Studies on the physical properties of modified starch-filled HDPE film

To improve the physical properties of starch-filled polyolefin, starch was modified into more hydrophobic material by the introduction of cholesterol unit, and the different starch-compositioned high-density polyethylene (HDPE) films were prepared with addition of either native starch or modified starch to compare their physical properties. The addition of either native starch or modified starch resulted in decreased crystallinities in all the different composite films containing starch. Interestingly, HDPE-blown films containing more than 10% native starch (HDPE/ST) showed a steeper decrease in crystallinity than correspondent HDPE containing the modified starch (HDPE/MS). Improvement of the dispersion and adhesion in HDPE/MS and HDPE/ST were also observed; but at high starch content, the HDPE/MS films showed higher tensile strength and elongation than the HDPE/ST. The degradation of HDPE/MS films in active sludge condition was much faster than that of the HDPE/ST films, although the degradation rate of HDPE/MS films in alpha-amylase condition were slower than the one of HDPE/ST films. (C) 1996 John Wiley & Sons, Inc.