Morphology fibrillar

The tensile properties of the extruded blends and composites are presented in Table 2. Compared to the neat PP, a clear reinforcement was achieved after twin-screw blending. The reinforcing effect was even more pronounced with the higher take-up speed (H), evidently due to the extremely fibrillar morphology, as seen in Fig. 3. 

In both the blends and composites, the addition of LCP reinforced the PP matrix considerably. On the basis of the fibrillar morphology throughout the specimens, even better mechanical properties were expected for the composites than for the blends. The poorer than expected reinforcement was primarily due to the lack of adhesion between fiber and matrix. 

This argument was put forth In 1962 by Judge and Stein (1) to explain the behavior of polyethylene networks under a constant load. That same year Smith (4) showed that a folded-chain morphology was thermodynamically favored at lower temperatures (high crystallization) whereas at temperatures near the melting point (low crystallization) fibrillar morphology was stable a transformation of one morphology Into the other was thermodynamically... 

The addition of water to solutions of PBT dissolved in a strong acid (MSA) causes phase separation in qualitative accord with that predicted by the lattice model of Flory (17). In particular, with the addition of a sufficient amount of water the phase separation produces a state that appears to be a mixture of a concentrated ordered phase and a dilute disordered phase. If the amount of water has not led to deprotonation (marked by a color change) then the birefringent ordered phase may be reversibly transformed to an isotropic disordered phase by increased temperature. This behavior is in accord with phase separation in the wide biphasic gap predicted theoretically (e.g., see Figure 8). The phase separation appears to occur spinodally, with the formation of an ordered, concentrated phase that would exist with a fibrillar morphology. This tendency may be related to the appearance of fibrillar morphology in fibers and films of such polymers prepared by solution processing. 

The fibrillar morphology of Shirakawa polyacetylene is an advantage in applications requiring a high surface area but a problem in many other cases, especially the study of diffusion and transport processes and the possible device applications where re-... 

The diffusion behaviour of Shirakawa polyacetylene is complicated by its fibrillar morphology and high surface area, so that weight changes depend on pore transport and surface adsorption, as well as on diffusion into the fibrils. Chien 6) has reviewed earlier studies of the diffusion of dopant counter-ions in Shirakawa polymer and has emphasised the wide range of values of diffusion coefficient which are reported and which depend a great deal upon the morphological model chosen to interpret experimental data. 

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