LAUSR

ABSTRACT In this study, xylan extracted from chestnut sawdust was used to synthesize the copolymers of xylan-graft-poly(L-lactide) (xylan-g-PLLA) by grafting L-lactide monomer onto xylan and using 4-dimethylaminopyridine as a catalyst at 80°C. Depending on the synthesis conditions and parameters, synthesized xylan-g-PLLAs were either water-soluble which form homogeneous plastic films after drying at room temperature or water-insoluble ones which do not form films at all. A Graeco-Latin design of experiments was used to determine the effects of three factors (reaction time, amount of L-lactide, and amount of the catalyst) on the results of the grafting reaction: the degree of substitution (DS) and the degree of polymerization (DP) of the copolymers. The DS and DP determined by 1HNMR showed that they increase according to the amount of L-lactide and decrease according to the reaction time while the catalyst had no influence on the copolymerization reaction. Grafting of PLLA onto xylan was confirmed by Fourier transform infrared (FT-IR) and 1HNMR analyzes. FT-IR spectra showed absorption bands at 1,784 cm−1 characteristic of the ester functions (C˭O) and 1HNMR spectra revealed signals between 1 and 2.5 ppm corresponding to the protons of the aliphatic chains. Thermal properties show that the temperatures of start of degradation of copolymers are lower than those of PLLA and xylan. The N,N-dimethylacetamide results showed that the glass transition temperature of xylan-g-PLLA film was 147°C. We found that the Young’s modulus of this film is close to that of polypropylene.