A hot melt adhesive from polyester waste

Hot melt adhesives were prepared from polyester waste in three steps: Step I: Polyester waste was degraded to a monomer stage, i.e. bis-(2-hydroxyethyl)terephthalate (BHET) (1) by means of different metal acetates in the presence of ethylene glycol. The reaction in the presence of zinc acetate gave the highest yield of BHET (95%). Step II: Esterification of (I) with isophthalic acid in situ led to the formation of an esterified product (II). Step III: Further esterification of (II) with sebacic acid in situ, followed by polycondensation in the presence of antimony oxide and triphenylphosphate, led to the formation of the hot melt adhesive (III) based on BHET via the intermediate esterified product (IV). The hot melt adhesive, possessing a highest adhesive strength of 620 (psi) was obtained in a total reaction period of five hours. The present paper also details the effect of isophthalic acid and sebacic acid on the adhesive strength of (III).