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Varada A Rajulu - One of the best experts on this subject based on the ideXlab platform.
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effects of spent tea leaf powder on the properties and functions of cellulose green Composite Films
Journal of environmental chemical engineering, 2016Co-Authors: J Duan, Obi K Reddy, Lina Zhang, B Ashok, Varada A RajuluAbstract:Abstract The aim of the present work was to develop novel bio-based polymer Composite Films with improved tensile and thermal properties. In this work, cellulose and spent tea leaf powder (STLP) were used as the matrix and filler respectively in the preparation of bioComposite Films. To make cellulose solution, cotton linters were dissolved in pre-cooled aqueous solution of 8 wt.% Lithium hydroxide and 15 wt.% urea. Tea is an important beverage of household and hotels and spent tea leaves form a conjugal solid waste. STLP was added to cellulose solution in 5–25 wt.% of weight of cellulose. The cellulose and cellulose/STLP Composite Films were prepared by regeneration method using ethyl alcohol coagulation bath. The dry Films were characterized by optical microscopy, scanning electron microscopy, Fourier transform infrared spectroscopy, thermogravimetric analysis, and tensile tests. The effect of STLP loading on the properties of the cellulose/STLP Composite Films was studied. The results indicated that the Composite Films had higher tensile properties and thermal stability than the cellulose matrix. The dye adsorption ability of cellulose and cellulose/STLP Composites in wet form was also studied. It was observed that the Composite wet Films had higher dye adsorption capacity than the matrix. Results of this study indicated STLP to be a promising green filler for polymer matrices.
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preparation and properties of biodegradable spent tea leaf powder poly propylene carbonate Composite Films
International Journal of Polymer Analysis and Characterization, 2015Co-Authors: Guangmei Xia, Obi K Reddy, Jinming Zhang, Jun Zhang, Uma C Maheswari, J Jayaramudu, Varada A RajuluAbstract:The aim of the present work is to develop novel bio-based lightweight material with improved tensile and thermal properties. Spent tea leaf powder (STLP) was used as a filler to improve the tensile and thermal properties of polypropylene carbonate (PPC). Tea is an important material used in hotels and households, and spent tea leaf is a resulting solid waste. Composite Films with STLP were obtained by the solution casting method. These Films were characterized by optical and scanning electron microscopy, Fourier transform-infrared spectroscopy, thermogravimetric analysis, and tensile testing to examine the effect of filler content on the properties of the Composites. The results showed that Composite Films have increased tensile strength due to enhanced interfacial adhesion between the filler and the matrix. In addition, the Composite Films also exhibited higher thermal degradation temperatures than pure polypropylene carbonate. The morphology results indicate that there is a good interface interaction be...
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preparation and properties of self reinforced cellulose Composite Films from agave microfibrils using an ionic liquid
Carbohydrate Polymers, 2014Co-Authors: Obi K Reddy, Jinming Zhang, Jun Zhang, Varada A RajuluAbstract:a b s t r a c t The applications of natural fibers and their microfibrils are increasing rapidly due to their environment benefits, specific strength properties and renewability. In the present work, we successfully extracted cellulose microfibrils from Agave natural fibers by chemical method. The extracted microfibrils were characterized by chemical analysis. The cellulose microfibrils were found to dissolve in an ionic liquid 1-allyl-3-methylimidazolium chloride (AmimCl) to larger extent along with little quantity of undissolved microfibrils. Using this solution, the self-reinforced regenerated cellulose Composite Films were prepared. The raw fiber, extracted cellulose microfibrils and regenerated cellulose Composite Films were charac- terized by FTIR, 13 C CP-MAS NMR, XRD, TGA and SEM techniques. The average tensile strength, modulus and elongation at break of the self-reinforced cellulose Composite Films were found to be 135 MPa, 8150 MPa and 3.2%, respectively. The high values of tensile strength and modulus were attributed to the self-reinforcement of Agave fibers in their generated matrix. These self-reinforced cellulose biodegradable Composite Films prepared from renewable source can find applications in packaging field.
Akira Isogai - One of the best experts on this subject based on the ideXlab platform.
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surface hydrophobized tempo nanocellulose rubber Composite Films prepared in heterogeneous and homogeneous systems
Cellulose, 2019Co-Authors: Shunsuke Fukui, Tsuguyuki Saito, Toru Noguchi, Akira IsogaiAbstract:A surface-carboxylated nanocellulose was prepared from wood cellulose by catalytic oxidation with 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO). The fibrous TEMPO-oxidized cellulose with sodium carboxylate groups (TOC-Na) was surface-hydrophobized by counterion exchange with tetra-n-butylammonium [TOC-N(n-Bu)4]. This fibrous TOC-N(n-Bu)4 was mechanically disintegrated in water and N,N-dimethylformamide (DMF) to prepare dispersions of TEMPO-oxidized cellulose nanofibrils (TOCNs) with tetra-n-butylammonium counterions, i.e., TOCN-N(n-Bu)4/water and TOCN-N(n-Bu)4/DMF. TOCN-N(n-Bu)4/rubber Composite Films were prepared by mixing TOCN-N(n-Bu)4 and hydrogenated acrylonitrile–butadiene rubber (H-NBR), used as a polymer matrix, in heterogeneous and homogeneous systems with water and DMF, respectively, followed by casting and drying. The TOCN-N(n-Bu)4/H-NBR Composite Films prepared in the heterogeneous and homogeneous systems both had a high Young’s modulus of ~ 45 MPa and low coefficients of thermal expansion of ~ 20 ppm/K at a TOCN/H-NBR ratio of 5/100 (w/w). In contrast, the tensile strengths and strain-to-failure values of the Composite Films prepared using the two systems clearly differed. These different properties are probably caused by differences between the TOCN distributions in the H-NBR matrix and between the H-NBR matrix structures in the two systems. The Composite Films prepared in the homogeneous system with DMF as the medium are likely to have a more homogeneous distribution of TOCN elements in a homogeneous H-NBR polymer matrix, resulting in a higher tensile strength and work-of-fracture at TOCN/H-NBR = 5/100 (w/w) compared with those of the Films prepared in the heterogeneous system with water.
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preparation and characterization of zinc oxide tempo oxidized cellulose nanofibril Composite Films
Cellulose, 2017Co-Authors: Ruizhi Ning, Chunnan Wu, Miyuki Takeuchi, Tsuguyuki Saito, Akira IsogaiAbstract:ZnO particle/water and 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)-oxidized cellulose nanofibril (TOCN)/water dispersions were mixed at various ratios under stirring. The aqueous ZnO/TOCN mixtures were sonicated, cast, and dried to prepare ZnO/TOCN Composite Films with various ZnO/TOCN weight ratios. The ZnO contents of the Films were controlled to 0–50% (w/w). When the ZnO content was increased to 5–50%, the porosity of the Composite Films increased to 14–23%. This is probably because the positively charged ZnO particles and negatively charged TOCN elements formed aggregates in both aqueous mixtures and dried Films. The ZnO/TOCN Composite film of thickness 10 µm containing 10% ZnO had more than 80% light transmittance at 600 nm, and high UV-screening properties. The Composite Films containing 25 and 50% ZnO had almost perfect UV-screening properties, but their light transmittances at 600 nm were only 60–80%. All the Composite Films had low coefficients of thermal expansion (<10 ppm/K). Because the Composite Films consisted of stiff TOCNs and ZnO, but had porous structures, the tensile strength and strain-to-failure decreased slightly with increasing ZnO content from 0 to 10%. The Composite film containing 50% ZnO had explicitly ductile properties because of its high porosity.
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properties of poly acrylamide tempo oxidized cellulose nanofibril Composite Films
Cellulose, 2014Co-Authors: Takanori Kurihara, Akira IsogaiAbstract:Self-standing Composite Films consisting of 2,2,6,6-tetramethylpiperidine-1-oxyl-oxidized cellulose nanofibril (TOCN) and anionic poly(acrylamide) (PAM) in various weight ratios were prepared by casting and drying of homogeneous mixtures of aqueous TOCN dispersion and PAM solution. PAM/TOCN Composite Films consisting of 25 % PAM and 75 % TOCN had clearly higher Young’s modulus (13.9 GPa) and tensile strength (266 MPa) than 100 % TOCN film (10.8 GPa and 223 MPa, respectively) or 100 % PAM film (4.9 GPa and 78 MPa, respectively), showing that PAM molecules have mechanical reinforcement ability in TOCN matrix. Some attractive interactions are likely formed between TOCN element surfaces and PAM molecules. In contrast, no such mechanical improvements were observed for poly(vinyl alcohol)/TOCN or oxidized starch/TOCN Composite Films prepared as references. Moreover, the mechanical properties of the PAM/TOCN Composite Films were further improved by controlling molecular mass and branching degree of the PAM. The high optical transparency and low coefficient of thermal expansion of the 100 % TOCN film were mostly maintained in the TOCN Composite film containing 25 % PAM.
Obi K Reddy - One of the best experts on this subject based on the ideXlab platform.
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effects of spent tea leaf powder on the properties and functions of cellulose green Composite Films
Journal of environmental chemical engineering, 2016Co-Authors: J Duan, Obi K Reddy, Lina Zhang, B Ashok, Varada A RajuluAbstract:Abstract The aim of the present work was to develop novel bio-based polymer Composite Films with improved tensile and thermal properties. In this work, cellulose and spent tea leaf powder (STLP) were used as the matrix and filler respectively in the preparation of bioComposite Films. To make cellulose solution, cotton linters were dissolved in pre-cooled aqueous solution of 8 wt.% Lithium hydroxide and 15 wt.% urea. Tea is an important beverage of household and hotels and spent tea leaves form a conjugal solid waste. STLP was added to cellulose solution in 5–25 wt.% of weight of cellulose. The cellulose and cellulose/STLP Composite Films were prepared by regeneration method using ethyl alcohol coagulation bath. The dry Films were characterized by optical microscopy, scanning electron microscopy, Fourier transform infrared spectroscopy, thermogravimetric analysis, and tensile tests. The effect of STLP loading on the properties of the cellulose/STLP Composite Films was studied. The results indicated that the Composite Films had higher tensile properties and thermal stability than the cellulose matrix. The dye adsorption ability of cellulose and cellulose/STLP Composites in wet form was also studied. It was observed that the Composite wet Films had higher dye adsorption capacity than the matrix. Results of this study indicated STLP to be a promising green filler for polymer matrices.
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preparation and properties of biodegradable spent tea leaf powder poly propylene carbonate Composite Films
International Journal of Polymer Analysis and Characterization, 2015Co-Authors: Guangmei Xia, Obi K Reddy, Jinming Zhang, Jun Zhang, Uma C Maheswari, J Jayaramudu, Varada A RajuluAbstract:The aim of the present work is to develop novel bio-based lightweight material with improved tensile and thermal properties. Spent tea leaf powder (STLP) was used as a filler to improve the tensile and thermal properties of polypropylene carbonate (PPC). Tea is an important material used in hotels and households, and spent tea leaf is a resulting solid waste. Composite Films with STLP were obtained by the solution casting method. These Films were characterized by optical and scanning electron microscopy, Fourier transform-infrared spectroscopy, thermogravimetric analysis, and tensile testing to examine the effect of filler content on the properties of the Composites. The results showed that Composite Films have increased tensile strength due to enhanced interfacial adhesion between the filler and the matrix. In addition, the Composite Films also exhibited higher thermal degradation temperatures than pure polypropylene carbonate. The morphology results indicate that there is a good interface interaction be...
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preparation and properties of self reinforced cellulose Composite Films from agave microfibrils using an ionic liquid
Carbohydrate Polymers, 2014Co-Authors: Obi K Reddy, Jinming Zhang, Jun Zhang, Varada A RajuluAbstract:a b s t r a c t The applications of natural fibers and their microfibrils are increasing rapidly due to their environment benefits, specific strength properties and renewability. In the present work, we successfully extracted cellulose microfibrils from Agave natural fibers by chemical method. The extracted microfibrils were characterized by chemical analysis. The cellulose microfibrils were found to dissolve in an ionic liquid 1-allyl-3-methylimidazolium chloride (AmimCl) to larger extent along with little quantity of undissolved microfibrils. Using this solution, the self-reinforced regenerated cellulose Composite Films were prepared. The raw fiber, extracted cellulose microfibrils and regenerated cellulose Composite Films were charac- terized by FTIR, 13 C CP-MAS NMR, XRD, TGA and SEM techniques. The average tensile strength, modulus and elongation at break of the self-reinforced cellulose Composite Films were found to be 135 MPa, 8150 MPa and 3.2%, respectively. The high values of tensile strength and modulus were attributed to the self-reinforcement of Agave fibers in their generated matrix. These self-reinforced cellulose biodegradable Composite Films prepared from renewable source can find applications in packaging field.
Rajesh Kumar Srivastava - One of the best experts on this subject based on the ideXlab platform.
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the strain sensing and thermal mechanical behavior of flexible multi walled carbon nanotube polystyrene Composite Films
Carbon, 2011Co-Authors: Rajesh Kumar Srivastava, Venkata S.m. Vemuru, You Zeng, Satish Nagarajaiah, Pulickel Madhavapanicker Ajayan, Robert Vajtai, Anchal SrivastavaAbstract:Abstract The strain sensing and thermal–mechanical behaviors of well dispersed multi-walled carbon nanotube/polystyrene (MWCNT/PS) Composite Films with different wt.% of carbon nanotubes were analyzed. The thermal–mechanical properties are studied using a dynamical mechanical analyzer and the results give their storage modulus (E′) and loss modulus (E″) as a function of temperature. We found an increase in E′ of up to 122% at 80 °C for a 6 wt.% MWCNT/PS Composite compared to PS. The glass transition temperature increased significantly with an increase in MWCNTs concentration. The strain sensing behavior of the Films is measured by applying an axial load over film which is attached to a brass specimen. The Composite Films exhibit excellent strain sensing behavior for different MWCNT contents. The result shows that an electromechanical response of the Composite Films varies linearly with applied strain even at high strains.
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ni filled flexible multi walled carbon nanotube polystyrene Composite Films as efficient microwave absorbers
Applied Physics Letters, 2011Co-Authors: Rajesh Kumar Srivastava, Anchal Srivastava, Robert Vajtai, T N Narayanan, A Reena P Mary, M R Anantharaman, Pulickel Madhavapanicker AjayanAbstract:In this letter, we report flexible, non corrosive, and light weight nickel nanoparticle@multi-walled carbon nanotube–polystyrene (Ni@MWCNT/PS) Composite Films as microwave absorbing material in the frequency range of S band (2-4 GHz). Dielectric permittivity and magnetic permeability of Composites having 0.5 and 1.5 wt. % filler amount were measured using the cavity perturbation technique. Reflection loss maxima of −33 dB (at 2.7 GHz) and −24 dB (at 2.7 GHz) were achieved for 0.5 and 1.5 wt. % Ni@MWCNT/PS Composite Films of 6 and 4 mm thickness, respectively, suggesting that low concentrations of filler provide significant electromagnetic interference shielding.
Kevin B Hicks - One of the best experts on this subject based on the ideXlab platform.
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Composite Films from pectin and fish skin gelatin or soybean flour protein
Journal of Agricultural and Food Chemistry, 2007Co-Authors: Marshall L Fishman, Kevin B HicksAbstract:Composite Films were prepared from pectin and fish skin gelatin (FSG) or pectin and soybean flour protein (SFP). The inclusion of protein promoted molecular interactions, resulting in a well-organized homogeneous structure, as revealed by scanning electron microscopy and fracture−acoustic emission analysis. The resultant Composite Films showed an increase in stiffness and strength and a decrease in water solubility and water vapor transmission rate, in comparison with Films cast from pectin alone. The Composite Films inherited the elastic nature of proteins, thus being more flexible than the pure pectin Films. Treating the Composite Films with glutaraldehyde/methanol induced chemical cross-linking with the proteins and reduced the interstitial spaces among the macromolecules and, consequently, improved their mechanical properties and water resistance. Treating the protein-free pectin Films with glutaraldehyde/methanol also improved the Young's modulus and tensile strength, but showed little effect on the ...
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Composite Films from pectin and fish skin gelatin or soybean flour protein
Journal of Agricultural and Food Chemistry, 2007Co-Authors: Linshu Liu, Marshall L Fishman, Chengkung Liu, Kevin B HicksAbstract:Composite Films were prepared from pectin and fish skin gelatin (FSG) or pectin and soybean flour protein (SFP). The inclusion of protein promoted molecular interactions, resulting in a well-organized homogeneous structure, as revealed by scanning electron microscopy and fracture-acoustic emission analysis. The resultant Composite Films showed an increase in stiffness and strength and a decrease in water solubility and water vapor transmission rate, in comparison with Films cast from pectin alone. The Composite Films inherited the elastic nature of proteins, thus being more flexible than the pure pectin Films. Treating the Composite Films with glutaraldehyde/methanol induced chemical cross-linking with the proteins and reduced the interstitial spaces among the macromolecules and, consequently, improved their mechanical properties and water resistance. Treating the protein-free pectin Films with glutaraldehyde/methanol also improved the Young's modulus and tensile strength, but showed little effect on the water resistance, because the treatment caused only dehydration of the pectin Films and the dehydration is reversible. The Composite Films were biodegradable and possessed moderate mechanical properties and a low water vapor transmission rate. Therefore, the Films are considered to have potential applications as packaging or coating materials for food or drug industries.