Polymer melt-processable

In polymer melt processing, the crystallization half-time, 0/2, is often a more useful parameter than the Avrami rate constant. An experienced individual can often estimate the processing conditions of a new polymer by comparing its 0/2 value with those of known polymers. Figure 11.6 compares the ty2 parameters of PET, PTT and PBT, with PTT falling in between the other two polyesters. 

Piau, J.M., Agassant, J-F. (1996) Rheology for polymer melt processing. Elsevier, Amsterdam... 

J. R. A. Pearson, Mechanical Principles of Polymer Melt Processing, Oxford Pergamon Press, Oxford, 1966. 

D. Roylance, Use of Penalty Finite Element Analysis of Polymer Melt Processing, Polym. Eng. Sci., 20, 1029-1034 (1980). 

There are many polymer chain modification reactions of different types that have been carried out on polymer melts processed in single and twin rotor extruders. This activity, (4-6) in the analysis of polymerization reactors, driven by market forces seeking to create value-added polymers from commodity resins, started in the mid-1960s in industrial research laboratories (7). Indeed much of the early work is to be found in the patent literature.1 Although in recent times more publications, both industrial and academic can be found in the open literature, there is still a good deal of industrial secrecy, because the products of reactive polymer processing are of significant commercial value to industry. Below we will deal briefly with two important examples of such reactions. 

Nalawade SP, Picchioni F, Janssen LPBM (2006) Supercritical carbon dioxide as a green solvent for processing polymer melts processing aspects and applications. Prog Polym Sci 31(1) 19—43... 

Denn, Polymer Melt Processing Foundations in Fluid Mechanics and Heat Transfer Duncan and Reimer, Chemical Engineering Design and Analysis An Introduction Fan and Zhu, Principles of Gas-Solid Flows Fox, Computational Models for Turbulent Reacting Flows... 

Comprehensive investigations of the polymer melting process in co-rotating twin screw extruders by Bastian/Gabor [9] yielded the following results ... 

Kissi NE and Piau J-M, "Stability Phenomena During Polymer Melt Extrusion" in Piau J-M and Agassant J-F (Eds), "Rheology for Polymer Melt Processing", Rheology Series, Vol. 5, Elsevier, Amsterdam, 1996, pp 389-420. Langelaan HC and Gotsis AD, J Rheol 40 (1996) 107. 

Piau J-M and Agassant J-F (Eds), Rheology for Polymer Melt Processing", Rheology Series, Vol. 5, Elsevier, Amsterdam, 1996. 

Rheology for Polymer Melt Processing J-M. Piau and J-F. Agassant (editors) 1996 Elsevier Science B.V. 

We presented some applications of the bireftingence techniques for the characterization of orientation and stress field in both simple and complex deformations. The validity of the stress optical law in these particular flow situations was checked and assessed. Birefringence techniques appear to be very powerful for the study of polymer melt processing and for the understanding of polymer flow behaviour. 

Rheology for polymer melt processing / [edited by] J.-M. Piau and J. -F. Agassant. 

The evolution of the experimental anisotropy as a function of the temperature is shown in Fig. 8. As expected, the decay rate increases as the temperature increases. For the highest temperature (t > 50 °C), it can be noticed that the anisotropy decays from a value close to the fundamental anisotropy of DMA to almost zero in the time window of the experiment (about 60 ns). This means that the initial orientation of a backbone segment is almost completely lost within this time. This possibiUty to directly check the amplitude of motions associated with the involved relaxation is a very useful advantage of FAD. In particular, it indicates that in the temperature range 50 °C 80 °C, we sample continuously and almost completely the elementary brownian motion in polymer melts. Processes too fast to be observed by this technique involve only very small angles of rotation and cannot be associated with backbone rearrangements. On the other hand, the processes too slow to be sampled concern only a very low residual orientational correlation, i.e. they are important only on a scale much larger than the size of conformational jumps. 

This paper has described an analytical tool which can predict velocities, stresses, and temperatures in nonisothermal flow situations of the sort encountered in many polymer melt processing operations. Such a model cannot be expected to replace the experience and intuition which provide the basis for most process design today, but it is hoped that this inexpensive and easily implemented model can provide a means by which the process designer s intuition might be expanded. Properly used, it can be a valuable additional tool at the process designer s disposal. 

In the presence of a stream of hot air or high temperature and low pressure (e.g., during polymer melt processing) volatility becomes very important it is governed by the rate of diffusion of antioxidants, which, in turn, determines the rate at which the surface is replenished. " The influence of polymer sample shape and the structure and molar mass of antioxidants on volatility has received much attention. The rate of evaporation of antioxidants from rubber and polyethylene, for example, was found to be inversely proportional to the thickness of the sample and directly proportional to its surface area. Furthermore,... 

Nalawade, S. P., Pocchioni, F., and Janssen, L. P. B. M. (2006) Supercritical carbon dioxide as a green solvent for processing polymer melts processing aspects and applications. Prog. Polym. Sci. 31, 19-43 Gibbs, J. W. (1982) Collected Papers Thermodynamics and Statistical mechanics (Nauka, Moscow) in mssian... 

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