Solid-phase extrusion process

As it has been noted above, in the indicated compositions solid-phase extrusion process the sharp drop of (p, (from 0.26 up to -0.05) within the range of A, = 1 3 is observed, that results to corresponding increase from 2.63 up to -2.87 [5]. As it is known [12], between the parameters J and (p the intercommunication exists, expressed by the Eq. (1.12). In Fig. 14.1 the dependences, calculated according to the Eqs. (1.9) and (1.12) eomparison is shown. As one can see, the good conformity between them is observed, that confirms the made above conclusion - local order regions deeay (9 decrease) in solid-phase extrusion process is the d growth eause [11]. 

The data of Figs. 4.10 and 4.11 comparison shows, that the value obtained according to the dependences D- (q) and D (q), corresponds to the value X, at which fracture stress o -drop (Fig. 14.10) or interfacial boundaries polymer-filler fracture begins [2]. Thus, within the frameworks of multifractal formalism interfacial boundaries fracture of componors in solid-phase extrusion process is realized by polymer matrix structure regular fractal state achievement [56]. 

Kozlov, G. V, Aloev, V. Z., Novikov, V. U., Beloshenko, V. A., Zaikov, G. E. (2001). The Change of Deformation Mechanism and Structure in Solid-Phase Extrusion Process of Polymerization-Filled Compositions. Plast Massy, 3,21-23. 

During the last ten years there have been several notable advances in the development of ultra high modulus polyethylene and polypropylene. This has been achieved most simply by tensile drawing , but also by hydrostatic extrusion , ram extrusion and die drawing all of which are solid phase deformation processes. In polyethylene, an alternative approach has been the production of fine ultra high modulus fibres from dilute solution, either by crystallisation in an elongational flow field or by stretching fine fibres spun to form a gel from dilute or reasonably dilute solution, 13 ... 

A central issue in the development of effective processes has been the increase in axial modulus with deformation ratio (i.e. draw ratio or extrusion ratio). It has been shown that all the solid phase deformation processes give oriented materials which are equivalent to a very good approximation. In polyethylene, it is of some interest to compare the measured mechanical anisotropy at 20°C and -YJ5 C with that predicted theoretically (Table 1). 

However, in Ref [36] although the good conformity of theory and experiment was obtained, but parameters A, and were not identified within the frameworks of polymers structure or properties. Therefore, the goals propounded above were solved on the example of 5deld process description of polymerization-filled compositions (componors) on the basis UHMPE, prepared by solid-phase extrusion method [2],... 

Hence, the cited above results shown correctness and expediency of multifractal formalism in it s the simplest variant for analysis of structure changes at polymerization-filled compositions on the basis of UHMPE during solid-phase extrusion. The observed experimentally during extrusion process effects were received the quantitative description within the frameworks of this formalism. Let us note purely geometrical character of main multifractal characteristics calculation, independent on polymer matrix and filler properties [56]. 

Esterification is the first step in PET synthesis but also occurs during melt-phase polycondensation, SSP, and extrusion processes due to the significant formation of carboxyl end groups by polymer degradation. As an equilibrium reaction, esterification is always accompanied by the reverse reaction being hydrolysis. In industrial esterification reactors, esterification and transesterification proceed simultaneously, and thus a complex reaction scheme with parallel and serial equilibrium reactions has to be considered. In addition, the esterification process involves three phases, i.e. solid TPA, a homogeneous liquid phase and the gas phase. The respective phase equilibria will be discussed below in Section 3.1. 

The table shows that the process can eliminate volatile compounds much more efficiently than non-volatile substances. Volatiles, like toluene and chlorobenzene, are already efficiently removed by step (ii) alone. Toluene was no longer measurable at a detection limit of 0.4 ppm. The other volatile, chlorobenzene, was recovered at 5.5 % of the initial concentration after the extrusion step. After the post-condensation step, the amount of toluene in the final product was likely to be far below the limit of detection since the detection limit was already determined after the extrusion step. Chlorobenzene also could not be found above the limit of detection. These results show very impressively that a conventional recycling process (consisting of steps (i) and (ii)) for post-consumer PET removes volatile real-life contaminants very efficiently, for example solvents and fuel. An additional vacuum treatment during solid-phase post-condensation further decreases any level of volatile compounds in the final product. 

Monoliths are mainly produced by extrusion, although other methods are applied, in particular for the production of metal monoliths from thin corrugated sheets. The size of the channels and the wall thickness can be varied independently, and the optimal values depend on the particular application. Therefore, an optimum can be established between the amount of the solid phase (catalyst loading), the void space in the monolith, and the wall thickness. As a consequence of the extrusion process and the use of plasticizers, the channel walls are not completely dense but possess a macroscopic porosity, t)q)ically 30-40%. Thus, the thermal expansion properties can also be adjusted. 

The concentration of API in a solid solution formulation is typically evaluated to understand the effect of dmg loading on solid solution properties such as propensity for phase instability. The addition of some APIs directly influences properties critical to melt extrusion process design and development. For example, APIs influence melt rheology as plasticizers, anti-plasticizers, or fillers. 

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