Surface structure and properties of poly-(ethylene terephthalate) hydrolyzed by alkali and cutinase

Abstract

a b s t r a c tThis study was aimed at comparatively investigating the hydrolysis of crystalline and amorphous poly-(ethylene terephthalate) films by alkali and cutinase. Changes of surface properties were investigated by FTIR spectroscopy (ATR mode). The A 1341 /A 1410 and I 1120 /I 1100 absorbance ratios, and the full width at half maximum of the carbonyl stretching band (FWHM 1715 ) were used to evaluate the polymer crystallinity and its changes upon hydrolysis. The effect of different treatments on chain orientation was evaluated by calculating R ratios of appropriate bands. The spectroscopic indexes showed that both alkali and enzyme treatments induced structural and conformational rearrangements with a consequent increase in crystallinity in both amorphous and crystalline films. The crystalline PET film was modified more strongly by alkali than by cutinase, while the opposite occurred for the amorphous one. The trend of the water contact angle (WCA) clearly indicates that alkali is more effective than cutinase in enhancing hydrophilicity of PET films and that the effect is stronger on amorphous than on crystalline films. The values of WCA correlate well with the FTIR indexes calculated from the spectra of hydrolyzed crystalline PET films. The mechanism of the surface hydrolysis of PET by alkali and cutinase is discussed.

Recycling of poly(ethylene terephthalate) – A review focusing on chemical methods

“…Generally, PET was incubated in the enzymatic solution at temperatures between 30 to 60°C for a period of time ranging from 3 to 14 days. Residual PET and solution were separated for product characterization [130][131][132][133]. As shown in Table 1, different enzymes such as saccharomonospora viridis cutinase polyesterase, thermobifidia fusca hydrolase, cutinase and lipase were applied for PET degradation.…”

“…Mueller discussed the general applicability of thermobifidia fusca hydrolase for PET de-polymerization without mentioning a main degradation product or its yield [131]. Donelli et al [132] only studied the surface morphology of PET treated with cutinase and did not make a qualitative or quantitative statement of possible reaction products. In contrast, Zhang et al [133] studied the application of lipase as degrading agent for diethylene glycol terephthalate (DGTP) and PET at 30°C and 14 days.…”

Expression and characterization of a cutinase (AnCUT2) from Aspergillus niger

“…Enzymatic degradation of PCL and PET pellets (SigmaAldrich, St. Louis, MO, USA) was performed according to Sulaiman et al [7] and Donelli et al [24] with slight modifications. Both PCL and PET pellets were incubated with 1% (w/v) SDS for 30 min at 50°C and then washed with distilled water.…”

Falha por stress cracking em híbridos PET/argila

“…Mesmo na ausência de fluidos agressivos, há relatos de que cargas argilosas aceleram a degradação da matriz de PET [31][32][33] . Essa ação degradativa é atribuída aos grupos hidroxila presentes nas plaquetas de argila, os quais seriam responsáveis por provocar cisão hidrolítica de ligações éster nas moléculas de PET [33] .…”

“…Essa ação degradativa é atribuída aos grupos hidroxila presentes nas plaquetas de argila, os quais seriam responsáveis por provocar cisão hidrolítica de ligações éster nas moléculas de PET [33] . De acordo com Bär [34] , os sítios catalizadores de degradação presentes na argila podem ser decorrentes tanto dos grupos hidroxila, os quais são fortemente ácidos no vértice da camada do silicato, como de íons de metais de transição que não foram trocados no interior das galerias ou de defeitos cristalográficos entre as camadas.…”