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Characteristics and uses of LLDPE plastic materials, advantages and disadvantages of LLDPE plastic

May 9, 2024

Characteristics and uses of LLDPE plastic materials, advantages and disadvantages of LLDPE plastic

Abbreviated as LLDPE

Scientific name: Linear low-density polyethylene Low pressure low-density polyethylene

Monomer ethylene - a gas produced in petroleum refining

Natural color linear high-density polyethylene is an opaque white waxy material with a specific gravity lighter than water, soft and tough, but slightly harder than LDPE and can also elongate slightly. It is non-toxic and odorless

The combustion characteristics are flammable and can continue to burn after leaving the fire. The upper end of the flame is yellow and the lower end is blue. It will melt during combustion, with liquid droplets and no black smoke emitted. At the same time, it emits the odor of paraffin burning

The differences among the three materials of LDPE HDPE LLDPE: The main difference between LDPE and HDPE is in density, which leads to differences in mechanical properties, one is rigid and the other is flexible; The main difference between LLDPE and them is in their molecular structure. LLDPE has more branched chains, so this material is both flexible and rigid.

Advantages: acid and alkali resistance, organic solvent resistance, excellent electrical insulation, and can still maintain a certain degree of toughness at low temperatures. The mechanical strength such as surface hardness, tensile strength, and rigidity are higher than LDPE, but lower than HDPE; LLDPE has the best puncture resistance and tear resistance, making it particularly suitable for producing films. The produced films are thinner than LDPE, but have higher strength.

Disadvantages: poor mechanical performance, poor breathability, easy deformation, aging, brittleness, lower brittleness than PP, easy stress cracking, low surface hardness, and easy scratching. Difficult to print, surface discharge treatment is required during printing, electroplating is not allowed, and the surface is dull.

Used for extruding packaging films, tapes, cables; The produced film, also known as pseudo paper film

Used for injection molding low-end daily necessities and casings

Used for extrusion blow molding containers, hollow products, bottles

The LLDPE with general injection performance has a melting point of 170 ℃ and a decomposition temperature of 300 ℃; The adjustable range of injection temperature is relatively large. When injection molding, the general operating temperature is between 200 ℃ and 260 ℃; Its apparent viscosity is high and its fluidity is poor. It is difficult to inject LLDPE alone. Therefore, it is necessary to increase the power of the injection molding machine or add other low molecular weight plastics to increase its fluidity; As it is an olefinic plastic, it does not absorb water and does not need to be dried during production. However, for product quality, it can be dried at 60 ℃ for 1 hour to discharge floating water; Linear low-density polyethylene has a high melt viscosity, low flow length ratio, and lower flowability than LDPE and HDPE. Thin walled products may lack adhesive, so the gate and runner are relatively large; The product is prone to static electricity and the surface is prone to dust absorption. The shrinkage rate is 16 ‰; The overflow value is 0.05mm