Commingled poly(butylene terephthalate)/unidirectional glass fiber composites: Influence of the process conditions on the microstructure of poly(butylene terephthalate)

The microstrocture of poly(butylene terephthalate) (PBT) has been investigated at the different stages of the manufacture of a new generation of composite materials, i.e., commingled Twintex® PBT/glass fiber composites. From differential scanning calorimetry and wide angle X‐ray scattering analysis in addition to density measurements and optical microscopy observations, it was concluded that the different stages of the composite manufacture induce some changes in the crystalline forms of PBT. In particular, the drawing of PBT can promote the formation of the β phase. The analysis of the crystallization kinetics points out the nucleation role played by the fibers. It is concluded that the growth of a transcrystalline region in the vicinity of fibers is promoted by the elevated pressure and temperature used in the manufacturing process of the composites.