Preparation of LDPE-Acetylated/Butyrylated Starch Blend Blow Films and Characterization

Development of modified plastics has been studied through the LDPE-acylated starch blend films to examine the effect of different acyl groups and degrees of substitution (DS) on properties of films. Corn starch was modified with acetyl and butyryl groups and films were prepared by blending acylated starch with low density polyethylene (LDPE). Systematic studies were done to observe the effect of acyl groups, DS and starch concentration on the properties and biodegradability of the blend films. It was observed that blend films containing 5% acetylated and butyrylated starches of high DS (2.5, 1.7) maintained 75% and 83% of tensile strength of LDPE films. Thermal analysis results indicated that acetylated and butyrylated starch blend films decomposed at 370 A degrees C and 389 A degrees C which were higher than the decomposition temperature of native starch film (349 A degrees C). Scanning electron micrographs of blend films containing high DS acylated starch showed well dispersed starch particles due to improvement in dispersion between starch and LDPE. Water absorption capacity of high DS acetylated and butyrylated starch blend films (4.18% and 3.76%, respectively) was lower than that of native starch films (5%). This study has an advantage because of blown films prepared can be integrated with the present manufacturing systems without any other requirement.