There are so many highly useful biomaterials available for use as fibres it would be impossible to discuss each here. This section focuses on two well-known example biomaterials: spider silk and hemp fibre.

Spider silk is a remarkable material: it can be many times stronger than steel, twice as elastic as nylon,  it is highly stretchable and waterproof. Dragline spider silk is actually stronger than the man-made material Kevlar (Kevlar being several times stronger than steel). As a consequence, numerous research groups are seeking ways to recreate this exceptional natural biomolecule with countless potential uses.

Current researchers are seeking to unravel the molecular composition of this material and amplify its production through insertion of genes to into other organisms.

The motivation is clear: wear-resistant fabrics, exceptionally strong, thin ropes, rust-free metal replacements, surgical tissues and even artificial tendons and ligaments provide enormous incentive for researchers trying to understand this highly successful biodesign.

Although there a re many different silk secretions in nature, the strongest (yet determined) is the dragline silk of the golden orb-weaving spider, Nephila clavipes.

This biomaterial has a remarkably high tensile strength combined with an ability to stretch without snapping. The dragline silk of Nephila clavipes is stronger, more elastic and even more waterproof than the silkworm silk currently used fine clothing.

Researchers at Cornell university have determined that the primary constituents of spider silk are two simple amino acids, glycine and alanine. One of the key aspects of the silk strength is the exact physical alignment of these common biomolecules.

History:

in 1709 René-Antoine Ferchault de Réaumur (a french naturalist) was asked to investigate uses for spider silk. He first attempted to produce stockings and gloves from the silk acquired from egg sacs. The limiting factor was the quantity involved: it required far too many spiders to produce sufficient silk. As well, unlike silk-worms, spiders are fiercely individualistic and cannot be kept in close contact with each other.

Earlier usage of spider silk appears in numerous cultures: ancient Greeks stanched bleeding wounds with cobwebs while indigenous peoples of Australia have employed the silk of certain spiders for fishing lines. In New Guinea indigenous peoples have produced fishing nets, head gear, and bags out of spider silk.

The properties of spider silk are significant. In addition to its strong (yet remarkably elastic physical properties) spider silk has one highly significant physical property which make analysis challenging indeed. Inside the spider's abdomen the silk is liquid, which passes through a series of tubes to the spinnerets where it comes out as a solid. It is the a unique combination of chemical constituents and mechanical manipulation which produce the remarkable properties of spider silk.

Since it is impossible to grow sufficient spiders in captivity to produce enough silk, much of the current research is pursuing the insertion of silk-producing genes in other species (such as E.coli). Current limits to this trans-species genetic modification include the poor expression of the silk genes and dramatically reduced yields.

Hemp Fibre

Hemp has been cultured by humans for thousands of years. Products include:

1. Food: Seeds used as food, oils, etc.
2. Paper and paper products
3. Cosmetics (oils and fats)
4. Plywood and industrial laminates
5. Rope: Hemp fibres (some of the strongest plant fibres known) to produce some of the finest nautical-grade rope ever produced
6. Fabrics: clothing (now a major industry) tarpaulins,  bale / wagon cover, canvas and sailcloth

History:

Hemp has a long history with many indigenous peoples. The cultivation of hemp was banned in Canada In 1938 and re-introduced in 1998 as an industrial agricultural commodity. This long period of industrial exile was a result of the incorrect association with THC-containing cannabis species, now clarified through stringent analytical protocols. The industrial type of hemp is described as a bast fibre, (like.flax and  jute).

Structure:

1. Stalk: the hemp stalk is made up of hurds (short, woody fibres). The outer portions of the stalk containing longer fibres.
2. Hemp plants consist of ~ 30% bast fibre, 60% hurd, and 10% dust and waste.

Bast fibres:

1. Primary bast fibre: long and strong fibres, typically lower in lignin
2. Secondary bast fibre: more lignin and shorter length
3. Tow: extremely short fibres

Fibre Strength:

Ancient mariners understood the physical strengths of hemp fibres. The table below compares the properties of a number of reference materials to hemp.

Cellulose (%) Lignin (%) Mean Length of Fibre (mm) Mean Width of Fibre (mm) Tensile Strength (psi*1000) Young’s Modulus (psi*1000) Cotton 85-90 .7-1.6 25 0.02     Flax – (Seed) 43-47 21-23 30 0.02 157 14,500 Hemp 57-77 9-13 20 0.022 131 10,005 Abaca 56-63 36-45 6 0.024     Coniferous wood 40-45 26-34 4.1 0.025     Sisal 47-62 7-9 3.3 0.02     Kenaf 44-57 15-19 2.6 0.02     Jute 45-63 21-26 2.5 0.02 123 9,280 Wheat Straw 33-39 16-23 1.4 0.015     Deciduous wood 38-49 23-30 1.2 0.03     Glass Fibre E         246-508 10,200 Glass Fibre S         290-653 12,325 Glass Fibre C         247-406 10,150 Kevlar Fibre         406 7,945 to 21,315 Carbon Fibres         270-638 33,350 to 78,300 Ceramic         247-429 14,500 to 60,900 Steel         406 29,000 Boron         508 60,175 Al-alloy         87 10,295 Nylon         145 870

Other Example Natural Fibers:

	Avian Keratin Protein Fibres (from feathers)
	Keratin Fibre Nonwovens For Erosion Control
	Keratin Fibers For Nanofiltration (removal of ions from solutions)
	Alginate And Chitosan Fibers For Medical Uses
	Natural Fibers With Low Moisture Sensitivity: Flax Fibres Bast Fibres