Morphology of PET Cords at Different Stages of Simulated Tire Building

Abstract

The effect of simulated tire-building steps on morphological characteristics of polyethylene terephthalate (PET) cords and their final dimensional stability is reported. Twisted single-ply cords were sequentially processed for mimicking dip coating (without real latex treatment), thermal curing (without embedding them in rubber matrix), and creep deformation. The degree of crystallinity and crystalline orientation factor ( fc) of the samples remained essentially unchanged in the course of the simulated manufacturing steps. As measured by birefringence, overall orientation of the cords increased in the coating step but decreased during simulated curing. Overall orientation again increased after creep testing. As measured by wide-angle X-ray diffraction, the cords having higher oriented amorphous (mesophase) content displayed the least variation in overall orientation during processing steps and the best dimensional stability.