Adesivos poliuretanicos derivados de PET reciclado : sintese, caracterização e aplicação




In Brazil, the production and recycling index of poly(ethylene terephthalate) -PET have been increased. Therefore it is necessary to increase the possibilities for utilizing this polymer waste. This work aims the chemical recycling as a way to obtain value added products from PET waste. Postconsumer PET bottles were first depolymerized by glycolysis with diethylene glycol or a mixture of diethylene glycol /propylene glycol and zinc acetate as catalyst. The glycolyzed products were reacted with different amounts of adipic acid to yield polyester polyols with different molar mass, and the polyester polyols were them reacted with toluene diisocyanate in the presence of a solvent (ethyl acetate) to obtain polyurethane adhesives. These adhesives were prepared to be used in flexible packaging and were compared with a commercial adhesive. The glicolyzed products and the polyester polyols were characterized by acid value, hydroxyl value and differential scanning calorimetry (DSC). The polyols polyester presented number average molecular weights between 895 to 1725 g/mol. The urethane prepolymers were characterized by isocyanate content (%NCO) and viscosity. After curing by the air moisture, the polyurethane adhesives were characterized by DSC, termogravimetry (TGA) and peel resistance. The adhesive samples presented different viscosity and glass transition temperature depending on the polyol polyester used to prepare them. The adhesives were applied to PET/polyethylene films and presented good adhesion to these substrates.


poliois poliesteres reciclagem quimica pet adesivos poliuretanicos

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