SÍNTESE, CARACTERIZAÇÃO E AVALIAÇÃO DAS PROPRIEDADES FÍSICO-QUÍMICAS DE UM NOVO TENSOATIVO DERIVADO DA RECICLAGEM QUÍMICA DO POLI(TEREFTALATO DE ETILENO) PÓS-CONSUMO.

Abstract

This work presents results of the chemical recycling of polyethylene terephthalate (PET) post-consumer through alkaline hydrolysis and catalyzed glycolysis. The alkaline hydrolysis was carried out with a solution of NaOH (10.82 molL-1), at 90ºC, 9 hours and, subsequent acidification with concentrated H2SO4. Catalyzed glycolysis was performed using EG and Zn (Ac)2, at 190°C and 1.5 h of reaction. Both processes presented good yields (97 and 70% for TPA and BHET, respectively). Synthesis strategies for a surfactant from BHET and TPA were studied. For the BHET, three distinct methods were tested and the products were characterized by FTIR and 1H NMR. The most promising result, BHETEO, occurred through the reaction between BHET and TEO for 72 h at 100°C. For the modification of the TPA, 2 methods, also characterized by FTIR and 1H NMR were evaluated. The products obtained, TPTEOH and TPTEA, presented yield of 58% and 66%, respectively. TPTEOH was prepared in three steps, firstly, an intermediate (TPCOH) was prepared by reaction between TPA and 6-chloro-1-hexanol in basic medium, followed by preparation of TPETEO from the reaction of TPCOH and TEO. Finally, the TPTEO was subjected to cleavage reaction using NaI, TMSCl, CH2CN and H2O. The compounds structures, BHETEO, TPTEOH and TPTEA, were proposed. Some physical-chemical properties of the BHETEO, TPTEOH and TPTEA samples were evaluated, such as: boiling point, refractive index, density, pH, solubility, photosensitivity, zeta potential, hydrodynamic size and thermogravimetric analysis. The TPTEA sample presented a higher boiling point between the samples mentioned (171ºC). The refractive indices did not vary significantly, as well as the density values. The BHETEO, TPTEOH and TPTEA samples presented acid pH, being: 5.43, 3.12 and 3.66, respectively. The solubility analyzes present relevant results, allowing the suggestion of aggregation forms to the samples in polar and non-polar solvents of the lamellar and vesicle type - BHETEO were solubilized in hexane, dichloromethane, ethyl acetate and ethanol and did not solubilize in water. The TPTEOH sample was solubilized in all solvents mentioned. The TPTEA sample was solubilized in the solvents mentioned, except in hexane. The photosensitivity test showed the resistance of the samples to electromagnetic radiation (UV-vis), with no sign of degradation in the spectroscopic analyzes of UV-vis. The thermal analyzes emphasized the low thermal stability of the samples. The degradation started around 50ºC, with total degradation around 130ºC. The Zeta potential analyzes presented results around -21.7 mV for the BHTEO sample, -1.06 mV for TPTEOH and 2.30 mV for TPTEA. The size analyzes by DLS show remarkable stability of the BHETEO and TPTEA samples with increasing temperature. On the other hand, the TPTEOH sample presented a highly influenceable size at the temperature increase (10 to 60ºC), initial size 149 nm and final size 819 nm. From the results obtained by the physical-chemical analysis it is concluded that, the behavior of the BHETEO, TPTEOH and TPTEA samples is attributed to their aggregation forms in solvents of different polarities.