HILLTOP SPINNING and WEAVING CENTRE

Established in 1990

POSTED Saturday, February 4, 2012

PROPRIETORS: SUE & BILL CHITTY

Natural fibres

 

Natural fibres include those produced by plants, animals, and geological processes. They are biodegradable over time. They can be classified according to their origin:

 

   * Vegetable fibres are generally based on arrangements of cellulose, often with lignin: examples include cotton, hemp, jute, flax, ramie, and sisal. Plant fibres are employed in the manufacture of paper and textile (cloth), and dietary fibre is an important component of human nutrition.

   * Wood fibre, distinguished from vegetable fibre, is from tree sources. Forms include groundwood, thermomechanical pulp (TMP) and bleached or unbleached kraft or sulfite pulps. Kraft and sulfite, also called sulphite, refer to the type of pulping process used to remove the lignin bonding the original wood structure, thus freeing the fibres for use in paper and engineered wood products such as fibreboard.

   * Animal fibres consist largely of particular proteins. Instances are spider silk, sinew, catgut, wool and hair such as cashmere, mohair and angora, fur such as sheepskin, rabbit, mink, fox, beaver, etc.

   * Mineral fibres comprise asbestos. Asbestos is the only naturally occurring long mineral fibre. Short, fibre-like minerals include wollastonite, attapulgite and halloysite.

 

Human-made fibres

 

Synthetic or man-made fibres generally come from synthetic materials such as petrochemicals. But some types of synthetic fibres are manufactured from natural cellulose, including rayon, modal, and the more recently developed Lyocell. Cellulose-based fibres are of two types, regenerated or pure cellulose such as from the cupro-ammonium process and modified cellulose such as the cellulose acetates.

 

fibre classification in reinforced plastics falls into two classes: (i) short fibres, also known as discontinuous fibres, with a general aspect ratio (defined as the ratio of fibre length to diameter) between 20 to 60, and (ii) long fibres, also known as continuous fibres, the general aspect ratio is between 200 to 500[1].

 

Cellulose fibres

 

   * Cellulose fibres are a subset of man-made fibres, regenerated from natural cellulose. The cellulose comes from various sources. Modal is made from beech trees, bamboo fibre is a cellulose fibre made from bamboo, soy silk is made from soybeans, seacell is made from seaweed, etc.

 

Mineral fibres

 

   * fibreglass, made from specific glass, and optical fibre, made from purified natural quartz, are also man-made fibres that come from natural raw materials.

   * Metallic fibres can be drawn from ductile metals such as copper, gold or silver and extruded or deposited from more brittle ones, such as nickel, aluminum or iron.

   * Carbon fibres are often based on carbonised polymers, but the end product is pure carbon.

 

Polymer fibres

 

   * Polymer fibres are a subset of man-made fibres, which are based on synthetic chemicals (often from petrochemical sources) rather than arising from natural materials by a purely physical process. These fibres are made from:

         o polyamide nylon,

         o PET or PBT polyester

         o phenol-formaldehyde (PF)

         o polyvinyl alcohol fibre (PVA)

         o polyvinyl chloride fibre (PVC)

         o polyolefins (PP and PE)

         o acrylic polyesters, pure polyester PAN fibres are used to make carbon fibre by roasting them in a low oxygen environment. Traditional acrylic fibre is used more often as a synthetic replacement for wool. Carbon fibres and PF fibres are noted as two resin-based fibres that are not thermoplastic, most others can be melted.

         o Aromatic polyamids (aramids) such as Twaron, Kevlar and Nomex thermally degrade at high temperatures and do not melt. These fibres have strong bonding between polymer chains

         o polyethylene (PE), eventually with extremely long chains / HMPE (e.g. Dyneema or Spectra).

         o Elastomers can even be used, e.g. spandex although urethane fibres are starting to replace spandex technology.

         o polyurethane fibre

 

   * Coextruded fibres have two distinct polymers forming the fibre, usually as a core-sheath or side-by-side. Coated fibres exist such as nickel-coated to provide static elimination, silver-coated to provide anti-bacterial properties and aluminum-coated to provide RF deflection for radar chaff. Radar chaff is actually a spool of continuous glass tow that has been aluminum coated. An aircraft-mounted high speed cutter chops it up as it spews from a moving aircraft to confuse radar signals.

 

Microfibres

 

Micro fibres in textiles refer to sub-denier fibre (such as polyester drawn to 0.5 dn). Denier and Detex are two measurements of fibre yield based on weight and length. If the fibre density is known you also have a fibre diameter, otherwise it is simpler to measure diameters in micrometers. Microfibres in technical fibres refer to ultra fine fibres (glass or meltblown thermoplastics) often used in filtration. Newer fibre designs include extruding fibre that splits into multiple finer fibres. Most synthetic fibres are round in cross-section, but special designs can be hollow, oval, star-shaped or trilobal. The latter design provides more optically reflective properties. Synthetic textile fibres are often crimped to provide bulk in a woven, non woven or knitted structure. fibre surfaces can also be dull or bright. Dull surfaces reflect more light while bright tends to transmit light and make the fibre more transparent.

 

Very short and/or irregular fibres have been called fibrils. Natural cellulose, such as cotton or bleached kraft, show smaller fibrils jutting out and away from the main fibre structure. (Thanks Wikopedia)

 

I could go on but I’ve run out of space.