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LDPE has SPI resin ID code 4 Schematic of LDPE branching structure. Low-density polyethylene (LDPE) is a thermoplastic made from the monomer ethylene.It was the first grade of polyethylene, produced in 1933 by John C. Swallow and M.W Perrin who were working for Imperial Chemical Industries (ICI) using a high pressure process via free radical polymerization. [1]
Polyethylene is classified by its density and branching. Its mechanical properties depend significantly on variables such as the extent and type of branching, the crystal structure, and the molecular weight. There are several types of polyethylene: Ultra-high-molecular-weight polyethylene (UHMWPE)
LDPE and LLDPE have unique rheological or melt flow properties. LLDPE is less shear sensitive because of its narrower molecular weight distribution and shorter chain branching. During a shearing process, such as extrusion, LLDPE remains more viscous and, therefore, harder to process than an LDPE of equivalent melt index.
This process affects mechanical properties of the polymers and decreases their volume because of a more compact packing of aligned polymer chains. [4] [7] The chains interact via various types of the van der Waals forces. The interaction strength depends on the distance between the parallel chain segments, and it determines the mechanical and ...
Among them, HDPE has better thermal, electrical and mechanical properties, while LDPE and LLDPE have better flexibility, impact properties and film forming properties. LDPE and LLDPE are mainly used for plastic bags, plastic wraps, bottles, pipes and containers; HDPE is widely used in various fields such as film, pipelines and daily necessities ...
The Properties of Polyethylene Crystallized Under the Orientation and Pressure Effects of a Pressure Capillary Viscometer, Journal of Applied Polymer Science vol. 14, pp. 2305–2317 (1970). Kanamoto, On Ultra-High Tensile by Drawing Single Crystal Mats of High Molecular Weight Polyethylene, Polymer Journal vol. 15, No. 4, pp. 327–329 (1983).
In a similar way, the Phillips slurry process uses silica-based catalysts in contact with a fast-moving hydrocarbon and polyethylene slurry to precipitate high density polyethylene. [18] Processing will determine the properties of the HDPE. The method used to synthesize the HDPE is crucial because the micro structure of the HDPE will vary.
The characterization of mechanical properties in polymers typically refers to a measure of the strength, elasticity, viscoelasticity, and anisotropy of a polymeric material. The mechanical properties of a polymer are strongly dependent upon the Van der Waals interactions of the polymer chains, and the ability of the chains to elongate and align ...