Morphology evolution, mechanical properties, Mullins effect, and its reversibility of polylactide/nitrile butadiene rubber thermoplastic vulcanizates plasticized by dioctyl phthalate

Abstract

Thermoplastic vulcanizates (TPVs) based on polylactide (PLA)/nitrile butadiene rubber (NBR) blends were prepared by dynamic vulcanization where the PLA phase was plasticized by dioctyl phthalate (DOP), and the influence of DOP dosage on mechanical properties, morphology evolution, Mullins effect, and its reversibility were investigated systematically. The experimental results indicated that the mechanical properties of PLA/NBR TPVs were improved significantly with the addition of DOP. Compared with that of the PLA/NBR TPVs, the Shore A hardness was decreased obviously, while the elongation at break was increased slightly with increasing DOP dosage. Mullins effect results showed that the TPVs incorporated with DOP had the relatively lower stress-softening effect. The recovery ability of the maximum stress could be remarkably enhanced by increasing heat treatment temperature. Morphology studies showed that the network microstructure of the co-continuous phases was denser with the increasing dynamic vulcanization time; however, the network microstructure of the co-continuous was changed slightly with the addition of DOP.