Polyethylene particles, melting point

Slurry phase (or suspension) process. The uniquedooldng equipment in Figure 23—5 is a loop reactor. This process also takes place in a solvent (in this case, normal hexane, isobutane, or isopentane) so that the mixture can be pumped continuously in a loop while the polymerization is taking place. Feeds (the solvent, comonomer if any, ethylene and Ziegler-Natta catalyst) are pumped into the loop and circulated. Polymerization rakes place continuously at temperatures below the melting point of the polyethylene allowing solid polymer particles to form enough to form slurry. The reaction takes place at 185—212°F and 75—150 psi. A slurry of HOPE in hexane is drawn off continuously or intermittently. 

U.S. Pat. No. 7,022,751 [111] describes a fiber-reinforced composite plastic material comprising thermoplastic polymers such as HDPE, LDPE, polypropylene, PVC, and polystyrene a high melting point waste polymer fiber material such as polyethylene terephthalate and nylon, an inorganic filler, such as glass and other material, and an organic filler such as wood or particles of a thermoset plastic, such as rubber and polyurethane foam. 

Polypropylene (PP) and polyethylene (PE) microporous separators (e.g. with 20 jxm thickness and 50% porosity) are used for electrically separating the positive electrode and negative electrode. SEM of microporous separator is shown in Figure 12.1.4. As organic solvents are wettable to PP and PE, the solvents can penetrate into such micropores. The pore size of the separator is normally less than 0.5 (tm, in order to ensure that fine active ceramic particles of electrodes do not pass through the separator. A PP/PE/PP layered separator is often used for practical Li-ion batteries because of a shut down effect. When battery temperature approaches tbe melting point of PE (130°C), micropores of only PE are suddenly closed, and the battery reaction coming from Li-ion transportation is stopped by tbe separator. 

Fig. 23. The total energy as a function of temperature while annealing the polyethylene particle which consists of 12,000 atoms with a chain length of 100 heads. The open circles are the total energy calculated from MD simulations and the dashed lines show the least squares fit. The intersection of extrapolated straight lines corresponds to the melting point, 7, = 245 K. The slopes of the lines CL are 6.47 and 7.24 cal/(mol-K), respectively. The insert shows the heat capacity calculated from the total energy...

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