Water Uptake Behavior and Young Modulus Prediction of Composites Based on Treated Sisal Fibers and Poly(Lactic Acid)

The main aim of this work was to study the effect of sisal fiber surface treatments on water uptake behavior of composites based on untreated and treated fibers. For this purpose, sisal fibers were treated with different chemical treatments. All surface treatments delayed the water absorption of fibers only for a short time of period. No significant differences were observed in water uptake profiles of composites based on fibers with different surface treatments. After water uptake period, tensile strength and Young modulus values of sisal fiber/poly(lactic acid) (PLA) composites were decreased. On the other hand, composites based on NaOH + silane treated fibers showed the lowest diffusion coefficient values, suggesting that this treatment seemed to be the most effective treatment to reduce water diffusion rate into the composites. Finally, Young modulus values of composites, before water uptake period, were predicted using different micromechanical models and were compared with experimental data.The authors are grateful for the financial support from the Basque Country Government in the frame of Consolidated Groups (IT-776-13) and Elkartek 2015 FORPLA3D project. Technical and human support provided by SGIker (Universidad del Pais Vasco-Euskal Herriko Unibertsitatea (UPV/EHU), Ministerio de Economia y Competitividad (MINECO), Gobierno Vasco-Eusko Jaurlaritza (GV/EJ), European Regional Development Fund (ERDF) and European Science Foundation (ESF)) is also gratefully acknowledged