HMW-HDPE

In the sheeting market, the low density polyethylenes are less important than the high density resins. The high density resins have excellent chemical resistance, stress-crack resistance, durabiUty, and low temperature properties which make them ideal for pond liners, waste treatment faciUties, and landfills. In thicker section, HMW-HDPE sheet makes good containers, trays, tmck-bed liners, disposable items, and concrete molds. The good durabiUty, abrasion resistance, and light weight are critical elements for its selection. 

High molecular weight HDPE (HMW-HDPE) is used for blown film and for demanding moulding and structural uses. Examples are blow moulded drums for packing dangerous chemicals and pressure piping. 

Figure 16 Dart impact strength of HMW-HDPE films. Source Ref. 132.

HMW-HDPE high molecular weight-high JIT just-in-tolerance... 

PROCESSING STABILIZERS for HMW-HDPE PROCESSING STABILITY -Lupolene 5260Z (BASF)... 

High density/weight, 61 High temperature loss, 61, 306 High viscosity of hot melt, 62 High-density boards, 209 High-molecular weight HDPE (HMW-HDPE), 52... 

Fully rotating nips with the winder attached are used for HMW-HDPE film because they result in better roll formation for the very low gauge film. If these are used with upward extrusion, it requires dealing with roll handling on the second story. If extrusion is downward, roll handling is easier, but extrusion is complicated. 

HMW-HDPE resins have high viscosity because of their high molecular weight. This presents problems in processing and, consequently, these resins are normally produced with broad MWD. 

The principal applications of HMW-HDPE are in film, pressure pipe, large blow-molded articles, and extruded sheet. HMW-HDPE film now finds application in T-shirt grocery sacks (with 0.6-0.9-mil thick... 

Table 29-03. Physical Properties of Equistar Chemicais Alathon HMW-HDPE for Film...

Alathon HMW-HDPE Film-grade Resins, Polymer Products, Equistar Chemical Company, (http // WWW. equistarchem. com/html/polymer/eva/ HMW HDPE.htm)... 

Alathon, Polyethylene (HDPE, HMW-HDPE), Equistar Chemicals... 

Norloie, HMW-HDPE film, sheet, and bag products, NAFCO Corp. 

Fig. 29. Optimized mold base for a 60-L can be made from HMW-HDPE. Dimensions are defined in Table 4. Courtesy of Hoechst AG.

Ruiz, F. A., High performance mineral reinforcement concrete for LLDPE and HMW-HDPE blown film extrusion. Journal of Plastic Film and Sheeting 2002 18 25-31. 

HMI human machine interface HMW-HDPE high molecular weight-high density polyethylene H2O water H-P Hagen-Poiseuille HPLC high pressure liquid chromatography HPM hot pressure molding HRC hardness Rockwell C (C scale)... 

The HMW-HDPE with a bimodal MWD is primarily used in film applications to fabricate grocery bags (T-shirt bags) and other merchandise bags. However, polyethylene with a bimodal MWD is also used in premium blow-molding markets and high-pressure pipe applications such as natural gas distribution pipe. 

The bimetallic catalyst was evaluated in a continuous, gas-phase flu-idized-bed pilot reactor at 95°C that produced about 20lb/hr of HMW-HDPE at an ethylene partial pressure of 180 psi, hydrogen/ethylene molar ratio of 0.005-0.008,1-hexene/ethylene molar ratio of 0.015 and trimeth-ylaluminum (TMA) as cocatalyst. A comparison of the product properties of the HMW-HDPE produced with the bimetallic catalyst in a single polymerization reactor to a similar product available commercially using two polymerization reactors operated in series is shown in Table 4.14. The gel permeation chromatogram (GPC) of the bimodal HMW-HDPE produced in a single reactor with the bimetallic catalyst is shown in Figure 4.28. 

Table 4.14 Comparative properties of bimodal HMW-HDPE prepared in a single reactor and tandem slurry process.

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