This study systematically examines the effect of alkali-treated cellulose-rich Calamus tenuis fiber content on the performance of epoxy-based polymer composites fabricated via open-mold casting with dead-weight compression. The fibers, mainly composed of cellulose, were treated with 7.5% (w/v) NaOH for four hours to remove hemicellulose, lignin, and waxes, thereby improving surface reactivity and interfacial fiber/matrix adhesion. Treated fibers were incorporated into the epoxy resin at loadings from 0 to 25 wt% in 5 wt% intervals. The novelty of this work lies in systematically correlating alkali-induced chemical modification and interfacial morphology (SEM and AFM) with mechanical, thermal, and moisture-absorption behaviour across a broad range of fibre loading. FTIR analysis confirmed the effective removal of non-cellulosic components, enhancing fiber-matrix bonding, while XRD revealed that the cellulose I crystalline structure was preserved, promoting better structural integrity. Mechanical testing showed that 15 wt% fiber loading provided optimal performance, with a 39.21% increase in tensile strength, 35.62% rise in flexural strength, and 68.49% improvement in impact strength compared to neat epoxy. Thermal analyses (TGA and DSC) indicated enhanced thermal stability, with a peak degradation temperature of 357.28 °C. SEM and AFM analyses showed improved fiber dispersion and interfacial bonding, attributed to surface roughening after alkali treatment. Moisture absorption analysis revealed that neat epoxy exhibited very little water uptake (0.480 ± 0.012 wt%), whereas the highest absorption was observed for 25 wt% untreated composites (5.029 ± 0.052 wt%). However, when the fibers were treated with NaOH, the water uptake decreased to 4.735 ± 0.048 wt% at the same loading level, confirming the effectiveness of alkali treatment. Overall, 15 wt% NaOH-treated cellulose-rich Calamus tenuis fiber-reinforced epoxy composites exhibit excellent mechanical, thermal, and moisture-resistant properties, showing potential for lightweight structural applications.
Kar et al. (Sat,) studied this question.