Polymer low-density polyethylene

An independent development of a high pressure polymerization technology has led to the use of molten polymer as a medium for catalytic ethylene polymerization. Some reactors previously used for free-radical ethylene polymerization at a high pressure (see Olefin polymers, low density polyethylene) have been converted to accommodate catalytic polymerization, both stirred-tank and tubular autoclaves operating at 30—200 MPa (4,500—30,000 psig) and 170—350°C (57,83,84). CdF Chimie uses a three-zone high pressure autoclave at zone temperatures of 215, 250, and 260°C (85). Residence times in all these reactors are short, typically less than one minute. 

A test set of 6 to 13 aroma compound partition coefficients between different food contact polymers (low density polyethylene (LDPE), high density polyethylene (HDPE) polypropylene (PP), polyethylene terephthalate (PET), polyamide (PA)) and different food simulant phases (water, ethanol, aqueous ethanol/water mixtures, methanol, 1-propanol) were taken from the literature (Koszinowski and Piringer, 1989, Baner, 1992, Franz, 1990, Koszinowski, 1986, Franz, 1991, Baner, 1993, Piringer, 1992). Table 4-2 shows the test set of 13 different aroma compounds, with their properties and their structures. The experimental data were compared to estimations using different estimation methods of UNIFAC-FV, GCFLORY (1990), GCFLORY (1994) and ELBRO-FV. 

Figure 10.17 DSC curves of plastic waste containing several polymers low density polyethylene (LDPE), high density polyethylene (HDPE), polypropylene (PP), Nylon-6 , Nylon-66 and poly-tetrafluoroethylene (PTFE). (Reproduced with kind permission of Springer Science and Business Media from M. Brown, Introduction to Thermal Analysis, Kluwer Academic Publishers, Dordrecht. 2001 Springer Science.)...

Acrylonitrile Butadiene Styrene Acrylonitrile Styrene Acrylate Cyclic Olefin Copolymer Polyethylene Chlorotrifluoroethylene Polyethylene Tetrafluoroethylene Ethylene Vinyl Acetate Fluorinated Ethylene Propylene High Density Polyethylene High Performance Polyamide Liquid Crystalline Polymer Low Density Polyethylene Linear Low Density Polyethylene Medium Density Polyethylene Polyamide (Nylon)... 

Moreover, various values of these parameters are listed for the following polymers low-density polyethylene (LDPE), high-density polyethylene, and polypropylene (PP) [9]. 

The effects of reprocessing on polymers Low density polyethylene, European Polymer Journal, 16 (1980) 11, p. 1037-1042... 

Table 10.17 IR spectroscopic data for model nitrates and nitrites and for polymers (low density polyethylene (LDPE) and isotactic polypropylene (IPP) containing NO groups [363]. 

Characterisation studies have been carried out on the following polymers. Low density polyethylene [60], high density polyethylene [60, 61], t-butyl methacrylate-4-vinyl pyridine copolymer [62], styrene butadiene copolymer [63], PS [64-70], polyethylene oxide [64], polypropylene oxide [71, 72], glycidyl methacrylate [73],... 

Crystalline polymers show the greatest interaction with minerals. In amorphous polymers, minerals merely increase stiffness, with little or no reinforcing effect. Polypropylene, high density polyethylene, thermoplastic polyester and polyamides are crystalline polymers. Low density polyethylene, polystyrene and polycarbonate are amorphous. 

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