Ldpe Hdpe Lldpe

- Sep 24, 2019-

PE is commonly used in three major categories, namely, LDPE HDPE LLDPE, three polyethylene monomers are the same, but in the synthesis of these polyethylenes.


When the process conditions are different, three different kinds of polyethylene are produced, and the properties of the three materials are quite different.




LDPE


LDPE for short


Commonly known as flower or tube material


Scientific Name Low Density Polyethylene High Pressure Polyethylene


English name low density polyethylene


Ethylene monomer is a gas produced in petroleum refining


Natural color polyethylene is a translucent white wax-like material, light in proportion to water, soft and tough, slightly elongated, non-toxic, tasteless combustion characteristics flammable, after fire can continue to burn, the flame is yellow at the top, blue at the bottom, when burning, it will melt, liquid drops, no black smoke, at the same time, stone. The odor of wax burning.


Advantages: acid and alkali resistance, resistance to organic solvents, excellent electrical insulation, low temperature, can still maintain a certain degree of toughness.


Shortcomings: poor mechanical properties, poor air permeability, easy deformation, easy aging, brittle, easy stress cracking, low surface hardness, easy scratch. It is difficult to print. When printing, it needs surface discharge treatment. It cannot be electroplated and the surface is lusterless.


Uses for extrusion packaging film, laminated film, hose


Used for Injection Molding of Low Grade Commodities and Shells


Extrusion blow-moulding containers


The melting point of low molecular weight polyethylene with injection plasticity is 120 C, which is very similar to paraffin wax. The melting point of general polyethylene is 140 C, and the decomposition temperature is as follows.


The injection temperature can be adjusted in a wide range, which is often used in the washing machine for changing materials of other raw materials. When injection moulding, the commonly used temperature is 170 - 220 C.


Because it is olefin plastics, it does not absorb water and does not need to be coaxed in production. But for product quality, it can be dried at 60 C for 1 hr to discharge floating water.


Polyethylene has high melt viscosity, low flow-length ratio, and thin-walled products may lack glue, so the gate and runner are relatively large; the products are easy to carry static electricity and surface is easy.


Dust absorption. The shrinkage rate was 16 and the overflow margin was 0.05 mm.




HDPE


HDPE for short


Hard soft glue


High Density Polyethylene Low Pressure Polyethylene


English name high density polyethylene


Ethylene Monomer - A Gas Produced in Petroleum Refining


High density polyethylene (HDPE) is an opaque white wax material with light specific gravity, softness and toughness, but it is slightly harder than LDPE, slightly elongated, non-toxic, odorless and flammable. It can continue to burn after fire. The upper end of the flame is yellow and the lower end is blue. When burning, it will melt, with liquid dropping and no black. Smoke emits, at the same time, the odor of burning paraffin


Advantages: acid and alkali resistance, resistance to organic solvents, excellent electrical insulation, low temperature, can still maintain a certain degree of toughness. Surface hardness, tensile strength, rigidity and other mechanical strength are higher than LDPE, close to PP, tougher than PP, but surface finish is not as good as PP.


Shortcomings: poor mechanical properties, poor air permeability, easy deformation, easy aging, brittle, brittle lower than PP, easy stress cracking, low surface hardness, easy scratch. Difficult to print, printing, surface discharge treatment, can not be electroplated, the surface is glossy.


Uses for extrusion packaging film, rope, woven bags, fishing nets, water pipes


Used for injection moulding of low-grade commodities and shells, non-load-bearing components, rubber boxes, turnover boxes


For extrusion blow-moulding containers, hollow products, bottles


The melting point and decomposition temperature of HDPE with general injection properties are 142 ~C and 300 ~C, and the adjustable range of injection temperature is large. Generally used in injection moulding


Temperature is 180-230 C; because it is olefin plastics, it does not absorb water and does not need to be coaxed in production, but for product quality, it can be dried at 60 C for 1 hr to discharge floating water; polyethylene has high melt viscosity, small flow-length ratio, and thin-walled products may lack glue, therefore, the gate and runner are relatively large; The face is susceptible to dust. The shrinkage rate was 16 and the overflow margin was 0.05 mm.




LLDPE


LLDPE for short


Known as Linear Low Density Polyethylene Low Pressure Low Density Polyethylene


Ethylene Monomer - A Gas Produced in Petroleum Refining


Native Linear High Density Polyethylene (LDPE) is an opaque white waxy material with lighter specific gravity than water, softer and tougher, but slightly less than LDPE.


Hard, slightly elongated, non-toxic, tasteless


Combustion characteristics are flammable, can continue to burn after fire, the flame is yellow at the top and blue at the bottom. When burning, it will melt, there will be droplets of liquid, no black smoke, at the same time, it will emit the odor of paraffin burning.




The difference between LDPE HDPE LLDPE and HDPE is mainly in density, which results in mechanical properties.


Difference, a rigid, a flexible; LLDPE and their differences, mainly in the molecular structure, LLDPE has more branched chains, therefore, this kind of material.


Material is flexible and rigid.


Advantages: acid and alkali resistance, resistance to organic solvents, excellent electrical insulation, low temperature, can still maintain a certain degree of toughness. Surface Hardness, Tensile Strength, Rigidity


The mechanical strength of LLDPE is higher than that of LDPE, but lower than that of HDPE. LLDPE has the best puncture resistance and tear resistance, especially suitable for thin film production.


The film is thinner than LDPE, but its strength is higher.


Shortcomings: poor mechanical properties, poor air permeability, easy deformation, easy aging, brittle, brittle lower than PP, easy stress cracking, low surface hardness, easy scratch. Difficult to print, printing, surface discharge treatment, can not be electroplated, the surface is glossy.


Uses for extrusion packaging film, tape, cable; produced film, also known as paper-like film


Used for Injection Molding of Low Grade Commodities and Shells


For extrusion blow-moulding containers, hollow products, bottles


The melting point and decomposition temperature of LLDPE with general injection properties are 170 C, 300 C and injection temperature.