Synthesis of biodegradable cellulosic plastics having poly(L-lactic acid) graft chains

Acetylated waste pulps (PAcs) having several degrees of substitution (DS) were synthesized from waste pulp (Pulp) treated under several conditions. When 1 wt% of conc. H2SO4 to Pulp was used and the reaction temperature was 60 degreesC, PAc was obtained in the highest yield. Deacetylated waste pulps (DAPAcs) were synthesized from PAc that had a DS of 2.66. The degree of deacetylation increased with the reaction time. Several types of graft copolymers were synthesized from PAc or DAPAc and L-lactic acid (PAc-graft-PLA and DAPAc-graft-PLA, respectively). The PLA content in graft copolymers increased with increasing numbers of unreacted hydroxyl groups in glucose units, and the glass transition points (T-g) of graft copolymers decreased with increasing PLA contents. A biodegradation test for PAc-graft-PLA and DAPAc-graft-PLA was performed using cellulase in 0.1 M acetic buffer solution (pH 5.5) at 37 degreesC. The biodegradability of graft copolymers was depressed by the introduction. of PLA units.