EPE is also known as pearl cotton. Polyethylene foam cotton is non-crosslinked closed-cell structure, is a new type of environmentally friendly packaging materials. It is composed of low-density polyethylene resin by physical foaming to produce countless independent bubbles. Overcome the ordinary styrofoam fragile, deformation, poor responsiveness shortcomings. It has many advantages such as waterproof and moisture-proof, shockproof, sound insulation, heat preservation, good plasticity, strong toughness, recycling, environmental protection, strong resistance to collision, etc. It also has very good chemical resistance. It is an ideal substitute for traditional packaging materials. Widely used in electronic and electrical appliances, instruments, computers, audio, medical equipment, industrial control chassis, lighting, handicrafts, glass, ceramics, home appliances, spraying, furniture, alcohol and gift packaging, hardware, toys, fruits and vegetables, shoes, the inner packaging, daily necessities, and other products packaging. After adding anti-static agent and flame retardant, it shows its excellent performance.
EPE pearl cotton is also used in a large number of handbags and bags elastic lining, industrial production of sound insulation, thermal insulation materials, agricultural thermal insulation materials, aquaculture floatation equipment, protective pads for sporting goods, water work life-saving equipment, families, hotels, flooring decoration, cushions and so on. Its tubes are used in a large number of air-conditioning, stroller, children's toys, home furnishings and other industries.
EPE and a variety of fabric bonded products are a variety of vehicles and living room good interior decoration materials. EPE and aluminum foil or aluminized film composite products have excellent anti-infrared ultraviolet ability, is some chemical equipment, cold storage and camping equipment car sunshade substitute.
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The above is taken from:/view/686111.htm
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As for density, just look up polyethylene.
Polyethylene
Polyethylene is the most structurally simple polymer and the most widely used polymer material.
It is made by joining repeating -CH2- units. Polyethylene is produced by addition polymerization of ethylene (CH2=CH2).
The properties of polyethylene depend on how it is polymerized. High-density polyethylene (HDPE) is produced by Ziegler-Natta polymerization under moderate pressure (15-30 atm), catalyzed by organic compounds. Polyethylene molecules polymerized under these conditions are linear and have long molecular chains with molecular weights in the hundreds of thousands. If it is in high pressure (100-300MPa), high temperature (190-210 ° C), peroxide-catalyzed conditions of free radical polymerization, the production of low-density polyethylene (LDPE), it is branched structure.
Polymerization pressure size: high pressure, medium pressure, low pressure;
Polymerization implementation methods: slurry method, solution method, gas phase method;
Product density size: high-density, medium-density, low-density, linear low-density;
Product molecular weight: low molecular weight, ordinary molecular weight, ultra-high molecular weight.
Polyethylene characteristics
Polyethylene odorless, non-toxic, feel like wax, has excellent low-temperature resistance (the lowest temperature can be up to -70 ~ -100 ° C), good chemical stability, can withstand most of the acids and alkalis (not resistant to oxidizing properties of the acid), insoluble in common solvents at room temperature, water absorption is small, excellent electrical insulation properties; but polyethylene is very good for the environmental stress (chemical and mechanical effects). However, polyethylene is very sensitive to environmental stress (chemical and mechanical effects), poor heat aging resistance.
The nature of polyethylene varies from species to species, mainly depending on the molecular structure and density.
Types of polyethylene
(1) LDPE: low-density polyethylene, high-pressure polyethylene
(2) LLDPE: linear low-density polyethylene
(3) MDPE: medium-density polyethylene, bimodal resin
(4) HDPE: high-density polyethylene, low-pressure polyethylene
(5) UHMWPE: ultra-high molecular weight polyethylene
(6) modified polyethylene: CPE, cross-linked polyethylene (PEX)
(7) ethylene **** polymer: ethylene-propylene **** polymer (plastic), EVA, ethylene-butylene **** polymer, ethylene-other olefins (eg, octenyl POE, cycloalkenes) **** polymer, ethylene-unsaturated ester **** polymers (EAA, EMAA , EEA, EMA, EMMA, EMAH)
Linear polyethylene with a molecular weight of 3,000,000-6,000,000 is known as ultra-high molecular weight polyethylene (UHMWPE). UHMWPE is so strong that it can be used to make bulletproof vests.
Main methods:
Liquid-phase method (subdivided into solution method and slurry method) and gas-phase method (the type of phase of the material in the reactor). The slurry method with Ziegler catalyst is mainly used in China.
Conditions and process description: purity of more than 99% of the ethylene in the presence of catalyst titanium tetrachloride and dichlorodiethylaluminum, in the pressure of 0.1-0.5MPa and the temperature of 65-75 ℃ gasoline polymerization to get the slurry of HDPE. The residual catalyst is destroyed by alcoholysis, neutralized, washed, and the gasoline and unpolymerized ethylene are recovered, and the product is obtained by drying and granulation.
Chemical name: Polyethylene
English name: Polyethylene (PE for short)
Specific gravity: 0.94-0.96 g/cm3 Molding shrinkage: 1.5-3.6% Molding temperature: 140-220 ℃
Characteristics: corrosion resistance, excellent electrical insulation (especially high frequency insulation), can be Chlorination, chemical crosslinking, irradiation crosslinking modification, can be glass fiber reinforced. Low-pressure polyethylene has high melting point, rigidity, hardness and strength, low water absorption, good electrical properties and radiation resistance; high-pressure polyethylene has good flexibility, elongation, impact strength and permeability; ultra-high molecular weight polyethylene has high impact strength, fatigue resistance and wear resistance. Low-pressure polyethylene is suitable for making corrosion-resistant parts and insulating parts; high-pressure polyethylene is suitable for making films, etc.; ultra-high molecular weight polyethylene is suitable for making vibration-damping, wear-resistant and transmission parts.
Molding characteristics:
1. Crystalline material, moisture absorption is small, do not need to be fully dried, excellent fluidity flow is sensitive to pressure, molding is recommended to use high-pressure injection, the material temperature is uniform, fast filling speed, holding pressure is sufficient. It is not suitable to use direct gating to prevent uneven shrinkage and increase of internal stress. Pay attention to choose the location of the gate to prevent shrinkage and deformation.
2. Shrinkage range and shrinkage value is large, the direction is obvious, easy to deformation warping. Cooling speed should be slow, the mold is set up with cold material cavity, and cooling system.
3. The heating time should not be too long, otherwise decomposition will occur.
4. When soft parts have shallow side grooves, they can be forcibly demolded.
5. Melt rupture may occur, and should not be in contact with organic solvents to prevent cracking