Uniform fiber orientation and transcrystallization formed in isotactic polypropylene/short glass fiber composites via a shear‐induced orientation extrusion

Abstract

The orientation of short glass fibers (SGFs) and the interfacial interaction between SGFs and isotactic polypropylene (iPP) matrix play main roles in the final properties of the iPP/SGFs composites. Here we show a self-design shear-induced orientation extrusion (SIOE) to efficiently fabricate the iPP/SGFs composites with evenly dispersion and orientation of SGFs in the whole iPP matrix. The shear stress and the orientation of SGFs are also benefit to induce transcrystals which enhance the interfacial interaction between SGFs and iPP matrix. The crystallinity in average of the iPP/5.0 wt% SGFs composites shows nearly 10% higher than that of pure iPP extruded by the SIOE system. The iPP/ 5.0 wt% SGFs composites extruded by high shear stress not only exhibit higher yield strength and Young's modulus than that of the composites extruded by low shear stress but also maintain high tensile strength and strain at break. The enhancement of mechanical properties is ascribed to the uniform dispersion and orientation of SGFs, high crystallinity, and high interfacial interaction between SGFs and iPP matrix induced by transcrystals. POLYM. COMPOS., 00:000-000, high interfacial interaction between SGFs and iPP matrix induced by transcrystals. POLYM. COMPOS., 39:3168-3177, 2018. FIG. 3. The optical micrographs of the iPP/5.0 wt% SGFs composites extruding with 0 OE (a, a 0 ), 2 OEs (b, b 0 ), 6 OEs (c, c 0 )and 8 OEs (d, d 0 ). The observation direction for a, b, c and d is vertical to the flow direction, while the observation direction for a 0 , b 0 , c 0 and d 0 is parallel to the flow direction. The scar bar for all images is 200 lm.FIG. 4. Non-isothermal crystallization of the iPP/5.0 wt% SGFs composites extruded with different number of OEs, including crystallization (a) and melting (b) curves. FIG. 5. The XRD spectra of the iPP/5.0 wt% SGFs composites extruded with different number of OEs. 6 POLYMER COMPOSITES-2017

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