Journal of Polymers and the Environment最新文献

The packaging industry needs to develop new materials to replace conventional plastics. This is where bioplastics, primarily derived from biopolymers such as proteins, come into play in addressing this problem. However, given their overall mechanical properties, cross-linking methods are needed to improve their performance compared to synthetic counterparts. Thus, this article proposes the development of bioplastics using pea protein as a biopolymer and glycerol as a plasticizer in different ratios (60/40 and 70/30), and incorporating transglutaminase as a natural cross-linking agent (0.25% and 0.50% concentrations), using compression molding as a processing technique for the development of prototypes. Therefore, the mechanical, thermal, optical, physicochemical, and functional properties were analyzed, demonstrating, first of all, the obtention of a material with a glass transition temperature of approximately 65–70 °C lower than that of conventional plastics such as PET. In this way, the materials showed an improvement in flexural properties (obtaining an elastic modulus of 1–2 MPa), at the expense of a deterioration in tensile tests (with a Young’s Modulus of 20–30 and 45–50 MPa for the 60/40 and 70/30 formulations, respectively). Similarly, opacity was increased by incorporating the enzyme into the formulation, highlighting its role in the 70/30 formulation with 0.50% of the enzyme. Moreover, this enzyme also reduced the water absorption capacity by approximately 13%. This demonstrates the potential application of this type of material in dry product packaging, which maintains its properties after a period of 125 min with a moisture content of 3–5%, highlighting its viability for the development of more environmentally responsible packaging solutions.

In this study, we introduce a one-step semi-solid extrusion 3D printing strategy to fabricate gelatin-polyvinylpyrrolidone (GAG-PVP) scaffolds loaded with a low dose (0.5 wt%) of alendronate (ALN) and crosslinked in situ with 1 wt% genipin. The genipin-crosslinked ALN scaffold (GAG-PVP-GEN-ALN) demonstrated enhanced functional performance compared to both non-crosslinked GAG-PVP and GAG-PVP-ALN controls. Its peak swelling reached 462% at 5 h, surpassing the 362% of the unmodified scaffold and preventing the rapid dissolution observed for GAG-PVP-ALN, before gradually deswelling for 96 h. Water contact angle measurements confirmed that genipin fully restored surface hydrophobicity (101.9°), counteracting the pronounced wettability induced by ALN (47.8°) and exceeding the 78.2° of the GAG-PVP matrix, which is consistent with swelling ratio. Differential scanning calorimetry (DSC) indicated enhanced thermal stability of the crosslinked gelatin, with shifts in both glass transition and denaturation temperatures reflecting greater molecular rigidity despite the presence of glycerol as a plasticizer. Mechanical testing showed that while alendronate alone reduced mechanical performance, the combined inclusion of alendronate and genipin significantly enhanced scaffold properties compared to gelatin-polyvinyl pyrrolidone blend: tensile strength increased from 19.7 MPa to 39.8 MPa, elastic modulus rose from 805 MPa to 1174 MPa, and microhardness improved from 9.24 MPa to 22.3 MPa, values nearing those of native cancellous bone. The sustained ALN release profile extended from an abrupt 3 h burst in GAG-PVP-ALN to a controlled 48 h delivery in GAG-PVP-GEN-ALN, following first-order kinetics. Both direct and indirect cytotoxicity assays confirmed high cell viability (> 85%) without morphological abnormalities. These results highlight that embedding low-dose ALN within a genipin-crosslinked gelatin-PVP network results in a mechanically robust, biocompatible scaffold with tunable swelling and prolonged drug release, offering a versatile platform for localized bone tissue engineering.

In polymer optics for LED luminaires, materials are lacking which combine properties needed for a modern, circular, and biobased economy and the high technological demands. With respect to this the photostability of optical-grade polylactide (PLA) compounds with fatty acid amides as clarifiers was evaluated. Clouding of the PLA is avoided by the incorporation of two fatty acid amides with favorable performance, namely N, N′-ethylenebis(stearamide) and N, N′-ethylenebis(12-hydroxystearamide). To enable the application of such novel PLA compounds in compact LED luminaires, high photostability at elevated temperatures is essential. The compounds were irradiated with high radiant fluxes at 450 nm for a total of 5000 h. Earlier studies have already attributed high photostability to neat PLA under those conditions, whereas optical-grade polycarbonate showed signs of aging after a few hundred hours. The present study demonstrates identical photostability for the PLA compounds containing fatty acid amides. During the first thousand hours, the UV–Vis transmission of all tested PLA samples increased, while haze levels remained unchanged. Furthermore, thermal and infrared spectroscopic analyses reveal no signs of incipient photodegradation. Although a decrease in the molecular weight of the samples was identified by size exclusion chromatography, fatty acid amides are proven to have no adverse effects on the photothermal aging of PLA. These findings confirm the high photostability of optical-grade PLA compounds, making them viable eco-friendly alternatives for the replacement of fossil-based polymers in optics.

Nowadays, the development of flexible electrodes through green processes for sustainable development has received much attention. Hence, the objective of this work is to fabricate a novel, free-standing polyaniline/polyvinyl alcohol/cellulose (PANI/PVA/cellulose) electrode using gamma irradiation as an efficient green technology for practical production. Cellulose was extracted from sugarcane bagasse through alkaline treatment, then combined with PVA and PANI to form a composite film via gamma irradiation at a dose of 40 kGy at ambient temperature, with a dose rate of 9.18 kGy/h, followed by hydraulic pressing. The chemical and crystalline structures, thermal stability, morphology, wettability and mechanical properties of the flexible electrode were characterized by FTIR, XRD, TGA, FE-SEM, contact angle measurement, and a universal testing machine respectively. Four-point probe and EIS measurement were employed to investigate the electrical conductivity. The ternary composite PANI/PVA/cellulose film formed a three-dimensional network with porosity ranging from 24.2 ± 0.5% to 67.6 ± 5.1%. In the presence of PANI improved the morphology and porosity of the composite films, resulting in enhanced ion transfer and electrical conductivity. Furthermore, the tensile strength and elongation at break increased to 22.1 ± 1.1 MPa and 25.0 ± 5.0%, respectively with the addition of 0.5 wt% PANI. The obtained PANI/PVA/cellulose composite film is considered as a potential candidate to replace the commercial electrode in energy storage devices due to its cost-effectiveness, eco-friendliness, and flexibility.

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An innovative solvent casting method was used to develop a series of biodegradable PCL/APTES-functionalized bioactive glass (F-BG) nanocomposites, with the goal of creating bone scaffolds that provide both robust mechanical support and a favorable biological environment. The study systematically evaluated composites with BG content ranging from 15% to 45%. Mechanical testing showed that the PCL/32% F-BG composite exhibited the highest flexural strength (25.8 MPa), while the PCL/45% F-BG composite achieved the highest elastic modulus (1793 MPa). This enhanced mechanical performance is crucial, as it allows the scaffold to more closely match the mechanical properties of adjacent bone tissue, a key factor for successful osteointegration. Microstructural analysis confirmed the uniform dispersion of the 56 nm BG nanoparticles, which underpinned the superior properties. Furthermore, comprehensive biological evaluations) including hydrophilicity, controlled degradation, and cytocompatibility using NIH3T3 cells (demonstrated the composite’s excellent biological response. The biocompatibility of the nanocomposites was confirmed by the MTT assay, which showed a notable increase in cell viability from approximately 84% for neat PCL to over 92% for the optimal 32% F-BG composite.

Graphical Abstract

Block copolymers, unlike reactive compatibilizers, can stably localize at the interface without reducing biodegradation rate, making them attractive compatibilizers for PLA/PBAT blends. For industrial use, they should be synthesized from commercial PBAT by melt polymerization to lower costs. However, melt polymerization is exposed to ambient moisture, leading to concurrent formation of PLA homopolymer. In this study, PLA–PBAT block copolymers were synthesized by both solution and melt polymerization with different lactide feed ratios. Melt polymerization was performed in an internal mixer as a precursor to reactive extrusion. Products were characterized by NMR, FT-IR, GPC, DSC, and TGA, and performance in blends was evaluated using DSC, SEM, and UTM. Melt samples displayed two cold crystallization peaks. The high-temperature peak corresponded to PLA homopolymer and became more pronounced with increasing lactide feed ratio. This suggests that excess lactide was consumed in homopolymerization. The presence of PLA homopolymer was more clearly observed in DTA than in GPC. In blends, melt samples improved tensile strength gradually with increasing lactide ratio, whereas solution samples showed the highest strength at a 1:1 PBAT-to-lactide ratio. At the ratio, the blend with solution samples exhibited higher tensile strength than that with melt samples. However, this difference was mitigated when melt samples with higher lactide ratios were incorporated at contents of 5 phr or less. The pristine blend formed metastable α′ crystals, while melt-sample-containing blends exhibited both α and α′ structures, with the α form becoming more dominant at higher lactide ratios.

Membrane technology is a promising solution for industrial wastewater treatment, though membrane fouling remains a major limitation. In this study, PVDF membranes were fabricated by incorporating 3-glycidoxypropyltrimethoxysilane (GPTMS)-modified cellulose (C-GPTMS) derived from oil palm empty fruit bunches (OPEFB) to enhance hydrophilicity and reduce fouling. C-GPTMS was synthesized via reflux and introduced into PVDF membranes via phase inversion. The resulting membranes exhibited increased water flux and significantly improved dye rejection up to 90% for methylene blue (MB) and 80% for reactive yellow (RY). Antifouling performance was also enhanced, with flux recovery ratios (FRR) reaching 99% for MB and 85% for RY. After five filtration cycles, the membranes retained over 80% of their initial flux, demonstrating excellent reusability for dye removal in wastewater treatment.

The hydrogel was synthesized via aqueous solution polymerization using carboxymethyl starch (CMS) as the base polysaccharide, ammonium persulfate (APS) as the initiator, N,N’-methylenebisacrylamide (MBA) as the crosslinker, and acrylamide (AAm) and acrylic acid (AAc) as the monomers. FTIR, XRD, FESEM, and TGA were used to characterize the synthesized hydrogel. Inhibitor concentration, crosslinker concentration, weight ratio of monomers, and weight ratio of CMS to total monomers were evaluated and optimized to affect swelling capacity. Hydrogel swelling behavior was investigated in relation to pH, time, temperature, and salinity of water. The samples exhibited the greatest swelling at pH 7 due to the carboxylate anions formed from their constituents. In distilled water at 25 °C, the sample prepared under optimized conditions absorbed 812.1 g/g of water. Increasing the temperature to 80 °C caused a 1050 g/g increase in swelling capacity. In addition, the hydrogel exhibited different swelling behavior in NaCl, MgCl₂, CaCl₂, FeCl₃, and AlCl₃ aqueous solutions, and its swelling ratio decreased with increasing cation valence. A Super Case II transport mechanism has also been demonstrated (diffusion exponent n ≥ 1.0), indicating that rapid water uptake is primarily driven by accelerated polymer chain relaxation.

Graphical Abstract

Recently, due to environmental concerns, research has been directed to develop water-based adhesives to replace chemically derived toxic, and non-biodegradable traditional adhesives. In the present study, the exopolysaccharide produced by Priestia aryabhattai KAG-18 (EPS/KAG-18) demonstrated adhesiveness, showing potential as an eco-friendly adhesive that can bind various surfaces, including wood, metal, and acrylic. The lap shear strength of the EPS/KAG-18 adhesive bonded teak wood to teak wood, pine wood to pine wood, metal-to-metal, and acrylic-to-acrylic exhibited 6.87 ± 0.68 MPa, 5.80 ± 0.96 MPa, 34.03 ± 1.37 MPa, 0.44 ± 0.09 MPa, respectively. At higher EPS/KAG-18 adhesive, teak wood to teak wood joints showed higher shear strength, compared to other specimens. A commercially available polyvinyl acetate (PVA) based adhesive exhibited lap shear strength of 7.87 ± 0.54 MPa for teak wood, 6.83 ± 1.57 MPa for pine wood, 6.05 ± 2.71 MPa for metal, and 0.70 ± 0.25 MPa for acrylic. Thermal stability tests using TGA and DSC analyses revealed that the EPS/KAG-18 adhesive remained stable up to 250 °C without the presence of a glass transition. FT-IR spectroscopy indicated the presence of hydroxyl and carboxyl groups in EPS/KAG-18 characteristics of polysaccharides. Contact angle measurements indicated a hydrophilic nature on wood and metal surfaces (< 90°) and hydrophobic characteristics on acrylic substrates (> 90°). EPS/KAG-18 (3.0 to 9.0% w/v) solutions showed shear-thinning rheology, G’ > G”, and best fit to the Herschel–Bulkley model applicable for fluids with yield stress. Finite element analysis (FEA) of the EPS/KAG-18 bonded single lap joint of acrylic specimens revealed that the stress was concentrated at the edges of the joint, while minimal stress was observed in the central region. Hence, in the present study, we report for the first time the modelling of rheological behaviour and FEA of adhesive joints along with its adhesive properties.

Chitosan/polyvinylpyrrolidone (CH/PVP) scaffolds incorporating varying concentrations of dicalcium silicate (CS) particles − 0, 5, and 15 wt% (the corresponding codes CS0/CH: PVP, CS5/CH: PVP, and CS15/CH: PVP, respectively) - were fabricated using the freeze-drying technique to control their physicochemical properties, biocompatibility, drug release profile, and antimicrobial activity. Different analytical techniques were used, such as Transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) to determine structural and compositional characteristics of either ceramic powder or scaffolds. In vitro bioactivity and biodegradation were evaluated using simulated body fluid (SBF) maintained at 37 °C. Scanning electron microscopy (SEM) images indicated extensive apatite formation on the CS15/CH: PVP scaffold, forming a dense mineralized layer on its surface. The impact of incorporating CS on drug release behavior was examined using gentamicin as a model antibiotic agent. Results showed that increasing CS content led to a significant decrease in the drug release rate, suggesting a sustained release profile. Cytotoxicity tests using the human fibroblast cell line BJ1 demonstrated that all scaffold formulations exhibited minimal toxicity and were comparable to the negative control. The antimicrobial effectiveness was tested against Bacillus subtilis, Staphylococcus aureus, Escherichia coli, Salmonella typhi, and Candida albicans, demonstrating the scaffolds’ broad-spectrum antibacterial and antifungal capabilities. Overall, the CS/CH: PVP scaffolds presented a multifunctional platform with potential for bone tissue regeneration and localized antibiotic delivery.