Satish Kumar

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Name: Kumar, Satish

Organization: Georgia Institute of Technology , USA

Department: School of Materials Science and Engineering

Title: Professor(PhD)

TOPICS

Polymer

Material Chemistry

Carbon Nanotubes

Chemicals
References

Orientation and interfacial stress transfer of cellulose nanocrystal nanocomposite fibers

Co-reporter:Huibin Chang, Jeffrey Luo, H. Clive Liu, Amir A. Bakhtiary Davijani, Po-Hsiang Wang, Satish Kumar

Polymer 2017 Volume 110(Volume 110) pp:

Publication Date(Web):10 February 2017

DOI:10.1016/j.polymer.2017.01.015

•Polar plot of 1095 cm−1 Raman band in cellulose nanocrystals under VV mode shows a two-fold symmetry.•Polar plot of 1095 cm−1 Raman band in cellulose nanocrystals under VH mode shows a four-fold symmetry.•Highly oriented CNC along fiber axis is confirmed by Raman spectroscopy.•Interfacial stress transfer between CNC and polymer fiber is characterized.Orientation and interfacial stress transfer in cellulose nanocrystals (CNC) reinforced polyacrylonitrile (PAN) nanocomposite fibers were determined by Raman spectroscopy. The 1095 cm−1 Raman band was used to quantify the orientation of CNC in composite fiber. Under VV (vertical/vertical) mode, polar plots of all composite fibers showed a two-fold symmetry. Under VH (vertical/horizontal) mode, it showed a four-fold symmetry. The CNCs are highly oriented in the composite fiber, which is confirmed by second and fourth order orientation parameters:〈P2(cosθ)〉 and〈P4(cosθ)〉. The 1095 cm−1 Raman band shift under uniaxial deformation was used to characterize the interfacial shear stress transfer between PAN matrix and CNCs.Download high-res image (290KB)Download full-size image

Ductile polyacrylonitrile fibers with high cellulose nanocrystals loading

Co-reporter:Huibin Chang, Jeffrey Luo, H. Clive Liu, Amir A. Bakhtiary Davijani, Po-Hsiang Wang, George S. Lolov, Ryan M. Dwyer, Satish Kumar

Polymer 2017 Volume 122(Volume 122) pp:

Publication Date(Web):28 July 2017

DOI:10.1016/j.polymer.2017.06.072

•Well-dispersed cellulose nanocrystals (CNCs) in polyacrylonitrile (PAN) fiber were prepared.•PAN fibers containing 40 wt% CNCs were successfully spun by gel-spinning method.•For 40 wt% CNCs loaded PAN fibers, drawing process make the composite fiber more ductile.•CNCs can improve the mechanical performance of polyacrylonitrile fiber.Polyacrylonitrile (PAN) fibers containing up to 40 wt% cellulose nanocrystals (CNCs) were processed. Structure, mechanical, and dynamic mechanical properties of these fibers were systematically investigated. The crystallinity, crystal size and crystallite orientation of PAN in PAN and PAN/CNC fibers significantly increases as the draw ratio increases from 4x to 15x. As compared to the control PAN fiber at a draw ratio of 4x, work of rupture increases by a factor of 2 only for 1 wt% CNC loading, and tensile modulus increased by a factor of two at the same draw ratio in fibers containing 40 wt% CNC. Though PAN/CNC 40 wt% fiber is brittle at 4x draw ratio, the elongation at break is significantly improved as fiber was drawn to a draw ratio of 29x and becomes comparable to that for the control PAN fiber at high draw ratio. This is the first study of such a high concentration of nano reinforcement in PAN fibers with good mechanical properties. These results should prove important in reinforcing broader class of polymers with CNCs and other nanomaterials, without making them brittle, which is a common draw back with many reinforcements and fillers.Download high-res image (160KB)Download full-size image

Revival of nitrogen-containing bisphosphonate-induced inhibition of osteoclastogenesis and osteoclast function by water-soluble microfibrous borate glass

Co-reporter:He Yuan, Li-na Niu, Kai Jiao, Dan-dan Pei, Chandrani Pramanik, Ji-yao Li, Regina Messer, Satish Kumar, David H. Pashley, Franklin R. Tay

Acta Biomaterialia 2016 Volume 31() pp:312-325

Publication Date(Web):February 2016

DOI:10.1016/j.actbio.2015.12.009

Abstract

Bisphosphonate-related osteonecrosis of the jaw (BRONJ) is a serious skeletal complication associated with the long-term oral or intravenous use of nitrogen-containing bisphosphonates (N-BPs). Here, we investigated the effects of an ionic cocktail prepared from water-soluble microfibrous borate glass on neutralizing the inhibitory effects of two heterocyclic N-BPs, risedronate or zoledronic acid, on osteoclastogenesis, apoptosis of differentiated osteoclasts and osteoclast function. Cell growth and proliferation assays were first performed on RAW 264.7 cells to optimize the concentrations of the ionic cocktail and N-BPs to be used for static cell culture. The pre-osteoclasts were then stimulated with RANKL to differentiate into osteoclasts. The effects of the ionic cocktail and N-BPs on osteoclast differentiation, apoptosis and function were subsequently examined using 3 series of experiments conducted at the gene, protein, morphological and functional levels. After concentration optimization, the ionic cocktail was found to partially reverse N-BP-induced inhibition of osteoclastogenesis, stimulation of osteoclasts apoptosis and reduction of osteoclast resorptive activity. Ultrastructural examination of osteoclasts that had been exposed to either N-BP identified classical features of late apoptosis and secondary necrosis, while osteoclasts exposed simultaneously to the concentration-optimized ionic cocktail and N-BPs exhibited only signs of early apoptosis that were possibly reversible. Taken together, the results of the 4 series of experiments indicate that the ionic cocktail produced from dissolution of borate glass dressings has the potential to rescue the adverse effects of heterocyclic N-BPs on osteoclast differentiation and function. These results warrant further confirmation using dynamic cell culture and small animal BRONJ models.

Statement of significance

Long-term oral and intravenous use of nitrogen-containing bisphosphonates (N-BPs) may result in bisphosphonate-related osteonecrosis of the jaw (BRONJ) due to the suppression of normal bone turnover. There is no effective treatment for such a complication to date. This work reported the use of an ionic cocktail derived from water-soluble microfibrous borate glass to revert heterocyclic N-BP-induced inhibition of osteoclastogenesis, stimulation of osteoclasts apoptosis and reduction of osteoclasts resorption in static cell culture condition. This ionic cocktail may have the potential to be further developed into a new adjunctive treatment for BRONJ.

A mechanistic study of the interaction of water-soluble borate glass with apatite-bound heterocyclic nitrogen-containing bisphosphonates

Co-reporter:Chandrani Pramanik, Parveen Sood, Li-na Niu, He Yuan, Sushanta Ghoshal, Walter Henderson, Yaodong Liu, Seung Soon Jang, Satish Kumar, David H. Pashley, Franklin R. Tay

Acta Biomaterialia 2016 Volume 31() pp:339-347

Publication Date(Web):February 2016

DOI:10.1016/j.actbio.2015.12.008

Abstract

Long-term oral and intravenous use of nitrogen-containing bisphosphonates (N-BPs) is associated with osteonecrosis of the jaw. Although N-BPs bind strongly to bone surfaces via non-covalent bonds, it is possible for extrinsic ions to dissociate bound N-BPs from mineralized bone by competitive desorption. Here, we investigate the effects and mechanism of using an ionic cocktail derived from borate bioactive glass for sequestration of heterocyclic N-BPs bound to apatite. By employing solid-state and solution-state analytical techniques, we confirmed that sequestration of N-BPs from bisphosphonate-bound apatite occurs in the presence of the borate-containing ionic cocktail. Simulations by density functional theory computations indicate that magnesium cation and borate anion are well within the extent of the risedronate or zoledronate anion to form precipitate complexes. The sequestration mechanism is due to the borate anion competing with bisphosphonates for similar electron-deficient sites on the apatite surface for binding. Thus, application of the borate-containing ionic cocktail represents a new topical lavage approach for removing apatite-bound heterocyclic N-BPs from exposed necrotic bone in bisphosphonate-related osteonecrosis of the jaw.

Statement of significance

Long-term oral consumption and injections of nitrogen-containing bisphosphonates (N-BPs) may result in death of the jaw bone when there is traumatic injury to the bone tissues. To date, there is no effective treatment for such a condition. This work reported the use of an ionic cocktail derived from water-soluble borate glass microfibers to displace the most potent type of N-BPs that are bound strongly to the mineral component on bone surfaces. The mechanism responsible for such an effect has been identified to be cation-mediated complexation of borate anions with negatively-charged N-BPs, allowing them to be released from the mineral surface. This borate-containing cocktail may be developed into a novel topical rinse for removing mineral-bound N-BPs from exposed dead bone.

Polyacrylonitrile solution homogeneity study by dynamic shear rheology and the effect on the carbon fiber tensile strength

Co-reporter:Bradley A. Newcomb;Prabhakar V. Gulgunje;Yaodong Liu;Kishor Gupta;Manjeshwar G. Kamath;Chrani Pramanik;Sushanta Ghoshal;Han Gi Chae

Polymer Engineering & Science 2016 Volume 56( Issue 3) pp:361-370

Publication Date(Web):

DOI:10.1002/pen.24261

Poly(acrylonitrile-co-methacrylic acid) (PAN-co-MAA)/N,N-dimethylformamide (DMF) solutions were prepared and dynamic shear rheology of these solutions were investigated. With increasing stirring time up to 72 h at 70°C, the polymer solution became less elastic (more liquid-like) with a ∼60% reduction in the zero-shear viscosity. Relaxation spectra of the PAN-co-MAA/DMF solutions yield a decrease in relaxation time (disentanglement time, τ_d), corresponding to an about 8% decrease in viscosity average molecular weight. The log-log plot of G′ (storage modulus) versus G″ (loss modulus) exhibited an increase in slope as a function of stirring time, suggesting that the molecular level solution homogeneity increased. In order to study the effect of solution homogeneity on the resulting carbon fiber tensile strength, multiple PAN-co-MAA/DMF solutions were prepared, and the precursor fibers were processed using gel-spinning, followed by continuous stabilization and carbonization. The rheological properties of each solution were also measured and correlated with the tensile strength values of the carbon fibers. It was observed that with increasing the slope of the G′ versus G″ log-log plot from 1.471 to 1.552, and reducing interfilament fiber friction during precursor fiber drawing through the addition of a fiber washing step prior to fiber drawing, the carbon fiber strength was improved (from 3.7 to 5.8 GPa). This suggests that along with precursor fiber manufacturing and carbonization, the solution homogeneity is also very important to obtain high strength carbon fiber. POLYM. ENG. SCI., 56:361–370, 2016. © 2016 Society of Plastics Engineers

Microfibrous borate bioactive glass dressing sequesters bone-bound bisphosphonate in the presence of simulated body fluid

Co-reporter:Chandrani Pramanik, Tianda Wang, Sushanta Ghoshal, Lina Niu, Bradley A. Newcomb, Yaodong Liu, Carolyn M. Primus, Hailan Feng, David H. Pashley, Satish Kumar and Franklin R. Tay

Journal of Materials Chemistry A 2015 vol. 3(Issue 6) pp:959-963

Publication Date(Web):06 Jan 2015

DOI:10.1039/C4TB02035A

Ion exchange occurs between borate bioactive glass and simulated body fluid. Borate bioactive glass dressings may be used for managing bisphosphonate-related osteonecrosis of the jaw through the formation of a complex incorporating leached calcium and borate ions and sequestered bone-bound bisphosphonates.

Stress transfer in polyacrylonitrile/carbon nanotube composite fibers

Co-reporter:Bradley A. Newcomb, Han Gi Chae, Prabhakar V. Gulgunje, Kishor Gupta, Yaodong Liu, Dmitri E. Tsentalovich, Matteo Pasquali, Satish Kumar

Polymer 2014 Volume 55(Issue 11) pp:2734-2743

Publication Date(Web):27 May 2014

DOI:10.1016/j.polymer.2014.04.008

Gel spun polyacrylonitrile/carbon nanotube (PAN/CNT) composite fibers have been produced, and the stress-induced G′ Raman band shifts in the CNTs have been monitored to observe stress transfer during fiber strain. Improvements in CNT quality, CNT dispersion, and post-processing fiber drawing are shown to increase the stress transfer from the matrix to the CNT. Radial breathing mode (RBM) intensity of specific CNT chiralities confirms CNT debundling during fiber processing. During PAN/CNT fiber straining, there reaches a plateau in the CNT G′ downshift, signifying that the stress on the CNT is maintained despite continued straining of the PAN/CNT fiber. Correlating CNT strain with CNT modulus and volume fraction allows for the interfacial shear strength (τi) of the PAN-CNT interface to be determined. The as-spun and fully drawn PAN/CNT-A (99/1) nano composite fibers exhibit τi of 13.1 and 30.9 MPa, respectively, while an improved CNT dispersion (PAN/CNT-A (99.9/0.1)) results in τi equal to 44.3 MPa.

Functional polymer–polymer/carbon nanotube bi-component fibers

Co-reporter:An-Ting Chien, Prabhakar V. Gulgunje, Han Gi Chae, Aniruddha S. Joshi, Jaeyun Moon, Bo Feng, G.P. Peterson, Satish Kumar

Polymer 2013 Volume 54(Issue 22) pp:6210-6217

Publication Date(Web):18 October 2013

DOI:10.1016/j.polymer.2013.08.061

Graphene Nanoribbons as an Advanced Precursor for Making Carbon Fiber

Co-reporter:Changsheng Xiang, Natnael Behabtu, Yaodong Liu, Han Gi Chae, Colin C. Young, Bostjan Genorio, Dmitri E. Tsentalovich, Chenguang Zhang, Dmitry V. Kosynkin, Jay R. Lomeda, Chih-Chau Hwang, Satish Kumar, Matteo Pasquali, and James M. Tour

ACS Nano 2013 Volume 7(Issue 2) pp:1628

Publication Date(Web):January 22, 2013

DOI:10.1021/nn305506s

Graphene oxide nanoribbons (GONRs) and chemically reduced graphene nanoribbons (crGNRs) were dispersed at high concentrations in chlorosulfonic acid to form anisotropic liquid crystal phases. The liquid crystal solutions were spun directly into hundreds of meters of continuous macroscopic fibers. The relationship of fiber morphology to coagulation bath conditions was studied. The effects of colloid concentration, annealing temperature, spinning air gap, and pretension during annealing on the fibers’ performance were also investigated. Heat treatment of the as-spun GONR fibers at 1500 °C produced thermally reduced graphene nanoribbon (trGNR) fibers with a tensile strength of 378 MPa, Young’s modulus of 36.2 GPa, and electrical conductivity of 285 S/cm, which is considerably higher than that in other reported graphene-derived fibers. This better trGNR fiber performance was due to the air gap spinning and annealing with pretension that produced higher molecular alignment within the fibers, as determined by X-ray diffraction and scanning electron microscopy. The specific modulus of trGNR fibers is higher than that of the commercial general purpose carbon fibers and commonly used metals such as Al, Cu, and steel. The properties of trGNR fibers can be further improved by optimizing the spinning conditions with higher draw ratio, annealing conditions with higher pretensions, and using longer flake GONRs. This technique is a new high-carbon-yield approach to make the next generation carbon fibers based on solution-based liquid crystal phase spinning.Keywords: carbon fiber; coagulation; fiber spinning; graphene nanoribbon

Polyethylene Crystallization Nucleated by Carbon Nanotubes under Shear

Co-reporter:Marilyn L. Minus, Han Gi Chae, and Satish Kumar

ACS Applied Materials & Interfaces 2012 Volume 4(Issue 1) pp:326

Publication Date(Web):December 12, 2011

DOI:10.1021/am2013757

Polyethylene crystallization under shear has been studied in the presence of single-wall, few-wall, and multiwall carbon nanotubes (SWNT, FWNT, and MWNT). Polyethylene crystal d-spacings for (110) and (200) planes in polyethylene/carbon nanotubes (CNT) are smaller than in the control polyethylene without CNT and the polymer chain is oriented along the CNT axis. The single-wall carbon nanotube templated polyethylene crystals do not redissolve in boiling xylenes; instead, the chain morphology transforms to an amorphous conformation but remains oriented along the nanotube axis. SWNT crystal peaks were also observed in polyethylene/SWNT fibers.Keywords: carbon nanotubes; crystallization; polyethylene; shish-kebab;

Gel-spun carbon nanotubes/polyacrylonitrile composite fibers. Part III: Effect of stabilization conditions on carbon fiber properties

Co-reporter:Yaodong Liu, Han Gi Chae, Satish Kumar

Carbon 2011 Volume 49(Issue 13) pp:4487-4496

Publication Date(Web):November 2011

DOI:10.1016/j.carbon.2011.06.045

The oxidative stabilization process of gel-spun carbon nanotube (CNT)/polyacrylonitrile (PAN) composite fibers have been studied and optimized. Optimum stabilization time depends on both the applied tension and temperature. Various characterization methods including thermal shrinkage, dynamic mechanical analysis, infrared spectroscopy, and wide angle X-ray diffraction are used to monitor the chemical and structural evolution during stabilization and carbonization. The relationship between the stabilization conditions of CNT/PAN composite fiber and the tensile properties of the resulting carbon fibers were investigated. By optimizing stabilization conditions, CNT/PAN based carbon fibers with a tensile strength of 4 GPa and a tensile modulus of 286 GPa were obtained using batch carbonization processing at 1100 °C.

Gel-spun carbon nanotubes/polyacrylonitrile composite fibers. Part II: Stabilization reaction kinetics and effect of gas environment

Co-reporter:Yaodong Liu, Han Gi Chae, Satish Kumar

Carbon 2011 Volume 49(Issue 13) pp:4477-4486

Publication Date(Web):November 2011

DOI:10.1016/j.carbon.2011.06.042

Gel-spun polyacrylonitrile (PAN) and carbon nanotube (CNT) composite fibers have been stabilized using various processing conditions to study the kinetics of stabilization reactions. Differential scanning calorimetry, infrared spectroscopy, wide angle X-ray diffraction and thermo-gravimetric analysis studies suggest that individual stabilization reactions can be separated at different stabilization stages when inert and oxidative environments are used in sequence. Among various stabilization reactions, it was found that the cross-linking has the highest activation energy, followed by cyclization and oxidation. The oxidation preferentially occurs with the cyclized structure and the shrinkage during stabilization is affected by the gaseous environment. The addition of CNTs reduces both entropic and reaction shrinkages, and improves the maximum tension that a fiber can bear during stabilization in both inert and oxidative environments.

Gel-spun carbon nanotubes/polyacrylonitrile composite fibers. Part I: Effect of carbon nanotubes on stabilization

Co-reporter:Yaodong Liu, Han Gi Chae, Satish Kumar

Carbon 2011 Volume 49(Issue 13) pp:4466-4476

Publication Date(Web):November 2011

DOI:10.1016/j.carbon.2011.06.043

Addition of carbon nanotubes (CNTs) in polyacrylonitrile (PAN) fibers significantly improves the mechanical properties of the resulting carbon fibers. This study focuses on the effect of different types of CNTs on chemical, mechanical and structural changes during the stabilization of gel-spun CNT/PAN composite fibers. Among the different types of CNTs, it was observed that CNTs containing more walls had lower reinforcement efficiency than CNTs containing fewer walls. Similarly CNTs containing fewer walls exhibited higher orientation of the ladder polymer and greater effect on the formation of β-amino nitrile in the stabilized fibers. Wide angle X-ray diffraction, infrared spectroscopy, and scanning electron microscopy were used to determine the optimum stabilization time. Additionally, it was found that the higher tension applied during stabilization improved the properties of the stabilized fibers, and the addition of CNTs increased the maximum tension that the fiber can bear.

Lysozyme Coated DNA and DNA/SWNT Fibers by Solution Spinning

Co-reporter:Dhriti Nepal;Marilyn L. Minus

Macromolecular Bioscience 2011 Volume 11( Issue 7) pp:875-881

Publication Date(Web):

DOI:10.1002/mabi.201000490

Structure and electrochemical properties of activated polyacrylonitrile based carbon fibers containing carbon nanotubes

Co-reporter:Sudhakar Jagannathan, Han Gi Chae, Rahul Jain, Satish Kumar

Journal of Power Sources 2008 Volume 185(Issue 2) pp:676-684

Publication Date(Web):1 December 2008

DOI:10.1016/j.jpowsour.2008.08.093

Solution spun polyacrylonitrile (PAN), PAN/multi-wall carbon nanotube (MWCNT), and PAN/single-wall carbon nanotube (SWCNT) fibers containing 5 wt.% carbon nanotubes were stabilized in air and activated using CO2 and KOH. The surface area as determined by nitrogen gas adsorption was an order of magnitude higher for KOH activated fibers as compared to the CO2 activated fibers. The specific capacitance of KOH activated PAN/SWCNT samples was as high as 250 F g−1 in 6 M KOH electrolyte. Under the comparable KOH activation conditions, PAN and PAN/SWCNT fibers had comparable surface areas (BET surface area about 2200 m2 g−1) with pore size predominantly in the range of 1–5 nm, while surface area of PAN/MWCNT samples was significantly lower (BET surface area 970 m2 g−1). The highest capacitance and energy density was obtained for PAN/SWCNT samples, suggesting SWCNT advantage in charge storage. The capacitance behavior of these electrodes has also been tested in ionic liquids, and the energy density in ionic liquid is about twice the value obtained using KOH electrolyte.

SURVEYING FROM THE AIR

Co-reporter:E. Lester Jones

Science 1920 Vol 52(1355) pp:574-575

Publication Date(Web):17 Dec 1920

DOI:10.1126/science.52.1355.574

THE DIRECTORSHIP OF THE MAINE AGRICULTURAL STATION

Co-reporter:Chas. D. Woods

Science 1920 Vol 52(1355) pp:584-585

Publication Date(Web):17 Dec 1920

DOI:10.1126/science.52.1355.584

High surface area carbon from polyacrylonitrile for high-performance electrochemical capacitive energy storage

Co-reporter:Kishor Gupta, Tianyuan Liu, Reza Kavian, Han Gi Chae, Gyeong Hee Ryu, Zonghoon Lee, Seung Woo Lee and Satish Kumar

Journal of Materials Chemistry A 2016 - vol. 4(Issue 47) pp:NaN18299-18299

Publication Date(Web):2016/11/02

DOI:10.1039/C6TA08868F

High surface area carbon with a surface area of 3550 m2 g−1 is synthesized via a low-cost, scalable process from polyacrylonitrile. The composite electrodes consisting of high surface area carbon and carbon nanotubes delivered a high capacitance of ∼174 F g−1 in symmetric configurations, and a high capacity of ∼150 mA h g−1 in asymmetric configurations against lithium metal with excellent rate-performance at practical mass loading and bulk densities.

Microfibrous borate bioactive glass dressing sequesters bone-bound bisphosphonate in the presence of simulated body fluid

Co-reporter:Chandrani Pramanik, Tianda Wang, Sushanta Ghoshal, Lina Niu, Bradley A. Newcomb, Yaodong Liu, Carolyn M. Primus, Hailan Feng, David H. Pashley, Satish Kumar and Franklin R. Tay

Journal of Materials Chemistry A 2015 - vol. 3(Issue 6) pp:NaN963-963

Publication Date(Web):2015/01/06

DOI:10.1039/C4TB02035A