Lignin Modified by Formic Acid on the PA6 Films: Evaluation on the Morphology and Degradation by UV Radiation.

Kraft lignin coming from a paper industry was purified and the modified fraction by formic acid (FKL) was isolated to be used as an inhibitor of UV-photodegradation in polyamide 6 (PA6) films. Samples containing up to 1.00% of FKL in mass were prepared by casting using formic acid as solvent. The effects of UV light irradiation on these films (Hg lamp, 96 h) were studied by SEM, FTIR and XRD. It was observed that the variation of the carbonyl group content, crystallinity and morphology of the PA6 films were reduced by the FKL incorporation. Samples that were less susceptible to UV light were those that contained between 0.50 and 1.00% of LKF. This phenomenon is observed in both, difratometric and spectroscopic analyses, since it showed lower variation in results with relation to the same non-irradiated films. [ABSTRACT FROM AUTHOR]