Properties of Recycled and Virgin Poly(ethylene terephthalate) Blend Fibers

Material from recycled poly(ethylene terephthalate) (PET) chips obtained from used water bottles was extruded with virgin fiber-grade PET chips in blends of 20, 40, and 70 wt %. Filament fibers from the recycled/virgin PET blends were spun using a melt spinning process and drawn by a thermal drawing process to improve their mechanical properties. As the virgin PET chips were compounded with recycled PET chips, the thermal degradation temperature (T-d) and the melting temperature (T-m) were increased, and the crystallization temperature (T-c) and crystallization rate were decreased. This means that virgin PET has a better thermal stability but a lower crystallization rate than recycled PET. The double melting behavior observed in the case of the drawn fibers may have been a consequence of larger crystallites or areas of crystallites being formed during the thermal drawing process. The birefringence and mechanical properties, such as tensile strength and tensile modulus, increased and elongation at break decreased for the drawn fibers, and this was attributed to the orientation induced during crystallization. The effect of the virgin PET content in the blends on mechanical properties was investigated; 30/70 wt % recycled/virgin blended fibers showed comparable mechanical properties to virgin PET fibers. (C) 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 128: 1250-1256, 2013