Ethylene-vinyl alcohol copolymer /thermoplastic starch

These discoveries provided the technology base for commercialization efforts of starch-based plastics by the Novon division of the Warner-Lambert Company.157,158 The thermoplastic compositions were based on blends of destructurized starch and various hydrophilic polymers, such as ethylene-vinyl alcohol copolymers (EVOH). Hydrophobic polymers and additives, such as plasticizers and lubricants, could also... 

Thermoplastic starch and ethylene-vinyl alcohol copolymer (EVOH) copolymer systems, depending on the processing conditions, starch type and copolymer composition, can generate a wide variety of morphologies and properties [89-98], Different microstructures have been observed as a function of different hydrophylicity of the synthetic copolymer from a droplet-like to a layered one [92], An in-depth description of this aspect will be presented in section 2.4.6. 

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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