LCP Blends

The transport properties of incompatible blends of poly(ethylene terephthalate) (PET) and a blend composed of 40mol% PET and 60mol% Rodrun 3000 were investigated, using dichloromethane as permeant [68]. Blends submitted to physical aging showed a decrease in permeability of a proportion that was increased in line with the amount of LC phase present, and by a larger contribution that was derived from the polymeric matrix. This decrease in permeability was essentially attributed to a lowering of sorption, as the diffusional behavior of the different samples was the same. 

Data relating to the diffusivity and solubUity of methanol in blends of polyether-sulfone (PES) and a type of LCP, poly(hydroxyl-benzoic add (73 mol%)-co-hydroxy-naphthoic add (27 mol%)) have been reported by Wiberg et cd. [69]. Samples were taken from injection-molded and compression-molded specimens over a wide range of compositions. The solubility of methanol was proportional to the PES content. Values beyond 40% LCP were not available because of the low methanol diffusion in blends with a high LCP content consequently, the LCP phase 

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In the work reported here, we produced highly fibrillar polypropylene (PP)-LCP blends that were subsequently processed by injection molding without melting the LCP fibers again in order to create tough PP-LCP... 

In an earlier study (44) on the effect of viscosity ratio on the morphology of PP-LCP blends we found that the viscosity ratio is a critical factor in determining the blend morphology. The most fibrillar structure was achieved when the viscosity ratio (i7lcp i7pp) ranged from about 0.5-1. At even lower viscosity ratios the fiber structure was coarser, while at viscosity ratios above unity, the LCP domains tended to be spherical or clusterlike (Fig. 1)=... 

Since the processing conditions and mixing equipment have a crucial effect on the morphology of immiscible polymer blends [45], experiments were carried out in four different types of extruders to find optimal conditions for blend preparation and fibrillation. Nevertheless, the morphologies of PP-LCP blends produced by... 

Figure 1 Optical micrographs in the flow direction of the extruded strands of the PP-LCP blends exhibiting viscosity ratios of (a) t7lcp i7pp = 0,6, and (b) 2.8 [44].

Figure 2 Optical micrographs of melt mixed PP-LCP blends single-screw extruded at melt temperatures of (a) 250°C, and (b) 260°C.

Figure 3 Twin-screw extruded PP-LCP blend processed at a melt temperature of 290°C with low- (left) and high-draw ratio (right). Upper micrographs are taken from the core and lower ones from the skin region.

As sparse as the dataset describing mainchain nematic LCP blends with conventional polymers is, it is rich compared to the almost non-existent data on the blending of other types of LCPs-side chain polymers, flexible spacer polymers, smectics, etc. 

The preparation and properties of blends of an HBA/HNA LCP with poly(phenylene sulfide) and poly(etherether-ketone) is described in the chapter by Baird et al. LCP/LCP blends is the subject of the chapter by... 

DeMeuse and Jaffe. In another chapter, Brostow et al. discuss the phase behavior of binary and ternary mixtures containing an LCP component. The kinetics of thermally induced phase separation of an HBA/PET LCP blended with poly(ether imide) are described by Zheng and Kyu. 

DEMEUSE JAFFE Investigations into the Structure of LCP—LCP Blends 441... 

Standard mixing conditions were to melt blend the samples at 300 C for five minutes at a rotor speed of 40 RPM. The effect of mixing history on the structure of the LCP/LCP blends has not been investigated in the present work. Such a study has been reported by Mehta and Baird (i ).The samples were, then, given two minutes at 5 RPM followed by programming the rotor speed to 100 RPM in a two minute period. The speed is, then, instantaneously lowered back down to 5 RPM in two minutes. This is followed by two minutes at 5 RPM to determine whether the ramp test has affected the sample i n any way. 

DEMEUSF, JAFFE Investigations into the Structure ofLCP-LCP Blends 447... 

LCP blended with another LCP processability, HDT > 200°C, impact strength Charbonneau etal., 1995... 

Figure 7.22. Concentration dependence of shear viscosity of PP/LCP blends dotted line represents the fluidity equation,...

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