How are corn husks used in different materials?
In an article recently published in the Cleaner Production Journal, the researchers examined corn by-products and described the effect of chemical treatment and the chemical composition of corn husks. They further assessed 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 Engineering Applications. Image Credit: bonchan/Shutterstock.com
Growing environmental concerns have prompted the extensive use of agricultural waste to manufacture sustainable and environmentally friendly products. The use of agricultural waste reduces its accumulation while minimizing the risks of environmental pollution.
The corn husk is derived from the second largest crop in the world: corn. The prospect of producing fibers from corn husks has been considered due to their low cost and abundant availability. The stalks and husks of corn plants have been used to generate natural cellulosic fibers for the textile industry, among others. In addition, since lignocellulosic material can come from biomass, it can be used as a substrate during the production of biomaterials, thus serving as a substitute for non-biodegradable materials. In this review, the team explored corn husk fiber (CHF) conversion and research on its use, limitations, and research potential in technical applications.
Corn agricultural by-products
One of the most abundant forms of agricultural waste is corn, which when used as biomass has several advantages including high starch concentration, excellent stability, cost effectiveness, accessibility and biodegradability. CHFs with longer lengths have lower strength but higher elongation. While the elongation is significantly 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 used natural cellulosic fibers, namely jute, cotton and linen, it has less crystallinity. CHFs have reduced crystallinity, which results in improved elongation, higher moisture recovery, and more accessible regions for chemical reaction.
Corn Husk Applications
1. Production of flame retardant composites
Corn husk has been proven to have great potential as a material with various applications. Some earlier reports have revealed a relationship between flame retardancy and textiles made from corn husk fibers. Another study researched fire-resistant materials using corn husk biochar to create the biochar/high-density polyethylene (HDPE)/wood flour composite materials prior to the addition of Mg(OH)2 to increase flame retardant properties. Mg(OH)2 has a high heat capacity, which lowers the surface temperature of the material and reduces the rate at which it deteriorates when burned.
2. Corn husk in a polymer matrix
Using bio-waste materials like corn husk, many experiments have been done to strengthen polymers against different grades.
(1) Corn Husk/Polyester Composite
The researchers studied the mechanical characteristics as well as the water absorption of a CHF polyester composite and noted that the composite with 20% corn husk lignocellulosic exhibited the highest flex modulus and strength, while the composite with 15% fibers showed the highest tensile characteristics. Because lignin is less hydrophilic than cellulose, composites containing lignin have been found to exhibit lower water sorption than composites containing fibers. Thermoset polyester composite reinforced with 30% corn husk fiber also demonstrated the highest tensile strength and modulus.
(2) Corn Husk/Polypropylene Composite
Mechanically split shells (MSH) have been used by some researchers to create composites because they were comparatively more economical and environmentally friendly. It has been claimed that because MSH has a significantly lower aspect ratio and crystallinity than jute, its mechanical capabilities were found to be inferior to those of jute-PP composites. However, the team found no mention of an adjustment discovered to improve these mechanical qualities by modifying the flex and impact properties.
(3) Corn Husk/Polyethylene Composite
The effects of corn stalk, cob, husk, cob and leaf on the characteristics of HDPE composites were investigated in another study. They found that composites made from corn stalk and cob fibers had better flex modulus, tensile modulus, flexural strength, and tensile fracture toughness than composites made from fiber from corn husks, leaves and cobs.
3. Synthesis of biodegradable plastics and wood-plastic composites using corn husk
Recent studies suggest that corn by-products like corn husk, corn stalk, and corn cobs are possible supplies for reinforcement, while corn starch is used as a bioplastic matrix. These plastic composites can easily produce durable products and have better mechanical properties than traditional plastics, such as tensile strength, elongation, young modulus, tear resistance and biodegradability. These plastic composites can easily produce durable products and have better mechanical properties than traditional plastics.
Overall, the present study summarizes various research conducted on low cost biodegradable green agricultural waste such as corn husk. For a variety of applications, composite materials have been made with corn husks. Some prospective findings, results, and analyzes are highlighted in this review. According to the authors, these HFC analyzes offer new ideas for sustainable and environmentally beneficial products that will benefit their consumers and the environment.
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Ratna AS, Ghosh A, Mukhopadhyay S, Advances and Prospects of Corn Husk as a Durable Material in Composites and Other Engineering Applications, Cleaner Production Journal (2022) do: https://doi.org/10.1016/j.jclepro.2022.133563