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Polymers (Basel). 2019 Apr 19;11(4). pii: E722. doi: 10.3390/polym11040722.

Preparation and Characterization of Whey Protein-Based Polymers Produced from Residual Dairy Streams.

Author information

1
Department of Chemical Engineering, Masdar City Campus, Khalifa University, 54224 Abu Dhabi, UAE. bushra.chalermthai@ku.ac.ae.
2
Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA. wychan@mit.edu.
3
Department of Chemical Engineering, Masdar City Campus, Khalifa University, 54224 Abu Dhabi, UAE. yanauta@gmail.com.
4
Department of Chemical Engineering, Masdar City Campus, Khalifa University, 54224 Abu Dhabi, UAE. hanifa.alblooshi@ku.ac.ae.
5
Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA. bdolsen@mit.edu.
6
Department of Chemical Engineering, Biotechnology and Environmental Technology, University of Southern Denmark, 5230 Odense, Denmark. jesc@kbm.sdu.dk.

Abstract

The wide use of non-biodegradable, petroleum-based plastics raises important environmental concerns, which urges finding alternatives. In this study, an alternative way to produce polymers from a renewable source-milk proteins-was investigated with the aim of replacing polyethylene. Whey protein can be obtained from whey residual, which is a by-product in the cheese-making process. Two different sources of whey protein were tested: Whey protein isolate (WPI) containing 91% protein concentration and whey protein concentrate (WPC) containing 77% protein concentration. These were methacrylated, followed by free radical polymerization with co-polymer poly(ethylene glycol) methyl ether methacrylate (PEGMA) to obtain polymer sheets. Different protein concentrations in water (11-14 w/v%), at two protein/PEGMA mass-ratios, 20:80 and 30:70, were tested. The polymers made from WPI and WPC at a higher protein/PEGMA ratio of 30:70 had significantly better tensile strength than the one with lower protein content, by about 1-2 MPa (the best 30:70 sample exhibited 3.8 ± 0.2 MPa and the best 20:80 sample exhibited 1.9 ± 0.4 MPa). This indicates that the ratio between the hard (protein) and soft (copolymer PEGMA) domains induce significant changes to the tensile strengths of the polymer sheets. Thermally, the WPI-based polymer samples are stable up to 277.8 ± 6.2 °C and the WPC-based samples are stable up to 273.0 ± 3.4 °C.

KEYWORDS:

PEGMA; copolymerization; mechanical properties; protein-based polymer; whey protein

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