Preparation and characterization of peroxide‐based dynamically vulcanized thermoplastic elastomer of poly (lactic acid)/chloroprene rubber

• Published in: Polymer engineering and science 2022-05, Vol.62 (5), p.1485-1495
• Main Authors: Shahroodi, Zahra, Katbab, Ali Asghar
• Format: Article
• Language: English
• Subjects: Analysis; bi‐continuous micro morphology; chloroprene rubber; Dicumyl peroxide; Ductile-brittle transition; dynamic vulcanization; Elastomers; Hydrochloric acid; Hydrogen chloride; Identification and classification; Lactic acid; Magnesium oxide; Mechanical properties; Methods; Peroxides; poly (lactic acid); Polylactic acid; Rubber; Rubber, Artificial; Soybeans; Superconductors (materials); Thermal decomposition; Thermal resistance; Thermoplastics; toughness; Vulcanization
• ISSN: 0032-3888; 1548-2634
• DOI: 10.1002/pen.25937

Thermoplastic vulcanizates (TPVs) composed of crosslinked rubber phase with high chemical and thermal resistance have received great attention in pharmaceutical and biological applications. In the present work, attempts have been made to prepare TPVs based on poly (lactic acid) (PLA) and chloroprene rubber (CR) via a melt mixing process in the presence of dicumyl peroxide (DCP) and a combination of magnesium oxide (MgO) and epoxidized soybean oil (ESBO) as hydrochloric acid (HCl) scavenger to minimize CR degradation by DCP. A honeycomb co‐continuous micromorphology was observed for the fabricated TPVs samples through scanning electron microscopy, significantly different from the classical “sea‐island” micromorphology. However, the PLA/CR vulcanizates prepared by only DCP did not show enhanced mechanical properties due to the CR thermal decomposition by the DCP radicals. Therefore, a novel formulation was designed to prevent thermal decomposition of the CR phase during dynamic vulcanization by the incorporation of a combination of ESBO and MgO as efficient HCl scavenger. The stabilized TPV samples exhibited an intense brittle‐ductile transition effect and improved tensile mechanical. The obtained results implied the effectiveness of ESBO and MgO in stabilizing CR phase during peroxide dynamic vulcanization process. Dynamically vulcanized thermoplastic elastomers composed of PLA/CR were prepared by dynamic vulcanization and incorporation of peroxide‐based curing agent. As a result of dehydrochlorination in the CR phase which is accelerated by peroxide curing agent, we successfully formulated a system based on acid acceptors, which hindered thermal decomposition and enhanced mechanical properties. The samples showed matrix‐disperse to honeycomb co‐continuous micromorphology by increasing the rubber content. A significant enhancement in impact resistance as 22.5 times in comparison to the processed PLA was also observed in a blend with 40 wt% formulated‐based CR.