Search Results (45)

Poly(lactic acid) (PLA) has strong potential for use in sustainable packaging, automotive components, and structural materials; however, its inherent brittleness and limited thermal stability restrict broader application. To overcome these drawbacks, this study developed PLA-based composites reinforced with mica and compatibilized using poly(vinyl butyral) (PVB). To overcome the inherent brittleness and limited thermal stability of poly(lactic acid) (PLA), this study investigated the incorporation of mica as a reinforcing filler into PLA and PLA/poly(vinyl butyral) (PVB) composite systems. Five types of mica with varying particle sizes and densities were examined to evaluate their influence on the mechanical, thermal, and rheological properties of the composites. The PLA/PVB blend was prepared in an 8:2 weight ratio, and mica was added at 5 phr (35 g). PLA/mica composites showed limited improvement in mechanical performance due to poor interfacial compatibility between PLA and mica, resulting in decreased tensile strength and non-uniform filler dispersion. In contrast, the addition of PVB, a tough and flexible polymer containing hydroxyl groups (ca. 20 mol%) remaining after polymerization, significantly enhanced the interfacial interaction with mica and improved filler dispersion within the matrix. As a result, PLA/PVB/mica composites exhibited increased tensile strength and toughness. Thermal analysis revealed that mica restricted polymer chain mobility, leading to higher glass transition temperatures, while PVB promoted a more uniform crystalline structure. Rheological studies indicated that PLA/PVB/mica composites had higher complex viscosity and lower melt flow index (MFI) due to increased molecular interactions and reduced chain mobility. Notably, certain mica types containing Ca²⁺ ions catalyzed chain scission during melt processing, leading to reduced molecular weight and increased MFI. These findings demonstrate that the synergistic combination of PVB and mica can effectively improve the processability and performance of PLA-based composites, offering a promising route for developing sustainable materials for advanced applications. Full article

Food enrichment represents a novel feeding strategy for aquaculture. In the current study, juvenile Nibea albiflora (average weight 29.65 ± 0.13 g) were used and three feeding regimes (A—commercial diet; B—a diet comprising 90% commercial feed and 10% ice-fresh Palaemon gravieri; C—a diet consisting of 90% commercial diet, 5% ice-fresh Palaemon gravieri and 5% live Perinereis nuntia; named control group, Group 1, and Group 2) with comparable nutrient compositions: were designed to establish the food enrichment model and explore the effects of such feeding strategies on the fish. The cultivation period was 60 days, and the physiological, pathological, and RNA-seq analyses were performed to evaluate the effects. The results showed that the food enrichment feeding strategy significantly enhanced fish growth performance, immunity, and stress resistance without increasing the unit production cost (UPC). Furthermore, the tri-combined food feeding (C) was better than the two-combined food feeding (B). Liver transcriptomic analysis revealed that, in the comparison between the control group and Group 1, the up-regulated genes (alox15b, gng7, hif1a, ppara, and pla2g) and down-regulated genes (ins, gck, il4i1) influenced fish physiology and further improved growth. Similar to the comparison between the control group and Group 2, the major functional genes included ugt, nlrp3, mx1, col1a, gst (up-regulated), and map2k1, myc, mmp9, wnt7, socs3 (down-regulated) that participated in regulating the body growth, immunity, and stress resistance. The up-regulated genes (ins, mhc2, foxo3, ppara, and mx1) alongside the down-regulated genes (egfr, fos, cyc, myc, and mmp9) probably contributed to the enhanced efficacy of the tri-combined food feeding compared to the two-combined food feeding. In summary, this study demonstrates the beneficial effects of such a food enrichment model on the fish and provides empirical evidence supporting the implementation of the feeding strategies in the healthy culturing of the fish. Full article

Novel multifunctional fibrous materials were prepared by simultaneous dual spinneret electrospinning of two separate solutions differing in composition. This technique allowed for the preparation of materials built of two types of fibers: fibers from poly(vinyl alcohol) (PVA), chitosan (Ch), and rosmarinic acid (RA), and poly(L-lactide) (PLA) fibers containing lidocaine hydrochloride (LHC). Confocal laser scanning microscopy (CLSM) analyses showed that both types of fibers are present on the surface and in the bulk of the new materials. The presence of all components and some interactions between them were proven by attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy. RA and LHC were in an amorphous state in the fibers, and their presence affected the temperature characteristics and the crystallinity, as detected by differential scanning calorimetry (DSC) and X-ray diffraction analyses (XRD). The presence of PVA/Ch/RA fibers enabled the hydrophilization of the surface of the multifunctional fibrous materials (the water contact angle value was 0°). The newly developed materials demonstrated adequate mechanical properties, making them suitable for use in wound dressing applications. The RA-containing fibrous mats possessed high radical-scavenging activity (ca. 93%), and the combining with LHC led to an enhancement of this effect (ca. 98.5%). RA-containing fibrous mats killed all the pathogenic bacteria S. aureus and E. coli and decreased the titer of fungi C. albicans by ca. 0.4 log for a contact time of 24 h. Therefore, the new materials are prospective as antibacterial and atraumatic functional wound dressings, as systems for local drug delivery, and in medical skincare. Full article

In this study, multifunctional nanocomposite membranes were fabricated using biopolymeric polylactic acid (PLA) and cellulose acetate (CA) composites via electrospinning. The hydrophobic nanocomposite membranes were reinforced with varying concentrations of silicon dioxide (silica/SiO₂) nanoparticles. The developed PLA–CA–SiO₂ nanofibrous membranes are characterized using field emission scanning electron microscopy (FE- energy-dispersive SEM), energy-dispersive X-ray (EDX), elemental mapping, X-ray diffraction analysis (XRD), Fourier-transform infrared spectroscopy (FT–IR), thermal gravimetric analysis (TGA), and differential scanning calorimetry (DSC) techniques. Various physical and mechanical properties of the bio-nanocomposite membrane, such as tensile testing, infrared thermal imaging, ultraviolet–visible spectroscopy (UV–Vis), water contact angle, hydrostatic pressure resistance, and breathability are also investigated. The analysis revealed that a small concentration of silica nanoparticles improves the morphological, mechanical, and thermal characteristics of nanocomposite membranes. The addition of silica nanoparticles improves the UV (A & B), visible and infrared blocking efficiency while also enhancing the waterproofness of protective textiles. The PLA–CA–SiO₂ biopolymer nanocomposite membrane has a fibrous microstructure and demonstrated the tensile strength of 11.2 MPa, a Young’s modulus of 329 MPa, an elongation at break of 98.5%, a hydrostatic pressure resistance of 27 kPa, and a water contact angle of 143.7°. The developed electrospun composite membranes with improved properties provide strong potential to replace petroleum-based membranes with biopolymer-based alternatives, promising improved and wider usage for bio-related applications. Full article

Reinforcing PLA composites with natural fibres is a prominent strategy for improving PLA’s properties while benefiting from its intrinsic biodegradation. However, these composites may be susceptible to an inefficient stress-transferring process due to the weak intermolecular interactions between PLA and natural fibres. A well-known practice is to incorporate coupling agents to improve polymer–fibre adhesion, such as carboxylic acids (CAs) and grafted copolymers. CAs are a more affordable and biodegradable option for improving PLA/natural fibre interface strength, resulting in a material with superior mechanical and thermal properties. In this context, this research discusses the potential use of mono (C6 and C8) and di (CC6 and CC8) carboxylic acids as coupling agents in PLA/pecan nutshells (PN) composites. PLA/PN composites with four different CAs were processed in a twin-screw extruder and subsequently injection moulded. The results indicated an increase in the flexural strength of the PLA due to the presence of PN in the neat composite. The use of CAs increased the storage modulus of PLA/PN composites, while C6 and CC8 reduced the PLA composite tan δ peak height. The PLA’s T_g in PLA/PN composite shifted to lower temperatures after the incorporation of CAs while increasing the PLA crystallinity degree. These results strongly suggested that besides acting as efficient coupling agents, these acids also exerted roles as nucleating agents and plasticisers. Full article

This study evaluated the pH, fluoride (F), and calcium (Ca) concentrations in saliva-derived microcosm biofilms following treatments with dentifrices applied at different amounts and F concentration. Human saliva was inoculated into McBain culture medium, and treatments were applied at 72/78/96 h (1 min). Fluoridated dentifrices containing 550 or 1100 ppm F (550F and 1100F, respectively) were used at the following combinations (intensities): (i-1) 550F/0.08 g or 1100F/0.04 g; (i-2) 550F/0.16 g or 1100F/0.08 g; (i-3) 550F/0.32 g or 1100F/0.16 g. A negative control (fluoride-free dentifrice—PLA) was also included. Biofilm F and Ca were measured with an ion-selective electrode and colorimetrically, respectively, while pH in the culture medium was measured with a pH electrode. Data were subjected to ANOVA and Student–Newman–Keuls’ test (p < 0.05). F-dentifrices did not significantly alter pH compared to PLA, except for 1100F at i-3. Biofilm F levels at i-1 and i-2 were comparable, for both 550F and 1100F, while 1100F at i-3 led to the highest biofilm F concentration. All F-groups showed significantly higher Ca levels than PLA, especially at i-2 and i-3. In conclusion, the interplay between dentifrice amount and F concentration was more influential on the biofilm’s inorganic composition and pH than either variable alone. Full article

Developing biocompatible and biodegradable materials for food packaging is crucial for addressing environmental concerns and ensuring food safety. In this study, we present a novel food packaging film composed of poly(lactic acid) (PLA) and biogenic vaterite CaCO₃-Ag hybrid microspheres. A non-solution technique was employed to prepare these films, ensuring the sustainability and simplicity of the production process. X-ray diffraction and infrared spectroscopy analyses confirmed the stability and compatibility of the vaterite CaCO₃-Ag microspheres within the PLA matrix. Cytotoxicity tests using human dermal fibroblast cells demonstrated complete biocompatibility of the films, even at high concentrations. Antimicrobial efficacy was assessed through minimum inhibitory concentration (MIC) testing, which demonstrated that PLA film containing 7 wt% vaterite CaCO₃-Ag hybrids effectively inhibited both gram-positive and gram-negative bacteria at concentrations as low as ≤0.067 g/mL. Mechanical testing showed that the modulus and strength of PLA film increased significantly with the embedding of 5 wt% of vaterite CaCO₃-Ag hybrid, reaching a maximum of 5.63 ± 1.51 GPa and 48.07 ± 13.81 MPa, respectively. Thermal analysis indicated improved thermal stability with the addition of the microspheres. Synchrotron X-ray absorption spectroscopy confirmed the stability of the vaterite structure and the presence of both Ag⁰ and Ag⁺ species after embedding in PLA matrix. The composite films exhibited improved oxygen and water vapor barrier properties, making them suitable for packaging applications. These findings highlight the potential of PLA-vaterite CaCO₃-Ag hybrid films as sustainable and effective food packaging materials. Full article

Environmentally friendly biopolymer nanofibrous composite membranes with enhanced mechanical properties and thermal stability were fabricated via electrospinning with different compositions of polylactic acid (PLA) and cellulose acetate (CA). Firstly, PLA and CA composite membranes were prepared and optimized. Then, the optimized membranes were annealed at temperatures ranging from 80 °C to 140 °C, for annealing times between 30 and 90 min. The developed membranes were characterized by FE-SEM, XRD, FR-IT, TGA, DSC, tensile testing, water contact angle, and resistance to hydrostatic pressure. PLA 95-CA 5 was the optimum composite, with a tensile strength 9.3 MPa, an average fiber diameter of 432 nm, a water contact angle of 135.7°, and resistance to a hydrostatic pressure of 16.5 KPa. Annealing resulted in further improvements in different properties. The annealed membranes had thermally stable microporous structures, without shrinkage or deterioration in nanofiber structure, even at an annealing time of 90 min and an annealing temperature of 140 °C. By increasing either the annealing time or temperature, the crystallinity and rigidity of the nanofiber composite membranes were increased. The annealed membrane demonstrated a tensile strength of 12.3 MPa, a water contact angle of 139.2°, and resistance to a hydrostatic pressure of 36 KPa. Electrospinning of PLA-CA composite membranes with enhanced mechanical properties and thermal stability will pave the way for employing PLA-based membranes in various applications. Full article

Additive manufacturing, such as the 3D printing of composite materials for electronics is rapidly evolving, enabling the production of advanced electric and magnetic composites with tailored properties. These materials require special printing conditions and advanced control to maintain the desired material properties during the 3D printing process and in the final product design. Hence, determining the heating and energy consumption and estimating the efficiency of 3D printing is essential. This work modeled the fused filament fabrication 3D printing of composite materials with a polymer carrier matrix. A 3D time-dependent thermal model of a 3D printer extruder was developed and implemented using the finite element method to study and improve the efficiency of 3D printing. As the filler content influences the operational parameters and process energy consumption of the 3D printing process, the transient heating process parameters were estimated using different composite modifier contents. Two types of modifiers were considered: Fe₂O₃ and CaO, both mixed in a PLA carrier material. The volumetric fill ratio of the two modifiers did not exceed 45%, as the mixing dependency of the material properties is linear in this range. The power fluxes and power efficiency were estimated. The results provide new possibilities for better control methodologies and advanced additive manufacturing for new materials in electronics. Operational control can accelerate the 3D printing process, speeding up the heating of 3D-printed composite materials and reducing the printing time and total energy consumption. Furthermore, this research provides directions for new advanced 3D printing extruder designs with better power and energy heating efficiency. Full article

Replacing traditional disposable, non-biodegradable plastic packaging with biodegradable plastic packaging is one of the key approaches to address the issue of “white pollution”. PBAT/PLA/inorganic filler composites are widely utilized as a biodegradable material, commonly employed in the field of packaging films. However, the poor dispersion of inorganic fillers in the polymer matrix and the limited compatibility between PBAT and PLA have led to inferior mechanical properties and elevated costs. In this work, we propose a simple and effective strategy to improve the dispersion of nano-CaCO₃ in a PBAT/PLA matrix through solid-state shear- milling (S³M) technology, combined with mechanochemical modification and in situ compatibilization to enhance the compatibility between PBAT and PLA. The impact of varying milling conditions on the structure and performance of the PBAT/PLA/CaCO₃ composites was investigated. During the milling process, PBAT and PLA undergo partial molecular chain fragmentation, generating more active functional groups. In the presence of the chain extender ADR during melt blending, more branched PBAT-g-PLA is formed, thereby enhancing matrix compatibility. The results indicate that the choice of milling materials significantly affects the structure and properties of the composite. The film obtained by milling only PBAT and CaCO₃ exhibited the best performance, with its longitudinal tensile strength and fracture elongation reaching 22 MPa and 437%, respectively. This film holds great potential for application in the field of green packaging. Full article

High-strength biodegradable polymer composites have potential applications in a variety of biomedical applications. This study investigates the influence of silk fiber on the properties of the commonly used biodegradable polylactic acid-based composites, focusing on mechanical, rheological, morphological, and degradation characteristics. Mechanical tests revealed that the addition of 2.5 wt% silk fibers enhanced the ductility of PLA composites, increasing tensile strain at break from 7.39% for pure PLA to 11.51% for the composite. However, higher silk contents (≥10 wt%) resulted in lower elongation at breaks but higher moduli, indicating a trade-off between flexibility and the structural rigidity of the composite. Rheological tests demonstrated that the presence of silk fibers up to 7.5% improved the storage modulus, reflecting better network formation within the PLA matrix. Scanning Electron Microscopy (SEM) photomicrographs illustrated improved fiber dispersion, while higher contents introduced voids and stress concentrations, adversely affecting mechanical properties. Degradation tests in phosphate-buffered saline at 37 °C showed that silk additions slowed PLA degradation, suggesting controlled degradation suitable for biomedical applications. The optimal silk fiber content for balancing mechanical integrity and flexibility was identified to be ca 7.5 wt%, providing insights into the design of PLA/silk composites for enhanced performance in practical applications. Full article

Low-temperature additive manufacturing of magnesium (Mg) alloy implants is considered a promising technique for biomedical applications due to Mg’s inherent biocompatibility and 3D printing’s capability for patient-specific design. This study explores the influence of powder volume content, size, and morphology on the mechanical properties and viscosity of polylactic acid (PLA) matrix composite filaments containing in-house-produced magnesium–calcium (Mg-Ca) particles, with a focus on their application towards low-temperature additive manufacturing. We investigated the effects of varying the Mg-Ca particle content in a PLA matrix, revealing a direct correlation between volume content and bending strength. Particle size analysis demonstrated that smaller particles (D50: 57 μm) achieved a bending strength of 63.7 MPa, whereas larger particles (D50: 105 μm) exhibited 49.6 MPa at 20 vol.%. Morphologically, the filament containing spherical particles at 20 vol.% showed a bending strength that was 11.5 MPa higher than that of the filament with irregular particles. These findings highlight the critical role of particle content, size, and shape in determining the mechanical and rheological properties of Mg-Ca/PLA composite filaments for use in material extrusion additive manufacturing. Full article

In this work, we focused on the bioactivity and antibacterial behavior of PLA-based electrospun fibers, efibers, reinforced with both MgO and Mg(OH)₂ nanoparticles, NPs. The evolution of PLA-based efibers was followed in terms of morphology, FTIR, XRD, and visual appearance. The bioactivity was discussed in terms of hydroxyapatite growth after 28 days, considered as T28, of immersion in simulated body fluid, SBF. In particular, the biomineralization process evidenced after immersion in SBF started at T14 in both systems. The number of precipitated crystals increased by increasing the amount of both NPs. The chemical composition of the precipitated crystals was also characterized in terms of the Ca/P molar ratio after T28 of immersion in SBF, indicating the presence of hydroxyapatite on the surface of both reinforced efibers. Moreover, a reduction in the average diameter of the PLA-based efibers was observed, reaching a maximum reduction of 46 and 60% in the average diameter of neat PLA and PLA:OLA efibers, respectively, after 28 days of immersion in SBF. The antibacterial behavior of the MgO and Mg(OH)₂ NPs in the PLA-based electrospun fibers was tested against Escherichia coli, E. coli, as the Gram-negative bacteria, and Staphylococcus aureus, S. aureus, as the Gram-positive bacteria, obtaining the best antibacterial activity against the Gram-negative bacteria E. coli of 21 ± 2% and 34 ± 6% for the highest concentration of MgO and Mg(OH)₂ NPs, respectively. Full article

This study investigates the effect of scaffold architecture on bone regeneration, focusing on 3D-printed polylactic acid–bioceramic calcium phosphate (PLA-bioCaP) composite scaffolds in rabbit femoral condyle critical defects. We explored two distinct scaffold designs to assess their influence on bone healing and scaffold performance. Structures with alternate (0°/90°) and helical (0°/45°/90°/135°/180°) laydown patterns were manufactured with a 3D printer using a fused deposition modeling technique. The scaffolds were meticulously characterized for pore size, strut thickness, porosity, pore accessibility, and mechanical properties. The in vivo efficacy of these scaffolds was evaluated using a femoral condyle critical defect model in eight skeletally mature New Zealand White rabbits. Then, the results were analyzed micro-tomographically, histologically, and histomorphometrically. Our findings indicate that both scaffold architectures are biocompatible and support bone formation. The helical scaffolds, characterized by larger pore sizes and higher porosity, demonstrated significantly greater bone regeneration than the alternate structures. However, their lower mechanical strength presented limitations for use in load-bearing sites. Full article

In the last decade, among the emerging technologies in the area of bioplastics, additive manufacturing (AM), commonly referred to as 3D printing, stands out. This technology has gained great interest in the development of new products, mainly due to its capability to easily produce customized and low-cost plastic products. This work aims to evaluate the effect of supercritical foaming of 3D-printed parts based on a commercial PLA matrix loaded with calcium carbonate, for single-use sustainable food contact materials. 3D-printed PLA/CaCO₃ parts were obtained by 3D printing with a 20% and 80% infill, and two infill patterns, rectilinear and triangular, were set for each of the infill percentages selected. Supercritical fluid foaming of PLA/CaCO₃ composite printed parts was performed using a pressure of 25 MPa, a temperature of 130 °C for 23 min, with a fast depressurization rate (1 s). Closed-cell foams were achieved and the presence of CaCO₃ did not influence the surface of the foams or the cell walls, and no agglomerations were observed. Foam samples with 80% infill showed subtle temperature fluctuations, and thermogravimetric analysis showed that samples were thermally stable up to ~300 °C, while the maximum degradation temperature was around 365 °C. Finally, tensile test analysis showed that for lower infill contents, the foams showed lower mechanical performance, while the 80% infill and triangular pattern produced foams with good mechanical performance. These results emphasize the interest in using the supercritical CO₂ process to easily produce foams from 3D-printed parts. These materials represent a sustainable alternative for replacing non-biodegradable materials such as Expanded Polystyrene, and they are a promising option for use in many industrial applications, such as contact materials. Full article