1,720,984 research outputs found
New polyfunctional dendritic linear hybrids from terminal amine polyether oligomers (Jeffamine®): Synthesis and characterization
Full text linkNew dendritic polyether oligomers were synthesized from three different Jeffamines® and characterized. This class of polyfunctional oligomers, bearing on their surface methylester, carboxylic acid, nitrile or amine groups, could be interesting modifying agents to change the properties of materials. The optimization of the iterative synthetic methods, through Michael addition, hydrolysis or hydrogenation, gave first and second generation dendritic structures in good yields.Fil: Froimowicz, Pablo. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Departamento de Química Orgánica; Argentina. Grenoble Institute of Technology; FranciaFil: Gandini, Alessandro. Grenoble Institute of Technology; FranciaFil: Strumia, Miriam Cristina. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Departamento de Química Orgánica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto Multidisciplinario de Biología Vegetal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto Multidisciplinario de Biología Vegetal; Argentin
Triggering effect caused by elemental sulfur as a mean to reduce the polymerization temperature of benzoxazine monomers
Full text linkMixtures of different benzoxazine resins and elemental sulfur (S8) are prepared and then reacted at 120 °C, below the temperature for radical formation of sulfur. The progress of the reaction and the chemical structures of the main products are monitored and characterized by proton nuclear magnetic resonance spectroscopy (1H NMR) and Fourier transform infrared spectroscopy (FT-IR). Thermal analysis of all reactive systems are also performed and studied by differential scanning calorimetry (DSC). The introduction of S8 into benzoxazines generates a new structure bearing a Schiff base and a phenolic -OH within the reactive system, which then triggers the reduction of the polymerization temperature in about 15% when as low as 5 mol% of S8 is added.Fil: Rodriguez Arza, Carlos. Case Western Reserve University; Estados UnidosFil: Froimowicz, Pablo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Tecnología en Polímeros y Nanotecnología. Universidad de Buenos Aires. Facultad de Ingeniería. Instituto de Tecnología en Polímeros y Nanotecnología; Argentina. Case Western Reserve University; Estados UnidosFil: Ishida, Hatsuo. Case Western Reserve University; Estados Unido
Tailor-made and chemically designed synthesis of coumarin-containing benzoxazines and their reactivity study toward their thermosets
Full text linkCoumarins are used as a natural renewable resource to synthesize coumarin-containing benzoxazine resins. The coumarin-containing benzoxazines are fully characterized in terms of their chemical structure by Fourier-transform infrared spectroscopy and proton nuclear magnetic resonance spectroscopy. The influence of electronic effects caused by the substituents on the polymerization temperature is also evaluated. Thermal properties of the resulting thermosets are characterized by differential scanning calorimetry and thermogravimetric analysis, showing good stability and char yields higher than 50%. The coumarin-containing polybenzoxazine thermosets show Tg values in the range between 160 and 190 °C. Thus, the herein presented coumarin-containing benzoxazine resins are proven to be competitive monomers when compared with other petroleum-based benzoxazine resins toward the generation of high-performance thermoset.Fil: Froimowicz, Pablo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Tecnología En Polimeros y Nanotecnología. Universidad de Buenos Aires. Facultad de Ingeniería. Instituto de Tecnología En Polimeros y Nanotecnología; Argentina. Case Western Reserve University; Estados UnidosFil: Rodriguez Arza, Carlos. Case Western Reserve University; Estados Unidos. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Ohashi, Seishi. Case Western Reserve University; Estados UnidosFil: Ishida, Hatsuo. Case Western Reserve University; Estados Unido
Electronic effects of asymmetric and meta-alkoxy substituents on the polymerization behavior of bis-benzoxazines
Full text linkThree isomers of benzoxazine monomers based on m-alkoxyphenol and 4,4′-methylenedianiline were synthesized and successfully isolated by column chromatography. The molecular structures of benzoxazine monomers were confirmed by proton nuclear magnetic resonance (1H NMR) and Fourier-transform infrared (FT-IR) spectroscopy. The polymerization behavior evaluated by differential scanning calorimetry (DSC) shows that the asymmetric isomer, which has a methoxy group at the 5-position and 7-positions (5,7′MO-ddm), has only one exothermic peak between temperatures of the other two symmetric isomers. The 1H NMR spectrum of monomers shows that the type and position of alkoxy groups can exert different effects on the electron density of the oxazine ring, and may result in a sensitive trend of ring-opening. The difference in electron densities was verified by the Gaussian simulation calculation results of natural charges. In this work, we provide a fundamental molecular-level understanding of the polymerization mechanism of asymmetric bis-benzoxazines, which can provide possibilities for designing new benzoxazines in order to solve the potential disadvantages of benzoxazines/polybenzoxazines and/or enhance their advantages.Fil: Lyu, Ya. Case Western Reserve University; Estados UnidosFil: Rachita, Eric. Case Western Reserve University; Estados UnidosFil: Pogharian, Nicholas. Case Western Reserve University; Estados UnidosFil: Froimowicz, Pablo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Tecnología en Polímeros y Nanotecnología. Universidad de Buenos Aires. Facultad de Ingeniería. Instituto de Tecnología en Polímeros y Nanotecnología; ArgentinaFil: Ishida, Hatsuo. Case Western Reserve University; Estados Unido
Synthesis of a triptycene-containing dioxazine benzoxazine monomer and a main chain triptycene-polydimethysiloxane-benzoxazine copolymer with excellent comprehensive properties
No full textA novel triptycene-containing dioxazine benzoxazine monomer (TB-al) and a main-chain triptycene-containing dioxazine benzoxazine copolymer (poly(triptycene-containing dioxazine benzoxazine-co-polydimethylsiloxane), TB-al-co-PDMS) have been synthesized and fully characterized. Polymerization of the monomer, TB-al, and the copolymer, TB-al-co-PDMS, was studied by in situ FT-IR and DSC. Fire-related properties and thermal stability of the resulting thermosets were evaluated by TGA and micro-scale combustion calorimetry (MCC). The obtained thermosets, poly(TB-al) and poly(TB-al-co-PDMS), exhibit outstanding thermal stability with Td10 values of 320 and 450 °C, char yields of 44 and 72% at 800 °C, low flammability as determined by HRC, affording values of 69.6 and 31.6 J g−1 K−1, and THR values of 10.5 and 9.4 kJ g−1, respectively. Remarkably, poly(TB-al-co-PDMS) presents excellent dielectric performance with a dielectric constant of 2.37 at 1 MHz and good hydrophobicity revealed by the low water uptake value of 0.056% after 120 h of sample immersion in water at room temperature. The combined properties and advantages of these triptycene-based thermosets (poly(TB-al) and poly(TB-al-co-PDMS)) clearly indicate their great potential for applications in the field of high-performance polymers.Fil: Yang, Rui. Jiangsu University; ChinaFil: Xie, Lin. Jiangsu University; ChinaFil: Li, Nan. Jiangsu University; ChinaFil: Froimowicz, Pablo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Tecnología en Polímeros y Nanotecnología. Universidad de Buenos Aires. Facultad de Ingeniería. Instituto de Tecnología en Polímeros y Nanotecnología; ArgentinaFil: Zhang, Kan. Jiangsu University; Chin
Design and Synthesis of Bio-Based High-Performance Trioxazine Benzoxazine Resin via Natural Renewable Resources
Full text linkA new fully biobased trioxazine benzoxazine is synthesized by reacting resveratrol, furfurylamine, and paraformaldehyde via the Mannich condensation reaction. The chemical structure of this biobenzoxazine is characterized by 1H and 13C nuclear magnetic resonance and Fourier transform infrared (FT-IR) spectroscopies. 1H-1H nuclear Overhauser effect spectroscopy is utilized to unambiguously identify the isomer obtained. Monomer polymerization is investigated by differential scanning calorimetry and in situ FT-IR. Thermal stability of the fully polymerized polybenzoxazine is evaluated by thermogravimetric analysis, and flammability is assessed by microscale combustion calorimetry. The biothermoset obtained shows high thermal stability and low flammability, Td10 of 403 °C and char yield of 64%, respectively, low heat release capacity (54 J/gK), and low total heat release (9.3 KJ/g), thus exhibiting self-extinguishing and nonignitable properties. Consequently, this new fully biobased trioxazine benzoxazine and its corresponding polybenzoxazine possess excellent processability and thermal properties, suggesting great potential toward high-performance and fire-resistant materials.Fil: Zhang, Kan. Jiangsu University; ChinaFil: Han, Mengchao. Jiangsu University; ChinaFil: Liu, Yuqi. Jiangsu University; ChinaFil: Froimowicz, Pablo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Tecnología en Polímeros y Nanotecnología. Universidad de Buenos Aires. Facultad de Ingeniería. Instituto de Tecnología en Polímeros y Nanotecnología; Argentin
Simple and low energy consuming synthesis of cyanate ester functional naphthoxazines and their properties
Full text linkNaphthoxazines functionalized with a cyanate ester group are synthesized in high yield under moderate conditions, including room temperature synthesis, compared with general benzoxazine synthesis. Additionally, this synthesis can shorten reaction pathways for another cyanate ester functional benzoxazine whose polymer exhibits higher thermal properties than general polybenzoxazines. Catalytic polymerization evaluated by differential scanning calorimetry (DSC) indicates multiple exotherm maxima, seemingly including cyanate ester trimerization and polymerization of naphthoxazine. The nature of each exotherm is studied by Fourier transform infrared spectroscopy (FT-IR). Furthermore, their observed exothermic temperatures are lower than those of the reported normal benzoxazines, dicyanate ester blends and cyanate ester functional benzoxazines. Thermal properties determined by thermogravimetric analysis (TGA) and dynamic mechanical analysis (DMA), such as the char yield and glass transition temperature, are relatively high compared to those of ordinary polybenzoxazines, and polymerized blends of benzoxazines and dicyanate esters.Fil: Ohashi, Seishi. Case Western Reserve University; Estados UnidosFil: Pandey, Vivek. Case Western Reserve University; Estados UnidosFil: Rodriguez Arza, Carlos. Case Western Reserve University; Estados UnidosFil: Froimowicz, Pablo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Tecnología en Polímeros y Nanotecnología. Universidad de Buenos Aires. Facultad de Ingeniería. Instituto de Tecnología en Polímeros y Nanotecnología; Argentina. Case Western Reserve University; Estados UnidosFil: Ishida, Hatsuo. Case Western Reserve University; Estados Unido
Smart and sustainable design of latent catalyst-containing benzoxazine-bio-resins and application studies
Full text linkA straightforward synthetic approach to incorporate a hydrogen-bonding motif as part of a fully biobased benzoxazine monomer (NAR-fa) is developed, leading to the first latent catalyst-containing thermosetting resin derived from natural renewable resources. The acronym is derived from the phenol (naringenin) and amine (furfurylamine) used in the synthesis. Interestingly, the newly developed benzoxazine resin exhibits a long shelf life in spite of possessing the lowest polymerization temperature reported hitherto for pure benzoxazines, 166 °C. The hydrogen-bonding motif is identified as an important design feature for studying the thermal behavior of the resin. All most common thermal and fire related properties, such as the glass transition temperature (Tg), temperature at which the weight loss is 5 and 10% (Td5 and Td10), char yield (Yc), limiting oxygen index (LOI), heat release capacity (HRC), and total heat released (THR), were far superior to those of typical polybenzoxazines. As a natural consequence of these great characteristics, NAR-fa was applied in small amounts (5 mol%) as an initiator and a property modifier of other petroleum-based and natural renewable resourced benzoxazine-based systems. The thermal properties of the resulting copolymeric thermosets were maintained or slightly enhanced, while those related to fire improved by about 38 and 51% for THR and HRC, respectively. These results highlight the utility of the latent catalyst-containing resin design derived from natural renewable resources in the preparation of high-performance resins and thermosets.Fil: Kan Zhang. Jiangsu University; ChinaFil: Yuqi Liu. Jiangsu University; ChinaFil: Mengchao Han. Jiangsu University; ChinaFil: Froimowicz, Pablo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Tecnología en Polímeros y Nanotecnología. Universidad de Buenos Aires. Facultad de Ingeniería. Instituto de Tecnología en Polímeros y Nanotecnología; Argentin
Effect of Vanillin Concentration on the Properties of Poly(vinyl alcohol)‐Based Films Prepared to Potentially Replace Single‐Use Plastics
No full textPackaging starting materials produced by incorporating vanillin (V) into poly(vinyl alcohol) (PVA) to obtain biopolymer films to replace single-use plastics of limited degradation is presented in this work. Very homogeneous films are obtained by the casting technique. Different concentrations of V as an additive to produce the films and the manner in which they affect spectroscopic, thermal, and mechanical properties as well as their hydrophilicity/hydrophobicity balance and permeability behavior are analyzed. It is observed that increasing the concentration of V in the films increases the thermal stability, tensile strength, and tensile strain at failure, but decreases the Tg values, hydrophilicity, and water vapor permeability (WVP). Thus, the combined results suggest that these films show an excellent potential to be used as raw materials to manufacture eco-friendly packaging materials as a replacement for non-degradable single-use plastics. This procedure may be beneficial in several applied areas, such as in the food industry, where PVA is widely used although many properties must yet be enhanced, as accomplishes in the present work.Fil: Salum, Maria Laura. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Centro de Investigaciones en Hidratos de Carbono. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Centro de Investigaciones en Hidratos de Carbono; ArgentinaFil: Iguchi, Daniela. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Tecnología en Polímeros y Nanotecnología. Universidad de Buenos Aires. Facultad de Ingeniería. Instituto de Tecnología en Polímeros y Nanotecnología; ArgentinaFil: Fernandez Chevichuk, Stefania. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Tecnología en Polímeros y Nanotecnología. Universidad de Buenos Aires. Facultad de Ingeniería. Instituto de Tecnología en Polímeros y Nanotecnología; ArgentinaFil: Froimowicz, Pablo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Tecnología en Polímeros y Nanotecnología. Universidad de Buenos Aires. Facultad de Ingeniería. Instituto de Tecnología en Polímeros y Nanotecnología; Argentin
Quantitative studies on the: P -substituent effect of the phenolic component on the polymerization of benzoxazines
Full text linkThe pure monofunctional benzoxazines substituted by either electron donating or withdrawing groups are synthesized to verify the electronic effect on the polymerization behaviors without any complicated factors of the impurities. The analytical data of each compound are collected using 1H-NMR, 13C-NMR, and differential scanning calorimetry (DSC). In order to quantify the electronic effect on the polymerization behavior, the Hammett substituent constant is utilized and plotted against resonances of 1H-NMR, 13C-NMR spectra and DSC exotherm maximum temperature. The use of the Hammett substituent constant is reexamined by calculating the natural charge on the phenolic moiety via ab initio calculation using the Gaussian program and correlated with the polymerization exotherm temperature. The activation energies obtained using the Kissinger and Ozawa methods are related to the electronic effect of the substituents on the phenolic part.Fil: Ohashi, Seishi. Case Western Reserve University; Estados UnidosFil: Iguchi, Daniela. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Tecnología en Polímeros y Nanotecnología. Universidad de Buenos Aires. Facultad de Ingeniería. Instituto de Tecnología en Polímeros y Nanotecnología; Argentina. Case Western Reserve University; Estados UnidosFil: Heyl, Tyler R.. Case Western Reserve University; Estados UnidosFil: Froimowicz, Pablo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Tecnología en Polímeros y Nanotecnología. Universidad de Buenos Aires. Facultad de Ingeniería. Instituto de Tecnología en Polímeros y Nanotecnología; Argentina. Case Western Reserve University; Estados UnidosFil: Ishida, Hatsuo. Case Western Reserve University; Estados Unido
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