Search Results (1,002)

The incorporation of cellulosic-based fillers as reinforcements into biocomposites represents a promising strategy to enhance the performance of sustainable packaging materials. In this study, poly(lactic acid)/poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PLA/PHBV) films reinforced with 1 and 3 wt% of cellulose microfibers (CM) derived from yam, potato, and cassava hulls were developed through melt extrusion followed by compression molding. The physicochemical, mechanical, optical, microstructural, thermal, and molecular properties of the films were evaluated. Results showed that both the CM source and concentration significantly influenced the biocomposites performance. Cassava-derived CM at 3 wt% provided the best barrier properties, while increasing CM content, regardless of the source, generally reduced solubility, increased moisture content, enhanced stiffness, and decreased elongation at break, although excessive loading negatively affected structural homogeneity. CM incorporation also reduced film gloss and transparency, particularly in yam-based composites. Thermal analysis indicated a multi-step degradation process with only minor variations in thermal stability, and no major chemical modifications of the biocomposites were detected. Overall, cassava-derived CM produced the most balanced performance, highlighting the importance of filler source and loading in tailoring PLA/PHBV biocomposite functional properties. Full article

This study presents an experimental investigation of 3D-printed poly(lactic acid) samples (PLA) subjected to high-voltage AC stress. Although additive manufacturing is gaining importance in electrical engineering, studies on FDM-printed materials have concentrated mainly on mechanical behaviour. Their dielectric strength under oil-immersed high-voltage stress—a critical aspect for insulation applications—has not been systematically investigated. Additive manufacturing is increasingly considered for auxiliary insulating components in oil-immersed high-voltage equipment; however, process-induced voids and interlayer interfaces can intensify the local electric field and reduce dielectric strength. This work evaluates the AC breakdown strength of 3D-printed PLA specimens under oil immersion using the standard AC electrical strength test method for solid insulating materials. Two parameter sets were investigated: extrusion temperature (190–240 °C ) at a constant nozzle diameter, and nozzle diameter ($0.3$–$0.6 \mathrm{mm}$) at a constant extrusion temperature of $T_{\mathrm{e}}=200°\mathrm{C}$. Breakdown data were analysed using the standard two-parameter Weibull approach typically used in the statistical evaluation of electrical insulation breakdown strength, with the results additionally expressed in terms of the $B_{10}$, $B_{50}$, and $B_{90}$ percentiles. The experimental observations were interpreted using simplified electric-field simulations representing inter-bead and interlayer voids. The results indicate that, for a given material, there exists an optimal extrusion temperature that yields the highest electrical breakdown performance. Full article

Bone grafting remains limited, and the strategies to design even more structurally complex scaffolds—able to reproduce the hierarchical architecture of bone extracellular matrix—are rapidly growing. In this study, we report the fabrication of a hierarchically structured scaffold produced by layering poly(ε-caprolactone)/gelatin (PCL/Gt) or poly(lactic acid)/gelatin (PLA/Gt) electrospun nanofibers via coaxial electrospinning onto 3D-printed poly(lactic acid) (PLA) scaffolds via fused deposition modeling (FDM). After the printing process, PLA disks (10 × 1 mm, 20% infill, ~80% porosity, pore size ~1.57 mm) were coated with core/shell (PCL/Gt, PLA/Gt) fibers to investigate the in vitro interfacial response of osteoblasts in comparison with monocomponent fibrous coatings (PCL, PLA, Gt). SEM and TEM confirmed that core/shell fibers exhibited bead-free morphologies, with a significant reduction in fiber diameter (≈287–316 nm) and higher interfibrillar porosity compared to monocomponent fibers. FTIR and thermogravimetric analyses indicated the presence of hydrogen bonding between the polyester and gelatin, and the absence of residual solvent after deposition. At the same time, water contact angle measurements confirmed an increase in hydrophilic properties from 80–86° to 120° ascribable to the presence of gelatin. Accordingly, in vitro response of human fetal osteoblasts (hFOB 1.19) exhibited an evident improvement in the case of Gt-based fibrous coatings (i.e., PCL/Gt and PLA/Gt) in terms of early adhesion (4–24 h) and metabolic activity from 3 to 21 days, cell spreading into star-shaped morphologies, formation of extracellular matrix, and mineral phase deposition. In more detail, a remarkable increase in alkaline phosphatase activity was observed in Gt-based coaxial coatings from day 7 onward, with the highest values recorded for PLA/Gt. Overall, we demonstrated that the Gt-based coaxial fibrous coating provided a mix of topological and biochemical cues that synergistically promoted key osteoblast activities at the interface, supporting the regeneration of new bone tissue in highly tailored 3D-printed scaffolds, thus suggesting a promising strategy for personalized regenerative medicine. Full article

Tropical lignocellulosic residues are increasingly relevant feedstocks for lignin-containing nanocellulose composites, but their performance cannot be predicted from botanical origin or bulk lignin percentage alone. This review defines the interface as the geometrical boundary between phases and the interphase as the finite, compositionally graded region in which lignin distribution, nanocellulose morphology, adsorbed water, and the surrounding matrix jointly govern stress transfer and mass transport. Using an evidence-weighted framework, the literature is organized into the following categories: residual-lignin nanofibrils, redeposited-lignin systems, lignin nanoparticle assemblies, compatibilized thermoplastic hybrids, and all-lignocellulosic sheets. Representative quantitative observations show that controlled residual lignin can the increase water contact angle from approximately 35 degrees to 78 degrees and reduce oxygen permeability by up to 200-fold in nanopapers, while selected PLA/LCNF systems show tensile-strength and modulus increases of 37% and 61%, respectively; however, high or poorly distributed lignin can suppress fibrillation, lower viscosity, weaken gel networks, and reduce reproducibility. The most defensible near-term product windows are packaging layers, grease/oil barrier papers, coatings, paper-like multilayers, and selected porous media. Thermoplastic matrices remain process-sensitive, and biomedical, additive-manufacturing, nano-reactor, and energy-material claims require stronger validation of the extractables, rheology, humidity history, TEA/LCA metrics, and end-of-life behavior. This review, therefore, provides a critical, application-backward roadmap for tropical biorefineries in which interfacial function, wet handling, drying energy, and process integration are assessed together rather than treated as independent variables. The abbreviations used in the abstract are defined as follows: CNFs, cellulose nanofibrils; CNC, cellulose nanocrystals; LCNF, lignin-containing cellulose nanofibrils; LCNCs, lignin-containing cellulose nanocrystals; PLA, poly(lactic acid); PHB, polyhydroxybutyrate; PHAs, polyhydroxyalkanoates; PVA, poly(vinyl alcohol); DESs, deep eutectic solvents; TEA, techno-economic analysis; LCA, life-cycle assessment; ML, machine learning. Full article

Our investigation into Hibiscus rosa-sinensis fibers (HRFs) for composite applications involved a multi-step process, primarily fiber extraction through water retting and subsequent surface modification by using sodium hydroxide (NaOH) and trimethoxy methyl silane (TMMS). Through the compression molding technique, untreated HRF-reinforced poly-lactic acid (PLA) composites (UHRFCs), NaOH-treated HRF-reinforced PLA composites (NHRFCs), and TMMS-treated HRF-reinforced PLA composites (THRFCs) were fabricated. The experiments were conducted, and the findings revealed a substantial increase in properties of both NHRFCs and THRFCs compared to UHRFCs. Notably, these enhancements encompassed tensile strength (13.66% and 19.39%), tensile modulus (13.41% and 20.70%), flexural strength (15.98% and 23.17%), flexural modulus (17.13% and 26.58%), impact strength (15.62% and 33.07%), Shore-D hardness (4.19% and 5.00%), storage modulus (9.88% and 13.07%), loss modulus (7.52% and 17.36%), dielectric constant at 6.5 Hz (13.22% and 23.96%), and significant improvements in the acoustic resonance frequency at 1897 Hz (79.50% and 81%). Peak thermal degradation temperatures of these composites are 420.62 ± 3.43 °C, 439.51 ± 3.54 °C, and 469.07 ± 3.11 °C, respectively, and biodegradability results showing accelerated degradation within 30 days. These findings highlight the substantial effectiveness of treatments in enhancing diverse properties, underscoring the potential applicability of these composites in various industrial sectors requiring superior performance and sustainable materials. Full article

The increasing use of biodegradable polymers, especially poly (lactic acid) (PLA), has raised concern about their entry into conventional post-consumer recycling streams. This review examines the technical and systemic consequences of PLA contamination in the high-density polyethylene (HDPE) circular economy through the “drop-in delusion,” defined here as the mistaken assumption that a sustainability-marketed polymer can enter an established recycling stream without compromising system compatibility. Focusing on contamination-sensitive conditions in which segregation, sorting, or stream purity are insufficient to prevent cross-contamination, the review discusses the immiscibility of HDPE/PLA blends and the resulting changes in stiffness, ductility, toughness, and aging behavior. It also analyzes mitigation routes such as improved sorting, compatibilization, and policy measures, while emphasizing that the practical severity of contamination depends on local infrastructure and contamination levels. In addition, it considers the risk that contaminated materials diverted into lower-value applications may become more vulnerable to interfacial damage, weathering, and secondary fragmentation. Overall, the review argues that circular-plastics strategies must distinguish biodegradability from recycling-system compatibility to protect the quality and value of HDPE recyclates. Full article

Biodegradable materials offer promising alternatives to petroleum-based polymers. This study investigates poly(ε-caprolactone) (PCL) and poly(lactic acid) (PLA) nanocomposites reinforced with 1, 3 and 5 wt.% cellulose nanocrystals (CNCs) extracted from sugarcane bagasse via melt blending. The thermal, structural, morphological and biodegradation properties were evaluated using differential scanning calorimetry (DSC), scanning electron microscopy (SEM), X-ray scattering (WAXS/SAXS), Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and biodegradation tests. SEM results revealed uniform dispersion of CNCs at low concentrations, whereas agglomeration occurred at higher concentrations for both PCL and PLA. At 1 wt.% CNCs, there was minimal impact on the biodegradation rates of both polymers, despite achieving uniform dispersion. However, significant acceleration in biodegradation was observed at 5 wt.% CNCs, attributed to the enhanced hydrophilic nature of the nanocomposites. CNCs acted as nucleating agents in PCL crystallization, while reducing the crystallization rate of PLA. This led to a mass loss of 36.4% for PCL and 82.2% for PLA, correlating with increased and decreased crystallinities, respectively. The study concludes that the hydrophilic–hydrophobic balance has a more significant influence on biodegradation rates than crystallinity or CNC dispersion. Full article

This study evaluates the mechanical performance of FDM-printed poly(lactic acid) (PLA) structures joined using a portable Friction Stir Welding (FSW) device. A non-destructive optical band method was employed to assess weld homogeneity and material flow consistency. The influence of substrate infill density (15% and 100%) and tool pin geometry (cylindrical and truncated conical) was systematically analyzed. Results indicate that substrate density is the primary determinant of joint integrity; 100% infill specimens demonstrated superior structural homogeneity and consistent intensity profiles, whereas 15% infill specimens exhibited significant intensity fluctuations and poor consolidation, even with the addition of filler material. The mechanical evaluation revealed that the use of a tool pin is essential for effective load transfer, as specimens welded without internal agitation achieved only baseline tensile strengths of approximately 4 MPa. Among the pin-driven configurations, the cylindrical geometry outperformed the truncated conical design, reaching a peak tensile stress of 8.02 ± 1.42 MPa, corresponding to a joint efficiency of 27% relative to the 100% infill base material, compared to 6.25 ± 1.43 MPa. This performance gap is attributed to the cylindrical pin’s ability to maintain higher shear rates and more uniform pressure distribution at the weld root. These findings demonstrate the feasibility of portable FSW for structural joining of additively manufactured polymers and establish critical processing parameters for the optimization of portable FSW in engineering applications. Full article

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. Full article

Biodegradable polymer-coated surgical sutures represent a promising strategy for localized drug delivery to prevent post-surgical complications, such as restenosis, inflammation, and excessive tissue proliferation. In this study, bioactive coatings based on poly(L-lactic acid) (PLA), polycaprolactone (PCL), chitosan, and their binary blends were developed and applied to PLA-based surgical sutures for controlled release of sirolimus, tacrolimus, and paclitaxel. A total of 36 coated suture formulations were prepared using solvent-based deposition techniques and systematically evaluated. In vitro drug release studies conducted under physiological conditions (PBS, 37 °C) over a 12-week period demonstrated sustained and formulation-dependent release profiles. Cumulative drug release varied significantly depending on polymer composition, ranging from 17.53% to 90.93% for sirolimus, 70.93% to 98.50% for tacrolimus, and 34.62% to 67.65% for paclitaxel. PLA-based coatings generally exhibited faster release kinetics, whereas PCL-containing formulations showed slower, more sustained release. Binary polymer blends enabled fine-tuning of release profiles, demonstrating tunable drug delivery performance. All coatings maintained structural integrity during handling and simulated suturing conditions. These findings confirm that polymer composition plays a critical role in controlling drug release kinetics and demonstrate the feasibility of biodegradable polymer-coated sutures as a versatile platform for sustained, localized drug delivery in surgical and vascular applications. Full article

This study investigates the development of mechanically reprocessed poly(lactic acid) (rPLA) films reinforced with rice husk (RH) and rice husk biochar (RHB) to evaluate their processing behavior, key functional properties, and disintegration under composting conditions. rPLA was produced from PLA through an additional processing cycle to simulate the valorization of industrial PLA waste, while composites containing 1 and 3 wt.% RH or RHB 500 µm sized particles were manufactured by melt extrusion followed by a compression molding process. Reprocessing increased the melt flow index and decreased intrinsic viscosity and viscosimetric molecular weight, evidencing the occurrence of chain scission during mechanical reprocessing. The addition of RH slightly restricted melt flow and promoted higher surface hydrophilicity, whereas RHB showed a filler-loading-dependent effect on melt flow and increased surface hydrophobicity at low content, consistent with its carbonized and less polar nature. Both RH and RHB promote a nucleating effect, with increased crystallinity in RHB-containing films, and tensile tests showing that filler incorporation mainly reduced ductility compared with unfilled rPLA, while stiffness and strength was maintained or exhibited more moderate variations. Despite these contrasting trends in surface properties and thermo-mechanical performance, all formulations achieved complete disintegration within 21 days under composting conditions at laboratory scale level. Overall, RH and RHB provide a viable route to valorize agro-industrial residues in rPLA films and to tune structure–property relationships within the circular economy framework. Full article

The development of selective and sustainable catalysts is essential to enable the chemical recycling of mixed plastic waste. In this work, calcium-modified biochars derived from cocoa pod husk (CPH) and palm kernel shell (PKS) were prepared for treating a mixture of poly(ethylene terephthalate) (PET) and poly(lactic acid) (PLA). The aim was to separate the mixture through the PLA methanolysis, while maintaining the PET unreacted for a potential physical recycling. Biochar was ex situ modified with calcium precursor using a value-added concentrate recovered from the hydrothermal treatment of Jatropha fruit husk. Subsequently, a pyrolysis step was further applied to convert the calcium species into CaO, which is the active phase for the methanolysis reaction. Structural, microscopic, and spectroscopic analyses revealed that the carbon matrix strongly influences the evolution and stabilization of calcium phases during pyrolysis and post-treatment. CPH-derived biochars promoted the formation of highly dispersed CaO, whereas PKS favored the growth of larger, less reactive Ca(OH)₂ domains. As a result, the CPH_Ca10 (i.e., 10% desired calcium loading based on CPH-biochar mass) catalyst exhibited superior basicity and catalytic activity, achieving near-complete PLA conversion under mild conditions (90–110 °C) depending on the system with only 2 wt.% catalyst. Importantly, under these mild conditions, PET remained chemically intact, demonstrating the process’s high selectivity and applicability to mixed bioplastic–fossil plastic streams. This study highlights a circular, low-carbon route to producing effective Ca-based catalysts from agricultural residues. It establishes a promising strategy for selective depolymerization and separation in complex plastic waste systems. Full article

This study reports the development and characterization of hierarchical electrospun scaffolds based on poly (L-lactic acid) (PLA) and polyacrylonitrile (PAN) reinforced with calcium oxide (CaO) nanoparticles (18.5 ± 4.7 nm) for skin regeneration. Six configurations, including two five-layer multilayer systems (PLA/PAN/CaO and PAN/PLA/CaO), were evaluated to determine how composition and deposition sequence influence physicochemical, mechanical, and biological performance. FT-IR, XRD and DSC confirmed the successful integration of CaO, while thermal analysis evidenced an effect of chain mobility and interfacial interactions within multilayer systems. Cross-sectional SEM revealed the presence of both fibers with continuous interfaces. Nitrogen adsorption showed that CaO significantly increased the specific surface area (e.g., from 4.6 m²/g in neat PLA to 21.65 m²/g in PLA/CaO), with type IV isotherms indicating mesoporosity. Wettability assays demonstrated reduced contact angle in PLA (from 126.3° to 91.8°) and sequence-dependent surface properties in multilayers. Tensile testing confirmed that the multilayer architecture bridged the mechanical gap between compliant PLA and high-strength PAN, yielding intermediate moduli (~10–11 MPa) and balanced toughness. Antibacterial assays against S. aureus and E. coli showed that CaO significantly reduced bacterial viability, with PLA/PAN/CaO achieving the highest inhibition (up to 37.1%). In vitro HaCaT assays and in vivo implantation in BALB/c mice confirmed high cytocompatibility and biocompatibility. These findings demonstrate that multilayer electrospinning of PLA/PAN/CaO enables the design of structurally integrated, bioactive, and mechanically balanced scaffolds for advanced wound healing and dermal repair. Full article

This study developed poly(lactic acid) (PLA) biocomposites reinforced with pine wood flour (10, 20, and 30 wt%) to achieve the interphase through chemical modification. Specifically, the wood flour was treated with poly(propylene glycol) toluene 2,4-diisocyanate terminated (PEGTDI), while 1 wt% poly(lactic acid)-g-maleic anhydride (PLA-g-MA) was integrated as a reactive compatibilizer during extrusion and thermocompression. Fourier-transform infrared spectroscopy (FTIR) analysis corroborated the occurrence of urethane formation and ester/anhydride linkages, as substantiated by the presence of characteristic bands indicative of surface carbamation at 1645 and 1726 cm⁻¹. Thermal analysis revealed that both the pine wood flour and coupling agents promoted PLA crystallization; however, thermogravimetric analysis (TGA) indicated a decrease in thermal stability for functionalized composites, suggesting a trade-off between enhanced interfacial interaction and heat resistance. Mechanical testing demonstrated a significant reinforcement effect, with the Young’s modulus increasing by up to 22% in untreated composites. The coupling agents effectively optimized stress transfer at low fiber loadings (10 wt%), while flexural modulus improvements were predominant at higher loadings (20–30 wt%) regardless of treatment. These findings underscore the criticality of surface modification and compatibilizer selection for tailoring the structural and thermo-mechanical properties of PLA-based biocomposites, thereby providing a pathway for optimized performance in structural applications. Full article

Recently, more sustainable and biodegradable packaging materials have begun to attract attention in food packaging due to major, rising concerns related to plastic usage. This study aims to develop and characterize biodegradable food packaging materials, namely poly(lactic acid) (PLA) and poly(ε-caprolactone) (PCL) enriched with pomegranate peel extract (PoPE). Firstly, the optimal extract selected was a 24 h maceration of PoPE with 60% ethanol, after production with different solvents and methods. PLA- and PCL-based films were produced via melt compounding with the addition of PoPE at different concentrations (1, 3, 5 and 10%, w/w). FTIR confirmed that the PoPE did not modify the chemical backbones of PLA or PCL, with only a more pronounced O–H band in PCL, suggesting mainly non-covalent/physical interactions. UV–Vis spectroscopy showed tunable warm coloration and strong UV shielding with reduced transparency; for PLA ~3–5 wt.%, PoPE enabled near-complete UV blocking, while PCL achieved very high UV protection even at low loadings. PoPE improved toughness in PLA (3–5 wt.%) and maintained ductility in PCL (1–10 wt.%). PoPE-added PLA and PCL films maintained thermal stability up to 10 wt.% according to TGA results. DSC/XRD indicated a matrix-dependent crystallization response. PLA remained largely amorphous, whereas PoPE promoted PCL crystallinity without changing polymer crystal polymorphs. SEM images revealed homogenous dispersion of PoPE in the films. Full article