FABRICATION AND EVALUATION OF MULTISCALE THERMOPLASTIC COMPOSITES BASED ON IN-SITU POLYMERIZATION OF CYCLIC BUTYLENE TEREPHTHALATE

摘要

Mechanically flexible electrospun carbon and glass nanofibrous mats (ECNF-mats and EGNF-mats) were prepared by electrospinning followed by pyrolysis. A method was developed to fabricate two types of multiscale thermoplastic composites involving infiltration of molten cyclic butylene terephthalate (CBT) followed by in-situ polymerization under compression. For the first composite type, eight conventional carbon fabrics were interleaved with seven ECNF-mats followed by in-situ polymerization of the CBT. For the second composite type, eight conventional glass fabrics were interleaved with seven EGNF-mats followed by in-situ polymerization of the CBT. The study revealed that the incorporation of ECNF-mats or EGNF-mats into polybutylene terephthalate based composites led to significant improvements in mechanical properties. Specifically, compared to the corresponding control sample, the interlaminar shear strength, flexural strength, flexural modulus, and Work of Fracture (WOF) of the composite reinforced by ECNF-mats increased by 32%, 25%, 19%, and 33%, respectively; and the interlaminar shear strength, flexural strength, flexural modulus, and WOF of the composite reinforced by EGNF-mats increased by 66%, 43%, 17%, and 64%, respectively. Furthermore, these enhancements of out-of-plane properties were not at the expense of in-plane tensile strength or modulus.