Mechanical and thermal properties of thermoplastic elastomer based on low density polyethylene and ultra-fine fully-vulcanized acrylonitrile butadiene rubber powder (UFNBRP)

Ultra-fine fully vulcanized acrylonitrile butadiene rubber powder (UFNBRP) and low density polyethylene (LDPE) were used for preparing thermoplastic vulcanizates (TPVs). A simple blending technique was utilized as an alternative to a complex dynamic vulcanization process typically used for the preparation of TPVs. Blend composition ratio of UFNBRP/LDPE was varied, and the properties of the TPVs were investigated. Morphological result reveals that all blends exhibit a two-phase morphology in which the UFNBRP particles form the dispersed phase in the LDPE matrix. This implies successful TPV preparation. Viscoelastic behavior of the TPVs was found to be governed by UFNBRP loading. As expected, with increasing UFNBRP loading, the elastic contribution increases as evidenced by the decreases in sensitivity of storage modulus to test frequency and in creep compliance. The rheological results are in line with the improvements in rebound resilience and compression set. The presence of chemical crosslinks in UFNBRP in conjunction with the formation of a transient network of rubber particles is thought to be responsible for such increase in elastic response. Additionally, degree of crystallinity and oil resistance of the TPVs were found to decrease with an increase in UFNBRP loading. The suppression of LDPE crystallization is probably caused by the UFNBRP particles locating in the interlamellar spaces of the LDPE matrix.