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Nanocomposites based on recycled poly(ethylene terepthalate)

Tolga, Aslı
In this study, the effects of glycol type, organoclay type and concentration on the final properties of nanocomposites based on recycled poly(ethylene terephthalate) was investigated. For this purpose, first recycled PET was glycolysed and after that unsaturated polyester-montmorillonite nanocomposites were synthesized by using three different types of glycols (i.e. ethylene glycol (EG), propylene glycol (PG) and diethylene glycol (DEG)). As the first step, all the compositions were prepared by Cloisite 30B type of clay, and then for comparison of clay type, nanocomposites containing 1 wt. % of Cloisite 15A and Cloisite 25A type of clay were also synthesized. Morphological and mechanical analyses were performed for the characterization of the nanocomposites. According to the results of XRD analysis, for all glycol types maximum intercalation was observed in Cloisite 30B containing samples. Exfoliated structures were obtained in the samples containing EG at 1 wt. % Cloisite 30B content and DEG at 3 wt. % Cloisite 30B content. Mechanical tests showed that, for all properties, glycol type is the most effective experimental parameter. DEG based samples are the most flexible whereas PG based samples are the least flexible. EG and DEG based samples give maximum tensile strength and tensile modulus values at 1 wt. % clay loading. Samples prepared by DEG exhibited maxima in both flexural strength and modulus at 1 wt. % clay content. With respect to the organoclay type, Cloisite 30B containing samples gave the highest compatibility with the unsaturated polyester matrix as indicated by the tensile test results. Organoclay type and content had no positive effect on the impact strength. Clay particles acted as stress concentrators and lowered the impact strength.