Search Results (143)

Sulfur-containing polymers are unique sustainable materials with promise for the development of various adsorbents for environmental remediation. However, they have not been explored for CO₂ capture despite reports on its ability to decontaminate various aqueous pollutants. This study reports on the single-step synthesis of a diamine-functionalized sulfur-containing copolymer by the thermally induced radical copolymerization of N2,N2-Diallylmelamine (NDAM), a difunctional monomer, with sulfur and explores its use for CO₂ capture. The influence of reaction parameters such as the weight ratios of sulfur to NDAM, reaction temperature, time, and the addition of a porogen on the properties of aminated copolymer was investigated. The resulting copolymers were characterized using FTIR, TGA, DSC, SEM, XRD, and BET surface area analyses. The incorporation of NDAM directly imparted amine functionality while stabilizing the polysulfide chains by crosslinking, leading to a thermoset copolymer with an amorphous structure. The addition of a NaCl particle porogen to the S/NDAM mixture generated a mesoporous structure, enabling the resulting copolymer to be tested for CO₂ adsorption under varying pressures, leading to an adsorption capacity as high as 517 mg/g at 25 bar. This work not only promotes sustainable hybrid materials that advance green chemistry while aiding CO₂ mitigation efforts but also adds value to the abundant amount of sulfur by-products from petroleum refineries. Full article

In the present study, we prepared crosslinked particles of poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBH) to investigate their performance as impact modifiers. The mechanical properties of crystalline PHBH comprising 5.6 mol% 3-hydroxyhexanoate (3HHx) were modified by the addition of amorphous particles of PHBH with 28 mol% 3HHx (PHBH28). The tensile impact strength of the mixture was improved by the addition of PHBH28 particles, particularly when they were crosslinked. The size of the dispersed uncrosslinked PHBH28 particles was sensitive to the processing method. However, the crosslinked PHBH28 particles retained their form under any processing conditions, and a smaller particle size was achieved, leading to shear yielding. The samples containing crosslinked PHBH28 particles exhibited intense stress-whitening after impact testing. The resulting voids were ascribed to cavitation in the particles, which must have been responsible for the improved mechanical properties of the samples. Moreover, the crosslinked particles did not affect the excellent biodegradability of PHBH in seawater. Full article

In this study, the aerobic degradation of sweet potato (Ipomoea batatas; SP) and diamond yam (Dioscorea rotundata; DY) thermoplastic starch (TPS) blends, combined with polylactic acid (PLA) and varying ratios of citric acid (CA) as a crosslinker, was investigated in compost and seawater environments. After 50 d of composting, weight losses in the SP-TPS/CA/PLA blends were 56.9%, 52.3%, and 77.5%, while those of DY-TPS/CA/PLA were 55.8%, 52.2%, and 62.2% for 0%, 1%, and 5% CA, respectively. In seawater, the SP-TPS/CA/PLA blends showed weight losses of 52.9%, 46.8%, and 61.5%, and the DY-TPS/CA/PLA blends lost 35.2%, 32.1%, and 43.9% for the same CA ratios, respectively. In both media, SEM revealed structural damage, holes, cracks, and changes in coloration, reflecting microbial activity. Additionally, in compost and seawater, TGA results showed that PLA remained the predominant component after 50 d, as most of the degradation occurred on TPS due to its amorphous structure and higher hydrophilicity. In both media, the SP-TPS/CA5/PLA and DY-TPS/CA5/PLA blends exhibited faster degradation, whereas SP-TPS/CA1/PLA and DY-TPS/CA1/PLA displayed higher stability and lower disintegration. Additionally, all blends required over 50 d to degrade completely, as evidenced by the absence of a plateau phase in the biodegradability curves. Statistical analysis showed that, in seawater, the degradation behavior of the blends was similar to cellulose. However, the CA ratio had a greater impact on the compost degradation of the blends with SP-TPS than on DY-TPS. Therefore, the critical factors influencing the degradation of these blends are the starch source and the CA ratio. Full article

To understand the effect of the hydroxyl group and processing temperatures on dielectric losses of flame retardants and flame-retardant polymers, the performance difference between 6-methyldibenzo[c,e][1,2]oxaphosphinine 6-oxide (DOPO-Me) and 6-(hydroxymethyl)dibenzo[c,e][1,2]oxaphosphinine 6-oxide (DOPO-HM) has been investigated, respectively, in non-polar and polar polymers at 7–20 GHz. DOPO-HM and DOPO-Me differ by only one OH group. The former demonstrates a lower dissipation factor (Df) than the latter, owing to hydrogen bonds. In polystyrene and crosslinked polyphenylene oxide, both flame retardants increase a dielectric loss of flame-retardant polymers, with DOPO-HM being less detrimental because of its higher crystallizability and lower plasticization. In polar poly(methyl methacrylate) (PMMA), conformational changes in PMMA main chains caused by flame retardants and high processing temperatures lead to an early Df drop of PMMA at low loadings of the flame retardants. At high loadings, a change in the physical form of flame retardants from a primitive crystalline state to an amorphous state increases a dielectric loss of flame retardant PMMA, with DOPO-HM resulting in a slightly higher dielectric loss than DOPO-Me. These results prove that the effect of a hydroxyl group in organophosphorus structures on the dielectric loss of flame-retardant polymers is crucially dependent on its interaction with the polymer matrix. Full article

This study investigated the conversion of cellulose from rice husk (RH) and straw (RS), two types of agricultural waste, into Carboxymethyl cellulose (CMC). Cellulose was extracted using KOH and NaOH, hydrolyzed, and bleached to increase purity and fineness. The cellulose synthesis yielded a higher net CMC content for RH-CMC (84.8%) than for RS-CMC (57.7%). Due to smaller particle sizes, RH-CMC exhibited lower NaCl content (0.77%) and higher purity. FT-IR analysis confirmed similar functional groups to commercial CMC, while XRD analysis presented a more amorphous structure and a higher degree of carboxymethylation. A biodegradable film preparation of starch-based CMC using citric acid as a crosslinking agent shows food packaging properties. The biodegradable film demonstrated good swelling, water solubility, and moisture content, with desirable mechanical properties, maximum load (6.54 N), tensile strength (670.52 kN/m²), elongation at break (13.3%), and elastic modulus (2679 kN/m²), indicating durability and flexibility. The RH-CMC film showed better chemical and mechanical properties and complete biodegradability in soil within ten days. Applying the biodegradable film for tomato preservation showed that wrapping with the film reduced weight loss more efficiently than dip coating. The additional highlight of the work was a consumer survey in Thailand that revealed low awareness but significant interest in switching to alternative uses, indicating commercial potential for eco-friendly packaging choices and market opportunities for sustainable materials. Full article

Alginate-ZnO nanoparticles (ZnO_nano) composite wound dressing membranes were prepared with two different ZnO_nano concentrations (0.03 and 0.20 g ZnO/g sodium alginate) and cross-linked with two different calcium treatments (low and high Ca⁺⁺concentration) to evaluate the influence of nanoparticle content and cross-linking degree on membrane attributes. ZnO_nano addition did not significantly alter the mechanical properties, water vapor permeability, swelling degree in water and the alginate amorphous nature of the nanocomposite membranes. The increase in cross-linking degree, on the other hand, altered the microstructure of the membranes, increased the tensile strength and reduced the water vapor permeability of the nanocomposite membranes. The presence of ZnO_nano in alginate membranes granted them antibacterial activity in vitro against Pseudomonas aeruginosa and Staphylococcus aureus and substantially increased the absorption capacity in phosphate buffer and fetal bovine serum solutions, validating their potential use as wound dressings. Full article

This research investigates the production of galactomannan from Adenanthera pavonina L. in its crude form and its subsequent crosslinking with glutaraldehyde under various pH conditions. The study involved the creation of films and sponges from these materials, followed by a comprehensive analysis of their structural, thermal, swelling, and electrical properties. Galactomannan was crosslinked with a fixed concentration of 0.2 mol/L of glutaraldehyde, with pH levels ranging from 3 to 7. These films and sponges were prepared through a slow solvent evaporation process. The research encompassed multiple analytical techniques, including Fourier transform infrared spectroscopy, X-ray diffraction, thermogravimetry, swelling profile assessments, and impedance spectroscopy. The findings from structural analysis indicated that variations in pH did not alter the amorphous nature of the samples but did influence the interactions between galactomannan molecules and restricted the mobility of polymeric chains, which resulted in different dielectric responses. Crosslinked samples exhibited reduced water solubility compared to unprocessed galactomannan. Crosslinking also decreases the ability of the material to polarize and align in response to the electric field, which justifies why crosslinked samples present a lower dielectric constant than the crude sample. Full article

The properties of EVA copolymers with various vinyl acetate (VA) contents were compared, with EVA 206 (6 wt.% VA) and EVA 212 (12 wt.% VA) having the same melt flow indices of 2 g/10 min. The impact of electron irradiation at levels of 60, 120, and 180 kGy was studied. Four testing methods were employed as follows: wide-angle X-ray diffraction (WAXD); differential scanning calorimetry (DSC); dynamic mechanical analysis (DMA), using a high-temperature frequency sweep at 150 °C; and gel content analysis. The amount of crystalline phase was determined by WAXD and DSC. Copolymers with a higher VA content (EVA 212) had lower crystallinity. The increase in the amorphous phase allows for the greater movement of radicals, enabling them to react and form cross-links. The effects of the VA content, radiation dose, and frequency on dynamic mechanical properties were investigated by DMA. The DMA analysis focused on the shear storage modulus $G^{\prime }$, damping factor $\tan \delta$, and complex viscosity ${\eta }^{*}$. After irradiation, the damping factor $\tan \delta$ decreased with an increasing VA content, indicating improved elasticity and a higher degree of cross-linking. A gel content analysis was used to calculate the parameters of the Charlesby-Pinner and Charlesby–Rosiak equations, which help with the determination of the relationship between cross-linking and chain scission. The ratio of cross-linking to scission $G\left(X\right)/G\left(S\right)$ was higher for the EVA with a higher VA content (EVA 212). Due to a higher VA content (12 wt.%), EVA 212 exhibits more efficient network formation. Full article

Developing biodegradable complex fertilizers is crucial for sustainable agriculture to reduce the environmental impact of mineral fertilizers and enhance soil quality. This study evaluated chitosan-based hydrogel coatings for sodium alginate matrices encapsulating amino acid hydrolysates from mealworm larvae, known for their plant growth-promoting properties. The research aims to identify the potential of biopolymer matrices for producing biodegradable slow-release fertilizers and to outline future development pathways necessary for this technology to be usable in the fertilizer industry. Chitosan coatings prepared with citric acid and crosslinked with ascorbic acid optimized plant growth, while those using acetic acid negatively affected it. Water absorption and nutrient release tests showed that chitosan coatings reduced water uptake and slowed initial nutrient release compared to uncoated samples. Leaching assays confirmed controlled-release behavior, with an initial burst followed by stability, driven by alginate–chitosan interactions and ion exchange. The X-ray diffraction (XRD) analysis revealed that adding hydrolysate and chitosan increased amorphousness and reduced porosity, improving structural properties. Thermogravimetric analysis (TGA) and Fourier-transform infrared (FTIR) spectroscopy demonstrated enhanced homogeneity and the presence of chemical interactions, which led to improvements in the material’s thermal stability and chemical characteristics. Biodegradation tests indicated greater durability of chitosan-coated composites, although hydrolysate incorporation accelerated decomposition due to its acidic pH. Germination tests confirmed no phytotoxicity and highlighted the potential of biopolymeric matrices for slow nutrient release. These findings indicate the possibilities of chitosan-coated alginate matrices as sustainable fertilizers, emphasizing the importance of adjusting coating composition and hydrolysate pH for enhanced efficacy and environmental benefits. The main recommendation for future research focuses on optimizing the chitosan coating process by exploring whether adding hydrolysate to the chitosan solution can reduce diffusional losses. Additionally, investigating the use of glycerol in the alginate matrix to minimize pore size and subsequent losses during coating is suggested. Future studies should prioritize analyzing percentage losses during the crosslinking of the alginate matrix, chitosan coating, and final shell crosslinking. This pioneering research highlights the potential for encapsulating liquid fertilizers in biopolymer matrices, offering promising applications in modern sustainable agriculture, which has not been studied in other publications. Full article

High-Density Polyethylene (HDPE) and Low-Density Polyethylene (LDPE) films were used to create nanoplastic (NP) models, with the shape of delamination occurring during degradation. In the case of HDPE, selective degradation occurred not only in the amorphous part, but also in the crystalline part at the same time. Some of the lamellae that extend radially to form the spherulite structure were missing during the 30-day degradation. The length of these defects was less than 1 µm. HDPE disintegrated within units of spherulite structure by conformational defects in lamellae, and the size of the fragments obtained had a wide distribution. LDPE was synthesized by radical polymerization, so it contained a cross-linked part. The part was not sufficiently fused, and when it degraded, it delaminated and separated preferentially. The zeta potential reached a minimum value of approximately −20 mV at the degradation time of 21 days, and then increased. This complex dependence on degradation time was due to NP particle aggregation. The addition of 1% Triton(R) X-114 surfactant was effective in stabilizing the NP dispersion. The particle size remained constant at around 20 nm for degradation times of 15–30 days. Full article

This paper reviews the recent development of organic–inorganic hybrid dielectric materials for application as gate dielectrics in thin-film transistors (TFTs). These hybrid materials consist of the blending of high-k inorganic dielectrics with polymers, and their resulting properties depend on the amount and type of interactions between the organic and inorganic phases. The resulting amorphous networks, characterized by crosslinked organic and inorganic phases, can be tailored for specific applications, including gate dielectrics in TFTs. As dielectric materials, they offer a synergistic combination of high dielectric constants, low leakage currents, and mechanical flexibility, crucial for next-generation flexible electronics. Furthermore, organic–inorganic hybrid materials are easily processed in solution, allowing for low-temperature deposition compatible with flexible substrates. Various configurations of these hybrid gate dielectrics, such as bilayer structures and polymer nanocomposites, are discussed, with an emphasis on their potential to enhance device performance. Despite the significant advancements, challenges remain in optimizing the performance and stability of these hybrid materials. This review summarizes recent progress and highlights the advantages and emerging applications of low-temperature, solution-processed hybrid dielectrics, with a focus on their integration into flexible, stretchable, and wearable electronic devices. Full article

In this study, poly(vinyl-alcohol) (PVA)/chitosan (CS) polymer blend films with different amounts of CS (0, 5, 20 and 35 wt. %) crosslinked by glutaraldehyde (GA) were prepared. The structure and properties of the prepared polymer films were studied by means of dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC), and the time-lag permeation technique. The DMA analysis showed that CS reduces the crystallinity degree of PVA, leading to a higher amount of the amorphous phase contributing to the α relaxation that corresponds to the glass-to-rubber transition. However, the mobility of the amorphous phase can be restricted with crosslinking with 1 wt. % GA. Interaction between the PVA and the CS was confirmed by DCS analysis. Additionally, the influence of the CS and crosslinking on the permeation of nitrogen molecules was investigated. The permeation was examined by the time-lag method. It was found that the addition of CS and GA to PVA improves barrier properties. Full article

The tribological performance of PFPE oil and the Ti:WS₂/PFPE composite lubricating system with different oil amounts was investigated under a proton radiation (PR) irradiation environment. After PR irradiation, PFPE molecules occurred during cross-linking and a polymerization reaction and formed a volatile small molecular compound, which deteriorates the tribological performance of the Ti:WS₂/PFPE system. The tribological properties of the Ti:WS₂/PFPE system rely strongly on oil amount. For an unirradiated Ti:WS₂/PFPE system, the amorphous layer of transfer film near the sliding contact area was converted into a well-defined crystalline WS₂ layer with a (002) plane induced by the friction process. After PR irradiation, the transfer film became thicker and showed a wholly amorphous structure due to the difficulty in preventing the entrance of O and showed no reorientation with induced friction. Full article

Until now, no slow-release urea (SRU) fertilizer has been made using the screw press method and the powder of plant residues rich in polyphenols, which are considered eco-friendly materials due to some health benefits for agricultural soil. Therefore, the goal of this experiment was to synthesize a novel SRU fertilizer using “eco-friendly materials” and the “screw press method”. In order to achieve this goal, urea (U) was innovatively and highly intercalated between interlayers of impure montmorillonite (Mt) (bentonite) with the help of polyphenol-rich pomegranate peel powder (PPP) by a single-screw oil press machine. The experiment had five treatments, including a fixed ratio of U/Mt (4:1) with variable ratios of U/Mt/PPP (w/w), including 4:1:0 (F₁), 4:1:1 (F₂), 4:1:1.5 (F₃), and 4:1:2 (F₄). Control (U) and F₅ treatments (U/PPP at ratio of 4:1) were also included. These composites were fabricated using a single-screw oil press machine. The produced composites were characterized using FTIR, SEM, XRD, and TG analyses. The release pattern was studied using the White method. The XRD (low-angle) results revealed that the interlayer space of Mt increased from 12.3 Å in bentonite to 19.4 Å, 27.3 Å, 25.7 Å, and 0 Å in the F₁, F₂, F₃, and F₄ composites, respectively, which is an indicator of the high intercalation of U between the interlayers of Mt, especially in the F₂ treatment. The XRD (low- and normal-angle) analyses indicated that the two main reasons for the high intercalation in the F₂ treatment were, first, the complete conversion of urea from a crystalline to an amorphous state by PPP and, second, the increase in the interlayer space of Mt nano-sheets by PPP. It seems that PPP at a low concentration (F₂) can have a positive effect on the placement of U in the interlayer space, but at high concentrations (F₄), due to intensive pectin gelation, the space between the Mt layers grows until complete exfoliation. FTIR spectra and TG analysis also confirmed this hypothesis. SEM images revealed the formation of an intensive crosslink between U, Mt, and PPP. A release test in water revealed that only 10% of U in the F₂ treatment was released after 10 h, and 87% after 120 h, which indicates the satisfactory slow-release pattern of this composite. By comparing the results of the present study with the other SRUs reported in the literature, it can be concluded that the composite F₂, in addition to offering valuable polyphenol-rich plant materials, had an acceptable performance in the aspect of the U release pattern. Full article

We cross-linked unfractionated heparin (H) using epichlorohydrin (E), in the absence or presence of imidazole (I), using various ratios of H, E, and I substances. The objectives and goals were to use the reaction for the preparation of medical materials suitable for blood sample applications. Nuclear magnetic resonance indicated the involvement of an H-end sequence [H-(1→4)-β-D-GlcA-(1→3)-β-D-Gal-(1→3)-β-D-Gal-(1→4)-β-D-Xyl-α-Ser] in the linkage with the 2-hydroxypropyl bridge. The yields of the individual experiments were found to increase in the following ratios: 1H/1E/3I (24%) < 1H/1E/2I (32%) < 1H/3E (42%) < 1H/1E/1I (46%) < 1H/2E (64%) < 1H/1E (77%). According to size-exclusion chromatography with multiple-angle light scattering (SEC-MALS) analysis, the mass at the peak increased in the following order: H (9292 g/mol) < 1H/1E (9294 g/mol) < 1H/2E (9326 g/mol) < 1H/3E (9708 g/mol) < 1H/1E/2I (11,212 g/mol) < 1H/1E/3I (12,301 g/mol) < 1H/1E/1I (13,800 g/mol) and in the reverse order with the increase in amount of epichlorohydrin and imidazole, i.e., 1H/1E > 1H/2E > 1H/3E and 1H/1E/1I > 1H/1E/2I > 1H/1E/3I. X-ray diffraction revealed that all prepared films were amorphous. An evaluation of the surface morphology using atomic force microscopy (AFM) confirmed a relatively low films roughness (~0.9–3.6 nm). The surface reduced elastic modulus, determined by the PeakForce quantitative nanomechanical mapping (PF-QNM) technique, was found to increase by up to ~63% for films cross-linked with E in the absence of I when compared with the results for the H substrate. A negligible change in modulus was, however, observed for films cross-linked in the presence of I, or was even reduced by ~15% (1H/1E/3I) compared to that for the H substrate. This could be explained by the parallel cross-linking of H only with E within its serine end unit and in competition with only one nitrogen of I. According to the highest yield (77%) of 1H/1E, the preferred product is the following: H-(1→4)-β-D-GlcA-(1→3)-β-D-Gal-(1→3)-β-D-Gal-(1→4)-β-D-Xyl-α-Ser-CH₂-CH(OH)-CH₂-OH. For the 1H/1E/1I (46% yield), 1H/1E/2I (32%), and 1H/1E/3I (24%) products, the cross-linked motif was the same, and the difference represented the surplus amount of the imidazolium cation ionically bound to the heparin anionic groups. Full article