Lowdensity polyethylene

The chemical iadustry manufactures a large variety of semicrystalline ethylene copolymers containing small amounts of a-olefins. These copolymers are produced ia catalytic polymerisation reactions and have densities lower than those of ethylene homopolymers known as high density polyethylene (HDPE). Ethylene copolymers produced ia catalytic polymerisation reactions are usually described as linear ethylene polymers, to distiaguish them from ethylene polymers containing long branches which are produced ia radical polymerisation reactions at high pressures (see Olefin POLYMERS, LOWDENSITY polyethylene). 

Flat film -fromLDPE [OLEFIN POLYMERS - POLYETHYLENE - LOWDENSITY POLYETHYLENE] (Vol 17)... 

Leached glass fibers - pTHYLENE] (Vol 9) - [OLEFINPOLYMERS - POLYETHYLENE - INTRODUCTION] (Vol 17) - [OLEFINPOLYMERS - POLYETHYLENE - LOWDENSITY POLYETHYLENE] (Vol 17) - PLASTICPROCESSING] (Vol 19) - [HIGH PRESSURE TECHNOLOGY] (Vol 13) - [REFRACTORY FIBERS] (Vol 21)... 

Fig. 7 Changes in crystallinity near to the surface of a linear lowdensity polyethylene bar exposed to UV in the laboratory for 6 weeks. Samples taken at different depths from the exposed surface. Each sample was 0.1mm deep the corresponding result is plotted at the midpoint of the layer. (More details in Craig, I.H. White, J.R. Crystallization and chemicrystallization of recycled photo-degraded polyethylenes. Polym. Eng. Sci. 2005, 45, 588-595.)...

Refer also to Polyethylene, LDPE LowDensity Polyethylene), HMWDPE High Molecular Weight Polyethylene), and HDPE High Density Polyethylene). (Source Handbook of Polymer Science and Technology Volume 1 - Synthesis and Properties, N. P. Cheremisinoff - editor, Marcel Dekker Inc, New York, 1989.)... 

Refer also to Polyethylene, LDPE LowDensity Polyethylene), HMWDPE High Molecular Weight Polyethylene), and HDPE High Density Polyethylene),... 

Lignin has been studied as a component in many nonbiodegradable thermoplastics materials as a filler in lowdensity polyethylene and polypropylene... 

Certain preservative systems can be lost from certain plastic packs by sorption and solubility in the plastic and, if they are also volatile, by evaporation from the external surface which is in contact with the atmosphere. Reports, particularly as references in textbooks, often suggested that phenol could not be used as a preservative in lowdensity packs. Subsequent work, many years later, established that the solubility of phenol in polyethylene was relatively low and that sufficient phenol for adequate preservative efficacy could be retained by a number of methods, i.e. coating LDPE internally or externally, or enclosing the pack in an additional barrier overwrap (e.g. paper/foil/PE or similar foil-bearing barriers). 

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