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1.
Materials (Basel) ; 17(15)2024 Aug 05.
Artigo em Inglês | MEDLINE | ID: mdl-39124545

RESUMO

Improving the durability of short-rotation wood can be achieved through chemical and thermal modification. Chemical and thermal modification can have an impact on the physicochemical properties of wood, which can affect wood's surface characteristics and its resistance to weathering. The purpose of this study was to investigate the surface characteristics and artificial weathering resistance of chemically and thermally modified short-rotation teak wood coated with linseed oil (LO)-, tung oil (TO)-, and commercial oil-based coatings consisting of a mixture of linseed oil and tung oil (LT) and commercial oil-based polyurethane resin (LB) coatings. The short-rotation teak woods were prepared in untreated and treated with furfuryl alcohol (FA), thermal treatment (HT) at 150 and 220 °C, and combination of glycerol-maleic anhydride (GMA) impregnation with thermal treatment at 150 and 220 °C. The surface characteristics measured were surface free energy, wettability, Persoz hardness, bonding quality, and color changes before and after artificial weathering exposure. The results showed that chemical and thermal modifications treatment tended to reduce total surface free energy (SFE), hardness, wettability, and bonding quality. FA and GMA at 220 °C treatments provided homogenization effect on surface characteristics, especially in total SFE and wettability. The total SFE of untreated wood ranged from 45.00 to 51.13 mN/m, and treated wood ranged from 40.58 to 50.79 mN/m. The wettability of oil-based coating according to K-value ranged from 0.20 to 0.54. TO presented better photostability than LO. Short-rotation teak wood coated with oil-based commercial coatings presented better weathering resistance compared to pure natural drying oil. Commercial oil-based coatings provided better weathering protection for the chemically and thermally modified teak wood. The application of oil-based coatings on chemically and thermally modified short-rotation teak is being considered for the development of a better wood-protection system.

2.
Heliyon ; 10(12): e32885, 2024 Jun 30.
Artigo em Inglês | MEDLINE | ID: mdl-38975132

RESUMO

Tropical fruit peels from mangosteen, rambutan, and banana are rich in phytonutrients. Several studies reported that the phytonutrients improved rumen fermentation. Nevertheless, the combination of phytonutrients and essential fatty acids on rumen fermentation have not yet been investigated. Hence, the aim of this research was to investigate the influence of fruit peel pellets (mangosteen, rambutan, and banana peel; MARABAC) containing phytonutrients and tung oil supplementation on rumen fermentation and the degradability of nutrients. Four levels of MARABAC (0, 2, 4, and 6 %) and four levels of tung oil (0, 2, 4, and 6 %) were supplemented with concentrate according to a 4 × 4 factorial arrangement in a completely randomized design (CRD). Rumen fermentation parameters, including gas production, ammonia nitrogen (NH3-N), volatile fatty acids (VFA), nutrient degradability (IVDMD and IVOMD), and in vitro methane (CH4) production were determined. The results showed that there were no interactions between MARABAC and Tung oil treatments for all terms of kinetic gas and cumulative gas, IVDMD and IVOMD, and in vitro ammonia-nitrogen (NH3-N). However, when combining MARABAC and tung oil beyond the 4 % level, VFA and in vitro CH4 production was severely affected. The supplementation of MARABAC and tung oil decreased gas production and rumen nutrient degradability (p < 0.05). Acetate (C2) and propionate (C3) production were significantly affected by the level of MARABAC supplementation. NH3-N was dropped when levels of MARABAC and tung oil supplementation were increased. There were interactions between MARABAC and tung oil on total VFA and in vitro CH4 production at 8 h (h). In addition, in vitro CH4 production decreased (p < 0.05) with higher levels of MARABAC supplementation. It could be concluded that MARABAC and tung oil supplementation significantly contributed to improving the production of gas and could be applied to decrease rumen CH4 production, thereby reducing the emission of greenhouse gases.

3.
Int J Biol Macromol ; 277(Pt 1): 133847, 2024 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-39084982

RESUMO

Textiles with self-cleaning and anti-icing capabilities in cold climates are essential for outdoor workers and enthusiasts. Superhydrophobic modification of textile surfaces is effective in imparting these characteristics. Although there are numerous methods available for manufacturing superhydrophobic textiles, careful consideration is warranted for environmental concerns over fluorochemicals, stability of superhydrophobic coatings, and fabric breathability. In this work, we utilized biomass resources such as tung oil and behenic acid, along with zeolitic imidazolate framework (ZIF-8), to modify cotton fabrics, thereby creating an innovative behenic acid/tung oil/ZIF-8 modified cotton (BTZC) fabric with anti-icing and self-cleaning features. This material manifests a unique nanoflower-shaped surface morphology, demonstrating exceptional superhydrophobicity with a static water contact angle (CA) of 162° and a sliding angle (SA) of 2°. Moreover, BTZC excels in its thermal stability, breathability, and resistance to icing. Equally impressive is its robust stability, as evidenced through rigorous testing under continuous washing and abrasion, sustained high and low temperatures, extreme pH environments, and immersion in various chemical solvents. BTZC presents as a fluorine-free, durable, economically viable alternative for outdoor textile applications, marking substantial progress in the utilization of biomass and metal-organic framework materials in the textile industry and promising implications for value enhancement.


Assuntos
Fibra de Algodão , Interações Hidrofóbicas e Hidrofílicas , Têxteis , Zeolitas , Zeolitas/química , Compostos de Tungstênio/química
4.
Materials (Basel) ; 17(12)2024 Jun 08.
Artigo em Inglês | MEDLINE | ID: mdl-38930179

RESUMO

Loose-fill thermal composite insulation produced from surface-modified wood scobs has been explored as a potential fire-resistant material for building envelopes. This work involves fire resistance behavior comparisons between four coating systems consisting of liquid glass, liquid glass-tung oil, liquid glass-expandable graphite, and liquid glass-tung oil-expandable graphite. The techniques of thermogravimetric and differential thermogravimetric analyses, gross heat combustion via a calorimetric bomb, cone calorimetry, SEM imaging of char residues, and energy dispersive spectrometry for elemental analysis, as well as propensity to undergo continuous smoldering, were implemented. The coating technique resulted in greater thermal stability at a higher temperature range (500-650 °C) of the resulting loose-fill thermal composite insulation, reduced flame-damaged area heights after the exposure of samples at 45° for 15 s and 30 s, with a maximum of 49% decreased gross heat combustion, reduced heat release and total smoke release rates, improved char residue layer formation during combustion and changed smoldering behavior due to the formation of homogeneous and dense carbon layers. The results showed that the highest positive impact was obtained using the liquid glass and liquid glass-expandable graphite system because of the ability of the liquid glass to cover the wood scob particle surface and form a stable and strong expanding carbon layer.

5.
Materials (Basel) ; 17(12)2024 Jun 19.
Artigo em Inglês | MEDLINE | ID: mdl-38930369

RESUMO

As a renewable, environmentally friendly, natural, and organic material, wood has been receiving extensive attention from various industries. However, the hydrophilicity of wood significantly impacts the stability and durability of its products, which can be effectively addressed by constructing superhydrophobic coatings on the surface of wood. In this study, tung oil, carnauba wax, and silica nanoparticles were used to construct superhydrophobic coatings on hydrophilic wood surfaces by a facile two-step dip-coating method. The surface wettability and morphology of the coatings were analyzed by a contact angle meter and scanning electron microscope, respectively. The results suggest that the coating has a micron-nanosized two-tiered structure, and the contact angle of the coating is higher than 150° and the roll-off angle is lower than 10°. Sandpaper abrasion tests and UV diffuse reflectance spectra indicate that the coatings have excellent abrasion resistance and good transparency. In addition, the coated wood shows excellent self-cleaning and water resistance, which have great potential for applications in industry and furniture manufacturing.

6.
Int J Biol Macromol ; 272(Pt 2): 132602, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38788868

RESUMO

Tung oil is commonly utilized for coating protection in wooden products, often attracting attention for its appearance, antimicrobial capabilities, and insect-resistant coatings. However, its poor mechanical properties and poor weather resistance stem from excessive self-crosslinking of surplus conjugated double bonds and molecular chains, resulting in poor film wrinkling. Therefore, this study introduces natural rubber via the Diels-Alder reaction to consume the residual double bonds in tung oil, resulting in tung oil/natural rubber composite coatings (NRTO) with excellent mechanical properties and weather resistance. The results indicate that NRTO exhibits excellent mechanical properties, including high elongation (32 %) and strong adhesion (4.55 MPa). Furthermore, NRTO demonstrates outstanding acid resistance and UV aging resistance. Given its many benefits, NRTO film emerges as a promising candidate for substantially protecting wood surfaces in demanding environments.


Assuntos
Óleos de Plantas , Borracha , Madeira , Borracha/química , Madeira/química , Óleos de Plantas/química , Reação de Cicloadição , Fenômenos Mecânicos
7.
Polymers (Basel) ; 16(7)2024 Mar 26.
Artigo em Inglês | MEDLINE | ID: mdl-38611167

RESUMO

Tung oil (TO) microcapsules (MCs) with a poly(urea-formaldehyde) (PUF) shell were synthesized via one-step in situ polymerization, with the addition of graphene nanoplatelets (GNPs) (1-5 wt. %). The synergistic effects of emulsifiers between gelatin (gel) and Tween 80 were observed, with gel chosen to formulate the MCs due to its enhanced droplet stability. SEM images then displayed an increased shell roughness of the TO-GNP MCs in comparison to the pure TO MCs due to the GNP species on the shell. At the same time, high-resolution transmission electron microscopy (TEM) images also confirmed the presence of GNPs on the outer layer of the MCs, with the stacked graphene layers composed of 5-7 layers with an interlayer distance of ~0.37 nm. Cross-sectional TEM imaging of the MCs also confirmed the successful encapsulation of the GNPs in the core of the MCs. Micromanipulation measurements displayed that the 5% GNPs increased the toughness by 71% compared to the pure TO MCs, due to the reduction in the fractional free volume of the core material. When the MCs were dispersed in an epoxy coating and applied on a metallic substrate, excellent healing capacities of up to 93% were observed for the 5% GNP samples, and 87% for the pure TO MC coatings. The coatings also exhibited excellent corrosion resistance for all samples up to 7 days, with the GNP samples offering a more strenuous path for the corrosive agents.

8.
Polymers (Basel) ; 16(7)2024 Mar 27.
Artigo em Inglês | MEDLINE | ID: mdl-38611176

RESUMO

Within the realm of dental material innovation, this study pioneers the incorporation of tung oil into polyurea coatings, setting a new precedent for enhancing self-healing functionality and durability. Originating from an ancient practice, tung oil is distinguished by its outstanding water resistance and microbial barrier efficacy. By synergizing it with polyurea, we developed coatings that unite mechanical strength with biological compatibility. The study notably quantifies self-healing efficiency, highlighting the coatings' exceptional capacity to mend physical damages and thwart microbial incursions. Findings confirm that tung oil markedly enhances the self-repair capabilities of polyurea, leading to improved wear resistance and the inhibition of microbial growth, particularly against Streptococcus mutans, a principal dental caries pathogen. These advancements not only signify a leap forward in dental material science but also suggest a potential redefinition of dental restorative practices aimed at prolonging the lifespan of restorations and optimizing patient outcomes. Although this study lays a substantial foundation for the utilization of natural oils in the development of medical-grade materials, it also identifies the critical need for comprehensive cytotoxicity assays. Such evaluations are essential to thoroughly assess the biocompatibility and the safety profile of these innovative materials for clinical application. Future research will concentrate on this aspect, ensuring that the safety and efficacy of the materials align with clinical expectations for dental restorations.

9.
Int J Biol Macromol ; 256(Pt 1): 128114, 2024 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-37979750

RESUMO

In this study, waterborne UV-curable coatings with self-healing properties based on transesterification were prepared using renewable biomass resources for anti-corrosion application. Tung oil (TO)-based oligomer (TMHT) was synthesized through Diels-Alder reaction of TO with maleic anhydride, subsequent ring opening reaction with hydroxyethyl acrylate (HEA), and final neutralize reaction with triethylamine. A series of waterborne UV-curable coatings were prepared from cellulose nanofibrils (CNF) stabilized TMHT-based Pickering emulsions after drying and UV light-curing processes. It is suggested that CNF significantly improved the storage stability of Pickering emulsions. The obtained waterborne UV-curable coatings with CNF of 1-3 wt% exhibited remarking coating and mechanical performance (pencil hardness up to 5 H, adhesion up to 2 grade, flexibility of 2 mm, tensile strength up to 11.6 MPa, etc.), great transmittance (82.3 %-80.8 %) and great corrosion resistance (|Z|0.01Hz up to 5.4 × 106 Ω·cm2). Because of the presence of the dynamic ester bonds in TMHT, the coatings exhibited excellent self-healing performance (78.05 %-56.34 %) at 150 °C without catalyst and external force. More importantly, the |Z|0.01Hz of the self-healing coating was higher than that of the scratched coating, indicating that the self-healing performance could extend the service life of the coating in corrosion resistant application.


Assuntos
Óleos de Plantas , Prunella , Emulsões , Biomassa , Celulose
10.
Int J Biol Macromol ; 254(Pt 1): 127792, 2024 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-37923033

RESUMO

Tung oil derivatives are promising alternatives to traditional toxic plasticizers for improving the toughness of poly (lactic acid) (PLA) films. In this study, a tung oil-based quaternary ammonium salt (Q-ETO) was synthesized using a multi-step process involving epoxidation, ring opening, and substitution reactions. PLA based composite films with various amounts of Q-ETO were prepared by solvent casting. The impact of various amount of Q-ETO on PLA/Q-ETO composite films were evaluated with regard to their mechanical properties, hydrophilicity, water vapor permeability, optical properties, thermal stability, antibacterial properties, and leaching properties. The PLA/5%Q-ETO composite film yielded the highest elongation at break (82.52 ± 9.53 %), which was 153.67 % higher than that of pure PLA. All PLA composite films showed an antibacterial efficiency exceeding 90 % against both S. aureus and E. coli. Moreover, the PLA/Q-ETO composite film blocked the transmission of both ultraviolet and visible light while preventing the permeation of water vapor. The addition of Q-ETO only weakly affected the color and thermal stability of the PLA/Q-ETO composite film. Given the numerous advantages of the PLA composite film, it has significant potential for application as a food packaging material.


Assuntos
Anti-Infecciosos , Escherichia coli , Staphylococcus aureus , Vapor , Antibacterianos/farmacologia , Poliésteres , Embalagem de Alimentos , Ácido Láctico
11.
Polymers (Basel) ; 15(3)2023 Jan 21.
Artigo em Inglês | MEDLINE | ID: mdl-36771864

RESUMO

Novel monomethoxy poly(ethylene glycol) (mPEG) modified hydroxylated tung oil (HTO), denoted as mPEG-HTO-mPEG, was designed and synthesized for drug delivery. mPEG-HTO-mPEG consists of a hydroxylated tung oil center joined by two mPEG blocks via a urethane linkage. The properties of mPEG-HTO-mPEG were affected by the length of the mPEG chain. Three mPEG with different molecular weights were used to prepare mPEG-HTO-mPEG. The obtained three mPEG-HTO-mPEG polymers were characterized by nuclear magnetic resonance (NMR), Fourier transformation infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC) and gel permeation chromatography (GPC), respectively. Furthermore, the particle sizes of mPEG-HTO-mPEG micelles were evaluated by dynamic light scattering (DLS) and transmission electron microscope (TEM). A critical aggregation concentration (CAC) ranged from 7.28 to 11.73 mg/L depending on the chain length of mPEG. The drug loading and release behaviors of mPEG-HTO-mPEG were investigated using prednisone acetate as a model drug, and results indicated that hydrophobic prednisone acetate could be effectively loaded into mPEG-HTO-mPEG micelles and exhibited a long-term sustained release. Moreover, compared with HTO, mPEG-HTO-mPEG had no obvious cytotoxicity to HeLa and L929 cells. Therefore, monomethoxy poly(ethylene glycol) modified hydroxylated tung oil mPEG-HTO-mPEG may be a promising drug carrier.

12.
Materials (Basel) ; 15(9)2022 Apr 28.
Artigo em Inglês | MEDLINE | ID: mdl-35591530

RESUMO

The single light oil regenerating agent has certain limitations on the performance recovery of aged asphalt. In this study, tung oil, dioctyl phthalate (DOP), C9 petroleum resin, and organic montmorillonite (OMMT) were used to prepare the composite regenerating agent, and its optimal mix proportion was determined by the orthogonal experimental design. The rheological properties and anti-aging performance of reclaimed asphalt were studied by the dynamic shear rheometer (DSR) and bending beam rheometer (BBR); and the Fourier transform infrared (FTIR) spectrometer, gel permeation chromatography (GPC), and scanning electron microscope (SEM) were adopted to explore its microstructure, morphology, and mechanism of action. The results show that with the addition of tung oil composite regenerating agent, the rheological properties of aged asphalt can be effectively recovered, even better than that of base asphalt. By using the complex modulus aging index (CMAI) and phase angle aging index (PMAI) it is found that the anti-aging performance of reclaimed asphalt is better than that of base asphalt. With the optimal content of the tung oil composite regenerating agent, the contents of characteristic functional groups and macromolecular asphaltenes in the aged asphalt can be reduced, indicating that the composite regenerating agent is beneficial to the dispersion and dissolution of polar substances in the aged asphalt. After aging, a large number of wrinkles appear on the surface of the asphalt. However, the addition of the tung oil composite regenerating agent can make the asphalt surface smooth, which indicates that the tung oil composite regenerating agent can restore the microstructure and morphology of aged asphalt to a certain extent.

13.
Polymers (Basel) ; 14(9)2022 May 07.
Artigo em Inglês | MEDLINE | ID: mdl-35567076

RESUMO

In this work, tung oil was utilised as a catalyst-free self-healing agent, and an in-situ polymerization process was applied to encapsulate the tung oil core with a poly(urea-formaldehyde) (PUF) shell. The conventional poly(ethylene-alt-maleic-anhydride) (PEMA) polymer was compared to a more naturally abundant gelatin (GEL) emulsifier to compare the microcapsules' barrier, morphological, thermal, and chemical properties, and the crystalline nature of the shell material. GEL emulsifiers produced microcapsules with a higher payload (96.5%), yield (28.9%), and encapsulation efficiency (61.7%) compared to PEMA (90.8%, 28.6% and 52.6%, respectively). Optical and electron microscopy imaging indicated a more uniform morphology for the GEL samples. The thermal decomposition measurements indicated that GEL decomposed to a value 7% lower than that of PEMA, which was suggested to be attributed to the much thinner shell materials that the GEL samples produced. An innovative and novel focused ion beam (FIB) milling method was exerted on the GEL sample, confirming the storage and release of the active tung oil material upon rupturing. The samples with GEL conveyed a higher healing efficiency of 91%, compared to PEMA's 63%, and the GEL samples also conveyed higher levels of corrosion resistance.

14.
Polymers (Basel) ; 14(8)2022 Apr 11.
Artigo em Inglês | MEDLINE | ID: mdl-35458287

RESUMO

Through the optimized preparation of tung oil microcapsules, five kinds of microcapsules containing different core material content were obtained to explore the influence of microcapsules on water-based paint film and the self-healing ability of microcapsules. The results showed that the microcapsules had good appearance, and the microcapsules were successfully prepared. The color difference in the paint film increased with the increase in microcapsule content, and the gloss decreased gradually. The mechanical test showed that adding microcapsules increased the toughness of the paint film to a certain extent, and the performance of the paint film was unchanged or better. The results showed that paint film with the core-wall ratio of 0.78:1 had the best performance and self-healing function when microcapsules were added.

15.
Polymers (Basel) ; 14(6)2022 Mar 20.
Artigo em Inglês | MEDLINE | ID: mdl-35335580

RESUMO

Color is one of the most important characteristics of a material's appearance, which affects the additional value of bamboo and psychological feelings of users. Previous studies have shown that the dimensional stability, mildew resistance and durability of bamboo were improved after tung oil thermal treatment. In this study, the effects of tung oil thermal treatment on bamboo color at different temperatures and durations of time were investigated. The results show that the lightness (L*) of bamboo decreased as the tung oil temperature or duration of time increased. The red-green coordinates (a*) and color saturation (C*) of bamboo were gradually increased as the tung oil temperature rose from 23 °C to 160 °C, while the a* and C* were gradually decreased when the temperature continued to rise from 160 °C to 200 °C. There was no significant difference in the yellow-blue coordinates (b*) of bamboo when the duration was prolonged from 0.5 h to 3 h with tung oil thermal treatment at 140 °C. Eye movement data show that the popularity of bamboo furniture was significantly improved at 23-100 °C and slightly improved at 160-180 °C with tung oil treatment. Therefore, tung oil thermal treatment plays a positive role in improving visual effects and additional value of bamboo.

16.
Ultrason Sonochem ; 79: 105765, 2021 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-34600302

RESUMO

Epoxy resins made from vegetable oils are an alternative to synthesize epoxy resins from renewable sources. Tung oil is rich in α -eleostearic fatty acid, which contains three double bonds producing epoxy resins with up to three epoxy groups per fatty acid. This work studied the production of tung oil epoxy resin using hydrogen peroxide as an oxidizing agent and acetic and formic acid as percarboxylic acid precursors, applying low frequency high power ultrasound. This study evaluated the effects of ultrasound power density, hydrogen peroxide concentration, acetic acid concentration, and formic acid concentration on the yield into epoxy resin, selectivity, and by-products formation. Application of ultrasound was carried out using a 19 kHz probe ultrasound (horn ultrasound) with a 1.3 cm diameter titanium probe, 500 W nominal power, 2940 W L-1 maximum effective power density applied to the reaction mixture. Ultrasound technology yielded up to 85% of epoxy resin in 3 h of reaction. The use of formic acid resulted in a slightly lower oil conversion than acetic acid but with a much higher selectivity towards epoxidized tung oil. However, using acetic acid resulted in the production of high-value by-products, such as 2-heptenal and 2,4-nonadienal. The ultrasound-assisted epoxidation showed to be particularly efficient when applied to oils containing conjugated double-bonds.

17.
Macromol Rapid Commun ; 42(19): e2100342, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-34347319

RESUMO

Lithium-sulfur batteries (LSBs) suffer from well-known fast capacity losses despite their extremely high theoretical capacity and energy density. These losses are caused by dissolution of lithium polysulfide (LiPS) in ether-based electrolytes and have become the main bottleneck to widespread applications of LSBs. Therefore, there is a significant need for electrode materials that have a strong adsorption capacity for LiPS. Herein, a waterborne polyurethane (WPUN) containing sulfamic acid (NH2 SO3 H) polymer is designed and synthesized as an aqueous-based, ecofriendly binder by neutralizing sulfamic acid with a tung oil-based polyurethane prepolymer. UV-vis spectroscopy shows that the WPUN strongly immobilizes LiPS and thus is an effective inhibitor of the LiPS. Moreover, the WPUN binder has excellent adhesive and mechanical properties that improve the integrity of sulfur cathodes. The WPUN-based cathodes exhibit a significant improvement in their specific capacity and maintain a capacity of 617 mAh g-1 after 200 cycles at 0.5C. Besides, the LSBs assembled with the WPUN-based cathodes show good rate performance from 0.2C (737 mAh g-1 ) to 4C (586 mAh g-1 ), which is significantly higher than that of LSBs assembled with a commercial polymer binder. The structural design of the presented binder provides a new perspective for obtaining high-performance LSBs.


Assuntos
Lítio , Poliuretanos , Eletrodos , Óleos de Plantas , Enxofre
18.
Polymers (Basel) ; 13(11)2021 May 25.
Artigo em Inglês | MEDLINE | ID: mdl-34070232

RESUMO

This paper provides an overview of the recent progress in research and development dealing with polymers derived from plant oils. It highlights the widening interest in novel approaches to the synthesis, characterization, and properties of these materials from renewable resources and emphasizes their growing impact on sustainable macromolecular science and technology. The monomers used include unmodified triglycerides, their fatty acids or the corresponding esters, and chemically modified triglycerides and fatty acid esters. Comonomers include styrene, divinylbenzene, acrylics, furan derivatives, epoxides, etc. The synthetic pathways adopted for the preparation of these materials are very varied, going from traditional free radical and cationic polymerizations to polycondensation reactions, as well as metatheses and Diels-Alder syntheses. In addition to this general appraisal, the specific topic of the use of tung oil as a source of original polymers, copolymers, and (nano)composites is discussed in greater detail in terms of mechanisms, structures, properties, and possible applications.

19.
Polymers (Basel) ; 13(7)2021 Mar 29.
Artigo em Inglês | MEDLINE | ID: mdl-33805577

RESUMO

Polyhydroxyalkanoates (PHAs) are attractive new bioplastics for the replacement of plastics derived from fossil fuels. With their biodegradable properties, they have also recently been applied to the medical field. As poly(3-hydroxybutyrate) produced by wild-type Ralstonia eutropha has limitations with regard to its physical properties, it is advantageous to synthesize co- or terpolymers with medium-chain-length monomers. In this study, tung oil, which has antioxidant activity due to its 80% α-eleostearic acid content, was used as a carbon source and terpolymer P(53 mol% 3-hydroxybytyrate-co-2 mol% 3-hydroxyvalerate-co-45 mol% 3-hydroxyhexanoate) with a high proportion of 3-hydroxyhexanoate was produced in R. eutropha Re2133/pCB81. To avail the benefits of α-eleostearic acid in the tung oil-based medium, we performed partial harvesting of PHA by using a mild water wash to recover PHA and residual tung oil on the PHA film. This resulted in a film coated with residual tung oil, showing antioxidant activity. Here, we report the first application of tung oil as a substrate for PHA production, introducing a high proportion of hydroxyhexanoate monomer into the terpolymer. Additionally, the residual tung oil was used as an antioxidant coating, resulting in the production of bioactive PHA, expanding the applicability to the medical field.

20.
Plants (Basel) ; 10(1)2021 Jan 12.
Artigo em Inglês | MEDLINE | ID: mdl-33445566

RESUMO

As biorationals, plant oils offer numerous advantages such as being natural products, with low ecotoxicological side effects, and high biodegradability. In particular, drying glyceride plant oils, which are rich in unsaturated fatty acids, might be promising candidates for a more sustainable approach in the discussion about plant protection and the environment. Based on this, we tested the protective and curative efficacy of an oil-in-water-emulsion preparation using drying plant oils (linseed oil, tung oil) and a semi-drying plant oil (rapeseed oil) separately and in different mixtures. Plant oils were tested in greenhouse experiments (in vivo) on green beans (Phaseolus vulgaris L.) against bean rust (Uromyces appendiculatus). We observed that a 2% oil concentration showed no or very low phytotoxic effects on green beans. Both tested drying oils showed a protective control ranging from 53-100% for linseed oil and 32-100% for tung oil. Longer time intervals of 6 days before inoculation (6dbi) were less effective than shorter intervals of 2dbi. Curative efficacies were lower with a maximum of 51% for both oils when applied 4 days past inoculation (4dpi) with the fungus. Furthermore, the results showed no systemic effects. These results underline the potential of drying plant oils as biorationals in sustainable plant protection strategies.

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