High-density polyethylene bimodal

Bimodal polymer, 20 165 Bimodal polymerization, 20 531 Bimodal reactor technology, for high density polyethylene, 20 170 Bimodal weight ratio, 70 17 Bimolecular reaction, 74 625 Bimolecular recombination coefficient, 74 833... 

High density extruded planks, 23 404 High density lipoproteins (HDLs), 5 135-137 10 829 niacin and, 25 798 High density polyethylene (HDPE), 10 596-595 11 225 16 21 17 724 20 149-179 24 267, 268. See also HDPE entries analysis of, 19 566 as barrier polymer, 3 377 bimodal reactor technology for, 20 170 blow molding of, 20 171-172 blown film applications, 20 173-174 catalysts used for, 20 152-155 chemical resistance of, 20 166 commercial applications of,... 

Application The Borstar polyethylene (PE) process can produce a broad range of bimodal and unimodal linear-low-density polyethylenes (LL-DPE), medium-density polyethylenes (MDPE) and high-density polyethylenes (HOPE). The Borstar PE consists of a loop reactor and a gas-phase reactor In series. 

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. 

Application To produce bimodal and multimodal high-density polyethylene (HOPE) using the stirred-tank, heavy-diluent Hostalen ACP process. 

Shen, H.-W. Luan, T. Xie, B.-H. Yang, W. Yang, M.-B., Rheological Behaviors and Molecular Weight Distribution Characteristics of Bimodal High-Density Polyethylene. J.Appl. Polym. Sci. 2011,121,1543-1549. 

Figure 13.31 Environmental stress cracking resistance (ESCR) plotted against strain-hardening modulus for a range of EIDPEs, both catalyst based with broad molecular weight distribution, and bimodal. Points labelled reproducibility are repeated tests on the same sample. (Reproduced from Kurelec, L, Teeuwen, M., Schoffeleers, El. et al. (2005) Strain hardening modulus as a measure of environmental stress crack resistance of high density polyethylene. Polymer, 46, 6369. Copyright (2005) Elsevier Ltd.)...

High-density polyethylene (PE-HD) Hostalen CRP 100 Black, MFR = 0.23 g/10 min (190 °C/5.0 kg), the soot content of 2.25%, prod. Basell Olefins was used as the matrix polymer. This PE-HD is a bimodal polyethylene, whose structure is characterized by the presence of two fraction of different molecular weight of polymer. Bimodal structure of PE-HD has a beneficial effect of its mechanical properties during long-term durability test. Higher resistance of this PE-HD to mechanical action as compared to other polyethylenes makes it suitable for use in the construction of various pipelines where it is important that the mechanical properties are a function of time as high as possible [27]. 

An example of the output is shown in Figure 2 for polyethylene NBS 1476. The LALLS trace shows a peak at the high molecular weight end (low retention time) which is barely noticeable on the DRI trace. This suggests a very small amount of high molecular weight, highly branched material. This type of bimodal peak in the DRI trace is often seen in branched EP (ethylene-propylene polymers) or LDPE (low density polyethylene) samples. 

Current investigations indicate that the stress-cracking induced, sloping curve branch does not appear in internal pressure creep tests. Bimodal PE-HD types are therefore quite stress-cracking resistant, which can be explained by the reverse incorporation of comonomers. Bimodal polyethylene is a reactor blend of a low-molecular, high-density homopolymer and a low-density, high-molecular copolymer. Short-term tests on notched specimens of bimodal PE-HD show considerably reduced stress-cracking sensitivity [830]. 

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