Dispersed phases morphology

Fig. 8. Emulsion morphology diagram, illustrating where the microemulsion in various macroemulsion morphologies is a continuous phase or dispersed phase. Morphology boundaries (—), aqueous, continuous (--------------), oleic, continuous (--), microemulsion, continuous.

The SEM investigation shows that the particle size of the dispersed domain size decreased from 3.3 to 1.1 fxm with the incorporation of 6 wt%, EMA, and this indicates the increased surface area of the dispersed phase morphology. The increase in surface area led to effective compatibilization and is responsible for the increased adhesion strength and tensile impact strength of compatibilized blends. 

Yilmaz, G., Jongboom, R.O.J., Fell, H., and Hennink, W.E. (2001). Encapsulation of sunflower oil in starch matrices via extrusion effect of the interfacial properties and processing conditions on the formation of dispersed phase morphologies. Carbohydr. Polym. 45, 403-410. 

Liang H, Favis BD, Yu YS, Eisenberg A. Correlation between the interfacial tension and dispersed phase morphology in interfacially modified blends of LLDPE and PVC. Macromolecules 1999 32 1637-1642. 

Besides the cases of coincident crystallization reported previously, recent investigations on PP/PA-6 blends in which a compatibihzing agent had been used to obtain a finer and more homogeneous dispersed phase morphology also mentioned coincident crystallization of the PA-6 droplets with the PP matrix [Ikkala et al., 1993 Moon et al., 1994]. However, this has not been observed in the binary blend. 

Table 5.3 shows dramatic examples of the stabilization of dispersed phase morphology in the presence of a compatibilizing copolymer. In all examples essentially no change in dispersed phase particle size occurs after annealing under static conditions for up to 90 min. The data shown in this Table 5.3 should be compared with those presented in Table 5.2, where the dispersed phase mean dimensions were presented for similar, uncompatibilized blends. 

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... 

At low concentration of the second polymer, blends have dispersed-phase morphology of a matrix and dispersed second phase. As the concentration increases, at the percolation threshold volume fraction of the dispersed pase, ([) = 0.16, the blends structure changes into co-continuous. Full co-continuity is achieved at the phase inversion concentration, ( ). The morphology as well as the level of stress leads to different viscosity-composition dependencies (for more details see Chapter 7. The Rheology of Polymer Alloys and Blends ). 

Optical microscopy allows assessment of dispersed phase morphology hut provides little information about the dispersion mediiun. In contrast, electron microscopy gives more comprehensive information on the morphology of the continuous phase. 

Figure 1.24 Adding a compatibUizing agent, such as a DBG, to a polymer blend can improve its stability, but is more likely to result in a dispersed rather than a co-continuous morphology, (a) A two-dimensional shce through a compatihUized blend with a dispersed phase morphology containing a minority dark blue phase and a majority turquoise phase, (b) A molecular cartoon showing how the DBCs (top left) are segregated at the interface between the two phases. Reprinted from [193] with permission from NPG.

Recently, Tiwari and Paul (2011 a) carried out detailed studies on the effect of PP viscosity on the dispersed phase particle size, stability of dispersed phase morphology upon annealing, phase inversion behavior, and changes in the mechanical properties of PP/PP-g-MA/MMT/PS nanocomposites prepared with different molecular weight grades of PP. PP-g-MA was added to PP to facilitate dispersion of organoclay in the nonpolar PP moreover, it also provides better reinforcement effect when PP forms the continuous phase. 

Role of the Reaction Rate on the Dispersed Phase Morphology... 

Figure 7.8 Effect of MCE on the dispersed phase morphology of a PBT/AES blend containing 30wt% AES without compatibilizer (a) and with 5wt% of MCE (MCE contains 10wt% CMA) compatibilizer (b) (Larocca, N.M., Hage, E., and Pessan, LA unpublished results).

We successfully produced micron-size HDPE dispersed phase morphology at 300,400, and 500 rpm in PP, due to the shear intensive screw design. Improved stiffness and HDT properties due to glass fiber reinforcement are balanced with corresponding reduction in impact and elongational properties. 

Determination of dispersed phase morphology is most often conducted by SEM of fractured specimens. Fractures are prepared by manual... 

Determination of dispersed phase morphology is most often conducted by SEM of fractured specimens. Fractures are prepared by manual methods, after immersion in liquid nitrogen, or by standard physical testing procedures. The microstructure of the homopolymers should be examined for comparison with the multiphase polymer. SEI of an Izod fracture surface of a POM/PP copolymer is shown in Fig. 5.42. The two phases are incompatible, i.e. they are present as two distinct phases. The dispersed phase particles range from less than 0.5 to 2[xm in diameter. The sample fracture path follows the particle-matrix interface and holes remain where particles have pulled out of the matrix, showing there is little adhesion between the phases. 

Fig. 5.47 The dispersed phase morphology in an impact modified nylon is shown by phase contrast microscopy (A) and by TEM of a cryosection stained with ruthenium tetroxide (B). A STEM micrograph (C) shows regions that are less dense in a dark background. The dispersed phase structure suggests that there is more mass loss in the rubber phase than in the nylon matrix during exposure to the electron beam, permitting imaging of the particles without staining.

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