Fully biodegradable polylactic composites reinforced with bleached softwood fibers

Abstract

The increasing environmental awareness of the society has led to the development of materials with a lower environmental impact. Polylactic acid (PLA) is a biodegradable polymer with higher mechanical properties than PP. The scientific literature shows some interest in PLA reinforced biocomposites, but the published mechanical properties of such materials are comparatively low. In fact, the generation of a good interface, when the reinforcement contents are higher than 30%, is nowadays unsolved. The main objective of this study is to obtain PLA biocomposites with a good interface and with satisfactory improvements in their mechanical properties against reinforcement contents. Bleached pine fibers, used as reinforcement, were prepared and shred with 1/3 and 2/3 of diglyme, in order to avoid the formation of hydrogen bonds among the cellulose fibers. Then, composite materials were obtained through kinetic mixing. The composites were injection molded to make standard specimens and were submitted to tensile tests. The results showed that the addition of diglyme favored the formation of hydrogen bonds between the reinforcement and the PLA. Only the fibers treated with 2/3 diglyme followed a linear positive progression of its tensile strength when increasing reinforcement contents were added. Although suitable results were obtained, it seems that these composites