Canabo microfiber and chitosan biopolymer reinforced with recycled PLA matrix using 3D printing technology for bone scaffold application. A characterization analysis

Abstract

This study investigates the mechanical durability, time-dependent deformation, physicochemical stability, and thermal behaviour of recycled PLA–based composites reinforced with Canabo microfiber and crab-shell-derived chitosan nanoparticles fabricated for bone scaffold applications. Fatigue, creep, swelling–degradation, and thermogravimetric analyses were systematically conducted to evaluate the suitability of different composite formulations. The results demonstrate that hybrid reinforcement significantly enhances the functional performance of recycled PLA. Among all compositions, specimen C3 containing 40 vol.% microfiber and 3 vol.% chitosan nanoparticles exhibited superior fatigue resistance, recording fatigue lives of 25,169, 22,113, and 19,088 cycles at 25%, 50%, and 75% of UTS respectively, which is attributed to the optimal synergistic interaction between uniformly dispersed chitosan nanoparticles and microfibers that effectively bridge cracks, dissipate cyclic energy, and delay crack propagation. Specimen C3 also showed controlled swelling behaviour increasing from 11.63% to 16.03% and moderate degradation from 1.13% to 6.2% over 4 weeks, indicating a balanced hydrophilicity that supports gradual degradation while maintaining structural integrity, which is desirable for bone tissue regeneration. In contrast, specimen C4 with 5 vol.% chitosan nanoparticles exhibited the lowest creep strain values of 0.0064, 0.0073, and 0.0091 at 5000 s, 10,000 s, and 15,000 s respectively, due to increased stiffness and stronger restriction of polymer chain mobility under sustained loading. Specimen C4 also showed the highest thermal stability with a maximum degradation temperature of 321°C in TGA, attributed to higher filler content and enhanced char formation that delays thermal decomposition. Overall, the results confirm that controlled chitosan loading plays a crucial role in tailoring the mechanical durability, degradation behaviour, and thermal stability of recycled PLA composites for advanced bone scaffold applications.