A Novel Manufacturing Approach to Infuse Recombinant Spidroin Silk Protein into Hemp Yarns for Biocomposite Applications

This paper explores the infusion of A10-4mer, a recombinant protein mimicking the Major Ampullate Spidroin 2 (MaSp2) domain of spider dragline silk, into hemp yarn using 3D-printed infusion chambers for biocomposite applications. The process aims to enhance the reinforcement properties of bast fibers (hemp) and reduce the variability of natural feedstocks. Silk solution concentrations (0–0.50 wt%) were tested, and the infused yarn’s morphological, structural, and mechanical traits were analyzed via scanning electron microscopy, attenuated total reflectance Fourier transform infrared spectroscopy, and fluorescence microscopy. Results show that silk infusions ≤ 0.25 wt% using a converging chamber improved mechanical properties, likely due to efficient bonding and dispersion of silk within the fiber. In contrast, concentrations > 0.25 wt% decreased tensile modulus and breaking tenacity, although elongation at break and breaking toughness improved, attributed to a transition from fiber-like silk structures to a coating-like configuration. Overall, this research highlights the potential of (1) recombinant silk-infused hemp yarn as a cost-effective, high-performance material and (2) recombinant silk as a bioalloying agent to compensate for inherent hemp fiber mechanical property variation—offering a novel route toward more reliable and sustainable textile and biocomposite applications.