Bio-based plasticizer with excellent migration resistance applicable to PVC and PLLA films

Abstract

A bio-based plasticizer, (1',7',7'-trimethyldispiro [[1,3] dioxolane –2,2'- bicyclo [2.2.1] heptane-3',2''-[1,3] dioxolane]-4,4''-diyl) bis(methylene) dioctanoate (Camphor diketaloctoate, abbreviated as CDO), was designed to replace a traditional phthalate-based plasticizer. The structure of CDO was analyzed by 1H NMR. The characteristics of CDO plasticizers, which were judged to have excellent compatibility with polyvinyl chloride(PVC) due to their solubility parameters, were evaluated by thermal and mechanical analyses and compared with dioctylphthalate(DOP). PVC with 20% CDO added was thermally stable up to 251.9℃ and exhibited excellent strength and flexibility with a high glass transition temperature (Tg) derived from its robust and bulky structure. In addition, since CDO is intertwined with the polymer chain, it shows excellent migration properties in many solvents. Poly(l-lactic acid)(PLLA) films were prepared by adding 5wt% and 10wt% of CDO, which had good compatibility with PLLA through the solubility parameter, and compared with PLLA films containing dioctylphthalate (DOP). The thermal stability of the PLLA blends plasticized with different amounts of plasticizers was investigated by DSC and TGA. The 10% CDO-added PLLA film exhibited an initial decomposition temperature of 310.3℃ and good thermal stability at 57℃, a temperature higher than that of the 10% DOP-added PLLA film. The 10% CDO-added PLLA film extended the application range of the PLA film with high Tg derived from the solid and bulky structure of CDO. In terms of mechanical properties, CDO increased the elongation rate of pure PLLA more than 2.5 times and showed a better plasticizing effect than DOP. The results of our study suggest that CDO can be applied to the production of flexible PVC and PLLA and that the migration resistance can be extended to extend the application range of polymer films.