An investigation into thermoplastic matrix 3D woven carbon fibre composites

3D woven textile reinforced composites allow the optimisation and tailoring of specific material properties into the final component. The objective of this work is to investigate the processing characteristics of Cyclic Butylene Terephthalate (CBT) (supplied by Cyclics Corporation) which polymerises to form a thermoplastic, Polybutylene Terephthalate (PBT), and to impregnate a multi-layer carbon fibre 3D woven angle interlock fabric to produce a 3D woven thermoplastic composite. Through adjustments in process cycle, the significant processing parameters have been identified which optimise the production of thermoplastic PBT composite parts. 3D multi-layer reinforcements were manufactured on a modified textile loom to produce fabrics with fibres orientated in the warp, weft and through-the-thickness directions. Thermal and mechanical tests were conducted on the thermoplastic composite and comparisons were made to an epoxy composite with the same weave architecture. It was discovered from thermal analysis and optical microscopy that a highly crystalline matrix was developed as a result of the standard fabrication process with microcracks formed throughout the matrix. Reprocessing and annealing of the 3DCFCBT laminate reduced the crystallinity of the polymer structure.