Comparison of Polyethylene PE Melts Using Frequency Sweeps
A method is introduced for a characterization of polymer properties with respect to their molecular structure and processing behavior during thermoplastic processes such as blown/cast extrusion, extrusion blow molding or injection molding. The procedure can be applied in a fast and easy way. In addition to the measurement of three different polyethylene materials this report gives an overview about their chemical and application characteristics.
Polyethylene -[-CH2-CH2-]n- PE is a linear or branched hydrocarbon material. It was developed in 1933 by Reginald Gibson and Eric Fawcett at the British Imperial Chemical Industries (ICI).
LLDPE, Linear Low Density PE is a linear low density polymer due to the absence of long chain branching. It has a highly crystalline structure and is produced by co-polymerization of ethylene with butene, hexene or octene. The co-polymerization process produces a polymer that has a narrow molar mass distribution compared to LDPE and significantly different rheological properties.
Melting temperature, Tm = 122 °C / 124 °C. PE in general offers excellent electrical plus chemical resistance (oil, lubricants) and is relatively inexpensive. LDPE Low Density PE is a branched and therefore amorphous hydrocarbon material. It has a low density as the molecules are loosely packed. This makes the material rather soft in comparison to a HDPE.
Melting temperature, Tm = 98 °C / 115 °C,
Glass transition temperature, Tg = -25 °C.
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