Deposition of lysozyme bilayer films on hydrophilic (OH–Si) and hydrophobic (H–Si) surfaces in pr... more Deposition of lysozyme bilayer films on hydrophilic (OH–Si) and hydrophobic (H–Si) surfaces in presence of ions and their enhancement in hydrophobicity compare to the pure lysozyme film.
Fabrication of photocatalytically active cellulose nanofiber nanocomposite paper decorated with a... more Fabrication of photocatalytically active cellulose nanofiber nanocomposite paper decorated with a bimetallic ZnO/TiO2 nanohybrid for efficient hydrocarbon degradation in waste water samples.
Multi walled carbon nanotube (MWCNT)-polyaniline nanofiber-carbon dot (CD) nanohybrid was fabrica... more Multi walled carbon nanotube (MWCNT)-polyaniline nanofiber-carbon dot (CD) nanohybrid was fabricated using in-situ polymerization of aniline in the presence of MWCNT and CD. Different spectroscopic techniques like Fourier transform infrared spectroscopy (FTIR) and ultraviolet-visible (UV-vis) spectroscopy were used to study the formation of the nanohybrid. The obtained nanohybrid was incorporated in different weight percentages in the hyperbranched epoxy derived from renewable resources like sorbitol and monoglyceride of castor oil. The formation of the nanocomposites was also verified using spectroscopic, microscopic and diffraction techniques. The thermosetting nanocomposites with uniform and stable dispersion of nanohybrid demonstrated excellent mechanical properties, such as tensile strength (69 MPa), elongation at break (45%), scratch resistance (>10 kg) and impact resistance (16.7 kJ/m); good thermal stability (above 264°C) and high chemical resistance. The anticorrosion performances of the cured nanocomposites were studied on mild steel plates in 3.5% sodium chloride (NaCl) solution using potentiodynamic polarization method. The study showed that the nanocomposites with the highest percentage of the nanohybrid exhibited better anticorrosion performance (corrosion rate of 4.62•10 4 mpy) compared to the pristine thermoset. Thus, this study revealed that the hyperbranched epoxy with stable dispersion of the nanohybrid based nanocomposite can be potentially applied as a high performance anticorrosive material.
Renewable resource derived polymers are the most widely explored polymers from the past two decad... more Renewable resource derived polymers are the most widely explored polymers from the past two decades because of their non-toxicity and environment-friendly nature. Therefore, in the present study blends from two different bio-based polymers with the special architecture, viz. hyperbranched epoxy and hyperbranched polyester were prepared by mechanical mixing at different weight ratios. The prepared blends were characterized by Fourier transform infrared spectroscopy and X-ray diffraction technique. The thermosets of these blends showed good tensile strength (14.9 MPa), elongation at break (274%), impact resistance (21.3 kJ/m 2), scratch resistance (up to 6.5 kg) and thermal (Onset temperature: 224 C) properties indicating improvements in flexibility and thermostability up to an appreciable extent. The blends also showed good biodegradability when exposed to gram positive and gram negative bacterial stains.
The present study is focused on developing an environmentally benign bio–based epoxy thermoset th... more The present study is focused on developing an environmentally benign bio–based epoxy thermoset that can be used as a sustainable material for various engineering applications. So, renewable resources like sorbitol and castor oil are used to synthesize novel hyperbranched epoxy resins. Three hyperbranched epoxy resins of castor oil with varying ratios of sorbitol along with conventional reactants are reported here. The chemical structure of them is confirmed by FTIR and NMR studies. The epoxy thermosets cured by fatty acid derived poly (amido amine) showed excellent mechanical properties such as high impact resistance (upto 34.5 kJ/m); good tensile strength (upto 31 MPa); good elongation at break (upto 37%) and moderate scratch hardness (upto 5 kg); high thermal stability (upto 293 °C); high tensile adhesive strength (upto 2152 MPa); good chemical resistance in different chemical environments and acceptable biodegradability. Thus, the sorbitol modified castor oil based hyperbranched epoxy thermosets are found to be superior in toughness, biodegradability, elongation etc. compared to a linear epoxy resin without sorbitol as well as previously reported thermosets derived from bio–based materials like vegetable oil, starch and glycerol. Therefore, these thermosets possess great potential to be used as sustainable materials for various advanced applications.
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2019
The increase of blood sugar level in the human body causes severe health issues. Several electroc... more The increase of blood sugar level in the human body causes severe health issues. Several electrochemical and optical sensing methods were developed in this regard. However, the use of low cost, efficient chemosensors are mostly preferred for practical applications. In this context, a fluorescent nanohybrid of cellulose nanofiber (CNF) modified carbon dot (CD)-polyaniline nanofiber using a facile in-situ polymerization method was reported herein. The nanohybrid exhibited good sensing ability of glucose with concentration as low as 8 μM in 0.1 M phosphate buffer solution. Further, this nanohybrid was incorporated in different weight percentages in the biobased hyperbranched epoxy consisting of sorbitol and monoglyceride of castor oil as bio-based components, in addition to the conventional reactants. The formation of the nanocomposites was verified using spectroscopic, microscopic and diffraction techniques. The thermosetting nanocomposites showed good mechanical properties, such as tensile strength (39 MPa), elongation at break (82%), scratch resistance (> 10 kg) and impact resistance (16.5 kJ/m) and good thermal stability. The nanocomposites displayed good hematocompatibility with mammalian blood in accordance with anti-hemolytic studies. The nanocomposites exhibited better biodegradability compared to the pristine epoxy due to the presence of CNF and CD which accelerated the degradation process.
В работе рассматривается задача сетевой оптимизации. Для её решения предложена математическая мод... more В работе рассматривается задача сетевой оптимизации. Для её решения предложена математическая модель построения оптимальной структуры технической системы сетевого типа (трубопроводы, каналы связи, электрические и тепловые сети). В качестве критериев поиска решения приняты: экономичность и надежность структуры сети. Особое внимание уделено критерию надежности, учет которого предложено выполнить посредством применения меры неопределенности информации (информационной энтропии). Дано краткое обоснование роли неопределенности информации в задаче построения структуры системы. В основу построения математической модели положена модель Шеннона определения количества информации/ энтропии. Задача оптимизации включает в себя целевую функцию в упрощенной математической постановке и ограничения нелинейного вида, которые обладают важной ролью в поиске решения. Ограничения предложено строить по принципу полного перебора состояний элементов структуры. При построении ограничений при полном переборе состояний, энтропия, подлежащая расчету, может быть определена для двух противоположных состояний: энтропия работоспособного и неработоспособного состояний сети. Такое разделение энтропии на две составляющие является полезным для построения уравнений ограничения задачи по каждому из состояний. Решение задачи оптимизации, с наличием ограничений в виде алгебраических неравенств определения энтропии, позволяет строить сетевые структуры замкнутого и разомкнутого вида. ключевые слова: структурная оптимизация, структура технической системы, структурная надежность, мера неопределенности информации
American Journal of Engineering and Applied Sciences, 2016
Bio-based hyperbranched and linear epoxy resins were synthesized from monoglyceride of Ricinus co... more Bio-based hyperbranched and linear epoxy resins were synthesized from monoglyceride of Ricinus communis oil. The nanocomposites of these hyperbranched and linear epoxies with 1, 2 and 3 wt% of OMMT were also fabricated. The structures of the resins and their nanocomposites were analyzed by FTIR, NMR, XRD, SEM and TEM. The studies of performance characteristics of poly(amido amine) cured thermosetting nanocomposites showed significant improvements in tensile strength from 5.8 to 11.9 MPa, impact from 80 to >100 cm, scratch resistance from 4 to 9 kg, thermal stability from 213 to 316°C and chemical resistance over their pristine systems. Further, hyperbranched nanocomposites and bio-based epoxy thermosets exhibited better performance than the linear and petroleum based ones. The overall results, therefore, demonstrated hyperbranched epoxy/clay nanocomposites as potential materials for advanced applications.
Materials Horizons: From Nature to Nanomaterials, 2019
In recent times, bio-based hyperbranched polymers have attracted tremendous interest in industria... more In recent times, bio-based hyperbranched polymers have attracted tremendous interest in industrial and scientific research, owing to their promising and unique attributes over their synthetic conventional analogs. Industrially important bio-based hyperbranched polymers such as polyurethane, polyester, poly(ester-amide), and epoxy have been developed over the last two decades from Advanced Polymer and Nanomaterial Laboratory of Tezpur University. They are synthesized by the Ax + By (x, y ≥ 2) approach with or without solvent, following the dictates of “Green Chemistry.” Again, it is a well-known fact that “virginity is not virtue” in case of polymers and the conventional filled composite systems are inappropriate to improve the performance of such bio-based polymers and hence unable to meet the service demands of advanced applications. Thus, nanotechnology, in recent times, is adopted to develop a variety of nanocomposites of the above sustainable polymers with different types of nan...
Deposition of lysozyme bilayer films on hydrophilic (OH–Si) and hydrophobic (H–Si) surfaces in pr... more Deposition of lysozyme bilayer films on hydrophilic (OH–Si) and hydrophobic (H–Si) surfaces in presence of ions and their enhancement in hydrophobicity compare to the pure lysozyme film.
Fabrication of photocatalytically active cellulose nanofiber nanocomposite paper decorated with a... more Fabrication of photocatalytically active cellulose nanofiber nanocomposite paper decorated with a bimetallic ZnO/TiO2 nanohybrid for efficient hydrocarbon degradation in waste water samples.
Multi walled carbon nanotube (MWCNT)-polyaniline nanofiber-carbon dot (CD) nanohybrid was fabrica... more Multi walled carbon nanotube (MWCNT)-polyaniline nanofiber-carbon dot (CD) nanohybrid was fabricated using in-situ polymerization of aniline in the presence of MWCNT and CD. Different spectroscopic techniques like Fourier transform infrared spectroscopy (FTIR) and ultraviolet-visible (UV-vis) spectroscopy were used to study the formation of the nanohybrid. The obtained nanohybrid was incorporated in different weight percentages in the hyperbranched epoxy derived from renewable resources like sorbitol and monoglyceride of castor oil. The formation of the nanocomposites was also verified using spectroscopic, microscopic and diffraction techniques. The thermosetting nanocomposites with uniform and stable dispersion of nanohybrid demonstrated excellent mechanical properties, such as tensile strength (69 MPa), elongation at break (45%), scratch resistance (>10 kg) and impact resistance (16.7 kJ/m); good thermal stability (above 264°C) and high chemical resistance. The anticorrosion performances of the cured nanocomposites were studied on mild steel plates in 3.5% sodium chloride (NaCl) solution using potentiodynamic polarization method. The study showed that the nanocomposites with the highest percentage of the nanohybrid exhibited better anticorrosion performance (corrosion rate of 4.62•10 4 mpy) compared to the pristine thermoset. Thus, this study revealed that the hyperbranched epoxy with stable dispersion of the nanohybrid based nanocomposite can be potentially applied as a high performance anticorrosive material.
Renewable resource derived polymers are the most widely explored polymers from the past two decad... more Renewable resource derived polymers are the most widely explored polymers from the past two decades because of their non-toxicity and environment-friendly nature. Therefore, in the present study blends from two different bio-based polymers with the special architecture, viz. hyperbranched epoxy and hyperbranched polyester were prepared by mechanical mixing at different weight ratios. The prepared blends were characterized by Fourier transform infrared spectroscopy and X-ray diffraction technique. The thermosets of these blends showed good tensile strength (14.9 MPa), elongation at break (274%), impact resistance (21.3 kJ/m 2), scratch resistance (up to 6.5 kg) and thermal (Onset temperature: 224 C) properties indicating improvements in flexibility and thermostability up to an appreciable extent. The blends also showed good biodegradability when exposed to gram positive and gram negative bacterial stains.
The present study is focused on developing an environmentally benign bio–based epoxy thermoset th... more The present study is focused on developing an environmentally benign bio–based epoxy thermoset that can be used as a sustainable material for various engineering applications. So, renewable resources like sorbitol and castor oil are used to synthesize novel hyperbranched epoxy resins. Three hyperbranched epoxy resins of castor oil with varying ratios of sorbitol along with conventional reactants are reported here. The chemical structure of them is confirmed by FTIR and NMR studies. The epoxy thermosets cured by fatty acid derived poly (amido amine) showed excellent mechanical properties such as high impact resistance (upto 34.5 kJ/m); good tensile strength (upto 31 MPa); good elongation at break (upto 37%) and moderate scratch hardness (upto 5 kg); high thermal stability (upto 293 °C); high tensile adhesive strength (upto 2152 MPa); good chemical resistance in different chemical environments and acceptable biodegradability. Thus, the sorbitol modified castor oil based hyperbranched epoxy thermosets are found to be superior in toughness, biodegradability, elongation etc. compared to a linear epoxy resin without sorbitol as well as previously reported thermosets derived from bio–based materials like vegetable oil, starch and glycerol. Therefore, these thermosets possess great potential to be used as sustainable materials for various advanced applications.
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2019
The increase of blood sugar level in the human body causes severe health issues. Several electroc... more The increase of blood sugar level in the human body causes severe health issues. Several electrochemical and optical sensing methods were developed in this regard. However, the use of low cost, efficient chemosensors are mostly preferred for practical applications. In this context, a fluorescent nanohybrid of cellulose nanofiber (CNF) modified carbon dot (CD)-polyaniline nanofiber using a facile in-situ polymerization method was reported herein. The nanohybrid exhibited good sensing ability of glucose with concentration as low as 8 μM in 0.1 M phosphate buffer solution. Further, this nanohybrid was incorporated in different weight percentages in the biobased hyperbranched epoxy consisting of sorbitol and monoglyceride of castor oil as bio-based components, in addition to the conventional reactants. The formation of the nanocomposites was verified using spectroscopic, microscopic and diffraction techniques. The thermosetting nanocomposites showed good mechanical properties, such as tensile strength (39 MPa), elongation at break (82%), scratch resistance (> 10 kg) and impact resistance (16.5 kJ/m) and good thermal stability. The nanocomposites displayed good hematocompatibility with mammalian blood in accordance with anti-hemolytic studies. The nanocomposites exhibited better biodegradability compared to the pristine epoxy due to the presence of CNF and CD which accelerated the degradation process.
В работе рассматривается задача сетевой оптимизации. Для её решения предложена математическая мод... more В работе рассматривается задача сетевой оптимизации. Для её решения предложена математическая модель построения оптимальной структуры технической системы сетевого типа (трубопроводы, каналы связи, электрические и тепловые сети). В качестве критериев поиска решения приняты: экономичность и надежность структуры сети. Особое внимание уделено критерию надежности, учет которого предложено выполнить посредством применения меры неопределенности информации (информационной энтропии). Дано краткое обоснование роли неопределенности информации в задаче построения структуры системы. В основу построения математической модели положена модель Шеннона определения количества информации/ энтропии. Задача оптимизации включает в себя целевую функцию в упрощенной математической постановке и ограничения нелинейного вида, которые обладают важной ролью в поиске решения. Ограничения предложено строить по принципу полного перебора состояний элементов структуры. При построении ограничений при полном переборе состояний, энтропия, подлежащая расчету, может быть определена для двух противоположных состояний: энтропия работоспособного и неработоспособного состояний сети. Такое разделение энтропии на две составляющие является полезным для построения уравнений ограничения задачи по каждому из состояний. Решение задачи оптимизации, с наличием ограничений в виде алгебраических неравенств определения энтропии, позволяет строить сетевые структуры замкнутого и разомкнутого вида. ключевые слова: структурная оптимизация, структура технической системы, структурная надежность, мера неопределенности информации
American Journal of Engineering and Applied Sciences, 2016
Bio-based hyperbranched and linear epoxy resins were synthesized from monoglyceride of Ricinus co... more Bio-based hyperbranched and linear epoxy resins were synthesized from monoglyceride of Ricinus communis oil. The nanocomposites of these hyperbranched and linear epoxies with 1, 2 and 3 wt% of OMMT were also fabricated. The structures of the resins and their nanocomposites were analyzed by FTIR, NMR, XRD, SEM and TEM. The studies of performance characteristics of poly(amido amine) cured thermosetting nanocomposites showed significant improvements in tensile strength from 5.8 to 11.9 MPa, impact from 80 to >100 cm, scratch resistance from 4 to 9 kg, thermal stability from 213 to 316°C and chemical resistance over their pristine systems. Further, hyperbranched nanocomposites and bio-based epoxy thermosets exhibited better performance than the linear and petroleum based ones. The overall results, therefore, demonstrated hyperbranched epoxy/clay nanocomposites as potential materials for advanced applications.
Materials Horizons: From Nature to Nanomaterials, 2019
In recent times, bio-based hyperbranched polymers have attracted tremendous interest in industria... more In recent times, bio-based hyperbranched polymers have attracted tremendous interest in industrial and scientific research, owing to their promising and unique attributes over their synthetic conventional analogs. Industrially important bio-based hyperbranched polymers such as polyurethane, polyester, poly(ester-amide), and epoxy have been developed over the last two decades from Advanced Polymer and Nanomaterial Laboratory of Tezpur University. They are synthesized by the Ax + By (x, y ≥ 2) approach with or without solvent, following the dictates of “Green Chemistry.” Again, it is a well-known fact that “virginity is not virtue” in case of polymers and the conventional filled composite systems are inappropriate to improve the performance of such bio-based polymers and hence unable to meet the service demands of advanced applications. Thus, nanotechnology, in recent times, is adopted to develop a variety of nanocomposites of the above sustainable polymers with different types of nan...
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