High-strength biodegradable polymer composites have potential applications in a variety of biomedical applications. This study investigates the influence of silk fiber on the properties of the commonly used biodegradable polylactic acid-based composites, focusing on mechanical, rheological, morphological, and degradation characteristics. Mechanical tests revealed that the addition of 2.5 wt% silk fibers enhanced the ductility of PLA composites, increasing tensile strain at break from 7.39% for pure PLA to 11.51% for the composite. However, higher silk contents (≥10 wt%) resulted in lower elongation at breaks but higher moduli, indicating a trade-off between flexibility and the structural rigidity of the composite. Rheological tests demonstrated that the presence of silk fibers up to 7.5% improved the storage modulus, reflecting better network formation within the PLA matrix. Scanning Electron Microscopy (SEM) photomicrographs illustrated improved fiber dispersion, while higher contents introduced voids and stress concentrations, adversely affecting mechanical properties. Degradation tests in phosphate-buffered saline at 37 °C showed that silk additions slowed PLA degradation, suggesting controlled degradation suitable for biomedical applications. The optimal silk fiber content for balancing mechanical integrity and flexibility was identified to be ca 7.5 wt%, providing insights into the design of PLA/silk composites for enhanced performance in practical applications.

Acrylonitryl-butadiene-styrene (ABS) is an engineering polymer with intrinsic yellowness and translucency due to blue wavelength absorption and partial light transmission, respectively. Generally, using titanium dioxide pigment helps to whiten ABS polymer and reduce its intrinsic yellowness. Also, it can impart opacity to polymeric parts. However, it must be considered that this pigment may cause some unfavorable effects in ABS parts. In this article, effects of surface treatment type and content of TiO₂ pigment on optical aspects of a general purpose ABS have been investigated. In addition, physical and mechanical characteristics including tensile strength, izod impact strength and Rockwell hardness of the polymer have been studied. By adding titanium dioxide pigment opacity and whitening index increased and yellowness index decreased. It is important to note that surface treatment type of titanium dioxide pigment had no considerable effect on optical properties of titanium dioxide pigmented ABS polymer. The results showed that arising content of organic and inorganic surface treated TiO₂ pigments up to 0.5% and 1.5%, respectively, causes to increase impact strength and decrease yield stress and maximum strain of pigmented ABS samples. Above these percentages, impact strength decreased due to agglomeration and decreasing inter-particle spacing. Also hardness of all the ABS samples reduced in the presence of inorganic and organic treated titanium dioxide pigments.