Published Date 20 September 2016, Vol.149:332–339,doi:10.1016/j.carbpol.2016.04.117 Title Functionalization of MWCNT and their application in properties development of green wood nanocomposite
Author
Prasanta Baishya
Tarun K. Maji,
Department of Chemical Sciences, Tezpur University, Assam 784028, India
Received 28 February 2016. Revised 6 April 2016. Accepted 26 April 2016. Available online 29 April 2016.
Highlights
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A green route has been established for the preparation of natural polymer based nanocomposites.
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Easily available, unused, low cost soft wood has been used with the natural polymer.
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Water is used as a solvent in the preparation of wood composites.
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The incorporation of MWCNT in the composites increases the mechanical, thermal and water resistance properties of the wood starch composites.
Abstract
Starch based wood nanocomposites (WSNC) were prepared successfully from starch and soft wood with multi-walled carbon nanotube (MWCNT) as nano reinforcing agent through a completely green path. The most important part of this scheme was the use of water as the solvent. In this technique, starch was grafted with methylmethacrylate (MMA) and MWCNT was functionalised with hydroxyl groups (f-MWCNT). Dimethyloldihydroxyethyleneurea (DMDHEU) was used as a cross-linker to prepare the green material from methylmethacrylate grafted starch (MMA-g-starch), soft wood flour and functionalised MWCNT. The functionalization of MWCNT was confirmed by Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and Raman analysis. Different properties of the WSNC were investigated by varying the concentration of f-MWCNT. The prepared nanocomposites exhibited outstanding thermal stability, mechanical properties and water resistance capacity compared to untreated wood composites. The flammability of the wood composites decreased up to 30% with just addition of 0.50 phr f-MWCNT.
Published Date September 2016, Vol.87:142–149,doi:10.1016/j.indcrop.2016.04.017 Title In situ measurement of heat-treated wood cell wall at elevated temperature by nanoindentation
Author
Dong Xing a,b
Jian Li a
Xinzhou Wang b,c
Siqun Wang b,,
aCollege of Materials Science and Engineering, Northeast Forestry University, Harbin 150040, PR China
bCenter for Renewable Carbon, University of Tennessee, Knoxville, TN 37996, USA
cCollege of Materials Science and Engineering, Nanjing Forestry University, Nanjing 210037, PR China
Received 18 September 2015. Revised 25 March 2016. Accepted 3 April 2016. Available online 22 April 2016.
Highlights
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Nanoindentation was equipped with temperature control stage to achieve the real-time test at elevated temperature conditions.
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The 3D morphology of wood cell wall and compound middle lamella were recorded by scanning probe microscopy.
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XRD and SEM were used to detect the microstructure and crystallinity of heat-treated wood.
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The micromechanical properties of wood cell wall were discussed at elevated temperature condition.
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This study supplies the fundamental research of viscoelastic properties of heat-treated wood cell wall.
Abstract
Nanoindentation equipped with hot stage to investigate the temperature-dependent real-time mechanical behavior of wood cell wall is introduced. In this study, wood samples were heat-treated at 180 °C and 210 °C. The effects of heat treatment on Larix gmelinii (Rupr.) Kuzen, a species of larch native to eastern Siberia, were studied at the cell-wall level. Nanoindentation at high temperature was used to track changes in the micromechanical properties in the longitudinal direction and to obtain measurements for both the temperature-dependent reduced modulus and hardness. The average reduced modulus of the cell wall slightly increased, while hardness tended to increase after heat treatment under room temperature conditions. The nanoindentation tests showed that both the reduced modulus and hardness of the wood cell walls tended to decrease as the temperature increased from 20 °C to 180 °C. Moreover, it was shown that heat treatment resulted in better heat resistance compared to that of untreated wood, especially in the samples indented at 180 °C.
Corresponding author at: Center for Renewable Carbon, Department of Forestry, Wildlife and Fisheries, University of Tennessee, Jacob Drive, Knoxville, TN 37996, USA.
Published Date August 2016, Vol.26:332–339,doi:10.1016/j.nanoen.2016.05.020 Title Transparent and haze wood composites for highly efficient broadband light management in solar cells
aDepartment of Materials Science and Engineering, University of Maryland, College Park, MD 20742, USA
bMaterial Measurement Laboratory, National Institute of Standards and Technology (NIST), Gaithersburg, MD 20899, USA
Received 10 February 2016. Revised 9 May 2016. Accepted 12 May 2016. Available online 13 May 2016.
Highlights
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Highly transparent, broadband wood composites are demonstrated for the first time.
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A high optical transmittance (~90%) and a high haze (~80%) is achieved for effective light management.
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An 18% efficiency improvement is achieved when applying the transparent wood in GaAs solar cells.
Abstract
Highly efficient broadband light management to enhance the light trapping inside active layer is critical for many energy conversion devices such as thin film solar cells and photoelectrochemical cells. In this work, we demonstrate highly transparent, mesoporous wood composite via fast extraction of lignin along naturally formed low tortuosity channels followed by fast filling of polymers. The transparent wood displays a high optical transmittance and at the same time a high haze in a broad wavelength range between 400 nm and 1100 nm. With such unique optical properties, the transparent wood composite with cellulose nanofibers can be utilized for a range of optoelectronics, especially for solar cells and wide-angle lighting where light management is crucial to enhance device operation efficiency. We demonstrate that the newly developed transparent wood composite can function as a broad range light management layer and substantially improve the overall energy conversion efficiency by as much as 18% when simply coated with a GaAs thin film solar cell. Our research on wood based light management material provides an attractive platform for future development embracing green, disposable optoelectronic devices with efficient light management.
Mingwei Zhu received his Ph.D. in Materials Science from Zhejiang University, China. In 2004, he joined the National Laboratory of Solid State Microstructures, Nanjing University as a post doctor. In 2007, he joined the Department of Materials Science and Engineering, Nanjing University. Currently, he is an associate professor at the College of Engineering and Applied Science, Nanjing University. From 2015 to 2016, he is a visiting scholar at Department of Materials Science and Engineering, University of Maryland. His research interests include environmental materials and microstructures, flexible electronics and optics, energy conversion materials and sensors.
Tian Li received the B.S. degree in Electrical Engineering from Huazhong University of Science and Technology, Hubei, China in 2010, and Ph.D. degree with Prof. Mario Dagenais in Electrical and Computer Engineering from University of Maryland, College Park, USA, in 2015. She is currently a Postdoctoral Research Scholar with Dr. Liangbing Hu in University of Maryland, College Park, MD, USA. Her research interests include low-dimensional electronic and optical devices, flexible electronics, energy generation and storage. She received the ECE Distinguished Dissertation Fellowship and Outstanding Graduate Assistant Award in 2015 for the recognition of her Ph.D. work.
Chelsea Davis received a B.S. in Textile Engineering from North Carolina State University in 2005. She obtained her M.S. and Ph.D. in Polymer Science and Engineering from the University of Massachusetts Amherst in 2007 and 2012, respectively focusing on the use of surface instabilities for adhesion control. From 2012 to 2013, Dr. Davis was a Michelin Postdoctoral Research Fellow at the ESPCI in Paris investigating polymer-polymer adhesion. She then completed an NRC Postdoctoral Fellowship at the National Institute of Standards and Technology researching polymer composites from 2013 to 2015. Dr. Davis is currently a Materials Research Engineer at NIST.
Yonggang Yao is currently a Ph.D. candidate in Department of Materials Science and Engineering at University of Maryland. His research interests are 1D fiber (cellulose nanofibers, carbon nanofibers and carbon nanotubes) and 2D sheet (reduced graphene oxide) based materials and structures with superior properties used for light manipulation, energy storage, electrochemical catalysis etc.
Jiaqi Dai received his B.S degree in Materials Science and Engineering from Harbin Institute of Technology, 2013, China. He is currently a Ph.D. candidate in materials engineering under the supervision of Prof. Liangbing Hu at University of Maryland, College Park, USA. His research interests mainly focus on nanotechnologies, advanced energy storage devices, and scientific visualizations.
Mr. Yanbin Wang received his Master degree from University of Maryland in 2016. He is currently a Ph.D. student in Department of Mechanical Engineering, University of Maryland. His research interests mainly focus on synthesis of 2D materials and energy conversion.
Feras AlQatari is currently a junior in department of materials science and engineering, University of Maryland (UMD) at College Park. His current research interests are photonic, energy and bio-inspired materials.
Jeffrey W. Gilman received his B.A. in chemistry from Ithaca College, and his Ph.D. in organic chemistry from the University of California, Irvine from Kenneth Shea. He joined NIST in 1994 as a research polymer chemist. He is currently the leader of the Composites Project at NIST. His recent work focuses on interface imaging using fluorescence methods and cellulose nanofiber composites. He has over 60 peer-reviewed publications, several patents and has authored several book chapters. Dr. Gilman has successfully formed four NIST-Industry research consortia, and has had a number of externally funded research programs during the 20 years at NIST. In 1999 he was awarded the Department of Commerce Bronze Medal, and in 2009 the Jacob Rabinow Award for his nanocomposites work.
Liangbing Hu received his B.S. in applied physics from the University of Science and Technology of China (USTC) in 2002. He did his Ph.D. in at UCLA, focusing on carbon nanotube based nanoelectronics. In 2006, he joined Unidym Inc as a co-founding scientist. At Unidym, Liangbing's role was the development of roll-to-roll printed carbon nanotube transparent electrodes and device integrations into touch screens, LCDs, flexible OLEDs and solar cells. He worked at Stanford University from 2009 to 2011, where he work on various energy devices based on nanomaterials and nanostructures. Currently, he is an associate professor at University of Maryland College Park.
