The Experts below are selected from a list of 1959 Experts worldwide ranked by ideXlab platform

Jeffrey S. Moore - One of the best experts on this subject based on the ideXlab platform.

  • cyclic poly phthalaldehyde thermoforming a bulk transient material
    ACS Macro Letters, 2018
    Co-Authors: Adam M Feinberg, Christopher L Plantz, Edgar B Mejia, Scott R. White, Hector Lopez Hernandez, Nancy R. Sottos, Jeffrey S. Moore
    Abstract:

    Cyclic poly(phthalaldehyde) (cPPA) is a metastable and stimuli responsive polymer that undergoes rapid solid state Depolymerization and has been utilized as a packaging and encapsulating material for transient applications. However, the early onset Thermal Depolymerization of cPPA severely hinders the fabrication and processing of plastic parts. Herein, the Thermally triggered Depolymerization of cPPA was investigated and tailored to enable Thermal processing and molding of cPPA at moderate temperatures below the Thermal Depolymerization temperature. Stabilization of cPPA at elevated temperature was accomplished by removal of the latent Lewis acid catalyst BF3 and by addition of radical inhibitors and a Lewis base. Addition of a plasticizer to the stabilized cPPA enabled the fabrication of a monolithic solid polymer via hot press molding. Importantly, it is shown that the Thermally processed cPPA retains its stimuli responsive Depolymerization capability and will enable future work in the fabrication of b...

  • chemical treatment of poly lactic acid fibers to enhance the rate of Thermal Depolymerization
    ACS Applied Materials & Interfaces, 2012
    Co-Authors: Hefei Dong, Scott R. White, Nancy R. Sottos, Aaron P Esserkahn, Piyush Thakre, Jason F Patrick, Jeffrey S. Moore
    Abstract:

    When heated, poly(lactic acid) (PLA) fibers depolymerize in a controlled manner, making them potentially useful as sacrificial fibers for microchannel fabrication. Catalysts that increase PLA Depolymerization rates are explored and methods to incorporate them into commercially available PLA fibers by a solvent mixture impregnating technique are tested. In the present study, the most active catalysts are identified that are capable of lowering the Depolymerization temperature of modified PLA fibers by ca. 100 °C as compared to unmodified ones. Lower Depolymerization temperatures allow PLA fibers to be removed from a fully cured epoxy thermoset resin without causing significant Thermal damage to the epoxy. For 500 μm diameter PLA fibers, the optimized treatment involves soaking the fibers for 24 h in a solvent mixture containing 60% trifluoroethanol (TFE) and 40% H2O dispersed with 10 wt % tin(II) oxalate and subsequent air-drying of the fibers. PLA fibers treated with this procedure are completely removed ...

  • three dimensional microvascular fiber reinforced composites
    Advanced Materials, 2011
    Co-Authors: Aaron P Esserkahn, Jeffrey S. Moore, Nancy R. Sottos, Hefei Dong, Piyush Thakre, Jason F Patrick, Vitalii Vlaskovlasov, Scott R. White
    Abstract:

    and materials or lack of scalability and vascular complexity of the fabrication approach. Here we show that the introduction of sacrificial fibers into woven preforms enables the seamless fabrication of 3D microvascular composites that are both strong and multifunctional. Underpinning the method is the efficient Thermal Depolymerization of catalyst-impregnated polylactide (PLA) fibers with simultaneous evaporative removal of the resulting lactide monomer. The hollow channels produced are high-fidelity inverse replicas of the original fiber’s diameter and trajectory. The method has yielded microvascular fiber-reinforced composites with channels over one meter in length that can be subsequently filled with a variety of liquids including aqueous solutions, organic solvents, and liquid metals. By circulating fluids with unique physical properties, we demonstrate the ability to create a new generation of biphasic pluripotent composite materials in which the solid phase provides strength and form while the liquid phase provides interchangeable functionality. Microvascular composite fabrication begins with the mechanized weaving of sacrifi cial fi bers into 3D woven glass

Tuan Anh Nguyen - One of the best experts on this subject based on the ideXlab platform.

  • simulation and experimental investigation on carbonized tracking failure of epdm bn based electrical insulation
    Polymers, 2020
    Co-Authors: Muhammad Tariq Nazir, Bt Phung, Faizan Tahir Butt, Guan Heng Yeoh, Ghulam Yasin, Shakeel Akram, Muhammad Shoaib Bhutta, Shahid Hussain, Tuan Anh Nguyen
    Abstract:

    Ethylene propylene diene monomer (EPDM) is broadly employed as an insulating material for high voltage applications. Surface discharge-induced Thermal Depolymerization and carbon tracking adversely affect its performance. This work reports the electrical field modeling, carbon tracking lifetime, infrared Thermal distribution, and leakage current development on EPDM-based insulation with the addition of nano-BN (boron nitride) contents. Melt mixing and compression molding techniques were used for the fabrication of nanocomposites. An electrical tracking resistance test was carried out as per IEC-60587. Simulation results show that contamination significantly distorted the electrical field distribution and induced dry band arcing. Experimental results indicate that electric field stress was noticed significantly higher at the intersection of insulation and edges of the area of contamination. Moreover, the field substantially intensified with the increasing voltage levels. Experimental results show improved carbonized tracking lifetime with the addition of nano-BN contents. Furthermore, surface temperature was reduced in the critical contamination flow path. The third harmonic component in the leakage current declined with the increase of the nano-BN contents. It is concluded that addition of nano-BN imparts a better tracking failure time, and this is attributed to better Thermal conductivity and Thermal stability, as well as an improved shielding effect to electrical discharges on the surface of nanocomposite insulators.

Ayhan Demirbas - One of the best experts on this subject based on the ideXlab platform.

  • the influence of temperature on the yields of compounds existing in bio oils obtained from biomass samples via pyrolysis
    Fuel Processing Technology, 2007
    Co-Authors: Ayhan Demirbas
    Abstract:

    Abstract The influence of temperature on the compounds existing in liquid products obtained from biomass samples via pyrolysis were examined in relation to the yield and composition of the product bio-oils. The product liquids were analysed by a gas chromatography mass spectrometry combined system. The bio-oils were composed of a range of cyclopentanone, methoxyphenol, acetic acid, methanol, acetone, furfural, phenol, formic acid, levoglucosan, guaiacol and their alkylated phenol derivatives. Thermal Depolymerization and decomposition of biomass structural components, such as cellulose, hemicelluloses, lignin form liquids and gas products as well as a solid residue of charcoal. The structural components of the biomass samples mainly affect the pyrolytic degradation products. A reaction mechanism is proposed which describes a possible reaction route for the formation of the characteristic compounds found in the oils. The supercritical water extraction and liquefaction partial reactions also occur during the pyrolysis. Acetic acid is formed in the Thermal decomposition of all three main components of biomass. In the pyrolysis reactions of biomass: water is formed by dehydration; acetic acid comes from the elimination of acetyl groups originally linked to the xylose unit; furfural is formed by dehydration of the xylose unit; formic acid proceeds from carboxylic groups of uronic acid; and methanol arises from methoxyl groups of uronic acid

  • mechanisms of liquefaction and pyrolysis reactions of biomass
    Energy Conversion and Management, 2000
    Co-Authors: Ayhan Demirbas
    Abstract:

    In the liquefaction process, the micellar-like broken down fragments produced by hydrolysis are degraded to smaller compounds by dehydration, dehydrogenation, deoxygenation and decarboxylation. These compounds once produced, rearrange through condensation, cyclization and polymerization, leading to new compounds. Thermal Depolymerization and decomposition of biomass, cellulose, hemicelluloses and products were formed as well as a solid residue of charcoal. The mechanism of pyrolytic degradation of structural components of the biomass samples was separately studied. Cleavage of the aromatic C–O bond in lignin led to the formation of one oxygen atom products, and the cleavage of the methyl C–O bond to form two oxygen atom products is the first reaction to occur in the thermolysis of 4-alkylguaiiacol at 600–650 K. Cleavage of the side chain C–C bond occurs between the aromatic ring and the α-carbon atom.

Bt Phung - One of the best experts on this subject based on the ideXlab platform.

  • simulation and experimental investigation on carbonized tracking failure of epdm bn based electrical insulation
    Polymers, 2020
    Co-Authors: Muhammad Tariq Nazir, Bt Phung, Faizan Tahir Butt, Guan Heng Yeoh, Ghulam Yasin, Shakeel Akram, Muhammad Shoaib Bhutta, Shahid Hussain, Tuan Anh Nguyen
    Abstract:

    Ethylene propylene diene monomer (EPDM) is broadly employed as an insulating material for high voltage applications. Surface discharge-induced Thermal Depolymerization and carbon tracking adversely affect its performance. This work reports the electrical field modeling, carbon tracking lifetime, infrared Thermal distribution, and leakage current development on EPDM-based insulation with the addition of nano-BN (boron nitride) contents. Melt mixing and compression molding techniques were used for the fabrication of nanocomposites. An electrical tracking resistance test was carried out as per IEC-60587. Simulation results show that contamination significantly distorted the electrical field distribution and induced dry band arcing. Experimental results indicate that electric field stress was noticed significantly higher at the intersection of insulation and edges of the area of contamination. Moreover, the field substantially intensified with the increasing voltage levels. Experimental results show improved carbonized tracking lifetime with the addition of nano-BN contents. Furthermore, surface temperature was reduced in the critical contamination flow path. The third harmonic component in the leakage current declined with the increase of the nano-BN contents. It is concluded that addition of nano-BN imparts a better tracking failure time, and this is attributed to better Thermal conductivity and Thermal stability, as well as an improved shielding effect to electrical discharges on the surface of nanocomposite insulators.

  • Simulation and experimental investigation on carbonized tracking failure of EPDM/BN-based electrical insulation
    'MDPI AG', 2020
    Co-Authors: Mt Nazir, Bt Phung, Ft Butt, Gh Yeoh, Yasin G, Akram S, Bhutta Ms, Hussain S, Anh Nguyen T
    Abstract:

    Ethylene propylene diene monomer (EPDM) is broadly employed as an insulating material for high voltage applications. Surface discharge‐induced Thermal Depolymerization and carbon tracking adversely affect its performance. This work reports the electrical field modeling, carbon tracking lifetime, infrared Thermal distribution, and leakage current development on EPDMbased insulation with the addition of nano‐BN (boron nitride) contents. Melt mixing and compression molding techniques were used for the fabrication of nanocomposites. An electricaltracking resistance test was carried out as per IEC‐60587. Simulation results show that contamination significantly distorted the electrical field distribution and induced dry band arcing. Experimental results indicate that electric field stress was noticed significantly higher at theintersection of insulation and edges of the area of contamination. Moreover, the field substantially intensified with the increasing voltage levels. Experimental results show improved carbonized tracking lifetime with the addition of nano‐BN contents. Furthermore, surface temperature was reduced in the critical contamination flow path. The third harmonic component in the leakage current declined with the increase of the nano‐BN contents. It is concluded that addition of nano‐BN imparts a better tracking failure time, and this is attributed to better Thermal conductivity and Thermal stability, as well as an improved shielding effect to electrical discharges on the surface of nanocomposite insulators

  • Proceedings of the IEEE International Conference on Properties and Applications of Dielectric Materials
    'Institute of Electrical and Electronics Engineers (IEEE)', 2018
    Co-Authors: Tariq Nazir M, Bt Phung, Yu S, Zhang Y, Li S
    Abstract:

    Carbonized tracking due to Thermal Depolymerization on weather-shed materials of polymeric insulators is one of the key insulation failure modes, adversely affecting the reliability of power delivery networks. This paper investigates the tracking process and Thermal distribution of micron-AlN and hybrid micron-AlN + nano-silica filled silicone rubber composites. Micron sized aluminum nitride (AlN: 5∼10 μm) and nano-silica (SiO2: 20 nm) particles were procured for fabricating composites in this work. The inclined plane test according to IEC 60587 was used; tracking voltage method 2 was adopted with initial applied voltage of 3 kV and ramping rate of 0.25 kV/h over duration of 240 minutes. Measurement results show hybrid composites exhibit substantially lower tracking length as compared to micron-AlN filled composites. Thermal accumulation is found significantly reduced in hybrid composites which could be due to better Thermal stability and Thermal conductivity. Moreover, the hybrid set of filler particles may increase the surface area of particles in the composites, provide better scattering, reduce secondary electron collision and impede release of high energy causing Thermal Depolymerization

Muhammad Tariq Nazir - One of the best experts on this subject based on the ideXlab platform.

  • simulation and experimental investigation on carbonized tracking failure of epdm bn based electrical insulation
    Polymers, 2020
    Co-Authors: Muhammad Tariq Nazir, Bt Phung, Faizan Tahir Butt, Guan Heng Yeoh, Ghulam Yasin, Shakeel Akram, Muhammad Shoaib Bhutta, Shahid Hussain, Tuan Anh Nguyen
    Abstract:

    Ethylene propylene diene monomer (EPDM) is broadly employed as an insulating material for high voltage applications. Surface discharge-induced Thermal Depolymerization and carbon tracking adversely affect its performance. This work reports the electrical field modeling, carbon tracking lifetime, infrared Thermal distribution, and leakage current development on EPDM-based insulation with the addition of nano-BN (boron nitride) contents. Melt mixing and compression molding techniques were used for the fabrication of nanocomposites. An electrical tracking resistance test was carried out as per IEC-60587. Simulation results show that contamination significantly distorted the electrical field distribution and induced dry band arcing. Experimental results indicate that electric field stress was noticed significantly higher at the intersection of insulation and edges of the area of contamination. Moreover, the field substantially intensified with the increasing voltage levels. Experimental results show improved carbonized tracking lifetime with the addition of nano-BN contents. Furthermore, surface temperature was reduced in the critical contamination flow path. The third harmonic component in the leakage current declined with the increase of the nano-BN contents. It is concluded that addition of nano-BN imparts a better tracking failure time, and this is attributed to better Thermal conductivity and Thermal stability, as well as an improved shielding effect to electrical discharges on the surface of nanocomposite insulators.