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Three-dimensional (3D) shell-structured PLA/Flax biocomposites were fabricated using a novel method incorporating the 3D nonwoven web-forming process. PLA and flax fibers were blended in the fiber opening stage and converted to webs on the 3D mold using the air-laying principle. The 3D webs were then consolidated by through-air thermal bonding. The compression molding technique was used finally to convert the 3D webs to the biocomposites. The relationship between the main process parameters and the properties of the biocomposites was investigated. The results show that with increasing flax fiber content, the crush failure load, total energy absorption, specific energy absorption, and crush efficiency increased. The crushing properties decreased with increased molding temperature, but the crushing properties are not significantly affected by the molding time. The physical properties of 3D biocomposites were also evaluated and the appropriate processing parameters for 3D biocomposites were established. POLYM. COMPOS., 35:1244–1252, 2014. © 2013 Society of Plastics Engineers

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 air-laying 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.

Delamination is the most common failure mode in laminated compositesdue to the reduced strength in the through-the-thickness direction. Air-jettexturing was used to produce bulk and loops in the yarn which providesmore surface contact between the fibres and the resin. The development ofcore-and-effect textured glass yarns and the effect of texturing parameterswere presented in the previous paper. This paper describes the effect oftexturing on the mechanical properties including tensile properties, flexureproperties, inter-laminar shear strength (ILSS) and fracture toughness(Mode I) of glass laminated composites. The composites of plain and twillweave fabrics were developed from both the textured and non-texturedyarns. It was observed that the tensile properties decreased and theflexure properties remained unchanged after texturing. However,significant improvement was observed in inter-laminar shear strength andthe Mode I fracture toughness of the composites after texturing. Thebulkier, loopy structure of the textured yarn provided more surface contactbetween the fibre and the resin and significantly improved the bondingstrength