Design of Hygroscopic Bioplastic Products Stable in Varying Humidities

QC 20230626
https://doi.org/10.1002/mame.202200630
Hygroscopic biopolymers like proteins and polysaccharides suffer from humidity-dependent mechanical properties. Because humidity can vary significantly over the year, or even within a day, these polymers will not generally have stable properties during their lifetimes. On wheat gluten, a model highly hygroscopic biopolymer material, it is observed that larger/thicker samples can be significantly more mechanically stable than thinner samples. It is shown here that this is due to slow water diffusion, which, in turn, is due to the rigid polymer structure caused by the double-bond character of the peptide bond, the many bulky peptide side groups, and the hydrogen bond network. More than a year is required to reach complete moisture saturation (≈10 wt.%) in a 1 cm thick plate of glycerol-plasticized wheat gluten, whereas this process takes only one day for a 0.5 mm thick plate. The overall moisture uptake is also retarded by swelling-induced mechanical effects. Hence, hygroscopic biopolymers are better suited for larger/thicker products, where the moisture-induced changes in mechanical properties are smeared out over time, to the extent that the product remains sufficiently tough over climate changes, for example, throughout the course of a year.

Bettelli, Mercedes A.KTH,Polymera material(Swepub:kth)u1npa4iw (author)
Wei, Xin-FengKTH,Polymera material(Swepub:kth)u1jlh3ru (author)
Capezza, Antonio JoseKTH,Polymera material(Swepub:kth)u1fmvhux (author)
Sochor, BenediktDeutsches Elektronen-Synchrotron, DESY, Notkestraße 85, Hamburg, D-22607, Germany, Notkestraße 85 (author)
Nilsson, Fritjof,Docent,1978-KTH,Polymera material(Swepub:miun)frinil2200 (author)
Olsson, RichardKTH,Polymera material(Swepub:kth)u1ob386f (author)
Johansson, EvaSwedish University of Agricultural Sciences,Sveriges lantbruksuniversitet,Institutionen för växtförädling,Department of Plant Breeding,Department of Plant Breeding, Swedish University of Agricultural Sciences, P.O. Box 190, Lomma, SE-234 22, Sweden, P.O. Box 190(Swepub:slu)50282 (author)
Roth, Stephan V.KTH,Polymera material,Deutsches Elektronen-Synchrotron, DESY, Notkestraße 85, Hamburg, D-22607, Germany, Notkestraße 85(Swepub:kth)u1b0mjzr (author)
Hedenqvist, Mikael S.KTH,Polymera material(Swepub:kth)u10rkaxe (author)
Wei, Xinfeng (author)
KTHPolymera material (creator_code:org_t)
Sveriges lantbruksuniversitet

By the author/editor: Liu, Sirui; Bettelli, Merced ...; Wei, Xin-Feng; Capezza, Antonio ...; Sochor, Benedikt; Nilsson, Fritjof ...; show more...; Olsson, Richard; Johansson, Eva; Roth, Stephan V.; Hedenqvist, Mika ...; Wei, Xinfeng; show less...

About the subject

ENGINEERING AND TECHNOLOGY: ENGINEERING AND ...; and Chemical Enginee ...; and Polymer Technolo ...

By the university: Royal Institute of Technology; Swedish University of Agricultural Sciences; Mid Sweden University

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