Natural fiber
**1. Types of Natural Fibers:**
– Plant fibers:
– Seed fiber: e.g. cotton
– Leaf fiber: e.g. banana, pineapple (PALF)
– Bast fiber: e.g. flax, jute, kenaf, industrial hemp, ramie
– Fruit fiber: e.g. coconut fiber (coir)
– Stalk fiber: e.g. straws of wheat, rice, barley, bamboo, and straw
– Animal fibers:
– Animal hair (wool or hairs): e.g. sheep’s wool, goat hair (cashmere, mohair), alpaca hair
– Silk fiber: secreted by insects during cocoon preparation
– Examples: silk, sinew, catgut, angora, mohair, alpaca
**2. Natural Fiber Derivatives:**
– Chitin:
– Second most abundant natural polymer
– Highly crystalline and insoluble in many solvents
– Provides protection and structural support in living organisms
– Forms fibrils that contribute to hierarchical structures
– Exists as a copolymer with chitosan in nature
– Chitosan:
– Deacetylated derivative of chitin
– Soluble in acidic aqueous solutions
– Used in biomedical applications
– Less stable but easier to process than chitin
– Copolymer with chitin in nature
– Collagen:
– Structural protein in biological materials
– Types: I (skin, tendons), II (cartilage), III (reticular fibers)
– Forms triple helices, fibrils, and fibers
– Supports and strengthens body tissues
– Known as the ‘steel of biological materials’
**3. Industrial and Biocomposite Applications:**
– Applications:
– 19th-century knowledge weaving flax, hemp, jute, Manila hemp, sisal, and vegetable fibers
– Industrial use:
– Four animal fibers of industrial value: wool, silk, camel hair, and angora
– Four plant fibers of industrial value: cotton, flax, hemp, and jute
– Dominant fiber for textiles: cotton
– Natural fiber composites:
– Biodegradability, renewability, lower density, and processing costs
– Challenges: poor strength compared to glass fibers, difficulty bonding fibers and matrix
**4. Nanocomposites and Biomaterial Applications:**
– Nanocomposites:
– Offer superior mechanical properties
– Natural nanocomposites in biology: bone, abalone shell, nacre, and tooth enamel
– Use of nanosized biopolymers like collagen, cellulose, chitin, and tunican in synthetic matrices
– Biomaterial and biocompatibility:
– Chitin used in various medical and industrial applications
– Potential of natural fibers to be recognized as natural tissue by the body
– Applications of chitin in bone filling, drug carriers, antitumor agents, and biosensors
**5. Biomechanics and Material Properties:**
– Biomechanics of living tissues:
– Mechanical properties are crucial for understanding tissue behavior
– Aids in developing materials for medical applications
– Contributes to advancements in tissue engineering
– Natural materials in biomaterials and tissues:
– Offer unique properties suitable for biomedical applications
– Enhance biocompatibility and performance
– Inspire innovative designs in the biomedical field
– Surface energies and mechanical principles:
– Essential for material processing and fiber-matrix interactions
– Crucial for biomimetic designs and sustainable materials
– Explore new avenues for lightweight and strong materials