Properties of gluten foam composites containing different fibers and particulates

Authors: Chiou, Bor-Sen; Cao, Trung; McCaffrey, Zachariah - Zach; Bilbao-Sainz, Cristina; Wood, Delilah - De; Glenn, Gregory - Greg; Orts, William

Submitted to: Journal of Polymers and the Environment
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/15/2024
Publication Date: 5/10/2024
Citation: Chiou, B., Cao, T.K., McCaffrey, Z., Bilbao-Sainz, C., Wood, D.F., Glenn, G.M., Orts, W.J. 2024. Properties of gluten foam composites containing different fibers and particulates. Journal of Polymers and the Environment. https://doi.org/10.1007/s10924-024-03295-5.
DOI: https://doi.org/10.1007/s10924-024-03295-5

Interpretive Summary: Foams are widely used in packaging applications since they are lightweight and have superior energy absorbing properties. However, most foams are derived from petroleum-based resources. In this study, various fibers and particulates were added to wheat-based foams to produce foam composites. The fibers and particulates included milkweed fibers, hemp fibers, cotton fibers, walnut shells, torrefied walnut shells, and paraffin wax. Most of these foam composites were derived from renewable resources and were biodegradable. In general, foams containing fibers had better mechanical properties than those containing particulates. Also, foams containing milkweed fibers had the highest water uptake values. These results indicated that the addition of fibers and particulates to wheat gluten foams can improve their material properties.

Technical Abstract: Gluten-based foam composites containing various additives were produced to develop materials derived from mostly renewable resources. The fillers included walnut shells, torrefied walnut shells, paraffin wax, milkweed fibers, hemp fibers, and cotton fibers. The effects of the fillers on the foam composites’ properties were determined using scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis, compression testing, and water uptake measurements. SEM results showed that most of the fillers were well dispersed in the gluten matrix except for the cotton fibers, which produced agglomerated fiber bundles. Also, foams containing fiber fillers showed void spaces between some of the fibers and the gluten matrix, indicating poor interfacial adhesion. FTIR results indicated that foams had a more aggregated structure with higher ß-sheet contents than gluten powder. In general, foam composites containing fibers had larger compressive modulus values than those containing particulates, with the sample containing 10 wt% milkweed fibers having the highest value of 67.03 ± 12.01 MPa. Also, composites containing torrefied walnut shells had higher compressive strength values than those containing raw walnut shells, indicating better compatibility with the gluten matrix. Moreover, the foam composites containing milkweed fibers had the largest water uptake values of up to 270%.