Use of Wet-Laid Techniques to Form Flax-Polypropylene Nonwoverts as Base Substrates for Eco-Friendly Composites by Using Hot-Press Molding

摘要

The wet-laid process with flax (base) and polypropylene (binder) fibers has been used to obtain nonwovens for further processing by hot-press molding. Mechanical characterization of nonwovens has revealed that slight anisotropy is obtained with the wet-laid process as better tensile strength is obtained in the preferential deposition direction. The thermo-bonding process provides good cohesion to nonwovens, which is critical for further handling/shaping by hot-press molding. Flax:PP composites have been processed by stacking eight individual flax:PP nonwoven sheets and applying moderate temperature and pressure. As the amount of binder fiber is relatively low (<30 wt%) if compared with similar systems processed by extrusion and injection molding, it is possible to obtain eco-friendly composites as the total content on natural fiber (flax) is higher than 70 wt%. Mechanical characterization of hot-pressed flax:PP composites has revealed high dependency of tensile and flexural strength on the total amount of binder fiber as this component is responsible for flax fiber embedment which is a critical parameter to ensure good fiber-matrix interaction. Combination of wet-laid techniques with hot-press molding processes is interesting from both technical and environmental points of view as high natural fiber content composites with balanced properties can be obtained.