The Experts below are selected from a list of 191850 Experts worldwide ranked by ideXlab platform
Niranjan Karak - One of the best experts on this subject based on the ideXlab platform.
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bio based waterborne polyurethane carbon dot nanocomposite as a Surface Coating material
Progress in Organic Coatings, 2016Co-Authors: Biplab Ghosh, Satyabrat Gogoi, Suman Thakur, Niranjan KarakAbstract:Abstract Waterborne Surface Coating materials with low volatile organic compounds (VOCs) are environmentally friendly and hence the most desired materials for the modern society. The present study reports in situ fabricated thermosetting hyperbranched waterborne polyurethane (WPU)/carbon dot (CD) nanocomposites as Surface Coating materials. CD was used as a nanoreinforcing agent (at 0.25, 0.5 and 1.0 weight percentages) in the nanocomposites. The structures of the waterborne polyurethane and its fabricated thermosetting nanocomposites were analyzed by using different spectroscopic and analytical tools like Fourier transform infrared spectroscopy, nuclear magnetic resonance spectroscopy, UV–visible spectroscopy and X-ray diffractometry. The mechanical properties of the pristine thermosetting WPU were significantly improved after incorporation of CD (tensile strength from 4.5 to 8.5 MPa, elongation at break value from 96 to 136%, scratch hardness from 3 to 9 kg, impact strength from 70 to 100 cm). The thermal stability of WPU also enhanced from 250 to 280 °C after incorporation of CD in the matrix. Interestingly, the fabricated nanocomposites demonstrated an excitation wavelength and concentration dependent photoluminance behavior as well as exhibited good transparency. Thus, the fabricated WPU nanocomposites show great potential as low VOC containing environment friendly transparent Surface Coating material.
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bio degradable vegetable oil based hyperbranched poly ester amide as an advanced Surface Coating material
Progress in Organic Coatings, 2013Co-Authors: Sujata Pramanik, Rocktotpal Konwarh, Kalpana Sagar, Bolin Kumar Konwar, Niranjan KarakAbstract:Abstract Vegetable oil based hyperbranched poly(ester amide) (HBPEA) has enormous importance because of its unique characteristics. Thus the synthesis of HBPEA using N,N′-bis(2-hydroxy ethyl) castor oil fatty amide, maleic anhydride, phthalic anhydride and isophthalic acid as A 2 monomers and diethanol amine, as B 3 monomer was reported for the first time. The chemical structure of the synthesized resin was characterized by Fourier transform infrared (FTIR) and nuclear magnetic resonance ( 1 H NMR and 13 C NMR) spectroscopic techniques. The degree of branching (DB) (as vouched by 1 H NMR analysis) and initial degradation temperature were found to increase with the increment in B 3 monomer content. Resins with 5 and 10 wt% of B 3 monomer showed shear thinning behavior while rheopectic nature of HBPEA with 15 wt% of B 3 content was observed. The evaluation of tensile strength, elongation at break, abrasion resistance, adhesion strength, scratch hardness, gloss, impact strength and chemical resistance complemented by microbial and lipolytic degradation forward the epoxy cured thermosets as advanced biodegradable Surface Coating materials.
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castor oil based hyperbranched polyurethanes as advanced Surface Coating materials
Progress in Organic Coatings, 2013Co-Authors: Suman Thakur, Niranjan KarakAbstract:Abstract 21st Century is treated as the century for highly branched macromolecules, because of their unique structural architecture and outstanding performance characteristics, in the field of polymer science. In the present study, castor oil-based two hyperbranched polyurethanes (HBPUs) were synthesized via A2 + B3 approach using castor oil or monoglyceride of the castor oil as the hydroxyl containing B3 reactant and toluene diisocyanate (TDI) as an A2 reactant along with 1,4-butane diol (BD) as the chain extender and poly(ɛ-caprolactone) diol (PCL) as a macroglycol. The adopted ‘high dilution and slow addition’ technique offers hyperbranched polymers with high yield and good solubility in most of the polar aprotic solvents. Fourier transforms infra-red spectroscopy (FTIR) and nuclear magnetic resonance (NMR) analyses confirmed the chemical structure of synthesized polymers, while wide angle X-ray diffraction (WXRD) and scanning electron microscope (SEM) resulted the insight of their physical structures. The degree of branching was calculated from 1H NMR and found to be 0.57 for castor oil based hyperbranched polyurethane (CHBPU), while it was 0.8 for monoglyceride based hyperbranched polyurethane (MHBPU). The studies showed that MHBPU and CHBPU exhibited tensile strength 11 MPa and 7 MPa, elongation at break 695% and 791%, scratch hardness 5 kg and 4.5 kg, gloss 84 and 72, respectively. Thermal properties like thermo stability, melting point, enthalpy, degree of crystallinity and glass transition temperature (Tg); and chemical resistance in different chemical media were found to be almost equivalent for both the polyurethanes. The measurements of dielectric constant and lost factor indicated that both the HBPUs behave as dielectric materials. Thus the synthesized HBPUs have the potential to be used as advanced Surface Coating materials.
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vegetable oil based highly branched polyester clay silver nanocomposites as antimicrobial Surface Coating materials
Progress in Organic Coatings, 2010Co-Authors: Uday Konwar, Niranjan Karak, Manabendra MandalAbstract:Abstract The unison of nanotechnology and polymer science enables the development of novel silver-based polyester nanocomposite as an antimicrobial Coating material. Highly branched polyester/clay silver nanocomposites based on vegetable oil with different loadings of silver were prepared via reduction of silver salt by employing dimethylformamide as solvent as well as reducing agent at room temperature. Organically modified montmorillonite clay of 2.5 wt% was used as the nanofiller for the property improvement of the pristine polymer. The highly branched polyester resin was synthesized by condensation of 2,2-bis(hydroxymethyl) propionic acid with Mesua ferrea L. seed oil based carboxyl terminated pre-polymer, as reported earlier. FTIR, UV–vis, XRD, SEM and TEM studies substantiate the formation of well-dispersed silver nanoparticles within the clay gallery with an average size of 15 nm. The thermostability of the silver nanocomposites obtained by thermogravimetric analysis was enhanced by 20 °C. The mechanical properties such as tensile strength and scratch hardness were improved 4.5 and 2.6 units respectively and impact resistance improved a little by nanocomposites formation. The antimicrobial efficacy of the as-prepared silver nanocomposites was also premeditated and highly antibacterial activity against Gram negative bacteria ( Escherichia coli and Psuedomonas aeruginosa ) was observed. Excellent chemical resistance in various chemical media except in alkali has also been noticed. The study reveals that the polyester/clay silver nanocomposites based on vegetable oil show the potential to be applicable as antibacterial Surface Coating materials.
Julia B. Berthet - One of the best experts on this subject based on the ideXlab platform.
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a bioinspired omniphobic Surface Coating on medical devices prevents thrombosis and biofouling
Nature Biotechnology, 2014Co-Authors: Daniel C. Leslie, Julia B. Berthet, Thomas M. Valentin, Anna Waterhouse, Alexander L WattersAbstract:A non-stick Surface Coating makes medical devices anti-thrombogenic and resistant to biofilm growth.
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A bioinspired omniphobic Surface Coating on medical devices prevents thrombosis and biofouling
Nature Biotechnology, 2014Co-Authors: Daniel C. Leslie, Julia B. Berthet, Thomas M. Valentin, Benjamin D. Hatton, Philseok Kim, Arthur Nedder, Alexander L Watters, Anna Waterhouse, Abhishek Jain, Kathryn DonovanAbstract:Thrombosis and biofouling of extracorporeal circuits and indwelling medical devices cause significant morbidity and mortality worldwide. We apply a bioinspired, omniphobic Coating to tubing and catheters and show that it completely repels blood and suppresses biofilm formation. The Coating is a covalently tethered, flexible molecular layer of perfluorocarbon, which holds a thin liquid film of medical-grade perfluorocarbon on the Surface. This Coating prevents fibrin attachment, reduces platelet adhesion and activation, suppresses biofilm formation and is stable under blood flow in vitro. Surface-coated medical-grade tubing and catheters, assembled into arteriovenous shunts and implanted in pigs, remain patent for at least 8 h without anticoagulation. This Surface-Coating technology could reduce the use of anticoagulants in patients and help to prevent thrombotic occlusion and biofouling of medical devices.
Anna Waterhouse - One of the best experts on this subject based on the ideXlab platform.
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a bioinspired omniphobic Surface Coating on medical devices prevents thrombosis and biofouling
Nature Biotechnology, 2014Co-Authors: Daniel C. Leslie, Julia B. Berthet, Thomas M. Valentin, Anna Waterhouse, Alexander L WattersAbstract:A non-stick Surface Coating makes medical devices anti-thrombogenic and resistant to biofilm growth.
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A bioinspired omniphobic Surface Coating on medical devices prevents thrombosis and biofouling
Nature Biotechnology, 2014Co-Authors: Daniel C. Leslie, Julia B. Berthet, Thomas M. Valentin, Benjamin D. Hatton, Philseok Kim, Arthur Nedder, Alexander L Watters, Anna Waterhouse, Abhishek Jain, Kathryn DonovanAbstract:Thrombosis and biofouling of extracorporeal circuits and indwelling medical devices cause significant morbidity and mortality worldwide. We apply a bioinspired, omniphobic Coating to tubing and catheters and show that it completely repels blood and suppresses biofilm formation. The Coating is a covalently tethered, flexible molecular layer of perfluorocarbon, which holds a thin liquid film of medical-grade perfluorocarbon on the Surface. This Coating prevents fibrin attachment, reduces platelet adhesion and activation, suppresses biofilm formation and is stable under blood flow in vitro. Surface-coated medical-grade tubing and catheters, assembled into arteriovenous shunts and implanted in pigs, remain patent for at least 8 h without anticoagulation. This Surface-Coating technology could reduce the use of anticoagulants in patients and help to prevent thrombotic occlusion and biofouling of medical devices.
W Pang - One of the best experts on this subject based on the ideXlab platform.
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laser Surface Coating of mo wc metal matrix composite on ti6al4v alloy
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2005Co-Authors: W PangAbstract:Abstract Laser Surface alloying of Mo, WC and Mo–WC powders on the Surface of Ti6Al4V alloys using a 2 kW Nd-YAG laser was performed. The dilution effect upon the microstructure, microhardness and wear resistance of the Surface metal matrix composite (MMC) Coating was investigated. With a constant thickness of pre-placed powder, the dilution levels of the alloyed layers were found to increase with the incident laser power. The fabricated Surface MMC layer was metallurgically bonded to the Ti6Al4V substrate. The microhardness of the fabricated Surface layer was found to be inversely proportional to the dilution level. The EDAX and XRD spectra results show that new intermetallic compounds and alloy phases were formed in the MMC layer. With the existence of Mo content in the pre-placed powder, the β-phase of Ti in the MMC Coating can be retained at the quenching process. With increasing weight percentage content of WC particles in the Mo–WC pre-pasted powder, the microhardness and sliding wear resistance of the laser Surface Coating were increased by 87% and 150 times, respectively, as compared with the Ti6Al4V alloy. The Surface friction of the laser-fabricated MMC Coatings was also decreased as compared with the worn Ti6Al4V substrate.
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laser Surface Coating of mo wc metal matrix composite on ti6al4v alloy
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2005Co-Authors: W PangAbstract:Abstract Laser Surface alloying of Mo, WC and Mo–WC powders on the Surface of Ti6Al4V alloys using a 2 kW Nd-YAG laser was performed. The dilution effect upon the microstructure, microhardness and wear resistance of the Surface metal matrix composite (MMC) Coating was investigated. With a constant thickness of pre-placed powder, the dilution levels of the alloyed layers were found to increase with the incident laser power. The fabricated Surface MMC layer was metallurgically bonded to the Ti6Al4V substrate. The microhardness of the fabricated Surface layer was found to be inversely proportional to the dilution level. The EDAX and XRD spectra results show that new intermetallic compounds and alloy phases were formed in the MMC layer. With the existence of Mo content in the pre-placed powder, the β-phase of Ti in the MMC Coating can be retained at the quenching process. With increasing weight percentage content of WC particles in the Mo–WC pre-pasted powder, the microhardness and sliding wear resistance of the laser Surface Coating were increased by 87% and 150 times, respectively, as compared with the Ti6Al4V alloy. The Surface friction of the laser-fabricated MMC Coatings was also decreased as compared with the worn Ti6Al4V substrate.
Alexander L Watters - One of the best experts on this subject based on the ideXlab platform.
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a bioinspired omniphobic Surface Coating on medical devices prevents thrombosis and biofouling
Nature Biotechnology, 2014Co-Authors: Daniel C. Leslie, Julia B. Berthet, Thomas M. Valentin, Anna Waterhouse, Alexander L WattersAbstract:A non-stick Surface Coating makes medical devices anti-thrombogenic and resistant to biofilm growth.
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A bioinspired omniphobic Surface Coating on medical devices prevents thrombosis and biofouling
Nature Biotechnology, 2014Co-Authors: Daniel C. Leslie, Julia B. Berthet, Thomas M. Valentin, Benjamin D. Hatton, Philseok Kim, Arthur Nedder, Alexander L Watters, Anna Waterhouse, Abhishek Jain, Kathryn DonovanAbstract:Thrombosis and biofouling of extracorporeal circuits and indwelling medical devices cause significant morbidity and mortality worldwide. We apply a bioinspired, omniphobic Coating to tubing and catheters and show that it completely repels blood and suppresses biofilm formation. The Coating is a covalently tethered, flexible molecular layer of perfluorocarbon, which holds a thin liquid film of medical-grade perfluorocarbon on the Surface. This Coating prevents fibrin attachment, reduces platelet adhesion and activation, suppresses biofilm formation and is stable under blood flow in vitro. Surface-coated medical-grade tubing and catheters, assembled into arteriovenous shunts and implanted in pigs, remain patent for at least 8 h without anticoagulation. This Surface-Coating technology could reduce the use of anticoagulants in patients and help to prevent thrombotic occlusion and biofouling of medical devices.
