A multifunctional lactic acid based plasticizer used for plasticizing PVC and PLA: Endowing PLA elastic restore capability

A novel multifunctional plasticizer, cyclohexyl triethylene glycol oligo-lactate (CTLE) was designed by a two-step esterification reaction using green non-toxic biomass lactic acid as raw material. Its structure was characterized by 1H NMR, FT-IR and TOF-MS. Thermogravimetric analysis (TGA), tensile test and leaching test were used to evaluate the plasticizer effect of PVC or PLA blends. Compared with commercial plasticizers, CTLE showed more outstanding thermal stability, flexibility and migration stability. Under the same condition with the addition of 50 phr plasticizer, the CTLE plasticized PVC film had the lowest glass transition temperature (TgCTLE-50 = 24.6 °C) and the highest initial decomposition temperature (TiCTLE-50 = 265.4 °C). In PLA blends, only the CTLE plasticized PLA film could recover after fracture, and the stress relaxation test results showed that the stress value of PLA-CTLE-20 drops sharply to a non-zero value, showing elastic characteristics. We estimate that the excellent plasticity of CTLE is due to its molecular structure. Among them, a large number of polar groups form intermolecular forces with PVC chain segments to make the binding tight, and the ring structure increases the free volume between PVC chain segments.