Experimental and theoretical study of self-reinforced polypropylene/LCP blends

In situ composites of LCP in matrices of various molecular weight polypropylenes were extruded into prepregs and fibers with different draw ratios and compositions. In general, the longitudinal modulus and tensile strength increased with draw ratio, the LCP content and the matrix molecular weight. Drawing had only little effect on the transverse properties of the prepregs; however, the LCP content decreased the tensile strength, but influenced little on the modulus when the LCP composition was less than 25 wt.%. The molecular weight of the matrix has only slight effects on the transverse properties of the prepregs. Unidirectional and quasi-isotropic laminates were also prepared. Unidirectional laminates showed similar tendencies as their corresponding prepregs against draw ratio and the LCP content. However, composites made from pelletized fibers using injection molding show deteriorations in tensile properties. These properties were closely related to their morphology. Six polymers were selected as compatibilizing agents for PP/LCP fiber spinning process. Maleic anhydride and acrylic anhydride modified polypropylenes provided some modest improvements in the modulus and tensile strength of the fibers. Maleic anhydride modified EPDMs, however, undermined the tensile properties of the fibers.; Formulation of droplet elongation and breakup in the case where a single droplet suspended in an extensional flow field was performed. Droplet elongation increases with matrix viscosity and particle size, but reduces with droplet viscosity and elasticity, and interfacial tension. The matrix elasticity affects the velocity variation along the direction of extensional flow, which sequentially affects the elongation of the droplet in a more complex way. The viscoelastic properties of the matrix are more influential on the droplet deformation than that of the drop phase. The broken drop size and the critical deformation D_c are determined primarily by the viscosity ratio for Newtonian systems. For viscoelastic systems, the capillary number, viscosity ratio, and the elasticity of both phases all have complicated effects on the broken drop size and the critical deformation. Finally, the numerical simulation predicted the dispersed LCP morphology qualitatively correct.