Environmental Engineering Reference
In-Depth Information
soil erosion control; seed protection; weed control; and many other agricultural
and landscaping uses. Biodegradable jute geotextiles can be left to rot in the
ground, keeping the ground cool and making the land more fertile.
6.2.3.4
Hemp
Hemp is the common name for Cannabis sativa , cultivated for industrial (non-drug)
use. Licenses for hemp cultivation are issued in the European Union and Canada.
Hemp grows quickly and produces strong fibres. In the past hemp was widely used
for canvas (note the similar etymology) and other articles such as carpets and rope.
The ultimate fibre is flatter, less regular and more lignified than linen. In Europe, the
major application of hemp is in plastic-natural-fibre composites as filler, mainly for
the automotive industry. The microscopic protuberances on the surface of the fibre
represent the advantage of a stronger mechanical anchorage with the plastic matrix.
Another recent application is the fabrication of insulating mats for housing.
6.2.3.5
Ramie
Ramie ( Boehmeria nivea ) is one of the oldest fibre crops, principally used for
fabric production (including mummy cloths!) with antifungal and antibacterial
properties. It is a bast fibre, and the part used is the bark (phloem) of the vegetative
stalks. Unlike other bast crops, ramie requires chemical processing to de-gum the
fibre (up to 25% mass loss).
Ramie is not as durable as other fibres, so is usually used as a blend with other
fibres such as cotton or wool. It is known especially for its ability to hold shape,
reducing wrinkling and shrinking, and introduces a silky lustre to the fabric
appearance. It does not dye as well as cotton however, but its white colour is use-
ful in textile industry. It is similar to flax in absorbency, density and microscopic
appearance. Because of its high molecular crystallinity, ramie is strong but stiff
and brittle and will break if folded repeatedly in the same place; it lacks resiliency
and has a low elasticity and elongation potential. When wet, it exhibits greater
strength. Spinning the fibre is difficult due to its brittle quality and low elasticity,
and weaving is complicated by the hairy surface of the yarn, resulting from lack
of cohesion between the fibres. A greater utilisation of ramie would depend upon
the development of improved processing methods. Ramie is currently used to
make products such as industrial sewing thread, packing materials, fishing nets
and filter cloths. Shorter fibres and waste are used in paper manufacture.
6.2.3.6
Sisal
Sisal is an agave ( Agave sisalana ) that yields a stiff fibre used in making rope.
Sisals are sterile hybrids of uncertain origin. Although originating from the port of
Sisal in Yucatan, Mexico, they do not actually grow in Yucatan, which presently
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