Effect of starch on insulative fiber foam-paperboard composites

Authors: Glenn, Gregory - Greg; TONOLI, GUSTAVO H.D. - Federal University Of Lavras; SILVA, LUIZ EDUARDO - Federal University Of Lavras; Klamczynski, Artur; Wood, Delilah - De; Chiou, Bor-Sen; Lee, Charles; Hart-Cooper, William; McCaffrey, Zachariah - Zach; Orts, William

Submitted to: Polymers
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/24/2024
Publication Date: 3/26/2024
Citation: Glenn, G.M., Tonoli, G., Silva, L., Klamczynski, A.P., Wood, D.F., Chiou, B., Lee, C.C., Hart-Cooper, W.M., McCaffrey, Z., Orts, W.J. 2024. Effect of starch on insulative fiber foam-paperboard composites. Polymers. 16(7),911. https://doi.org/10.3390/polym16070911.
DOI: https://doi.org/10.3390/polym16070911

Interpretive Summary: Plastic foam is used extensively as internal packing/cushioning material in many of the billions of packages shipped each year through out the world. The large majority of packaging foams end up in landfills but significant amounts escape as litter in the landscape and ocean environments. In a coordinated effort, scientists at ARS and the Federal University of Lavras, Brazil demonstrated the use of starch and paperboard in making foam panels. The foam composites were lightweight, insulative, biodegradable, and had strength similar to polystyrene packaging foam. The results of this research show that plant-based materials could be used as a sustainable, renewable, and environmentally friendly alternative to single-use plastic foam packaging.

Technical Abstract: Single-use plastic foams are used extensively as interior packaging to insulate and protect items during shipment but have come under increasing scrutiny due to the volume sent to landfills and their negative impact on the environment. Insulative compression molded cellulose fiber foams could be a viable alternative but do not have the mechanical strength of plastic foams. To address this issue, fiber foam composites were made with or without the addition of a binder (starch) and three different reinforcing paperboard elements (angular, cylindrical, and grid). Compression molded foams and composites had a consistent thickness and a smooth, flat finish. Respirometry tests showed the fiber foams mineralized in the range of 37 to 49% over a 46 d testing period. All of the samples had relatively low density (Dd) and thermal conductivity (TC). The Dd of samples ranged from 33.1 – 64.9 kg/m3 and TC ranged from 0.039-0.049 W/mk. The addition of starch to the fiber foam (FF+S) and composites increased Dd , drying time (Td), and TC by an average of 18%, 55%, and 5.5%, respectively but also dramatically increased the mechanical strength. The FF+S foam and paperboard composites had 240% and 350% higher average flexural strength (sfM) and modulus (Ef), respectively than the FF-S composites. The FF-S grid composite and all the FF+S foam and composite samples had equal or higher sfM than EPS foam. Additionally, FF+S foam and paperboard composites had 187% and 354% higher average compression strength (CS) and modulus (Ec), respectively than the FF-S foam and composites. All the paperboard composites for both FF+S and FF-S samples had comparable or higher CS but only the FF+S cylinder and grid samples had greater toughness (Oc) than EPS foam. Fiber foams and foam composites are compatible with existing paper recycling streams and show promise as a biodegradable, insulative alternative to EPS foam internal packaging.