PP/EPDM-blends by dynamic vulcanization: Influence of increasing peroxide concentration on mechanical, morphological and rheological characteristics

Abstract

Thermoplastic vulcanizates (TPVs) combine the elastic properties of thermoset cross-linked rubbers with the melt processability of thermoplastics. The most representative examples of this class are the TPVs based on polypropylene (PP) and ethylene-propylenediene terpolymer rubber (EPDM). The PP/EPDM blends were produced by dynamic vulcanization in a continuous extrusion process. The influence of different peroxide concentrations was studied with regard to cross-link density, compression set, tensile strength/elongation at break and morphology. With increasing peroxide concentration, the cross-link density increases, leading to a reduction of the compression set by 50 %. The cross-linked blends show smaller dispersed EPDM particles than the uncured one. With a peroxide concentration between 0.2 and 0.6 % a maximum in tensile strength and elongation at break was found and with increasing peroxide concentration, the complex viscosity of the TPVs decreases. Compared to batch processes, the results show nearly the same trends.

Morphology, crystallization, and thermal and mechanical properties of dynamic vulcanization EPDM/PP thermoplastic elastomer

“…This observation is in accordance with the other reported result. 20 Therefore, it can be concluded that there should be an optimum DCP content (0.9% in this report) where the dynamically vulcanized EPDM/PP blends have the best outstanding tensile strength.…”

Molecular evolution during dynamic vulcanization of polyolefin mixtures for lead‐free thermoplastic vulcanized

“…Vulcanization of polyolefins is a well‐known process and is widely used for producing rubber materials . A similar process was used to produce thermoplastic vulcanisates (TPV) from mixtures of polyolefin elastomers and thermoplastics polymers Since 1996, Mixer Spa has produced medium voltage (MV) insulation compounds based on EPDM and EPDM/LDPE blends which are now commercially available . The complex materials with optimized thermoplastic elastomeric response were producer by MIXER in its laboratory by a structural design of composition followed by dynamic crosslinking.…”

“…1,2 A similar process was used to produce thermoplastic vulcanisates (TPV) from mixtures of polyolefin elastomers and thermoplastics polymers 3 Since 1996, Mixer Spa has produced medium voltage (MV) insulation compounds based on EPDM and EPDM/LDPE blends which are now commercially available. 4,5 The complex materials with optimized thermoplastic elastomeric response were producer by MIXER in its laboratory by a structural design of composition followed by dynamic crosslinking. The lead free MV insulation compound was submitted to dynamic crosslinking with peroxide in a melted polypropylene (PP) matrix the presence of various ethylene polymers and additives to optimize the ultimate properties.…”

“…The final objective is the design and production of TPVs with better processing behavior and predesigned performances in the final application with particular reference to the possibility of processing them as thermoplastic elastomers. 4,5 In previous papers some of us studied intensively the chemical reactivity of different olefin polymers and copolymers toward free radicals produced by thermal decomposition of peroxide in the polymer melt 7 and discovered that even these highly aggressive conditions allows to control the reaction selectivity by varying polymers molecular structure and reactive coagents. 8 Other similar effects were recently reported with various additives controlling the process at molecular level.…”

“…The final objective is the design and production of TPVs with better processing behavior and predesigned performances in the final application with particular reference to the possibility of processing them as thermoplastic elastomers. 4,5 In previous papers some of us studied intensively the chemical reactivity of different olefin polymers and…”