Prestrained twistless flax yarn as reinforcement for polymer‐matrix composites

Abstract

We report a technique to improve the mechanical performance of aligned fiber‐reinforced polymer‐matrix composites utilizing a twistless wrap‐spun yarn structure. Conventional wrap‐spinning technology introduces crimps to the yarn structure, which is a source of fiber misalignment in the final composites. Here, we report a twistless wrap‐spun yarn constructed from flax fibers and an extensible wrapping filament so that the yarn crimp can be removed during composite fabrication. This is achieved by applying a prestrain to the yarn while the resin is being cured during compression molding. The study demonstrates that this manufacturing technique can be simply and efficiently utilized to produce highly aligned and twistless natural fiber yarn‐reinforced polymeric composites with up to 25% and 45% improvements in mechanical properties.

A Self-Pumping Composite Dressing Improved Hypertrophic Scar Healing with Dual Therapy and Active-Fluid Transport

“…Standard pressure and knife-edged squeegee right-angled positioning were applied to avoid shear-pressure influence on Biopor ® AB viscosity. Referencing Gu et al's 7% pre-straining data, the warp insertion mobility design was realized at 10% pre-straining [37][38][39]. The same operator set a contamination-free printing table using paper and plastic sheets lined with water.…”

“…In a normal condition before pre-straining, the yarn extension straightened the warp insertions with a low yarn tension on the loops, constituting a "helical shape" [46,47]. Increasing the pre-straining would cause a higher density packing of loops until maturation [37][38][39]46,47]. At maturated biaxial tensioning, the biaxial tensioning exerted uniform pressure to reallocate yarn spaces for a "parallel-pile-up" loop state.…”

“…Thus, upon self-pumping, the enlarged contact areas eliminate high-pressure points and allowed dynamic pressure redistribution for shearfriction reduction. The pre-strained Biopor ® AB-coating, therefore, modified the interfaces' composition, structured for pressure redistribution and mechanical stress control, achieving scar therapeutics efficacy [29,30,37,38,[44][45][46][55][56][57]. The uniformly adhering structure also helps to avoid fluid-filled pockets where bacteria would otherwise proliferate [16].…”

“…The textile structural design typically has large specific areas of 10 2 -10 3 m 2 /kg, various porosity levels, and structurally defined fiber volume fractions for permeability and comfort [55][56][57]. By warp-knit structure application, biaxial tensioning conditioned "parallelpile-up" loops to print a "spiral-through-the-thickness" structure [35][36][37][38][39]45,46]. Each loop formed a stair step, and the connection of parallel-tightly packed loops yielded spirality.…”

Influence of Carbon Nanotubes Concentration on Mechanical and Electrical Properties of Poly(styrene-co-acrylonitrile) Composite Yarns Electrospun

“…The polymer-matrix composite (PMC) is defined as the combination of two or more materials, where their final physical and chemical properties result in better properties than their individual components [1,2]. The continuous phase corresponds to a polymeric matrix with different physical structures for example, films, yarns or fibers and bulk [3][4][5][6] and a dispersed phase composed of nanofillers, such as nanoparticles, nanofibers, nanocrystals, nanoclays, nanorods, or nanotubes [7][8][9][10][11].…”