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Report 1 of 5:
Inner
Style - UK
Introduction
In developing countries, there is a culture of reuse and recycling. Waste collectors roam residential areas in large towns and cities in search of reusable articles. Some of the products that result from the reprocessing of waste are particularly impressive and the levels of skill and ingenuity are high. Recycling artisans have integrated themselves into the traditional market place and have created a viable livelihood for themselves in this sector.
The process of tyre collection and reuse is a task carried out primarily by the informal sector. Tyres are seen as being too valuable to enter the waste stream and are collected and put to use. There are many ways in which tyres and inner tubes can be reused or reclaimed. Waste management dictates that re-use, recycling and energy recovery are superior to disposal and waste management options. Old inner tubes have many uses: swimming aids and water containers being two simple examples.
Rubber production
Rubber is produced from natural or synthetic sources. Natural rubber is obtained from the milky white fluid called latex, found in many plants; synthetic rubbers are produced from unsaturated hydrocarbons.
Natural rubber is extracted from the trees in the form of latex. The tree is ‘tapped’, that is, a diagonal incision is made in the bark of the tree and as the latex exudes from the cut it is collected in a small cup. The average annual yield is approximately 2½ kg per tree or 450 kg per hectare, although special high-yield trees can yield as much as 3000 kg per hectare each year.
The gathered latex is strained, diluted with water and treated with acid to cause the suspended rubber particles within the latex to coagulate. After being pressed between rollers to form thin sheets, the rubber is air (or smoke) dried and is then ready for shipment.
Vulcanisation
Crude latex is made up of a large number of very long, flexible, molecular chains. If these chains are linked together to prevent the molecules moving apart, then the rubber takes on its characteristic elastic quality. This linking process is carried out by heating the latex with sulphur (other vulcanising agents such as selenium and tellurium are occasionally used but sulphur is the most common). There are two common vulcanising processes:
- Pressure vulcanisation: This process involves heating the rubber with sulphur under pressure at a temperature of 150oC. Many articles are vulcanised in moulds that are compressed by a hydraulic press.
- Free vulcanisation: Used where pressure vulcanisation is not possible, such as with continuous, extruded products, it is carried out by applying steam or hot air. Certain types of garden hose, for example, are coated with lead, and are vulcanized by passing high-pressure steam through the opening in the hose.
The process of vulcanisation gives increased strength, elasticity and resistance to changes in temperature. It renders rubber impermeable to gases and resistant to heat, electricity, chemical action and abrasion. Vulcanised rubber also exhibits frictional properties highly desired for pneumatic tyre application.
The raw materials that make up tyres are natural and synthetic rubbers, carbon, nylon or polyester cord, sulphur, resins and oil. During the tyre making process, these are virtually vulcanised into one compound that is not easily broken down.
The major uses for vulcanised rubber are for vehicle tyres and conveyor belts, shock absorbers and anti-vibration mountings, pipes and hoses. It also serves some other specialist applications, such as in pump housings and pipes for handling of abrasive sludges, power transmission belting, diving gear, water lubricated bearings, etc.
Recycling tyres
The rubber used in tyres is a relatively easy material to reform by hand. It behaves in a similar manner to leather and has, in fact, replaced leather for a number of applications. The tools required for making products directly from tyre rubber are not expensive and are few in number, for example, shears, knives, tongs, hammers, etc., along with a wide range of improvised tools for specialised applications. Shoes, sandals, buckets, motor vehicle parts, doormats, water containers, pots, plant pots, dustbins and bicycle pedals are among the products manufactured from old tyres.
Inner Tube Ltd.
Many garages pay firms to remove old inner tubes and, in the United Kingdom, about 70% of inner tubes are burnt or buried in landfill sites. Inner Tube Ltd. is a viable business which produces a progressive and eco-friendly product by turning recyled inner tubes into stylish handbags, rucksacs (figure 1), mirrors, bikinis, skirts and accessories, such as filofax and mobile phone covers. These fashion accessories started life as an inner tube on the wheels of vehicles ranging from tractors to trucks and as a result are hard wearing and waterproof.
Making a bag uses 9 inner tubes and takes about 8 hours to complete. The factory produces about 100 handmade bags per day. The bags are designed using brown paper sewn together to provide a template for the rubber. Inner tubes from cars and lorries can be used although tractor inner tubes are the best because they are the largest and easiest to sew. The straps of the bags are made from discarded seat belts.
Advantages of reclaiming and recovering rubber
Rubber recovery can be a difficult process. There are many reasons, however, why rubber should be reclaimed or recovered:
- Recovered rubber can cost half that of natural or synthetic rubber.
- Recovered rubber has some properties that are better than those of virgin rubber.
- Producing rubber from reclaim requires less energy in the total production process than does virgin material.
- It is an excellent way to dispose of unwanted rubber products, which is often difficult.
- It conserves non-renewable petroleum products, which are used to produce synthetic rubbers.
- Recycling activities can generate work in developing countries.
- Many useful products are derived from reused tyres and other rubber products.
- If tyres are incinerated to reclaim embodied energy then they can yield substantial quantities of useful power. In Australia, some cement factories use waste tyres as a fuel source.
Whether rubber tyres are reused, reprocessed or hand crafted into new products, the end result is that there is less waste and less environmental degradation as a result.
For further information, please contact:
Inner Tube Ltd.
IT STORE
27a Albert Road
Southsea
Hants
PO5 2SE
United Kingdom
Tel/Fax +44 23 92 779933 |
This document is an output from a project funded by the UK Department for International Development (DFID) for the benefit of developing countries. The views expressed are not necessarily those of the DFID.
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