Polyethylene Terephthalate (PET) is an industrially important polymer due to its chemical resistance, clarity and thermal stability. These properties have lead PETs to be used in various industries, especially in packaging. Because of PET’s resistance to degradation, recycling have been in practice. Currently, mechanical recycling of PET is the most common approach. According to earlier studies, the Recycled PET(R-PET) has a lower Intrinsic Viscosity (IV) and Molecular Weight (MW) than Virgin PET (V-PET). These changes appear to result from the degradation of PET during the recycling process. With increasing demand for high performance PET in packaging industry for sensitive items such as foods and beverages, several oxygen barrier additives have been introduced to PET. Nylon-MXD6 is one of such additive which is commercially available however the effects of it on the recycling process and R-PET properties are not well established. The purpose of this study was to determine the impact of MXD6 on PET during multiple mechanical recycling process and the recycled product. A series of PET and PET/MXD6 blend were processed to simulate multiple recycling process at the laboratory scale. Specifically pure PET, pure MXD6 and PET/MXD6 (95/5) blend samples were prepared and recycled up to 3 times. Physical and structural properties of the R-PET and R-MXD6 and R-PET/MXD6 were characterized using different methods such as DSC, FTIR, TGA, XRD, Solution IV and NMR analyzes. The results show that adding MXD6 results in lower IV and MW of the R-Blend comparing to the R-PET. Moreover the crystallization kinetic study show that MXD6 slightly increases the crystallization kinetics of the blend and crystallization kinetic increases by the number of recycling step. Moreover the yellow color generation in the blend is more severe in higher recycling steps. In the second part of the project, a novel method to reduce the color generation in the PET/MXD6 blend during recycling process has been developed and applied. The preliminary studies indicate that there was a reduction in color generation during the mechanical recycling processes.

Impact of MXD6 on multiple mechanical recycling of PET and the recycled product properties

254th National Meeting (2017)

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