Abstract
Due to the poor compatibility caused by the large difference in hydrophilicity and interface between polylactic acid (PLA) and cellulose acetate (CA), the blending of the two materials is difficult and the application is limited. To solve this problem, a type of polyamide amine (PAMAM) dendrimer was introduced to modify PLA/CA blends in this work. The results showed that PAMAM could improve the compatibility of PLA/CA blends, promote the distribution of CA and crystallization of PLA. At the same time, adding PAMAM could enhance the mechanical properties of the blend material, and the toughness and tear strength were increased by 551% and 141%, respectively. In addition, the incorporation of PAMAM increased hydrophobicity and oxygen permeability of PLA/CA blends, and the oxygen permeability could be increased by up to three orders of magnitude. Degradation test results showed that the blend exhibited good biodegradability. The overall performance of the PLA/CA blend film was optimal when the content of PAMAM was 3 phr. The biodegradable blend films with excellent performance provided wide application prospect in the food green packaging fields.
Highlights
Polylactic acid (PLA) is a type of thermoplastic aliphatic polyester, which is completely biodegradable and has good biocompatibility [1]
The results showed that polyamide amine (PAMAM) could improve the compatibility of polylactic acid (PLA) / cellulose acetate (CA) blends, promote the distribution of CA and crystallization of PLA
At the same time, compared with the spectra of PAMAM in Fig. 1c, there was no obvious N-H peak of amide bond in PLA / CA blends with PAMAM, which proved that the amino group of PAMAM formed hydrogen bond with PLA and CA
Summary
Polylactic acid (PLA) is a type of thermoplastic aliphatic polyester, which is completely biodegradable and has good biocompatibility [1]. The compatibilization modification of PLA / CA blends includes grafting maleic anhydride on PLA[11], grafting long aliphatic chain on cellulose acetate [12], introducing the third component poly(hydroxyalkanoate) [13], PLA-g-CA graft copolymer [14], comb copolymer [15], transesterification agent to form PLA-co-CA copolymer [16], organic clay [17], etc These modification methods still have some problems, such as complicated process, difficult control, limited effect and large dosage, etc. The amino group on PAMAM formed strong hydrogen bond with ester group and hydroxyl group on PLA and cellulose acetate, which improved the interfacial compatibility and increased the distribution of CA, resulting in the improved mechanical properties and gas barrier capability, accelerated the degradation rate. The PLA / CA blend films with a small amount of PAMAM exhibited high performance and degradability, and possess wide application as gas barrier material in food packaging areas
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