Morphological, surface and density analysis of jute fiber-reinforced polymer composites fabricated by digital light processing (DLP)

Sustainable polymer composites compatible with additive manufacturing technologies have attracted increasing attention due to the demand for lightweight and environmentally conscious materials. In this study, polymer matrix composites reinforced with short jute fibers (Corchorus capsularis) were manufactured by Digital Light Processing (DLP) using both solid and auxetic geometries. Jute fibers were subjected to defibration, milling, and particle size classification, and the fraction passing through a 0.125 mm sieve was incorporated into a photocurable resin at 2.0, 2.5, and 3.0 wt%. The influence of fiber incorporation on morphology, internal structure, surface roughness, and density was investigated using scanning electron microscopy (SEM), micro-computed tomography (Micro-CT), optical profilometry, and Archimedes’ principle. SEM and qualitative Micro-CT observations revealed fiber incorporation within the polymer matrix and preservation of the auxetic architecture, although greater microstructural heterogeneity and localized fiber agglomeration were observed at higher fiber contents. Surface roughness increased with fiber addition, with Ra increasing from 416.26 nm for the neat resin to 1608.64 nm at 3.0 wt% jute. Density decreased from 1.174 to 1.036 g/cm3 for solid composites, while auxetic specimens exhibited substantially lower apparent densities, ranging from 0.531 to 0.675 g/cm3. Overall, the results demonstrate the feasibility of incorporating short jute fibers into photocurable resins for DLP manufacturing of solid and complex auxetic architectures, while highlighting a trade-off between increasing reinforcement content and maintaining microstructural uniformity.