Thermal decomposition behaviors and degradation kinetics of biobased polyesters with partial crosslinking to eliminate cyclic compounds

Abstract

A series of poly(butylene adipate-co-butylene itaconate) (PBAPI) copolyesters with and without a small amount of ethylenediaminetetraacetic acid (EDTA) were synthesized via melt polymerization. Thermogravimetric analysis -gas chromatography/mass spectroscopy (TGA-GC/MS) techniques were used to identify the thermal degradation behaviors. By introducing 0.1 mol % EDTA into BA/BI = 10/0, the dominant degradation product was converted from furan and cyclopentanone derivatives to CO2 and formation of cyclic compounds was notably inhibited. Moreover, similar tendencies were observed when the BI content increased, demonstrating that the existence ratio of CO2 and furan derivatives increased while the concentrations of cyclopentanone and cyclic compounds reduced during decomposition. Finally, no cyclic compound product was detected in the BA/BI = 7/3 copolyester. These results indicate that the introduction of both EDTA and BI inhibits generation of cyclic compounds, which are attributed to the formation of partial crosslinking for chemical structures. The nonisothermal degradation kinetic was also carried out to investigate the decomposition behaviors. The activation energy requirements at each degradation stage varied with the composition of BA/BI ratios and the introduction of EDTA, demonstrating further evidence of degradation behavior transformation.