Chemical recycling of pet bottle waste to terephthalic dihydrazide and its application as a versatile polymer additive

Abstract

The aim of the present work was to develop an efficient and newlineeconomically viable chemical recycling route based on aminolysis, for the newlinemanagement of postconsumer bottle grade PET wastes. In this perspective, newlinehydrazine monohydrate was used as the degradative agent to depolymerise newlinePET, since it is the strongest amine known till date to achieve complete newlinePET aminolysis within few hours. A novel low priced and eco-friendly newlinecatalyst (sodium carbonate) was used to decrease the PET degradation newlinetime. The aminolysed product (terephthalic dihydrazide (TDH)) was newlinecharacterized and the reaction parameters were optimized. The use of newlineTDH as a latent curing agent in diglycidyl ether of bisphenol A (DGEBA) newlinebased epoxy adhesives, as a polar nanofiller in dry acrylonitrile butadiene newlinerubber (NBR) and as a reagent in the synthesis of a macrocyclic newlinehydrazone, namely terephthalic acid bishydrazone (TAH) with newlineantioxidant properties have been investigated. The oxidation resistance newlineof TAH protected conventional natural rubber (NR) vulcanizates was newlineevaluated and compared with commercial antioxidants through thermal newlineageing studies of NR specimens conducted at 70 °C for 120 h and newline100 °C for 24 h. We have also explored the toughening effect of pristine newlinecarbon nanofibers and aminated carbon nanofibers in the prepared onecomponent TDH cured epoxy adhesive. Scope of this work involves newlinegeneration of a useful end product (TDH) from PET bottle waste and its newlinevarious applications. newline