Preparation and properties of bottle-recycled polyethylene terephthalate (PET) filaments

Bottle-recycled polyethylene terephthalate (R-PET) fibers were fabricated by the melt spinning method. Based on characteristics of R-PET chips, this study involved a primary exploration of the spinning parameters, including spinning temperature, spinning speed and spinneret plate. The properties of R-PET and original PET (O-PET) fibers were compared using scanning electron microscopy (SEM), tensile testing, sonic orientation, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and Fourier transform infrared spectroscopy (FTIR). Apparent morphological observation displays an irregular cross-sectional shape and a scattered diameter distribution for R-PET fibers. Compared with O-PET fibers, R-PET fibers demonstrate a greater breaking strength and smaller elongation at break, resulting from the lower crystallinity and higher degree of orientation. Furthermore, the R-PET fibers have the same chemical structure as that of O-PET fibers demonstrated by FTIR spectroscopy, but TGA results show that thermal stability of R-PET fibers is significantly inferior to that of O-PET fibers, as a result of too many impurities and oligomers during the recycling process.