On the thermal degradation of telechelic poly (lactic acid) and FLAX fiber biocomposites

Renewable resources based polymers have been the focus of materials science scientists since they help to protect the environment in addition to reducing the petroleum resources use. Among renewable polymers poly (lactic acid) (PLA) has emerged due to its biodegradable character and proper performance similar to engineering resins, which afford wide field of applications. In this work the thermal degradation of esterified PLA with itaconic acid (PLA ITA) and the biocomposite PLA ITA FLAX was investigated using thermogavimetry (TG) which data were corroborated through Fourier transform infrared spectroscopy (FTIR). Isothermal TGs scans and FTIRs spectra were acquired from 150 to 600°C, collected data evidenced that FLAX improved PLA ITA thermal stability, delaying the decomposition of PLA ITA by up to 100 min at 250°C, ensuring safer processability at higher temperatures. From the deconvolution of the DTG peaks, the peak at lower temperature is suggested to be linked to itaconic anhydride decomposition which undergoes macromolecule dissociation, converting into itaconic anhydride and releasing water and afterwards being converted into citraconic anhydride, while the peak at higher temperature is associated to the thermal degradation of telechelic PLA. Degradation mechanism is proposed, evidenced by changes in the wavelength of CO group under the effect of temperature, as evidenced in TG-IR spectra.