Mechanical enhancement, morphology, and crystallization kinetics of polyoxymethylene-based composites with recycled carbon fiber

Recycled carbon fiber (RCF) was employed as a reinforcing material to prepare polyoxymethylene (POM)-based composites through a simple melting extrusion. An effective approach was developed to clean and modify the surface of the as-received RCF with nitric acid and then with a silane coupling agent. The mechanical evaluation demonstrated that a significant reinforcement was achieved for POM/RCF composites due to the improved interfacial adhesion between the fibers and the matrix. The thermal stabilities of the composites were also improved in the presence of RCF. The morphological observation of impact fracture surfaces indicated that the RCF gained a homogeneous dispersion in POM matrix due to good interfacial boding between fibers and matrix. The studies on nonisothermal and isothermal crystallization behaviors showed that RCF acted as a nucleation agent for the crystallization of POM domain in composites; therefore, the crystallization rate and nucleation density increased remarkably due to the heterogeneous nucleating effect of RCF. These crystallization features may be advantageous for the enhancement of mechanical performance and processability of POM-based composites.