▲ Extrusion: The grade used for extrusion production generally has a melt index of less than 1 and a width to wide MWD. In the process of processing, the low MI can obtain the suitable melt strength. Wider MWD grades are more suitable for extrusion because they have higher production speeds, lower die pressure and less melt fracture trends.
PE has many plastic extrusion uses, such as wire, cable, hose, tubing and profile. Tubing applications range from thick-walled clarinet used in industrial and urban pipelines to a small section of natural gas yellow tube to 48in diameter. Large-diameter hollow-wall tubes made of concrete rain drains and other sewer lines have grown rapidly.
Sheet and thermoforming: The hot-formed lining of many large picnic freezers is made of PE, with toughness, light weight and durability. Other sheet and thermoforming products include fenders, tank linings, pan-basin shields, transport boxes and cans. A large number of rapidly growing sheet applications are mulch or pond-bottom villages, which are based on MDPE with toughness, chemical resistance and impermeable.
▲ Blow Moulding: The HDPE1/3 sold in the United States is used for blow moulding purposes. These range from bottles of bleach, oil, detergents, milk and distilled water to large refrigerators, car fuel tanks and cans. The characteristics of blow moulding, such as melt strength, ES-CR and toughness, are similar to those used for sheet and thermoforming applications, so similar grades can be used.
Injection-blow molding is usually used to make smaller containers (less than 16oz) for packaging pharmaceuticals, shampoos and cosmetics. One of the advantages of this process is the production of bottles automatically to the corners, do not need to be like the general blow molding process, such as the late trimming steps. Although some narrow MWD grades are used to improve surface finishes, generally use medium to wide MWD grades.
▲ Plastic Injection: HDPE has countless applications, ranging from reusable thin-walled beverage cups to 5-gsl cans, consumption of 1/5 of the domestic production of HDPE. Injection Grade General Melt Index (5~10) has higher fluidity grade with toughness and lower fluidity grade and machinable. Applications include thin-walled packaging for daily necessities and food, resilient, durable food and paint cans, high resistance to environmental stress cracking applications such as small engine fuel tanks and 90-gal garbage cans.
▲ Rotational Moulding: The material used in this process is generally crushed into powder material, which melts and flows in the heat cycle. Two types of PE are used for rotational moulding: general and cross-linked. General-grade MDPE/HDPE the usual density range from 0.935 to 0.945g/cc, with narrow MWD, so that the product has a high impact and the smallest warpage, the melt index of the general range of 3-8. Higher MI grades are usually not applicable because they do not have the desired impact and environmental stress cracking of the rolled products.
High-performance roll-moulding applications use the unique properties of their chemically cross-linked grades. These grades in the first section of the molding cycle, good fluidity, and then cross-linked to form its excellent resistance to environmental stress cracking, toughness. Wear resistance and weather resistance. cross-linked PE is only suitable for large packagings, ranging from 500-gal transport of various chemical tanks to 20,000-gal agricultural storage bins.
▲ Film: PE film processing general use of ordinary blown film processing or flat extrusion processing method. Most PE is used for thin films, universal low-density PE (LDPE) or linear low density PE (LLDPE) are available. HDPE film grade is generally used to require superior tensile and excellent anti-seepage of the place. For example, HDPE membranes are commonly used in commodity bags, grocery bags and food packaging.