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

#### **Tianran Chen 1,\*, Dana Kazerooni 1, Lin Ju 1, David A. Okonski 2 and Donald G. Baird 1,3**


Received: 26 July 2020; Accepted: 19 August 2020; Published: 24 August 2020

**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 di fferent 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.

**Keywords:** recycling; hybrid composites; polymer-matrix composites (PMCs); thermotropic liquid crystalline polymer; glass fibers
