Ultra high molecular weight polythene also known as UHMW-PE is a division of the thermoplastic polythene. It contains long chain with its molecular weight numbering in millions. The purpose of longer chains is to transfer the load efficiently to the polymer polythene by make the intermolecular interactions strong. The end results are very strong and tough material with highest consequence strength of any thermoplastic made. This material is highly does not corrode easily since it is resistant to corrosive chemicals but not oxidizing acids. This material also has low moisture absorption and low coefficient of friction, self lubricated and more so, highly anti abrasion.
Specific application of ultra high molecular weight polythene
Polymerization of ultra high molecular weight polythene is commercially available in many forms such as rods, fibers, and sheets. The powder that is obtained from UHMW-PE is molded into final product. Due to its good and outstanding characteristics of being resistant to wear, the product continues to have industrial use including the bottling sector and automotive industry. UHMW-PE has proved to be the best material for arthroplasty used in orthopedic and spine implants (Hearle, 2001). The material is also widely used in different areas like ballistic protection, increasing use and application in medical services and defense application as well.
The UHMW-PE provides good resistance to corrosion of materials from abrasive and chemical environments such as slurries and sand.
The polymer is suitable because of its impact resistance even at unfavorable temperatures and is very powerful to stainless steel. UHMW-PE has special characteristics that make it widely coveted. This important feature includes; good electrical and thermal insulation, self sub lubrication and chemical inertness, low moisture absorption and accepted in FDA for natural grades. In machines and fabricated form, UHMW-PE is used in material applications, power transmission, agriculture, and machines that process food, medical services textile and chemical processing, paper and pulp, maritime, mining, sewage treatment and water (Kurtz, 2004).
Fabrication of UHMW-PE
Ultra high molecular weight polythene is thermoplastic with its molecular weight being greater than 3.1 atomic mass unit. Because of high molecular weight, it has number of physical properties that helps it to have high impact strength and low rate of coefficient friction.
Properties of this polymer can be enhanced by use of additives like colorants, application of heat, UV stabilizers, wear resistant fillers, anti static agents and friction reducing lubricants. Ores are applied to increase the weight and make the UHMW-PE magnetically detectable. On the same note, other materials or fillers are used to increase environmental temperatures (Willert & Buchhorn, 1991).
Because of the semi crystalline feature, the polymer is passed through ram extrusion. The process of annealing is done before it passed to next stage into machining; this assists in eliminating processing difficulty caused by sintering. During the cooling process, parts are given room to shrink during the process of annealing. Before relieving stress, rough machining must be done in order to incorporate changes in all directions during final machining. The end products which includes; rods, sheets and tubes must be produced in all dimension stable parts. Therefore, to enhance this process, UHMW-PE are drilled, sawed, milled, turned and planned.
Cutting tools are contains high rakes angles and good ship clearance in order to prevent clogging during its use. Also, the feed rates are kept high so that less time is accepted for cutting tools to get maximum heat by friction. The polymer has the lowest coefficient of friction towards plastic materials and its resistant to chemicals (Hearle, 2001). This means that the metal chains and molecule can rub over one another without wearing down thus performing its work without any inconvenience. For instance, in mining industries, the ore and gravel move over UHMW-PE plates easily without decomposing.
Disadvantage of ultra high molecular weight polythene
The main disadvantage of this polymer is that it is not melt process able. Also, research has shown that it may have some health and environmental problems.
The polymer have future task in the sense that we will continue to understand and be knowledgeable about the wear mechanism of UHMW-PE on carbide coatings (Willert & Buchhorn, 1991). This will give us the guidance on the use of materials that are environment friendly in manufacture of plastics to avoid pollution. Medical services will be improved because the polymer will manufacture some products that will be used by medical practioneers.
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UHMW-PE has proved to be the most efficient polymer as compared to other polymers this because of its salient features like resistant to chemicals and does not corrode easily. Further, the polymer is applied in many sectors like the defense work, medical services and sheet or rods manufacture used in construction work. The polymer is fabricated by additives to increase its heat by friction and produce long lasting products. The product will be needed in future works because wear able to understand its wear mechanism on carbide coatings.