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Modification of polyethylene

Polyethylene (PE) in the atmosphere, under the influence of sunlight and oxygen, aging, discoloration, cracks, brittle or powdered, losing its mechanical properties. At processing temperatures, also due to oxidation, decline all make it melt, color, lines, so at the time of processing and use of the process or material should be considered. On modification of polyethylene is to join anti-oxidizing     agents, UV absorbers or carbon black, can significantly increase its anti-aging properties.
because polyethylene is a non-polar materials, so its excellent electrical insulating properties, dielectric constant and dielectric loss is independent of temperature and frequency, high frequency performance is better, is the optimization of raw material manufacture wire and cable insulation material.
PE and its residual stress within the products subject to stress or products, alcohols, aldehydes, ketones, vinegar contact polarity solvent such as surfactants or steam cracking, which is known as stress cracking, cracking more serious low molecular weight. POLYISOBUTYLENE selection process should be mixed for a class of polymers to reduce or eliminate stress cracking.
/> polyethylene polyethylene molding methods, injection molding, extrusion, blow molding, thermoplastic molding methods can be used, can also be used for spraying, welding, machining, etc.
injection due to the different density polyethylene resin, each has the proper melt flow rate range, usually melt flow rate of 10 – 20 g/1 Omin. High melt flow rate of resin. small molecular weight, boom of low, low processing temperatures, but poor mechanical properties of the finished product; resin with low melt flow rate, molecular weight, high viscosity and mechanical properties of the finished product (see table 2-2 >, but high processing temperatures. Width of the molecular weight distribution of resin (can use Add method of low molecular weight polyethylene), formed when liquid, mechanical properties and heat resistance of the product decreases. Density polyethylene resin, the product properties and crystallization speed is different, so different conditions, density and are listed in table 2-3   performance relationship. Molecular orientation of polyethylene during the injection molding process, cooling of the product remains oriented to a certain extent, enables the product along the direction of injection molding shrinkage increases, particularly thin-walled products. Due to the orientation may also make the gate around the fragile plastic injection products, improve temperature or use polyethylene of high melt flow rate, to avoid this undesirable phenomenon, but with high melt flow rate of impact toughness of low
products obtained from resin.
PE non-polar structure, therefore Hygroscopicity is small one, but because it is a nonconductor, proceeds of grain in storage during transport, especially in the dry atmosphere, easy to produce static electric
and adsorption of moisture in the air, resulting in excessive moisture content. If the moisture content of more than 0. 5% without drying directly to molding, products may have air bubbles.
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