Molecular weight medium-density polyethylene

P.J. Garrison, L.R. Wallace, D.L. Wise, J.H. Meas, Jr., L.V. Cribbs, J.A. Merrick-Mack, and P.L. Nygard, High molecular weight, medium density polyethylene, US Patent 6486270, assigned to Equistar Chemicals, LP (Houston, TX), November 26,2002. 

The obtained Ni(II) complex, containing an Ni-C (Ni-Ph) active bond, polymerises ethylene to high molecular weight high-density polyethylene, especially when precipitated with aliphatic hydrocarbon as the polymerisation medium. 

MMW-HDPE medium molecular weight high density polyethylene... 

Paxon 4700. A medium molecular-weight, high density polyethylene homopolymer film resin. 

Application The UNIPOL Polyethylene (PE) Process produces the widest array of linear low-density polyethylene (LLDPE), medium-density polyethylene (MDPE) and high-density polyethylene (HOPE) having unimodal or bimodal molecular weight distribution (MWD) using a single, low-pressure, gas-phase reactor. 

Figure 14 Contact angle of resin to alumina substrate (A) APP, 10,000, 20,000 molecular weight (B) APP, 6000 molecular weight (C) low-density polyethylene (D) EVA (30% vinyl acetate) (E), (F) medium-density polyethylene (G) polystyrene. (After Ref. 17.)...

The Fracture behavior of Medium Density Polyethylenes (MDPE) with different melt flow indexes (1.9 to 5.0 dg/min) employed in rotational molding were studied by Essential Work of Fracture (EWF). The EWF parameters obtained were equivalent for all samples examined regardless of their differences in comonomer content and molecular weights. Annealing of samples resulted in lower ductility values according to EWF parameters, in spite of minimum crystallinity changes. 

The objective of this work is to evaluate the fracture behavior of a series of commercial Medium Density Polyethylenes by the EWF technique and find correlations between the fracture parameters and the polymer properties (comonomer content, crystallinity, molecular weight and their distribution) for neat and annealed samples. 

Table 2 Diffusion data for low molecular weight organic substances in Polyethylenes (PE). Medium and High Density Polyethylenes (MDPE HDPE) 498...

Application The SCLAIRTECH1 technology (PE) process can produce linear-low-density, medium-density and high-density polyethylene (PE) with narrow to broad molecular weight distribution using either Ziegler-Natta (ZN) or proprietary single-site catalyst (SSC). 

Products SCLAIRTECH process can produce PE products with density range of 0.905-0.965 kg/m3, melt index (Ml) from 0.2 to in excess of 150, and narrow to broad molecular weight distribution (MWD). This allows producers to participate in the majority of the polyethylene market segments including among low-, medium- and high-density films, rotational, injection and blow molding applications. 

Blends of LLDPE/PP = 50 50, with or without compatibilizing ethylene-propylene copolymer, EPR, were studied by Dumouhn et al. [1984]. In spite of the expected immiscibihty, the blends showed additivity of properties with good superposition of the stress growth functions in shear and elongation, as well as with the zero deformation rate Trouton ratio, Rj, = 1. In earlier work, blends of medium density PE (MDPE) with small quantities of ultra-high molecular weight polyethylene (UHMWPE) were studied in shear and extension. Again, SH and Rj, = 1 were observed. 

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