This study explores the development of long fiber-reinforced thermoplastic (LFT) composites based on blends of poly(lactic acid) (PLA) and polyhydroxyalkanoate (PHA), reinforced with sisal fibers. A novel lab-scale LFT line was employed to fabricate the long fiber composites, effectively addressing the challenges associated with dispersing and processing high-aspect-ratio natural fibers. The rheological, mechanical, thermal, and morphological properties of the resulting bio-LFT composites were systematically characterized using FTIR, SEM, rotational rheology, mechanical testing, DSC, and TGA. The results demonstrated generally homogeneous fiber dispersion, although limited interfacial adhesion between the fibers and polymer matrix was observed. Mechanical tests revealed that sisal fiber incorporation significantly enhanced tensile strength and stiffness, while impact toughness decreased. Thermal analyses showed improved crystallinity and thermal stability with increasing PHA content and fiber reinforcement. Overall, this work highlights the potential of natural fibers to create high-performance, sustainable biocomposites and lays a solid foundation for future advancements in developing eco-friendly structural materials.

Poly(lactic acid) (PLA)-based biocomposites incorporating collagen (COLL) and hydroxyapatite (HA) were produced via melt micro-compounding and subsequent injection molding. 1,4-phenylene diisocyanate (PDI) was employed as a compatibilizer, while poly(ethylene glycol) (PEG) was used as a plasticizer. The morphological, thermal, rheological, and mechanical properties, as well as surface wettability, degradation behavior, and cytotoxicity, were comprehensively evaluated. SEM and DSC analyses revealed the phase distribution and thermal transitions, while rheological measurements showed that PEG reduced melt viscosity by increasing chain mobility. Mechanical performance was evaluated using tensile, impact, and DMA tests on standard specimens, indicating that HA primarily enhanced stiffness (elastic modulus), whereas PEG improved toughness, resulting in higher impact strength. Biodegradable bone screw prototypes were produced with the same formulations and subjected to torsion, enzymatic degradation, and MTT cytotoxicity tests. Degradation results indicated that biocomposites containing PEG, collagen, and HA exhibited accelerated mass loss. Overall, the 70/20/10 PLA/COLL/HA/PEG/PDI formulation was more suitable for soft (trabecular) bone tissue, while the 70/10/20 PLA/COLL/HA/PDI formulation showed advantages for hard (cortical) bone tissue applications.

This study investigates the crystallization behavior of poly(butylene succinate) (PBS) through blending with highly crystalline polyoxymethylene (POM) to address the inherently slow crystallization rate of PBS. The non-isothermal crystallization kinetics of the individual constituents within the blend systems were systematically investigated to elucidate their crystallization behavior under cooling conditions. In addition, the influence of multi-walled carbon nanotube (MWCNT) incorporation on the mechanical, thermomechanical, and morphological properties of PBS/POM blends was evaluated. The crystallization behavior was analyzed using kinetic approaches under non-isothermal conditions. Spherulite morphology was observed via polarized optical microscopy equipped with a controlled heating–cooling stage to elucidate spherulitic development. Scanning electron microscopy (SEM) revealed no obvious micron-scale phase separation in the PBS/POM blends, while the distinct crystallization behavior of the PBS and POM phases observed by differential scanning calorimetry (DSC) indicated that the two components retained their individual crystalline phases, supporting the partial miscibility of the blends. In the ternary systems, SEM observations showed a relatively uniform distribution of MWCNTs at the spatial scale accessible by SEM, with no pronounced micron-scale agglomerates readily discernible within the examined regions. Mechanical analyses demonstrated that the incorporation of MWCNTs enhanced the properties of the blends, particularly the elastic modulus and tensile strength. Kinetic analysis further indicated that MWCNTs influenced the crystallization behavior of the PBS and POM phases through nucleation effects, with their influence depending on the PBS/POM blend composition.