Kinetics of blending

Jana RN, Bhunia HP, Nando GB (1997) An investigation into the mechanical properties and curing kinetics of blends of low-density polyethylene and poly(dimethyl-siloxane) rubber. Thermochim Acta 302( 1-2) 1—9... 

The overall crystallization kinetics of blends can often be described by the Avrami equation [Avrami, 1939] ... 

Metin and Hartel (year ). Crystallization Kinetics of Blends of Cocoa Butter and Milk Fat or Milk Fat Fractions, J. Thermal Analysis 47(5), 1527-1544. 

In this section the crystallization kinetics of blends whose components are miscible in some proportion in the melt will be discussed. In such partially miscible systems, liquid-liquid phase separation could intervene and influence the crystallization process. Therefore, in order to properly analyze the crystallization kinetics in such systems it is necessary that the phase diagram be established. These systems represent a classical example where the melt structure plays an important role in governing the ensuing crystallization. The reason for this requirement will become clear as some typical phase diagrams, involving a crystallizable polymer, are examined. 

Miscible blends of high molecular weight polymers often exhibit LOST behavior (3) blends that are miscible only because of relatively low molecular weights may show UCST behavior (11). The cloud-point temperatures associated with Hquid—Hquid phase separation can often be adequately determined by simple visual observations (39) nevertheless, instmmented light transmission or scattering measurements frequendy are used (49). The cloud point observed maybe a sensitive function of the rate of temperature change used, owing to the kinetics of the phase-separation process (39). 

The kinetics of the reactive compatibilization of nylon-6-PP by acrylic acid modified PP was investigated by Dagli et al. [47]. The compatibilization reaction in this system involved the reaction between the acid group of acrylic acid modified PP and the amine group of nylon-6. A typical intensive batch mixer torque (t) vs time (t) trace for a ternary blend showing an increase in mixing torque upon the addition of PP-g-AA to a binary PP-NBR (85 7.5) blend is shown in Fig. 3. The kinetic... 

Since interactions at the molecular level between polymer components in the blends occur only in the amorphous phase, it is reasonable to assume that these effects are due to kinetic factors and, in particular, to the influence of a polymer component on the nucleation or crystallization kinetics of the other one. 

They have studied the properties of NR-epoxidized natural rubber (ENR) blend nanocomposites also. Vulcanization kinetics of natural mbber-based nanocomposite was also smdied. The effect of different nanoclays on the properties of NR-based nanocomposite was studied. The tensile properties of different nanocomposites are shown in Figure 2.7 [33]. 

The investigators studied various blends of the three polymers in order to control the rate of chain scission and thus influence the induction period and onset of drug release. None of the blends provided the desired 1-week zero-order kinetics. However, blends of different microsphere types did show promise in vitro (88). 

Rubisov, D. H. Krowinkel, J. M. Papangelakis, V. G. Sulphuric acid pressure leaching of laterites—universal kinetics of nickel dissolution for limonites and limonitic/saprolitic blends. Hydrometallurgy 2000, 58, 1-11. 

Shi, Y. and Jabarin, S. A., Transesterification reaction kinetics of poly(ethylene terephthalate)/poly(ethylene 2,6-naphthalate) blends, J. Appl. Polym. Sci., 80, 2422-2436 (2001). 

Figure 20.22 Plots of ln[- ln(1 - Xc) as a function of In a at various temperatures for P(HB80-ET20)/PET (weight ratio, 4 3) T, 144°C A, 149 °C , 153 °C , 157 °C [44]. From Park, J. K., Park, Y. H., Kim, D. J. and Kim, S. FI., Crystallization kinetics of TLCP with polyester blends, J. Korean Fiber Soc., 37, 69-76 (2000). Reproduced with permission of The Korean Fiber Society...

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