclusion of talc particles in PP/POE blends induced heterogeneous nucleation and considerably reduced the crystallization time. Consequently, the time required for processing was also greatly reduced. POLYM. COMPOS.,
Dynamically vulcanized EPDM/PP (ethylene-propylene-diene/polypropylene) elastomers reinforced with various amounts of organoclay were prepared using octylphenol-formaldehyde resin and stannous chloride dehydrate as vulcanizing agents. The effects of organoclay on vulcanization characteristics, rheological behavior, morphology, thermal stability and thermomechanical properties were studied. Experimental results showed that organoclay affected neither the vulcanization process nor the degree of vulcanization chemically. X-ray analysis revealed that these organoclay-filled thermoplastic vulcanizates (TPVs) were intercalated. With respect to the mechanical properties, organoclay increased both the strength and degree of elongation of TPVs. The morphological observation of fractured surfaces suggested that organoclay acted as a nucleating agent in TPVs, improving their mechanical properties. However, adding organoclay reduced the thermal stability of TPVs by decomposing the swelling agents in the organoclay.
This study investigates the effects of different types of curatives at polypropylene (PP) and ethylene propylene diene monomer (EPDM) blend ratios (100 : 40 phr) in dynamically vulcanized products. The thermoplastic vulcanizates are prepared by batch melt mixing of PP with EPDM, using pheolic resin, dicumyl peroxide, hydrosilyation, and complex systems as curatives. Observed changes in curing characteristics and mechanical properties of blends have been correlated with phase morphology, as attested by scanning electron micrographs. On the basis of the obtained results, different curative systems control final vulcanizing characteristics, mechanical properties, morphology, intermolecular interaction, and thermal properties of EPDM/PP blends.
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