Strengthen oriented poly (L-lactic acid) monofilaments via mechanical training

Abstract

Polymer materials have found extensive applications in the clinical and medical domains due to their exceptional biocompatibility and biodegradability. Compared to metallic counterparts, polymers, particularly Poly (L-lactic acid) (PLLA), are more suitable for fabricating biodegradable stents. As a viscoelastic material, PLLA monofilaments exhibit a creep phenomenon under sustained tensile stress. This study explores the use of creep to enhance the mechanical attributes of PLLA monofilaments. By subjecting the highly oriented monofilaments to controlled, constant force stretching, we achieved notable improvements in their mechanical characteristics. The results, as confirmed by tensile testing and dynamic mechanical analysis, revealed a remarkable 67 % increase in total elongation and over a 20 % rise in storage modulus post-mechanical training. Further microscopic analyses, including Atomic Force Microscopy (AFM) and Scanning Electron Microscopy (SEM), revealed enhanced spacing and cavity formation. These mechanical advancements are attributed to the unraveling and a more orderly arrangement of molecular chains in the amorphous regions. This investigation offers a promising approach for augmenting the mechanical properties of PLLA monofilaments, potentially benefiting their application in biomedical engineering.