Flax fiber-reinforced polylactic acid (PLA) biocomposites were made using a new technique incorporating an air-laying nonwoven process. Flax and PLA fibers were blended and converted to fiber webs in the airlaying process. Composite prepregs were then made from the fiber webs. The prepregs were finally converted to composites by compression molding. The relationship between the main process variables and the properties of the biocomposite was investigated. It was found that with increasing flax content, the mechanical properties increased. The maximum tensile strength of 80.3 MPa, flexural strength of 138.5 MPa, tensile modulus of 9.9 GPa and flexural modulus of 7.9 GPa were achieved. As the molding temperature and molding time increased, the mechanical properties decreased. The thermal and morphological properties of the biocomposites were also studied. The appropriate processing parameters for the biocomposites were established for different fiber contents. POLYM.

This work reports the effect of an alkaline environment and ultraviolet (UV) radiation on the physical, thermal, and tensile properties of different fibers selected as potential reinforcing elements to enhance the impact properties of brittle glass/silicate composites. The fibers, which included regenerated cellulosic (viscose and rayon), synthetic (ultrahigh molecular weight polyethylene, polypropylene, polyamide, acrylic), glass, ceramic, and steel, were aged in different alkaline solutions with pH ranging from 11.1 to 13.6 at 70°C for different periods of time and exposed to UV radiation for 330 h. The physical and thermal properties of aged fibers were studied using tensile testing, scanning electron microscopy, and simultaneous differential and thermogravimetric analysis. Results showed that the regenerated cellulosic fibers, acrylic, E‐glass, and A‐glass fibers could not withstand the highly alkaline environment. Overall, ultrahigh molecular weight polyethylene, UV‐stable polypropylene, polyamide 6.6, AR‐glass, ceramic (alumino borosilicate), and steel fibers performed very well under all conditions, indicating that they have the potential to be used as reinforcing elements in glass/silicate composites. Copyright © 2011 John Wiley & Sons, Ltd.

Biocomposites of flax reinforced polylactic acid (PLA) were made using a new technique incorporating an air-laying nonwoven process. PLA and flax fibers were mixed and converted to the webs in the air-laying process. Prepregs were then made from the fiber webs by thermal consolidation. The prepregs were finally converted to composites by compression molding. This study was investigated the biodegradability and water absorption properties of the composites. The composites were incubated in compost under controlled conditions. The percentage weight loss and the reduction in mechanical properties of PLA and biocomposites were determined at different time intervals. It was found that with increasing flax content, the mechanical properties of the biocomposites decreased more during the burial trial. The increasing of flax content led to the acceleration of weight loss due to preferential degradation of flax. This was further confirmed by the surface morphology of the biodegraded composites from scanning electron microscope image analysis. Morphological observations indicated severe disruption of biocomposites structure between 60 and 120 days of incubation.

No abstract

Semi-consolidated thermoplastic tapes were produced by spreading flax and polypropylene matrix fibres using a newly developed technology. This lightweight tape was structurally stable and contained 38% flax fibres by volume. The tapes were processed in unidirectional and woven fabric format for composite fabrication. We found that the flax/PP tape-based composites had 60-110% higher flexural modulus and 35-65% higher tensile modulus compared to flax/PP yarn based thermoplastics. Thermoanalytical results showed that the heating conditions used in the tape-making process did not degrade the flax fibres and PP matrix. We conclude that such semi-consolidated flax/PP tapes enable the achievement of properties not seen before for yarn-based composites, and therefore are an important step forward in optimising the reinforcing effect of natural fibres in composite applications.