Preparation and Characterization of Composite Blends Based on Polylactic Acid/Polycaprolactone and Silk.

Silk-reinforced polylactic acid/poly ε-caprolactone composites containing 1-7 wt % of silk fibers were fabricated through the melt-mixing method. The composites were then characterized by implementing Fourier transform infrared (FTIR), differential scanning calorimetry (DSC) and rheometry to investigate functional groups, thermal properties, rheological properties, and intrinsic viscosities of each composite. The crystallinity of the composites was found to decrease upon addition of silk, while, both storage modulus ( G') and loss modulus ( G″) were increased which is an indication of interface bonding between the polymer and silk. The composite containing 5% silk fiber (PLACLS5) showed the optimum results. The composites' morphological analysis was conducted by scanning electron micrograph coupled with energy dispersive X-ray (SEM-EDX) mapping to assess the fiber dispersion in the composite matrix. The contact angle measurements and in vitro degradation were performed to evaluate the hydrophilicity, free surface energy, and hydrolytic degradation of the composites. The results implied that addition of higher contents of silk fiber could reduce the degradation duration of the composites, which is due to the high hydrophilicity of the fiber, uniform fiber dispersion within the matrix, the porous structure, and consequently, the hydrophilic behavior of the composites. These composites can be great alternatives for both soft and hard tissue engineering applications.