Lignin-Base Modifier For Degradable Polymer

Lignin owns good UV and oxidation resistance,it can be used as a modifier for degradable polymers.However,it usually has poor compatibility with the polymer matrix.Lignin molecules contain a large number of hydroxyl groups,which could be chemically modified to further improve its dispersion in the matrix and the properties of the composites.In this paper,lignin was chemically modified by two methods and the modifiers were used to improve the properties of poly(_L-lactide)(PLLA)and Poly(butyleneadipate-co-terephthalate)(PBAT),respectively.The research contents are as follows:1.Lignin-grafted-poly(_D-lactide)(LGPD)was successfully prepared as a modifier to blend with PLLA.The results showed that the lignin structure in the PLLA/LGPD composites could facilitate the formation of the stereocomplex(SC)crystallites and promote the crystallization of the homo crystallites.The SC crystallites in PLLA/LGPD_Hblend had higher melting points and wider melting ranges comparing to the blends of four-armed poly(_D-lactide)(4a-PDLA)and PLLA.The composites had better ultraviolet absorption ability and mechanical properties comparing to PLLA.2.Epoxidized lignin was successfully synthesized and blended with PBAT as a modifier.Comparing to the unmodified lignin,the epoxidized lignin could promote the crystallization of PBAT more effectively,which was very important for the application of PBAT membranes.The two lignin-based modifiers shed some lights for expanding the application of lignin and its high-value utilization.