Phase morphology development

Everaert V, Aerts L, Groeninckx G (1999) Phase morphology development in immisdble PP/(PS/PPE) blends influence of the melt-viscosity ratio and blend composition. Polymer 40 6627-6644... 

Fig. 10.13 Melting of low density polyethylene (LDPE) (Equistar NA 204-000) in a starve-fed, fully intermeshing, counterrotating Leistritz LMS 30.34 at 200 rpm and 10 kg/h. (a) The screw element sequence used (h) schematic representation of the melting mechanism involving pellet compressive deformation in the calender gap (c) the carcass from screw-pulling experiments. [Reprinted by permission from S. Lim and J. L. White, Flow Mechanisms, Material Distribution and Phase Morphology Development in Modular Intermeshing counterrotating TSE, Int. Polym. Process., 9, 33 (1994).]...

S. Lim and J. L. White, Flow Mechanisms, Material Distribution and Phase Morphology Development in a Modular Intermeshing Counterrotating Twin Screw Extruder of Leistritz Design, Int. Polym. Process., 9, 33—45 (1994). 

Table 7.6 provides a partial reference to studies on the effects of flow on the morphology of polymer blends [Lohfink, 1990 Walling, 1995]. Dispersed phase morphology development has been mainly studied in a capillary flow. To explain the fibrillation processes, not only the viscosity ratio, but also the elasticity effects and the interfacial properties had to be considered. In agreement with the microrheology of Newtonian systems, an upper bound for the viscosity ratio, X, has also been reported for polymer blends — above certain value of X (which could be significantly larger than the... 

S. Shahbikian, Phase Morphology Development and Rheological Behavior of Non-plasticized and Plasticized Thermoplastic Elastomer Blends (Ecole Polytechnique, Mraitreal, 2010),... 

Final morphology is the same in both CORI and ICRR Melts and mixes faster for a blend of HOPE and PS. Phase morphology develops faster along screw length Cho and White 1996... 

Published investigations of phase morphology development in polymer melt blends in twin-screw extruders began with the work of Plochocki et al. [137] in 1988. Since 1992, several different research groups have described investigations [76,138-147]. 

Several authors have developed empirical equations to predict the effect of coalescence on the phase morphology of binary polymer blends. Equation 1.4 relates the particle size of the dispersed phase at equilibrium to its composition in the blend [10]. This equilibrium equation was derived from a more complex expression where a rate constant for breaking fhe drops and one for fheir coalescence have been defined to account for the continuous process of phase morphology development resulting from a competition between breakup and coalescence. 

Another phenomenon that has to be considered in phase-morphology development is the transition from a droplet to a fiber-like dispersion. This transformation depends on the extent of the deforming forces, the capillary instabilities, and the coalescence as well as on the interfacial tension between the phases. The type of flow to which a particle is subjected, whether it is a shear flow or an elongational flow field, is a crucial parameter to... 

SEM photomicrograph of the smoothed and toluene-etched surfece of a PET ultra-low-density polyethylene (ULDPE)-g-DEM blend obtained in a discontinuous mixer by adding Ti(OBu)4 as a transesterification catalyst. (From M. B. ColtelH, Catalysed Reactive Compatibilization of Polyolefin and Poly(ethylene terephthalate) Blends Reactions Mechanisms and Phase Morphology Development, Ph.D. thesis. University of Pisa, Italy, 2005.)... 

A different approach was taken by Touhsaent et al. [2081. These authors synthesized two polymers, one of which formed a network, by simultaneous independent reactions in the same container. They have indicated that intercrosslinking reactions are eliminated by combining free radical (acrylate) and condensation (epoxy) polymerization. By this method, they modified an epoxy resin with poly(n-butyl acrylate) polymer. They have found that a two-phase morphology developed, consisting of co-continuous rubber domains (about 0.1—0.5 p-m) within the epoxy resin. The dimensions of the dispersed rubber phase domains and the extent of molecular mixing between the two components were found to depend on the relative reaction rates (or gel time) with respect to the rate of phase separation. Better mechanical properties resulted when the extent of molecular mixing was minimized and heterophase semi-IPNs were produced. 

Pagnoulle C, Konig C, Leemans L, Jerome R (2000) Reactive compatibilization of SAN/ EPR blends. 1. Dependence of the phase morphology development on the reaction kinetics. Macromolecules 33 6275-6283... 

An important part of the present chapter discusses the interrelation between reactive compatibilization and the blend phase morphology generation, as well as the crystallization behavior of reactively compatibilized blends containing crystallizable components. The phase morphology development in reactive blending is discussed in conjunction with the non-reactive blending approach. 

Reactive blending is an important technique which is very frequently used for control of the phase morphology, phase stabilization and interfacial adhesion in multiphase immiscible polymer blends. Recently a lot of attention has been focused on the reactive blending process in order to understand how phase morphology develops in reactively compatibilized blends. The stability of the in situ formed copol3aner at the interface and its influence on phase morphology generation, phase co-continuity and on the crystallization behavior of the ciystallizable component(s) are crucial aspects with respect to the blend material properties. 

In order to understand the influence of reactive blending on phase morphology development, it is important to review briefly the morphology development in non-reactive blending. The latter was a subject matter of many investigations [49-56]. 

In the case of the reactive melt-blending, the effects of the chemical reaction at the interface on the phase morphology development are multi-fold. The chemical reaction at the interface leads to ... 

Figure 3.8 Overview of phase morphology development results for the PA/EP-MA blend system with 20 wt% EP-MA. In the hatched region the samples could not be analyzed using the cryo-ultra-microtome technique [53]...

The mode of incorporation of the reactive compatibilizer in the blend has a strong effect on the phase morphology development. Studies in this direction clearly indicated that the finest morphology is obtained by pre-blending the reactive compatibilizer in the minor phase and then mixing with the major continuous phase [59]. 

It is also important to mention that further in-depth studies have to be undertaken for the quantitative analysis of the phase morphology development, phase co-continuity, phase stability, and the crystallization behavior of several reactive blend systems. 

Effect of the Interfaeial Reaction on the Phase Morphology Development. 89... 

It may, however, be anticipated that the final phase morphology and mechanical properties strongly depend on the kinetics and completeness of the interfacial reaction with respect to the blending time and the phase morphology development. This chapter aims at emphasizing the experimental parameters, which are expected to control the reactive compatibilization with a special attention to the kinetic control of the interfacial reaction and its consequence on the performances of the polyblends. 

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