Bio-based Textile Material: Biofiber

BULETIN TEKSTIL.COM/ Jakarta – Numerous steps and strategy to prevent environmental pollution is widely applied from the main material sourced from crude oil, therefore the material utilization is more focused on microorganisms, both living and dead. Utilization of these material is called Bio-based or Bio Material. Bio-based is a renewable and sustainable material.

A material is recognized as “Bio-based” if it is wholly or partly derived from biomass. Biobase content of a material is not an indicator of material’s biodegradability and not all bio-based bioplastics are biodegradable.

Generally, materials that undergo degradation by microbial activity and break down into water, biomass, carbon dioxide, and methane at the same rate as food, leaves, or paper, are considered biodegradable. Not every bioplastic is able to be decomposed by microorganisms and there are several biodegradable plastics that is 100% fossil-based.

Biofiber

Natural fiber is fiber derived from several natural sources such as plants or animals. The characteristics of this fiber is influenced by several factors such as geographical location, origin, extraction method, and processing. This fiber is able to be used as reinforcement in polymer matrices and numerous structural applications. Biofiber can be classified as plant fiber and animal fiber.

Plant-derived

Fiber extracted from plants and trees consists of cellulose, hemi-cellulose, lignin, pectin, wax, etc. The physical, morphology, chemical, and mechanical characteristics of plant fiber depend on several factors such as geography, part of the plant or tree of which the fiber is extracted, and the extraction method. Plant-derived fibers are also known as ligino-cellulose fiber and in the form of hair such as kapok, cotton, etc. Thick fiber such as coir and some in the form of bast fibers obtained from hemp, kenaf, kudzu, linden, etc. Plant fiber are divided into two primary and secondary fiber depends on the utilization of the plant or tree. Primary fiber consists of sisal, hemp, cotton, kenaf while those included as secondary fibers are by-products from plants such as bananas, pineapples, coir, oil palm, etc.

Animal-derived

Animal-derived fiber has a potential to be used as reinforcement in polymer matrices since it has excellent physical, chemical, and mechanical characteristics. Animal-derived fiber are sourced from several species of animals, such as wool that is sourced from alpacas, bison, sheep, angora, etc. Similarly, silk is obtained from a variety of insect sources, mostly from butterfly larvae (approximately 14.000 species) and also from spiders (approximately 4.000 species). In general, silk and wool are mostly used in the textile industry.

Recent research in wool includes electronic application of which a wool fabric coated with silver nanoparticles and used as touch capacitors to power LEDs. Further exploration of this system can be used on bio-medical devices to detect movement in muscle and joints of bones.

Based on a research done in 2019, silk fiber can be used in biomedical applications such as surgical implants and tissue engineering. A research on spider silk is proven to be more promising compared to other silk proteins because of its durability and mechanical performance. Polymer composites development reinforced with synthetic spider silk can be used as biological implants and to develop sustainable high-strength composites.

Quill is a secondary waste that contains keratin. The absorbance properties of keratin are used to produce absorbent sponges for refining purposes and also in microbial corrosion process applications. In recent research, a keratin sponge was developed to be more susceptible to oil absorbance. Further research on keratin-based material will pave the way for the development of large-scale composite sponges that can be used for cleaning lenses, extremely smooth surface, and precision engineering sectors.

Production method

A precise fiber extraction process is one of the main problem in biofiber production process. Fiber extraction technique is influenced by two factors, fiber type and application.

Animal fiber can be extracted by several ways. For example, silk from larvae is separated by slowly boiling in a solution containing soap. Fiber from spiders are extracted by anesthetizing the spiders then turning them upside down to expose spinnerets. The fibers are then removed by using brush, then separated. Since it is time consuming and not available commercially, a good extraction method is needed to be identified. Wool fibers are extracted manually and washed with water to get rid of dirt.

Natural fiber hydrophilicity and matrix hydrophobicity is one of the disadvantages when natural fiber is used as reinforcement in polymer composites. Hydrophilic characteristic of natural fiber can be reduced by chemical treatment and surface modification. Below are several treatment that can be done:

• Bleaching natural fibers is done by soaking the fibers in bleaching solution such as hydrogen peroxide (H₂O₂). This treatment is able to increase tensile strength and thermal stability of coconut fibers.
• Copolymerization technique is able to increase the thermal stability observed in pineapple leaf fibers.
• NaOH treatment or alkali treatment is able to remove hydroxyl bond and increase surface roughness, creating strong interface bond between fibers and matrix.
• Plasma process is capable to increase fibers surface roughness by surface etching, increasing the interfacial bond by forming an interlock with the matrix.
• Polymer coating on natural fibers increases compatibility between fiber and matrix.
• Potassium permanganate treatment on natural fibers improves their physicochemical characteristics by removing waxes and other impurities from natural fibers.

There is no standard on composite process among the surfaces for types of fibers. Chemical treatment is capable to change physical, chemical, thermal, and mechanical properties of natural fibers, also affected by several other factors such as time, temperature, and chemical concentration. Each combination of the factors above influence certain effects on the properties of plant-derived fibers. In order to develop materials with a better performance in every aspects, conducting further studies regarding the effect of chemically modified fibers on reinforced composites is important.

Biofiber benefits

Due to its excellent properties and its availability as a sustainable resource, biofiber possess numerous amount of advantages compared to synthetic fibers. Advantages of biofibers are:

• Biofiber utilization can promote new opportunities to society;
• Plant cultivation, able to reduce greenhouse gases and protect the earth from global warming;
• Biofiber process is rather effortless due to low process cost compared to synthetic fibers;
• Low wear of machine spare parts during biofiber processing;
• Biofiber is biodegradable; and
• Biofiber does not pollute the land, due to in recent years the use of synthetic fibers and synthetic materials pollute the land and waters, causing health hazards.

Biofiber limitations

Biofiber is hydrophilic, due to its moisture adsorption and is causing damage to the matrix when prepared as a composite. Biocompatibility is also one of biofiber’s disadvantages, improper wetting and bonding of the composites may result in reduced performance.

These limitations can be resolved through certain fiber modification techniques. Cellulose fiber break down quickly in humid and dark condition, while animal fiber such as wool and silk may get damaged by pest or insects. Biofiber is able to be developed by anti-microbes and anti-pests bonding materials that prevent bacterial degradation. Diameter, size, and shape of biofibers are irregular, which have a major impact in regulating the density, hardness, and strength of the composite. Mechanical strength and modulus of biofibers are lower compared to synthetic fiber.

Biofiber development

Many studies have reported biofiber treatment for its antimicrobial properties. Kapok fiber are treated with chitosan/AgClTiO₂ to give antimicrobial effects on textiles. Wool fibers are given natural antimicrobial colorants to prevent bacteria growth. Colorants T. chebula and A. tinctoria are used on wool fibers to prevent the growth of Bacillus subtilis and Staphylococcus aureus (gram prositive). Kenaf fiber reinforced clay cementitious composites shows better performance in building construction materials compared to synthetic reinforcements. Recently, smart yarn sensitive to humidity is being developed from animal-derived fibers such as silk for smart textile applications. Similarly, antibacterial cotton textiles can be produced using beeswax, propolis and chitosan. Numerous studies and research have been carried out that various development in bio-based fibers are being developed for the welfare of society that has potential impacts on textile, medical treatment, and surgical applications.

Bio-based fibers construction materials

Future scope of Biofiber

New technology advancement and environment conservation law has accelerated the replacement of synthetic fiber to biofiber. The demand of potential new raw materials with superior quality is always there. Therefore, the search of new biofibers identification is crucial.

There has been a large number of antibacterial textile exploration, but they are only resistant to certain strain of bacteria. Therefore, it is required to develop textiles with high resistance to many bacterial strains to be utilized in medical facilities to prevent various infectious diseases.

Cellulose based medical scaffold research is required and applicable on tissue engineering, surgical stitches, and recovery process due to its biocompatibility. Until recently, it is globally used in automotive and various light applications which also leaning towards electronics, biomedical, and aerospace applications.

Research in biofiber-coated conductive materials is still developing until now, it can also be developed to produce pressure sensors to monitor the movement of injured muscles and bones. Natural fibers have good heat resistance properties.

In recent research, Junctus maritimus fibers are used as reinforcement in cement for heat insulations in buildings. It was discovered that the result shows better performance in comparison to hemp fiber reinforcement. Biofibers reinforced construction materials can be further explored to minimize glass fibers usage.

In the future, biofiber will rule out the usage of carbon fiber and other synthetic fibers, due to its low cost and environment security, which can also provide jobs and revolutionize the use of synthetic materials.

(Red B-Teks/Agung)

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