Molecular weight low-density polyethylene

HMWLDPE See High Molecular Weight Low Density Polyethylene. 

High Molecular Weight Low Density Polyethylene n Thermoplastic with improved abrasion and stress crack resistance and impact strength, but poor processibility and reduced tensile strength. Also called HMWLDPE. 

SlbBan Bandyopadhyay, S., Brown, H. R. Environmental stress cracking of low molecular weight high density polyethylene. Polymer 22 (1981) 245-249. 

Via, J. C., Braue, C. L., Taylor, L. T. (1994) Supercritical fluid fractionation of a low molecular weight high density polyethylene wax using carbon dioxide, propane and propane modified carbon dioxide /ia/. Chem. 66, 603. 

Most polyethylene is acceptable for use in food contact applications. In some cases of plastomers, resins containing as much as 50% comonomer are acceptable (115). FDA compliance is based mainly on levels of migratable low molecular weight, low density olefins called hexane extractables and various additive levels. A letter of compliance or other certification should be received from the appropriate resin supplier before actual use. 

SFC has been used to determine oligomers in PET [124] and low molecular weight, high-density polyethylene wax [125]. Carbon dioxide, propane, and propane-modified carbon dioxide have been studied as eluents. 

HDPE melts at about 135°C, is over 90% crystalline, and is quite linear, with more than 100 ethylene units per side chain. It is harder and more rigid than low density polyethylene and has a higher melting point, tensile strength, and heat-defiection temperature. The molecular weight distribution can be varied considerably with consequent changes in properties. Typically, polymers of high density polyethylene are more difficult to process than those of low density polyethylene. 

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