Chemical modification of starch based biodegradable polymeric blends:: effects on water uptake, degradation behaviour and mechanical properties

The main disadvantages of biodegradable polymers obtained From renewable sources are their dominant hydrophilic character, fast degradation rate and, in some cases, unsatisfactory mechanical properties particularly under wet environments. One possible solution to this problem is to reduce the water-uptake ability of these materials and to enhance the respective mechanical behaviour by chemical modification. In this work, three based starch blends with: (i) a copolymer of ethylene and vinyl alcohol (SEVA-C), (ii) cellulose acetate (SCA), and (iii) poly-epsilon -caprolactone (SPCL) were chemically modified by chain crosslinking. This modification is based on the reaction between the starch hydroxyl groups and tri-sodium tri-meta phosphate. The obtained compounds were characterized by FTIR and the respective properties were assessed and compared to the original materials by means of the hydration degree, the degradation behaviour, contact angle measurements and mechanical testing. The results show that the water-uptake of these blends could be reduced up to 15% and that simultaneously stiffer materials with a less pronounced degradation rate can be obtained. (C) 2000 Elsevier Science Ltd. All rights reserved.