Application scope of low density polyethylene: suitable for packaging condiments, cakes, sugar, preserves, biscuits, milk powder, tea, fish floss and other foods. Packaging of medicines such as tablets and powder, and packaging of fiber products such as shirts, garments, knitted cotton products and chemical fiber products.
Both low density polyethylene and LLDPE have good rheology or melt fluidity. LLDPE has low shear sensitivity because of its narrow molecular weight distribution and short branches. In the shearing process (such as extrusion), LLDPE maintains a high viscosity, so it is more difficult to process than LDPE with the same melt index.
Extended data:
Low density polyethylene can be divided into high pressure method and low pressure method according to polymerization methods. According to the type of reactor, it can be divided into kettle method and tube method. Taking ethylene as raw material, it is sent into a reactor and polymerized under high pressure compression under the action of initiator. After unreacted ethylene is removed from the material from the reactor by a separator, it is melted, extruded, granulated, dried, mixed and sent to packaging.
Both low density polyethylene and LLDPE have good rheology or melt fluidity. LLDPE has low shear sensitivity because of its narrow molecular weight distribution and short branches. In the shearing process (such as extrusion), LLDPE maintains a high viscosity, so it is more difficult to process than LDPE with the same melt index. In the extrusion process, the lower shear sensitivity of LLDPE makes the stress relaxation of polymer molecular chain faster, so the sensitivity of physical properties to the change of expansion rate decreases.
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