Alternative to Phthalate Plasticizer for PVC/NBR Formulation Used in Automotive Fuel System with Biodiesel

Phthalates have been extensively used in rubbers formulation as plasticizer additive for PVC and NBR promoting processing parameters or for cost reduction. The most commonly used plasticizer in PVC compounds was di-2-ethylhexyl phthalate (DEHP) currently not recommend due toxicity. DEHP is listed as prohibited to the Global Automotive Declarable Substance List (GADSL). Phthalates alternatives are already available but the compatibility in automotive fuel system with biodiesel was not extensively understood. This aspect is important since plasticizer may migrate and change rubber properties. Tri-2-ethylhexyl trimellitate (TOTM) and di-2-ethylhexyl terephthalate (DEHT) were selected in this work as alternative additives to a rubber formulation since is not listed to GADSL and have good potential as plasticizer. The aim of this work was to compare the effect of biodiesel blend on polyvinyl chloride (PVC) and nitrile butadiene (NBR) rubber blend formulated with two plasticizers alternatives to phthalates (DEHT and TOTM). The comparison was based on mechanical properties, hardness and swell before and after aging in biodiesel per 3024h at 80°C. Plasticizers could influence the compatibility with biodiesel due changes on processing parameters. PVC/NBR plasticized with DEHT performed better than TOTM comparatively.