Roving and yarn are fibers twisted into a feedstock for weaving cloth or reinforcing composites. Product specifications include material type, dimensions, properties, applications, and structural features. Diameter and overall length are the most important dimensional specifications to consider. Material and electrical properties include use temperature, breaking strength or load, and electrical resistance. Roving and yarn are used in a wide variety of applications and may provide features such chemical or fuel resistance, electrical conductivity, or electrical insulation. Some products are flame retardant and weather-resistant. Others provide sound-proofing or acoustic insulation. Geotextiles and microfibers are also available.
There are many different material types for roving and yarn. Choices include synthetic and polymer, acetate and triacetate, acrylic and modacrylic, aramid, elastomeric, and fluropolymer. Synthetic roving and synthetic yarn is made of petroleum-based polymers and fibers. Acrylic and modacrylic fibers are unique among synthetic fibers because they have an uneven surface. Polyimide (polyphthalamide) fibers such as Kevlar® (DuPont) are among the most thermally-stable organic materials. Elastomers and rubber materials are characterized by their high degree of flexibility and elasticity. Fluropolymers such as Teflon (DuPont) provide superior chemical resistance, thermal stability, and low friction.
Material types for roving and yarn include nylon and polyamide, olefin and polyolefin, polyester, and both polybenzimidazole (PBI) and poly-p-phenylenebenzobisoxazole (PBO). Polyamides such as nylon materials are available in a large number of polymer structures with varying chemical and physical properties. Polyolefin is a broad category that encompasses several specific, linear polymer types, including polyethylene and polypropylene. Polyester fibers are used in all types of clothing and home furnishings, and as a reinforcing fiber in tires, belts, and hoses. Polybenzimidazole (PBI) is a synthetic fiber with no melting point and that does not ignite. This type of roving and yarn is used in high-performance protective apparel. Poly-p-phenylenebenzobisoxazole (PBO) has similar performance characteristics.
Roving and yarn are available in polyethylene, polypropylene, polyphenylene sulfide (PPS), rayon, styrene acrylonitrile (SAN), and Polyvinyl chloride (PVC). Olefin fibers that are based on low density polyethylene (LDPE), high density polyethylene (HDPE) and ultra-high molecular weight polyethylene (UHMW PE) have good friction and mechanical properties, but relatively low thermal stability. Polypropylene fibers are characterized by their resistance to moisture and chemicals. Polyphenylene sulfide (PPS) is a specialty fiber characterized by remarkable resistance to thermal and chemical attack, as well as outstanding resistance to heat, solvents, acids and alkalis, mildew, aging, UV light, and abrasion. Rayon roving and yarn is biodegradable.
Material types for roving and yarn include natural fibers such as cotton, wood, linen, flax, silk, and wool. Choices may also include glass or fiberglass, E-glass, and S-glass; rock woo and slag wood; ceramic materials such as alumina; boron, carbon, and graphite; silica and quartz; silicon carbide, and zirconia. Roving and yarn made of metallic materials is also available.