Polymer fast crystallizing

Neoprene 400. It contains a fast-crystallizing polymer with the highest chlorine content and the highest uncured cohesive strength among all anionic latexes. However, this latex has a relatively short open time and requires high lamination pressures to achieve coalescence. 

In the world of molecular simulation, it would be more conventional to consider that the present model is a coarse grained model of real polymers, where the real time-scale is much longer than that of the present MD simulation time-scale. However, we did not intend to make a coarse grained model. The crystallization of polymers was shown to be rather universal. Various kinds of polymers, either fast crystallizing or slow crystallizing, were known to follow the same scheme with respect to the molecular mechanism of crystallization. So we studied this simple model expecting that the present model would also follow the same crystallization scheme and show the general molecular mechanisms of polymer crystallization. 

In our case since we have a very fast crystallizing polymer (PBT), we wanted to see if there was any difference in the crystallization of the blends depending on how the study was performed. Two sets of studies were done, in which the samples were crystallized at 110°C in one of them from the glass and in the other from the melt. The crystallization half-times and ultimate crystallinities obtained for each component were plotted in Figures 24, 25, 26, and 27. 

Syndiotactic polystyrene (sPS) represents an important achievement in olefin polymerization catalysis. Syndiotactic PS is an industrially relevant thermoplastic material produced by Dow Chemical and Idemitsu Kosan Co. under the tradenames Questra and Xarec , respectively. Industrial interest on sPS originates from the remarkable properties exhibited by this highly crystalline polymer. The high melting temperature, 270 °C, the relatively fast crystallization rate (at least much faster than that of iPS), the high heat resistance, the low dielectric constant, the high elastic modulus, and an excellent resistance to chemicals explain the industrial interest for this material. Syndiotactic PS was considered as an innovative new resin option for the automotive, electrical, and electronic markets, appliances such as... 

Fully amorphous polyethylene is rather difficult to make because of its fast crystallization. By superfast quenching it was, however, possible to make small amounts of polyethylene glass of phase area 11 [6]. Glassy polymers are much more easily available for macromolecules that crystallize slowly, such as poly(ethylene terephthalate) and poly(oxy-l, 4-phenyleneoxy-1,4-phenylenecarboxy-1,4-phenylene) or macromolecules that have structural irregularities which prohibit crystallization completely, such as atactic polystyrene andpoly(methyl methacrylate). More details about the special properties of the transition 11— are discussed in Sect. 6.3. 

Quench. Cooling the melt to solidily the viscous extrudate is an important process parameter. Depending on the orientation process, the melt quenching process may be very different. The two primary extrudate geometries are a flat sheet and a tube. Most often, heat needs to be removed from the extrudate as quickly as possible. For semicrystalline polymers with a relatively slow crystallization kinetics, like PET, PEEK, or PPS, rapidly quenching the melt results in a molecular amorphous state. For semicrystalline polymers with a relatively fast crystallization kinetics, like polyethylene, polypropylene, or nylon 6, rapidly quenching the melt allows for the growth of smaller spherulites. 

Table 3 compares properties of PTT, PET, and PBT (40). They were measured on injection-molded samples using ASTM test methods. Tensile strength, flexural modulus, and notched Izod impact of PTT fall in between those of PET and PBT. All three polymers have similar electrical properties except for PET which has lower volume resistivity. The lower moisture absorptions of PTT and PBT are due to the high crystallinities from fast crystallization. 

The crystallization mechanism of polymers in liquid phase is still controversial, as we mentioned in section 1.1 Faraday Transactions, 1979). Nevertheless, for some fast crystallization kinetics, it is possible for a chain to be extended in the amorphous phase by a sucking process which is directly related to reptation (Klein, 1979). 

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