Influence of degree of substitution on physical properties and biodegradability of modified cellulose films from pineapple leaf, corn husk, and waste cotton fabrics under microwave energy

Abstract

This research investigated the effects of degree of substitution (DS) on physical properties and biodegradability (i.e., real composting condition, waste water treatment system condition, and enzymatic degradation) of modified cellulose films from pineapple leaf, corn husk, and waste cotton fabric. The modified cellulose was prepared in homogeneous LiCl/DMAc solvent system by esterification reaction under microwave energy at various microwave power and time using lauroyl chloride as an esterifying agent. After that, the chemical structure of the modified cellulose was characterized by FTIR and 1H-NMR. The results showed that modified cellulose from all cellulose sources exhibited evidence of esterification by showing the increasing in the ester bands at 1750 cm-1 (carbonyl C=O stretching of ester) and the decreasing in the intensity of O-H band at 3300 cm-1. In addition, all modified celluloses revealed an aggregation of fatty acid side chain groups on the surface thus resulted in rough surface and larger dimension. The optimum conditions for modification of pineapple leaf, corn husk, and waste cotton fabric that yield low, medium, and high degree of substitution (DS) values with reasonable %weight increase under microwave heating were 30 second 240 watt (DS 1.93), 60 second 240 watt (DS 2.23), and 90 second 160 watt (DS 2.46) for pineapple leaf, 90 second 320 watt (DS 1.99), 150 second 160 watt (DS 2.44), and 60 second 240 watt (DS 2.73) for corn husk, and 30 second 240 watt (DS 1.95), 90 second 160 watt (DS 2.27), and 90 second 240 watt (DS 2.48) for waste cotton fabrics. Then, modified cellulose films with different DS values were prepared by casting method with chloroform. It was found that the degree of substitution (DS) affected the physical and mechanical properties of esterified cellulose films that the gloss value and tensile properties increased with increasing of DS value while the wettability and water absorption decreased with increasing of DS value. In addition, biodegradability of esterified cellulose films was also dependent upon DS value where biodegradation rate increased with decreasing of DS value. Considering biodegradation condition, it was found that pineapple leaf and corn husk films had the highest biodegradability in real composting condition; while cotton films had the highest biodegradation rate in waste water treatment system condition.