Very low density polyethylene and high molecular weight high density polyethylene
DATE：2022/12/20 8:36:59 / READ： / SOURCE：This station
2.1.5 Very low density polyethylene
Very low density polyethylene is composed of ethylene and α It is made by copolymerization of olefins. a-olefins include 1-7 olefins, 1-octene, etc., which are mostly produced by gas phase method or liquid phase method. VLDPE is an abbreviation for very low density polyethylene.
The density of very low density polyethylene is 0.880~0.910g/cm ³， Low crystallinity, good flexibility; It has excellent mechanical properties, good impact resistance, filling property, optical property, penetration resistance and tear resistance; Non toxic, low water absorption; High thermal deformation temperature, good thermal stability and low temperature resistance; It has excellent environmental stress cracking resistance, excellent flexural cracking resistance and cold impact resistance; The product has good light transmittance. Its low temperature resistance, stress cracking resistance, flexural resistance and tensile strength are superior to low-density polyethylene.
At present, there is no manufacturer of very low density polyethylene in China. Table 2-23 shows the performance of VLDPE resin produced in the United States, and Table 2-24 shows the performance of VLDPE resin produced by Mitsubishi Petrochemical Company of Japan.
Very low density polyethylene resin has good processability because of its high comonomer content. Generally, injection, extrusion, blow molding and other methods can be used to process plastic products. Sometimes the coating method can also be used.
Shrinkage film, packaging film, medical packaging film and re packaging film are extruded by an extruder; The thinnest dimension of extrusion blown film can reach 5 μ M below; In addition, VLDPE resin can also be used to blend with PP resin or HDPE resin, extrude and blow molding film, and its tear strength and impact properties have been greatly improved; The insulating protective layer of medical hoses, wires and cables can also be formed by extrusion method.
The shrinkage of VLDPE products is low (1.5% of the products), which is only 1/2 of the shrinkage of LL DPE products. Injection molding containers, toys, vacuum cleaners and other products; Blends with PP resin are used to form automobile bumpers, dampers, mudguards and other products, which have good low-temperature impact properties.
The ultra-low density polyethylene resin produced by Exxon Company in the United States can be used to form medical hoses, corrugated boards, insulating materials, cables, etc. It is mainly used for extrusion and injection molding of plastic products. The very low density polyethylene resin produced by Mitsubishi Oil and Chemical Company of Japan can be extruded into films, plates, hoses, wire and cable insulation sheaths and other products by an extruder, or molded into products by injection molding or lamination.
The density of high molecular weight high density polyethylene is 0.944~0.954g/cm3, which has high relative molecular resistance to stress cracking, impact strength, tensile strength, rigidity, abrasion resistance and chemical stability ash content (the melt flow rate under the mass is 1.0~15g/10min; the powder appearance of high molecular weight high density polyethylene is superior to that of high density polyethylene, and its products can be used in harsh environments for a long time.
High molecular weight high density polyethylene can be used for extrusion, injection and blow molding of plastic products. " For strong impact fracture elongation, molding and pushing methods can also be used for forming and coating construction. Extruder can be used to extrude and shape various plastic pipes, wire and cable insulation sheaths and fiber optic inner tubes of fiber optic telephone devices for special purposes; Extrusion blow molding of various films and ultra-thin films. Injection molding of electronic and electrical components and large containers with an injection molding machine. The coating method can also be used as the lining of storage tanks and tanks.
Very low density polyethylene is composed of ethylene and α It is made by copolymerization of olefins. a-olefins include 1-7 olefins, 1-octene, etc., which are mostly produced by gas phase method or liquid phase method. VLDPE is an abbreviation for very low density polyethylene.
The density of very low density polyethylene is 0.880~0.910g/cm ³， Low crystallinity, good flexibility; It has excellent mechanical properties, good impact resistance, filling property, optical property, penetration resistance and tear resistance; Non toxic, low water absorption; High thermal deformation temperature, good thermal stability and low temperature resistance; It has excellent environmental stress cracking resistance, excellent flexural cracking resistance and cold impact resistance; The product has good light transmittance. Its low temperature resistance, stress cracking resistance, flexural resistance and tensile strength are superior to low-density polyethylene.
At present, there is no manufacturer of very low density polyethylene in China. Table 2-23 shows the performance of VLDPE resin produced in the United States, and Table 2-24 shows the performance of VLDPE resin produced by Mitsubishi Petrochemical Company of Japan.
Very low density polyethylene resin has good processability because of its high comonomer content. Generally, injection, extrusion, blow molding and other methods can be used to process plastic products. Sometimes the coating method can also be used.
Shrinkage film, packaging film, medical packaging film and re packaging film are extruded by an extruder; The thinnest dimension of extrusion blown film can reach 5 μ M below; In addition, VLDPE resin can also be used to blend with PP resin or HDPE resin, extrude and blow molding film, and its tear strength and impact properties have been greatly improved; The insulating protective layer of medical hoses, wires and cables can also be formed by extrusion method.
The shrinkage of VLDPE products is low (1.5% of the products), which is only 1/2 of the shrinkage of LL DPE products. Injection molding containers, toys, vacuum cleaners and other products; Blends with PP resin are used to form automobile bumpers, dampers, mudguards and other products, which have good low-temperature impact properties.
The ultra-low density polyethylene resin produced by Exxon Company in the United States can be used to form medical hoses, corrugated boards, insulating materials, cables, etc. It is mainly used for extrusion and injection molding of plastic products. The very low density polyethylene resin produced by Mitsubishi Oil and Chemical Company of Japan can be extruded into films, plates, hoses, wire and cable insulation sheaths and other products by an extruder, or molded into products by injection molding or lamination.
2.1.6 High molecular weight high density polyethylene
High molecular weight high density polyethylene is a new variety of polyethylene, with an average molecular weight of 200000~500000, which can be divided into homopolymer and copolymer. It is polymerized by slurry method or gas phase method under low pressure (0.48~3.1MPa) and low temperature (80~110 ℃) in the presence of homogeneous integral or Philips type efficient catalyst. HMWHDPE is the abbreviation of high molecular weight high density polyethylene.The density of high molecular weight high density polyethylene is 0.944~0.954g/cm3, which has high relative molecular resistance to stress cracking, impact strength, tensile strength, rigidity, abrasion resistance and chemical stability ash content (the melt flow rate under the mass is 1.0~15g/10min; the powder appearance of high molecular weight high density polyethylene is superior to that of high density polyethylene, and its products can be used in harsh environments for a long time.
High molecular weight high density polyethylene can be used for extrusion, injection and blow molding of plastic products. " For strong impact fracture elongation, molding and pushing methods can also be used for forming and coating construction. Extruder can be used to extrude and shape various plastic pipes, wire and cable insulation sheaths and fiber optic inner tubes of fiber optic telephone devices for special purposes; Extrusion blow molding of various films and ultra-thin films. Injection molding of electronic and electrical components and large containers with an injection molding machine. The coating method can also be used as the lining of storage tanks and tanks.
Author：admin