With continuous development of biodegradable polymers, new areas of applications are intensively researched. Modifications of these polymers are commonly conducted by an extrusion compounding process. While additives are changing desired properties, biodegradability of such composites can be deteriorated. The aim of the work is to investigate a novel, functional, organic additive, riboflavin (vitamin B-2), in terms of thermal stability, extrusion processability, wettability, surface energy, especially biodegradability, and when compounded with PLA. Additionally, a comparison of unmodified PLA resin, as well as PLA-modified with inorganic talc—which is known for its nucleation promotion in a variety of polymers—to PLA with riboflavin, was presented. Research reveals the outstanding thermal stability of riboflavin and the sufficient extrusion process properties with no significant changes of wettability and, surprisingly, a significant degradation rate as compared to pure PLA or and PLA with talc. The obtained results do not exclude further modifications of PLA depending on the target application, e.g., antimicrobial agents, flame retardants, etc.

Co-rotating twin-screw extrusion is an energy consuming process that is generally not fully optimised to a specific polymer. From the point of view of the efficiency of the extrusion process, the starting material should be characterised by small grain sizes in comparison to the screw channel area, small surface area to volume ratio and small internal friction between the pellets. To develop a model describing the effect of polylactide (PLA) grain size on the extrusion efficiency, a series of experiments with a twin-screw extruder were carried out during which the energy consumption; torque on shafts and temperature of the melt on the extruder die were monitored. As feed material, both the neat PLA with different grain sizes and the PLA with expandable graphite fillers and phosphorous-based flame retardants were used. Morphology and dispersion quality of the composites were examined using scanning electron microscopy (SEM); flammability, smoke production, mass loss and heat release rates were tested using cone calorimetry; and melt flow rate was determine using a plastometer. Moreover, the thermal properties of the obtained composites were determined using differential scanning calorimetry (DSC). The results show that the choice of the starting material affects both the efficiency of the extrusion process and the flame retardancy properties of the composite materials.

The properties of polylactide (PLA) composites containing up to 40 vol% of barium titanate (BT) powder were investigated. PLA/BT composites were fabricated using twin-screw extrusion, which ensured uniform filler dispersion. The results demonstrated that increasing the BT content in PLA improved the thermal stability, stiffness, and degree of crystallinity of the composite. The piezoelectric coefficient d ₃₃ also increased with higher BT content and longer polarization times, reaching a maximum value of 35 pC N⁻¹ for composites containing 40 vol% BT. Additionally, the studies revealed that the d ₃₃ coefficient is pressure dependent. Presented PLA/BT piezocomposites highlight the suitability of these materials for applications that require both biocompatibility and piezoelectric functionality, including regenerative medicine, energy harvesting, soft robotics, and electroactive biomedical devices.

Poly(lactic acid)/barium titanate (PLA/BT) composites exhibit piezoelectric properties desirable for bone tissue engineering, but their low biodegradability limits implant resorption. In this study, riboflavin (RF) is introduced as a dual-function additive that enhances biodegradation in PLA/BT composites. Its addition led to significantly increased microbial colonization and a five-fold higher mass loss compared to unmodified samples. These observations are consistent with the known polarity of RF and its role as a cofactor in microbial metabolism. The PLA/BT/RF composites are subjected to full characterization, including thermogravimetric analysis (TG), differential scanning calorimetry (DSC), tensile testing, dynamic mechanical analysis (DMA), dielectric permittivity measurements, and determination of piezoelectric coefficient d₃₃. Compared to PLA/BT, RF-containing composites exhibit significantly accelerated biodegradation, with mass loss reaching up to 16% after 28 days, while maintaining functional piezoelectricity (d₃₃ ≈ 3.9 pC/N). Scanning electron microscopy (SEM) performed after biodegradation reveals intensified microbial colonization and surface deterioration in the RF-modified samples. The data confirm that riboflavin serves as an effective modifier, enabling controlled biodegradation without compromising electromechanical performance. These results support the use of PLA-based piezoelectric composites for resorbable biomedical implants.

In the paper, the construction and properties of a layered piezoelectric transducer made of biodegradable materials are presented. The transducer consists of an electret layer, an elastic coating, and an outer structural layer. As the electret layer, the polylactide (PLA) foil with a thickness of 20 μm was used. The electrical properties of the foil, such as resis-tivity, relative permittivity, and charge decay, were examined. The elastic coating was made of natural rubber (NR), ensuring flexibility, while the outer structural layer was fabricated from PLA using a 3-D printing method. Two different shapes of the PLA-grid were exam-ined: hexagonal and striped, to evaluate their influence on the electromechanical perfor-mance of the device. In the paper, the model and electro-mechanical properties of the trans-ducer are presented. The electret foil was polarized using a high-voltage corona charging method. The maximal value of the piezoelectric coefficient, possible to obtain, was calcu-lated using the described model, and it is equal to d33MAX = 1.4 nC/N for a hexagonal struc-ture and 0.87 nC/N for a striped one. That corresponds to the maximal value of effective charge density qsMAX = 7.9 mC/m2 limited by Paschen’s law. The measured static value of the piezoelectric coefficient d33 was up to 280 pC/N. The presented results demonstrate the potential of biodegradable piezoelectric transducers for sustainable and environmentally friendly applications in energy harvesting and sensor technologies.