Bilayer films of Poly(lactic acid) and cottonseed protein for packaging applications

Authors: Biswas, Atanu; Cheng, Huai; Kuzniar, Gary; He, Zhongqi; Kim, Sanghoon; FURTADO, ROSELAYNE - Embrapa Tropical Agroindustry; ALVES, CARLUCIO - State University Of Ceará; Sharma, Brajendra - Bk

Submitted to: Polymers
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/10/2023
Publication Date: 3/13/2023
Citation: Biswas, A., Cheng, H.N., Kuzniar, G.M., He, Z., Kim, S., Furtado, R.F., Alves, C.R., Sharma, B.K. 2023. Bilayer films of Poly(lactic acid) and cottonseed protein for packaging applications. Polymers. 15(6). Article 1425. https://doi.org/10.3390/polym15061425.
DOI: https://doi.org/10.3390/polym15061425

Interpretive Summary: Because plastic packaging can cause microplastics and environmental pollution, there is a lot of interest in using agro-based materials as replacements. However, many agro-based materials like plant proteins and carbohydrates do not have the properties needed for packaging. A promising agro-based polymer is polylactic acid (PLA), which has good film properties but is relatively expensive. In this work, we devised a new packaging film, consisting of two layers, with PLA as one layer and washed cottonseed meal (CSM) as the second layer. CSM is an inexpensive co-product of cotton manufacturing, containing mostly proteins. We showed that the properties of this two-layer film took on some of the beneficial features of both PLA and CSM. Thus, the CSM layer reduced the cost of PLA, increased the opacity of the film, and made the overall film more biodegradable. Because this new film is agro-based, biodegradable, and sustainable, their use in food packaging can help mitigate the current reliance on petroleum feedstock and reduce the environmental problems of plastic waste and microplastics. Furthermore, the new use of cottonseed meal has the additional advantage of adding value to the cotton industry and providing more economic benefits to cotton farmers.

Technical Abstract: Poly(lactic acid) (PLA) is a common biobased film-former made from renewable biomass, such as polysaccharides, sugarcane, corn, or cassava. It has good physical properties but is relatively expensive when compared to the plastics used for food packaging. In this work, bilayer films were designed, incorporating a PLA layer and a layer of washed cottonseed meal (CSM), an inexpensive agro-based raw material from cotton manufacturing, where the main component is cottonseed protein. These bilayer films were made through the solvent casting method. The combined thickness of the PLA/CSM bilayer film was between 47 and 83 micrometers. The thickness of the PLA layer in this film was 10%, 30% or 50% of the total bilayer film’s thickness. Mechanical properties of the films, opacity, water vapor permeation, and thermal properties were evaluated. Since PLA and CSM are both agro-based, sustainable, and biodegradable, the bilayer film may be used as an eco-friendlier food packaging material, which helps reduce the environmental problems of plastic waste and microplastics. Moreover, the utilization of cottonseed meal may add value to this cotton byproduct and provide potential economic benefit to cotton farmers.