Poly(lactic acid) (PLA), the polymer object of this study, degrades by a biotic process after an abiotic hydrolysis process. Its degradation was evaluated after 600 days of exposure in a simulated marine environment (SME), as buriti fiber-reinforced composites having triacetin as coupling agent. Composites were obtained by extrusion and films were produced by compression molding. After between 60 and 600 days of exposure, PLA had a weight loss of 2.5%, PLA/T of 1.5%, and 10-12% of weight loss for PLA/B and PLA/B/T, respectively. PLA intercalates reduction, increase, and decrease of its crystallinity attributed to hydrolysis (up to 15 days), impairment of amorphous segments (45 days), and loss of integrity of the matrix (100-600 days), respectively. In the PLA/T composites, triacetin inhibited the diatom colonization process, having its crystallinity values increased after nearly 100 days of exposure with subsequent reduction. For samples with buriti fiber, changes in crystallinity were attributed to absorption of water and exposure of matrix amorphous segments. PLA degradation in a SME is evidently favored by the use of natural fibers since they make easier water access to the matrix and colonization by the protists group, diatoms, showing that the polymer can have reduced postuse shelf life as composites, with benefits while in use and at the same time post-use environmental benefits. Triacetin inhibits PLA colonization and degradation up to 45 days after exposure, after which it no longer influences the degradation process. V C 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43290.
The use of biodegradable polymers has aroused academic and technological interest directed to the replacement of conventional polymers aiming at reducing the environmental impact caused by these materials. Vegetable fibres as reinforcement elements provide gains in mechanical, thermal and degradation properties to polymer composites. The buriti fibre (Mauritia flexuosa) is an abundant crop of easy cultivation in tropical countries and its use in composites with poly(lactic acid) (PLA), can provide the development of a material with specific features, combining good mechanical properties and excellent degradation potential to the obtained composites. In this research, PLA and buriti fibre composites were developed with the use of triacetin as coupling agent. For a 30% content by mass of fibre, the results showed that the mechanical properties of the composites were similar to those of neat PLA. This was attributed to the fibre/matrix interaction observed by the SEM analysis and to an increase in crystallinity assessed by thermal properties.
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