Study on Polylactic Acid/Polybutylene Succinate Extended Chain Modification Materials
Liu Sawen, Gao Shanjun, Shen Chunhui, Qi Hongsheng, Chen Xiuling
Institute of Material Science and Engineering, Wuhan University of Technology, Wuhan 430070, China
Abstract：Poly-L-lactic acid (PLLA) was synthesized using L-lactic acid (L-LA) as raw materials. Then new block polymers were synthesized by adding highly efficient reactive chain extenders 2, 2'-(1, 3-phenylene)-dioxazoline (PBO) and 4, 4'-diphenylmethane diisocyanate (MDI) into PLLA/polybutylene succinate (PBS) blend. In the first step, the blend system in which the terminal group was mostly hydroxyl was produced by using PBO's characteristics that it was easy to react with carboxyl groups and inert to fatty alcohols, and the selectivity of PBO to carboxyl groups was verified by acid titration. The second step was to add MDI that was easy to react with hydroxyl groups, which caused the molecular chain growing further and improving the compatibility of the two phases. The products were subjected to nuclear magnetic resonance spectroscopy, Fourier transform infrared spectroscopy, scanning electron microscopy, differential scanning calorimetry, thermogravimetric analysis, melt index test and mechanical testing. The experimental data showed that the reaction formed an amide group and verified the selectivity of PBO to the carboxyl group. The compatibilization, processing fluidity and thermal stability of PLLA/PBS were improved by compatibilization and chain extension. With the increase of PBO and MDI content, the tensile strength and elongation at break of the material increased first and then decreased, and the impact strength was significantly improved, which changes the brittleness characteristics of the material.
Keywords：polylactic acid; polybutylene succinate; chain extension modification; composite
Liu Sawen，Gao Shanjun，Shen Chunhui，et al. Study on polylactic acid/polybutylene succinate extended chain modification materials[J]. Engineering Plastics Application，2020，48(3)：7-13.