Blend morphology, kinetics

Several authors have investigated the influence of compatibilization on the global blend morphology. However, only a few authors really tried to understand the effect of compatibilization in crystalline/crystalline polymer blends on the crystallization kinetics, melting behavior and semicrystalline morphology of the components. In Table 3.29 some recent results on this topic are summarized. 

M.E. Cordova, A.T. Lorenzo, A.J. Miillta-, L. Gani, S. Tence-Girault, L. Leibler, The influenee of blend morphology (co-continuous or sub-micrometer droplets dispersions) on the nucleation and crystallization kinetics of double crystalline polyethylene/polyamide blends prepared by reactive extrusion. Macromol. Chem. Phys. 212, 1335-1350 (2011)... 

Phase behaviour and erystallisation kinetics for the binaiy blend P(3HB)/ eellulose propionate (CP) were performed by Maekawa et Cellulose aeetate butyrate (CAB), which has a combination of high (160 °C) and Tg (113 °C), is an important thermoplastic cellulose ester that can biodegrade in a natural environment. In an attempt to make the best use of degradable polyester P(3HB), Wang et al. blended P(3HB) with CAB and studied the relationship between the blend morphology and its physieal properties. 

The blends of polyamides (PA) with various modified elastomers and polyolefins became the most common research platform for studying the fundamentals of reactive polymer blending. The favorable reactivity between the primary amine of the PA and anhydride in the second phase enabled researchers to examine many of the fundamental issues of reactive blending including, kinetics, characteristics of newly formed interfaces, morphology effect, and mechanics of failure to mention only a few. As will be seen later, this system has become one of the most significant commercial examples of reactive blending... 

The study revealed that at the three compositions investigated, that is, 10, 30, and 70% PS, the final blend morphology (particle diameter and its distribution) does not depend on the initial stages of the mixing procedure, but is built up mainly when both components are in the melt state. Furthermore, when the kinetics are considered, the phase morphology is developed very fast. For instance, the report showed that a residence time as short as 25 s in the extruder was sufficient to form the final blend morphology. 

Goldel et al. [77,78] investigated the kinetics of transfer of CNT between immiscible co-continuous phases during melt mixing. They demonstrated that if complete transfer of MWCNTs from San to PC takes 5 min in a discontinuous micro-compounder, it takes only 60-90 s in a continuous twin-screw extruder. The pre-mix of CNTs in one of the two polymer phases can be a determining factor for the final dispersion of CNTs in the blend. Moreover, the final morphology may be inconsistent with the thermodynamic predictions. Indeed, the first polymer that is in contact with the CNTs is thus adsorbed in a partially irreversible way as described by Baudouin et al. [79,80] and this adsorption can be responsible for the final blend morphology. 

Wang H, Composto RJ. Hydrodynamic-flow-driven wetting in thin film polymer blends growth kinetics and morphology. Phys Rev E 2000 61 1659-63. 

Compatibilized blends with addition of nanoparticles can become an alternative for conventional compatibilized blends containing block copolymers. Addition of oragnoclays to polymer blend affects multiple features thermodynamic phase behavior of the blend, the kinetics of phase separation and also the morphology formed in the two-phase region. Hemmati et al. proved that incorporation of organoclay evidently enhances the miscibility of PE and ethylene-vinyl acetate [EVA] phases in the amorphous regions of nanocomposites. In addition, the studies revealed that nanofiller influences the diffusion of polymer chains, which contributes to... 

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