Nonisothermal melting

Journal of Cellular Plastics 36, No.l, Jan./Feb.2000, p.29-44 NONISOTHERMAL MELTING AND CRYSTALLISATION OF FOAMED CROSSLINKED POLYETHYLENE Kotzev G Touleshkov N Christova D Nedkov E Bulgarian Academy of Sciences... 

Fig. 14.8 Simulation results for velocity, temperature, axial normal stress, and crystallinity fields for low-speed spinning of nylon-6.6. [Reprinted with permission from Joo et al., Two-dimensional Numerical Analysis of Nonisothermal Melt Spinning with and without Phase Transition, J. Non-Newt. Fluid Mech., 102, 37-70 (2002).]...

Figure 26-13. Arrangement of cells for measuring oxygen fugacities in a streaming nonisothermal melt by referring to only one nonisothermal dissolving zirconia reference electrode (see Equation 26-35). E, and = measured emfs Th = thermocouples measuring indicated temperatures = temperature of reference electrode = temperature at contact ZrO/melt , and T 2 temperatures of platinum measuring electrodes.

Xu C, Qiu Z (2009) Nonisothermal melt crystallization and subsequent melting behavior of biodegradable poiy(hydroxybutyrate)/ multiwalled carbon nanotubes nanocomposites. J Pol) Sci, Part B Polym Phys 47 2238-2246... 

Thus, in this section we describe melt crystallization, in which the crystal formation takes place from the polymer melt. Melt crystallization of polymers can be subdivided into (1) isothermal crystallization, a crystallization process that takes place at a definite, constant temperature and (2) nonisothermal melt... 

Nonisothermal Melt Crystallization. In routine DSC crystallization measurements of polymers, nonisothermal crystallization is typically used.This method is simple and gives practical results. At the same time, the information obtained is limited to the characteristic temperatures of crystallization. The sample is heated beyond the equilibrium melting point of the polymer, held there for several minutes for temperature equilibration, and also to destroy all nuclei, and then it is cooled at a specific constant rate to room temperature or below to record the crystallization exotherm. 

B.3 Draw Resonance of a Power-Law Nonisothermal Melt Spinning. Estimate the critical draw ratio for draw... 

Even though the nonisothermal crystallization leads to just small changes in the subsequent melting behavior of different types of triblock copolymers, isothermal experiments employed to calculate the equilibrium melting temperature, T, have shown that this parameter can exhibit significant changes depending on composition. It has been reported that in PS-fc-PB-fc-PCL tri-... 

Polymer processing operations, by and large, are nonisothermal. Plastics pellets are compacted and heated to the melting point by interparticle friction, solid deformation... 

Distributed Parameter Models Both non-Newtonian and shear-thinning properties of polymeric melts in particular, as well as the nonisothermal nature of the flow, significantly affect the melt extmsion process. Moreover, the non-Newtonian and nonisothermal effects interact and reinforce each other. We analyzed the non-Newtonian effect in the simple case of unidirectional parallel plate flow in Example 3.6 where Fig.E 3.6c plots flow rate versus the pressure gradient, illustrating the effect of the shear-dependent viscosity on flow rate using a Power Law model fluid. These curves are equivalent to screw characteristic curves with the cross-channel flow neglected. The Newtonian straight lines are replaced with S-shaped curves. 

Fig. 10.48 Numerical simulation results of nonisothermal flow of HDPE, Melt Flow Index MFI = 0.1 melt obeying the Carreau-Yagoda model for a typical FCM model wedge of e/h — 3 and =15. (a) Velocity (b) shear rate and (c) temperature profiles [Reprinted by permission from E. L. Canedo and L. N. Valsamis, Non Newtonian and Non-isothermal Flow between Non-parallel Plate - Applications to Mixer Design, SPE ANTEC Tech. Papers, 36, 164 (1990).]...

Fig. 10.51 Comparison between the calculated (average) and experimental temperatures at five axial positions. The entrance melt temperature was assumed to be 200°C. [Reprinted by permission from T. Ishikawa, S. Kihara, K. Funatsu, T. Amaiwa, and K. Yano, Numerical Simulation and Experimental Verification of Nonisothermal Flow in Counterrotating Nonintermeshing Continuous Mixers, Polym. Eng. Sci., 40, 365 (2000).]...

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