Lignin copolymer Thermoplastic

A few investigators have been able to modify wood to produce biodegradable thermoplastics. In 1992, for example, graft copolymers of lignin residue from paper manufacture and styrene were made. The materials are formable by conventional processes, and they are biodegradable. Degradation rates increase with lignin content, which varied from 10 to 50%. ... 

The utilization of TPS for the production of biodegradable plastics has increased and has been the object of several studies in the last decade. However, TPS has two main drawbacks namely its water affinity and its poor mechanical properties. To overcome these problems, the addition of other materials to TPS is necessary. In order to increase its water resistance, TPS has been blended with synthetic polymers and modified by cross-linking agents such as Ca and Zr salts. Substances such as waxes and lignin have also been tested to decrease the water uptake of starch-based materials. TPS s mechanical properties have usually been improved by addition of synthetic polymers, such as ethylene-acryhc acid and ethylene-vinyl alcohol copolymers. Another approach requires the use of natural fibers and mineral fillers. The inclusion of reinforcing fillers such as fibers could, however, enhance the degradation of thermoplastic starch because of the increase in the melt viscosity [79-81]. 

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