Preparation and characterization of carbon fiber/polylactic acid/thermoplastic polyurethane (CF/PLA/TPU) composites prepared by a vane mixer

Various quantities of carbon fibers (CFs) (from 5% to 20% in weight) were added to matrix by melt blending to produce polylactic acid (PLA)/thermoplastic polyurethane (TPU)/CF composites. Differential scanning calorimetry measurements revealed that the CF content and mixing time had little influence on the crystallization and melting behavior of PLA. Thermogravimetric analysis showed that the introduction of CFs tended to decrease the thermal stability of PLA/TPU/CF composites, and the increase of mixing time tended to increase the thermal stability of PLA/TPU/CF composites when the mixing time is <5 min. Rheological results showed that all the samples exhibited non-Newtonian and shear thinning characteristics. The storage modulus and complex viscosity both increased with the increase of the CF content. It also showed that the increase of mixing time tended to increase the storage modulus and complex viscosity of PLA/TPU/CF composites when the mixing time is <5 min. Scanning electron microscopy images showed that the TPU/PLA blends contain a continuous PLA phase with evenly distributed TPU particles in the size range of 0.25-3 mu m, and the blends are immiscible at the micron scale. Mechanical properties showed that the addition of proper CF content could lead to an obvious increase (about 11.43%) in tensile strength.