Small molecule plasticizers for improved migration resistance: Investigation of branching and leaching behaviour in PVC blends

Abstract

The influence of branching on plasticizer effectiveness and migration behavior of heptyl-succinate plasticizers blended with poly(vinyl chloride) (PVC) was evaluated. An increase of branching led to a decrease in migration of the plasticizers into both hexanes and vegetable oil medias. Additionally, a quantitative 1H NMR method was used to identify plasticizer concentration in the leachates and compared to a gravimetric standard test method. Overall, the quantitative 1H NMR method proved to be a more direct method to assess leaching. In comparison to commercial plasticizer di(2-ethylhexyl) phthalate (DEHP) and alternative plasticizer diheptyl succinate (DHPS), all of the branched species displayed superior migration resistance into hexanes (two to ten-fold). The glass transition temperatures and stress at break data indicated that the plasticizers comprised of up to three branches functioned as well as, or better than DEHP and DHPS. However, there was a decrease in plasticizer efficiency with compounds comprised of four or more branches.