Development of Recyclable and High-Performance In Situ Hybrid TLCP/Glass Fiber Composites

Tianran Chen,Lin Ju,Donald G Baird,Dana Kazerooni,David A Okonski

doi:10.3390/jcs4030125

Abstract

By combining the concepts of in situ thermotropic liquid crystalline polymer (TLCP) composites and conventional fiber composites, a recyclable and high-performance in situ hybrid polypropylene-based composite was successfully developed. The recycled hybrid composite was prepared by injection molding and grinding processes. Rheological and thermal analyses were utilized to optimize the processing temperature of the injection molding process to reduce the melt viscosity and minimize the degradation of polypropylene. The ideal temperature for blending the hybrid composite was found to be 305 °C. The influence of mechanical recycling on the different combinations of TLCP and glass fiber composites was analyzed. When the weight fraction ratio of TLCP to glass fiber was 2 to 1, the hybrid composite exhibited better processability, improved tensile performance, lower mechanical anisotropy, and greater recyclability compared to the polypropylene reinforced by either glass fiber or TLCP alone.

Highlights

The early constructions of vehicles like automobiles, locomotives, and aircraft were designed using dense metals with high strength capabilities
To generate the in situ thermotropic liquid crystalline polymer (TLCP)/glass fiber/polypropylene composites, the processing temperature has to be optimized using a series of rheological analyses
The rheological properties of TLCP above its melting point are critical in the processing of this material

Summary

Introduction

The early constructions of vehicles like automobiles, locomotives, and aircraft were designed using dense metals with high strength capabilities. Recent advancements in material science have enabled fiber-reinforced composites to replace traditional metals because of higher strength-to-weight ratios [1,2,3]. The advantages that fiber reinforced composite materials have over traditional metal materials include: (1) light weight, (2) high stiffness and strength, (3) corrosion resistance, and (4) design flexibility. These attributes have been embraced by the automotive industry, which has increased its use of fiber-reinforced composite materials to improve fuel efficiency and reduce greenhouse gas emissions. Glass fiber is especially attractive as a reinforcement for composites because of its low cost, superior mechanical and physical properties (e.g., stiffness and strength, impact resistance, stability, and durability). This outperforms aluminum with a tensile modulus of 68.9 GPa and tensile strength of 310 MPa [6,7]

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