可生物降解聚乙烯-羧甲基纤维素水凝胶薄膜

Biodegradation of PVP-CMC Hydrogel Film:A Useful Food Packaging Material

0引言 近年来,随着人们生态意识的不断增强,开发环保型包装材料已成为现代包装行业的热门研究方向之一。包装可分为三大类：初级包装（接触商品并随商品一并销售的包装）、二级包装（用于携带大量的初级包装商品的较大包装,例如盒子）、三级包装（用于协助大批量货物运输的包装,例如木托盘和塑料包装）。通常,二级包装和三级包装材料容易收集和清理回收。

Hydrogels can offer new opportunities for the design of efficient packaging materials with desirable properties（i.e. durability,biodegradability and mechanical strength）.It is a promising and emerging concept,as most of the biopolymer based hydrogels are supposed to be biodegradable,they can be considered as alternative eco-friendly packaging materials. This article reports about synthetic（polyvinylpyrrolidone（PVP））and biopolymer（carboxymethyl cellulose（CMC））based a novel hydrogel film and its nature of biodegradability under controlled environmental condition.The dry hydrogel films were prepared by solution casting method and designated as ＇PVP-CMC hydrogel films＇.The hydrogel film containing PVP and CMC in a ratio of 20：80 shows best mechanical properties among all the test samples（i.e.10：90,20：80,50：50,80：20 and 90：10）.Thus,PVP-CMC hydrogel film of 20：80 was considered as a useful food packaging material and further experiments were carried out with this particular hydrogel film.Biodegradation of the PVP-CMC hydrogel films were studied in liquid state（Czapec-Dox liquid medium＋soil extracts）until 8 weeks.Variation in mechanical,viscoelastic properties and weight loss of the hydrogel films with time provide the direct evidence of biodegradation of the hydrogels.About 38%weight loss was observed within 8 weeks.FTIR spectra of the hydrogel films（before and after biodegradation）show shifts of the peaks and also change in the peak intensities,which refer to the physico-chemical change in the hydrogel structure and SEM views of the hydrogels show how internal structure of the PVP-CMC film changes in the course of biodegradation.