The fiber‐matrix interface in Ioncell cellulose fiber composites and its implications for the mechanical performance

Abstract

Fiber‐reinforced composites based on natural fibers are promising alternatives for materials made of metal or synthetic polymers. However, the inherent inhomogeneity of natural fibers limits the quality of the respective composites. Man‐made cellulose fibers (MMCFs) prepared from cellulose solutions via wet or dry‐jet wet spinning processes can overcome these limitations. Herein, MMCFs are used to prepare single fiber epoxy composites and UD composites with 20, 30, 40, and 60 wt% fiber loads. The mechanical properties increase gradually with fiber loading. Young's modulus is improved three times while tensile strength doubles at a loading of 60 wt%. Raman spectroscopy is employed to follow conformational changes of the cellulose chains within the fibers upon mechanical deformation of the composites. The shift of the characteristic Raman band under strain indicates the deformation mechanisms in the fiber. Provided stress transfer occurs through the interface, it is a direct measure of the fiber‐matrix interaction, which is investigated herein. The shift rate of the 1095 cm−1 band decreases in single fiber composites compared to the neat fibers and continues to decrease as the fiber loading increased.

Effect of single-fiber properties and fiber volume fraction on the mechanical properties of Ioncell fiber composites

“…It was observed that as DR increased, fiber diameter decreased, accompanied by respective increases of nearly 25% and 20% in tensile modulus and strength, respectively. These findings are in accordance with an earlier study by the authors, which demonstrates that the orientation of the cellulose chains increases with higher DR s. 33…”

“…These findings are in accordance with an earlier study by the authors, which demonstrates that the orientation of the cellulose chains increases with higher DRs. 33 In consideration of the fiber geometry, orientation, and VFs mimicking the manufacturing process, the abovementioned random fiber deposition technique was implemented where the untrimmed fiber has a length, l, of 10 mm, average diameter of 14 μm, in-plane orientation θ of 0°, and polar orientation f of 0°, and the matrix has the dimensions of L = 10 mm, W = 0.3 mm, and T = 0.3 mm. The fibers exceeding the matrix boundaries were trimmed, and fiber length distribution after trimming operations was provided for the specimens with VF ¼ f16:7%, 25:5%, 35%, 55%g as seen in Figure 6.…”

“…Filaments were spun on a customized laboratory piston spinning system (Fourné Polymertechnik, Germany) following the previous investigations of the authors available in the literature. 32,33 The spin solution was then extruded through a 36-hole spinneret with a capillary diameter of 100 μm and a length-to-diameter ratio ( l / d ) of 0.2. After passing through a 1 cm air gap, the filaments were coagulated in a water bath (15°C) in which the filaments were guided by Teflon rollers to the godet couple.…”

Exploring the potential of regenerated Ioncell fiber composites: a sustainable alternative for high-strength applications

“…The fibers exhibited uniform breakage without evidence of debonding or pull-out, and no instances of adhesion or cohesion failure were observed. This finding aligns with a similar observation reported in prior studies, 48 underscoring the robust compatibility between the matrix and Ioncell fibers, a critical factor influencing mechanical properties. Comparatively, the fracture surface of the viscose fiber composite (VFRC) is presented in Fig.…”