In a paper recently published in the Journal of Cleaner Production, researchers reviewed corn byproducts and outlined the effect of chemical treatment and the corn husks’ chemical composition. They further evaluated the prospects and limitations of corn husks as well as future research directions.
Study: Advances and prospects of corn husk as a sustainable material in composites and other technical applications. Image Credit: bonchan/Shutterstock.com
Background
Mounting environmental concerns have prompted the extensive use of agricultural wastes to make sustainable and eco-friendly products. The utilization of agricultural wastes reduces their accumulation along with minimizing environmental pollution risks.
Corn husk is derived from the world’s second-largest crop: maize. The prospect of producing fibers using corn husks has been scrutinized due to their low expense and abundant availability. The stalks and husks of corn plants have been used to generate natural cellulosic fibers for the textile industry, among others. Moreover, since lignocellulosic material can be sourced from biomass, it can be used as a substrate during biomaterial production, thus serving as a replacement for non-biodegradable materials. In this review, the team explored corn husk fiber (CHF) conversion and the research on its utilization, limitation, and further potential for research in technical applications.
Agricultural Corn By-Products
One of the most abundant forms of agricultural waste is maize, which when used as biomass has several advantages including a high starch concentration, excellent stability, cost-effectiveness, attainability, and biodegradability. CHFs with longer lengths exhibit lower strength but higher elongation. While elongation is noticeably lower in cornstalk fibers, their strength is comparable to that of CHFs.
According to research, corn husk has a structure comparable to that of cotton fibers. However, compared to the three most widely used natural cellulosic fibers, namely jute, cotton, and linen, it has lesser crystallinity. CHFs have decreased crystallinity, which results in improved elongation, higher moisture recovery, and more regions that are accessible for a chemical reaction.
Applications of Corn Husk
1. Production of flame-retardant composites
Corn husk has been proven to have significant potential as a material with various applications. Some previous reports revealed a relationship between flame retardancy and textiles made of fiber from corn husks. Another study researched fire-resistant materials using corn husk biochar to create the biochar/ high-density polyethylene (HDPE)/wood flour composite materials before the addition of Mg(OH)2 to increase flame retardant properties. Mg(OH)2 has a high heat capacity, which lowers the material's surface temperature and reduces the rate at which it deteriorates when burned.
2. Corn husk in polymer matrix
Using bio-waste materials like corn husk, numerous experiments have been performed to strengthen polymers with respect to different qualities.
(1) Corn husk/polyester composite
Researchers investigated the mechanical characteristics as well as water absorption of a polyester CHF composite and noted that the composite with 20% of corn husk lignocellulosic exhibited the highest flexural modulus and strength while the composite with 15% fiber exhibited the highest tensile characteristics. Because lignin is less hydrophilic than cellulose, it was found that composites containing lignin displayed lower water sorption than fiber-containing composites. Thermoset polyester composite reinforced with 30% maize husk fiber also demonstrated the highest tensile strength and modulus.
(2) Corn husk/polypropylene composite
Mechanically split husks (MSH) were used by some researchers to create composites since they were comparatively more economical and environmentally benign. It was claimed that because MSH has a noticeably lower aspect ratio and lower crystallinity than jute, its mechanical capabilities were found to be inferior to those of jute-PP composites. However, the team found no mention of any adjustment discovered to enhance such mechanical qualities by altering flexure and impact properties.
(3) Corn husk/polyethylene composite
The effects of the stem, ear, husk, cob, and leaf from the corn stalk on the characteristics of HDPE composites were examined in another study. They found that composites manufactured from maize stem and cob fibers had better flexural modulus, tensile modulus, flexural strength, and tensile break strength than composites made from corn husk, leaf, and ear fibers.
3. Synthesis of biodegradable plastics and wood plastic composites using corn husk
Recent studies suggest that maize byproducts like corn husk, corn stalk, and corn cobs are possible supplies for reinforcement, while corn starch is employed as a bioplastic matrix. These plastic composites can readily produce sustainable products and have greater mechanical properties than traditional plastics, such as tensile strength, elongation, young modulus, tear strength and biodegradability. These plastic composites can readily produce sustainable products and have greater mechanical properties as compared to traditional plastics.
Conclusions
Overall, the present study summarized various research conducted on low-cost biodegradable green agricultural wastes, such as maize husk. For a variety of applications, composite materials have been made with corn husks. Some prospective findings, outcomes, and analyses are highlighted in this review. According to the authors, these analyses of CHFs offer novel ideas for environmentally beneficial, long-lasting products that will benefit their consumers and the environment.
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Source:
Ratna AS, Ghosh A, Mukhopadhyay S, Advances and prospects of corn husk as a sustainable material in composites and other technical applications, Journal of Cleaner Production (2022) doi: https://doi.org/10.1016/j.jclepro.2022.133563