Effect of continuous-phase composition

Effect of Continuous-Phase Composition. In order to determine the temperature range in which acrylamide mlcroemulslon polymerization could be conducted within a supercritical alkane continuous phase, the phase behavior of the Brlj mixture/water/acrylamide system in mixtures of propane (T - 97 C) and ethane (T, 32 C) was Investigated. In addition, extqploylng a mixture of ethane and propane allows us to examine the effect of the continuous-phase... 

Effect of Continuous Phase Composition. With increasing concentration of Shellsol T in the continuous phase and therefore decreasing bulk phase viscosity (as shown in Figure 13), the emulsion breaking efficiency increases (Figure 14). As expected, the mutual approach of the water droplets will be facilitated in lower viscous continuous phases. 

Figure 13. Effect of continuous phase composition on viscosity and emulsion viscosity. Experimental data Oemulsion, o organic phase fitted data —lnrj0 = exp -K (vol%)+K2] lnrj = lnri0 + K3.

Figure 14. Effect of continuous phase composition on emulsion breaking efficiency.

Poncet et al. (1999) monitored frequency-dependent dielectric measurements to examine the phase-separation process in poly(2,6-dimethyl-1,4-phenylene ether) (PPE) in a DGEBA-MCDEA resin. Dielectric measurements measured the build up in Tg both in the PPE-rich continuous phase and in the epoxy-rich occluded phases for 30-60-wt.% PPE mixtures. In the 30% PPE mixmre, the rate of reaction of the thermoset phase is equivalent to that of the neat system due to two opposing effects, namely a slower reaction rate due to dilution and a low level of conversion at vitrification due to the presence of high-Tg PPE. In the 60-wt.% mixture the dilution effect of the PPE has a large effect of decreasing the reaction rate. The continuous thermoplastic-rich phase vitrifies first, followed by the thermoset occluded phase. The final morphology (size of occluded particles and composition of continuous phase) is affected by kinetics, diffusion and viscosity during phase separation. 

Most work on SD focuses on the effects of temperature and composition on phase equilibria in binary polymer mixmres. However, in industrial processes other variables may be of equal importance, e.g., the shear stress and pressure. It is known that these variables are important for miscibility, hence for the morphology and performance. For example, during extrusion of PC/PBT blends the LCST was increased by at least 60°C, causing miscibility. The blend coming out from the extruder phase separated by the SD mechanism. The co-continuity of phases resulted in excellent performance. 

The component with the lower viscosity tends to encapsulate the more viscous (or more elastic) component (207) during mixing, because this reduces the rate of energy dissipation. Thus the viscosities may be used to offset the effect of the proportions of the components to control which phase is continuous (2,209). Frequently, there is an intermediate situation where a cocontinuous or interpenetrating network of phases can be generated by careflil control of composition, microrheology, and processing conditions. Rubbery thermoplastic blends have been produced by this route (212). 

In either case the resulting material Is a composite, with the polymer as the continuous phase or matrix, binding together the pieces of the discontinuous filler phase. The presence of filler can have a profound effect on the properties of the polymer composite, as Illustrated In Table 7.1. From this Table, It can be seen that the nature of the filler Is Important, with different effects being obtained with different fillers. 

In the production of crude oil, the greatest part of the crude oil occurs as a water-in-oil emulsion. The composition of the continuous phase depends on the water/oil ratio, the natural emulsifier systems contained in the oil, and the origin of the emulsion. The natural emulsifiers contained in crude oils have a complex chemical structure, so that, to overcome their effect, petroleum-emulsion demulsifiers must be selectively developed. As new oil fields are developed, and as the production conditions change at older fields, there is a constant need for demulsifiers that lead to a rapid separation into water and oil, as well as minimal-residual water and salt mixtures. 

It was the objective of this work to investigate the effect of variation in block architecture (number and the order of the blocks) on the crystallinity level, morphology, the stress-strain and hysteresis behavior of this series of polymers. In addition, the composition ratio of the two block types is expected to play a crucial role in determining the bulk material properties of the block copolymers. This is related to the fact that the mechanical properties of block copolymer are typically influenced more substantially by the behavior of the continuous phase, as will be demonstrated.(1,22)... 

On the other hand, silicones are used in organic composites. The application of alloys composed of the fully cured silicone rubber particles in a continuous thermoplastic phase, called thermoplastic silicone vulcanizate, which offers high-performance materials, has been reported.506,507 Functionalized POSS was not only co-polymerized, but also blended with poly(methylmethacrylate) to study the effect of silsesquioxanes on the thermal stability of thermoplastics.508... 

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