Microwave induced esterification of paper mulberry for degradable film preparation

Abstract

This research aimed to prepare biodegradable plastic film from paper mulberry, which is agricultural by-product, by mean of an esterification reaction with long chain fatty acid chloride in homogeneous media of N, N-dimethylacetamide/lithium chloride (DMAc/LiCl) In this system, lauroyl chloride and N, N- dimethylamino pyridine (DMAP) were used as an esterifying agent and catalyst, respectively. Prior to doing so, paper mulberry was pulped and delignified and then treated by acid hydrolysis in order to obtain paper mulberry powder. The optimum condition to prepare the esterified-paper mulberry was investigated in term of the amount of reagents used, microwave power and irradiation time. The results showed that the greatest % esterification (38.00 %) and % yield (154 %) were obtained under 90 watts microwave irradiation for 2 min. The melting transitions attributed to the side chain crystalline of lauric acid could enhance melt-processible. From SEM analysis, untreated paper mulberry showed smooth surface of short fiber whereas paper mulberry laurate exhibited aggregation of alkyl groups of lauroyl chloride on the surface. It was found that % esterification had marked influences on the formation and properties of plastic films. The resulting cellulose laurate film had % esterification ranging from 23.24 to 38.00 %. As the % esterification increased, the percent of water absorption, wettability, gloss value, and elongation of the film increased, whereas the tensile strength of the films decreased. Furthermore, it was found that an increase in substitution of lauric acid on hydroxyl groups of paper mulberry help promoting the biodegradability and photodegradability of paper mulberry laurate films.