Polyethylene PE molding method and testing standards

Polyethylene (polyethylene), abbreviated as PE, is a thermoplastic resin obtained by polymerization of ethylene. According to the molecular structure, it can be roughly divided into low-density polyethylene (LDPE, also known as high-pressure polyethylene), high-density polyethylene (HDPE, and Called low-pressure polyethylene), linear low-density polyethylene (LLDPE) and ultra-high molecular weight polyethylene (UHMWPE). Characteristics Polyethylene is odorless, non-toxic, feels like wax, has excellent low temperature resistance (the lowest temperature can reach -100~-70°C), has good chemical stability, and can withstand most acid and alkali corrosion (not resistant to Oxidizing acid), insoluble in general solvents at room temperature, low water absorption, and excellent electrical insulation. It is currently the most widely used general-purpose plastic. Molding method: Injection molding: At a certain temperature, the plastic is completely melted by stirring with a screw, and then injected into the mold cavity by high pressure, and after cooling and solidification, the molded product is obtained; compression molding: Put powder, granular or fiber plastic into In the mold cavity at the molding temperature, the mold is closed and pressurized to form and solidify; blow molding: the hot melt parison closed in the mold is blown to form a hollow product by means of gas pressure; extrusion molding: refers to Through the action between the barrel and screw of the extruder, the material is plasticized by heat and pushed forward by the screw, and continuously passes through the head to make various cross-section products or semi-products. Application areas: low-density polyethylene: relatively soft, low mechanical strength, mainly used for film products, wire wrapping, etc. High-density polyethylene: high hardness and mechanical strength, mainly used to manufacture non-load bearing components, shells, boxes, containers, etc. Linear low-density polyethylene: It combines the advantages of low-density polyethylene and high-density polyethylene, and can be used to manufacture films, non-load-bearing components, shells, boxes, containers, etc. Ultra-high molecular weight polyethylene: excellent performance, can be used as special engineering plastics, has certain applications in special fields requiring high strength and high modulus. Product Example Film polyethylene has a relatively soft texture due to its high molecular chain flexibility and is more suitable for manufacturing films. At the same time, due to the different molecular structures of different types of polyethylene, their properties are also different. Low-density polyethylene film is mainly used to make plastic wrap and agricultural mulch because of its softness and high transparency. High-density polyethylene film has a hard texture and is mostly used to make protective films. The linear low-density polyethylene film combines the advantages of the first two and is mostly used to make plastic bags, packaging bags, etc. Non-load-bearing components and products Polyethylene (except ultra-high molecular weight polyethylene) is one of the five general-purpose plastics. Its output is huge and the price is cheap. It is widely used in non-load-bearing or small-load-bearing shells and tanks in daily life , Boxes, containers, pipes, etc. Special engineering product ultra-high molecular weight polyethylene has ultra-high molecular weight, and its performance far exceeds that of ordinary polyethylene, and is often used in special fields. Ultra-high molecular weight polyethylene fiber has the advantages of light weight, high strength and high modulus. At the same time, because it is an organic fiber, it has good affinity with the resin matrix and is very suitable for use as a fiber reinforcement in the composite material industry. It has important applications in bulletproof, explosion-proof and stab-proof fields. Ultra-high molecular weight polyethylene rope has high strength and modulus and excellent aging resistance. It is often used in ship ropes and airplane parachute ropes. Ultra-high molecular weight polyethylene has good wear resistance and is used to make rails, pulleys and other easily worn components. Ultra-high molecular weight polyethylene has good corrosion resistance and high wear resistance, and can be used to manufacture oil pipelines and tailings collection pipes. Polyethylene Industry Chain The polyethylene industry chain is divided into three parts: upstream suppliers of polymer raw materials, midstream plastic raw materials suppliers, and downstream manufacturers of polyethylene products. Implementation of the standard GB-T1037---1988 Plastic film and sheet water vapor permeability test method Cup method GB-T1040---1992 Plastic tensile performance test method, Oriental Engineering No. 1, 5, 3, 4, 7 and 97 Ba Ren Zongran provides GB-T1842---1980 environmental stress cracking test method for polyethylene GB-T2918---1998 Standard environment for condition adjustment and testing of plastic specimens GB/T5470---1985 Plastic impact embrittlement temperature test method GB-T6672--1986 Plastic film and sheet thickness determination mechanical measurement method GB-T6673--1986 Plastic film and sheet length and width provisions GB-T9352--1988 Thermoplastic compression molding specimen preparation GB -T13663-2000 Polyethylene (PE) pipe for water supply GB-T13663.2-2005 Polyethylene (PE) piping system for water supply Part 2 Fittings Previous: Prospect of POF heat shrinkable film Next: Review of the invention and development of plastics (One)