Mechanical and thermo-mechanical peculiarity of functionally graded materials-based glass fiber-filled polybutylene terephthalate composites

This article proposes to develop novel functionally graded materials-based thermoplastic composites and present investigations on their mechanical and thermal properties. An especially designed mold and punch are used to fabricate functionally graded materials and homogeneous composites. Punch is a rotating member of the mold with a cavity at the center along the axis where the material is filled to produce desired samples. The punch rotates for 2 min at 1800 r/min for the gradation of fibers in functionally graded materials towards the outermost zone of the punch cavity. The punch is placed stationary for the fabrication of homogeneous composites. Functionally graded materials and homogeneous composites are fabricated with 15 wt.% and 30 wt.% glass fibers-reinforced polybutylene terephthalate. Neat polybutylene terephthalate is also fabricated for comparative study. The gradient of fiber distribution in functionally graded materials is verified by ignition loss test, hardness measurement, and scanning electron microscope analysis. Mechanical, fracture toughness, and thermo-mechanical peculiarity of functionally graded materials are investigated and compared with neat polybutylene terephthalate and homogeneous composites. Functionally graded materials outperform neat polybutylene terephthalate and homogeneous composites. This manufacturing technique shows a promising potential for fabrication of thermoplastics-based functionally graded materials which otherwise is difficult to produce because of their inherence characteristic to solidify at fast rate.