Interfacial modification on polyhydroxyalkanoates/starch blend by grafting ​in-situ

Pengwu Xu; Qingtao Zeng; Ying Cao; Piming Ma; Weifu Dong; Mingqing Chen

doi:10.1016/j.carbpol.2017.06.048

Interfacial modification on polyhydroxyalkanoates/starch blend by grafting in-situ

Carbohydr Polym. 2017 Oct 15:174:716-722. doi: 10.1016/j.carbpol.2017.06.048. Epub 2017 Jun 29.

Authors

Pengwu Xu¹, Qingtao Zeng¹, Ying Cao¹, Piming Ma², Weifu Dong¹, Mingqing Chen³

Affiliations

¹ The Key Laboratory of Food Colloids and Biotechnology, Ministry of Education, School of Chemical and Material Engineering, Jiangnan University, 1800 Lihu Road, Wuxi 214122, China.
² The Key Laboratory of Food Colloids and Biotechnology, Ministry of Education, School of Chemical and Material Engineering, Jiangnan University, 1800 Lihu Road, Wuxi 214122, China. Electronic address: p.ma@jiangnan.edu.cn.
³ The Key Laboratory of Food Colloids and Biotechnology, Ministry of Education, School of Chemical and Material Engineering, Jiangnan University, 1800 Lihu Road, Wuxi 214122, China. Electronic address: mq-chen@jiangnan.edu.cn.

PMID: 28821123
DOI: 10.1016/j.carbpol.2017.06.048

Abstract

The interfacial adhesion between polyhydroxyalkanoates (PHAs) and native starch is poor. To improve the interfacial adhesion, PHAs were in-situ grafted onto starch using dicumyl peroxide (DCP) as a free radical initiator. The grafting reaction was carefully characterized and confirmed by gel analysis and Fourier transform infrared spectroscopy (FT-IR). The gel yield of the PHAs/starch/DCP blend increased with the DCP concentration up to 2wt%. Meanwhile, obvious plastic deformation (stretched fibrils) was observed at the interface in the PHAs/starch/DCP blend in comparison with complete interfacial debonding in the PHAs/starch physical blend. The improved interfacial adhesion after grafting was further confirmed by a reduction in adhesion factor (A_f) obtained from dynamic mechanical analysis (DMA). The mechanical strength and the crystallization rate of the PHAs were deteriorated after incorporation of starch, and were backed up by the interfacial improvement. A linear relationship between the mechanical properties and the gel yield was discovered. In addition, the PHAs/starch/DCP blend exhibited higher decomposition active energy (E_a) and thus better thermal stability in comparison with the PHAs and the PHAs/starch physical blend. Therefore, this study provides a simple route to utilize low-cost starch as a component in biopolymer blend.

Keywords: Biopolymer blend; Grafting; Interfacial adhesion; Polyhydroxyalkanoates; Starch.