Effect of fibre orientation on the mechanical properties of polypropylene–lyocell composites

Abstract

Natural fibre reinforced plant structures are widely used in nature. These plant structures combine light weight with superior mechanical properties. The fibre orientations in plants are optimized to the occurring forces, especially to the bending of plants by wind forces. Therefore it is important to study the effect of fibre orientation to the mechanical properties of materials in a systematic experimental approach. In this study the effect of reinforcement fibre orientation on mechanical properties of biobased lyocell-reinforced polypropylene composite was analysed. For this purpose, special technique to produce composites with defined fibre orientation and fibre wetting was developed consisting of the production of intermingled hybrid yarn followed by defined yarn laying and thermoforming processes. The formed composites were subjected to tensile strength tests and dynamic mechanical analyses. The experimentally determined E-modulus was compared with values, calculated from the modified rule of mixture of Virk and Krenchel. The analysis showed that the experimental E-moduli were somewhat smaller than the theoretical values, which is indicative of a less than perfect interfacial bonding between the fibres and matrix. The influence of water on the composite performance was also analysed. It was shown that the composites sorb approximately 30% water by weight, and it has a strong influence on the E-modulus and other performance parameters.

Biocomposites of Bio-Polyethylene Reinforced with a Hydrothermal-Alkaline Sugarcane Bagasse Pulp and Coupled with a Bio-Based Compatibilizer

“…However, some samples presented several fibers distributed at different angles. Fiber orientation is important because it influences the final mechanical strength of filaments [32]. In addition to fiber orientation, the length of fibers is also affected by the manufacturing processes.…”

Fused Filament Fabricated Polypropylene Composite Reinforced by Aligned Glass Fibers

“…Much higher strain at break values for the (45, 135) raster could be attributed to the previously-discussed orientation of the short glass fibers’ in-plane and out-of-plane directions, according to Cordin et al [ 26 ] and the so-called modified rule of mixture (this rule suggests a strong orientation dependence of composite stiffness). Particularly, the more the angle of the fibers deviates from 0° and approaches a ± 45° angle, the softer the composite becomes, making the materials easier to deform and thus increasing the strain-at-break value.…”

Fiber orientation effect on fracture toughness of silk fiber-reinforced zeolite/HDPE composites

“…In the last decade, many studies have reported success in producing thermoplastic matrix composites that are natural fiber reinforced with the orientation of the fibers which are varied in the composites. In previous studies [1,2], mechanical properties of PP/cellulose fiber composites with randomly oriented fibers have been reported. In an extrusion process in the production of PP/CLY composites, it was reported that the distribution of cellulose fibers in the PP matrix could not be controlled, likewise in an injection molding process [3][4][5][6][7].…”