Dispersion in polymer melt

Prasanna K. Jog, Valeriy V. Ginzburg, Rakesh Srivastava, Jeffrey D. Weinhold, Shekhar Jain, and Walter G. Chapman, Application of Mesoscale Field-Based Models to Predict Stability of Particle Dispersions in Polymer Melts... 

Metzner (1985) pointed out that at high solids concentration levels, the theoretical equation (Equation 2.25) of Frankel and Acrivos appears to do a good job of portraying experimental data of rigid solids dispersed in polymer melts. 

Spin-spin relaxation measurements by the spin echo method with an applied field gradient are used for determining diffusion constants. When applied to alkanes it was shown that these measurements are able to determine the grade of dispersity in polymer melts. The method was tested on paraffin mixtures containing eicosane as the main component ... 

Kasaliwal, G. Villmow, T Pegel, S Potsehke, P. Influenee of material and proeessing parameters on carbon nanotube dispersion in polymer melts. In Polymer-carbon nanotube composites, preparation, properties and applications, MeNally, T. Potsehke, R, eds Woodhead Publishing Cambridge, UK, 2011 pp. 92-132. 

Though experimental data on suspensions of fibers in Newtonian dispersion media give more or less regular picture, a transition to non-Newtonian viscoelastic liquids, as Metzner noted [21], makes the whole picture far or less clear. Probably, the possibility to make somewhat general conclusions on a longitudinal flow of suspensions in polymer melts requires first of all establishing clear rules of behavior of pure melts at uniaxial extension this problem by itself has no solution as yet. 

The conceptual breakdown of polymer processing dating back to the first edition of 1979, presented earlier, remains the same. Yet the field and the industry, in the current transition period, have been focusing on and growing through what used to be called compounding, and is now expanded from the simple dispersion and distribution of fillers in polymer melts, to encompass microstructure development and stabilization in... 

One of the potential ways how to improve CNT dispersion in polymer matrixes is in-situ polymerization of monomers in presence of nanotubes. Monomers have very small shear viscosity in orders of about lO -lO"3 Pa.s, compared to relatively high viscosity of polymer melts, 103-106 Pa.s. This low viscosity helps to better impregnation and wetting of CNT material, which leads to more efficient dispersion and debundling of the nanotubes aggregates, especially when ultrasound is used as a dispersing agent. 

Use of dyes does not require fine dispersion and, being dissolved in polymer melt, they as a rule do not influence physico-mechanical properties of the melt and dyed fibre but sometimes improve them. Besides, the amount of dye, necessary to get bright tones of dyed fibre is less than at using pigments. However, dyes are mainly less thermostable and that is why they withstand less time of staying in melt. Light stability of the fibre, painted by these dyes, is also less in most cases which shows feasibility of purposeful search and synthesis of new dyes, especially meant for PA dyeing in mass. 

There are many works of patent character in which methods of obtaining PETP-fibres stock dyed [275-279] are described. Pigments (black and TiO2) in the form of dispersions and pastes and additives soluble in polymer melt [280] are used for dyeing and stabilization. 

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