| Investigation of Proton Conductivity of Cation-Exchanged, Sulfonated Poly(b-Styrene-b-Isobutylene-b-Styrene) Membranes |
Sep-2009 |
26 pages |
| Authors:
Eugene Napadensky; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
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 | In this study, membranes made with highly sulfonated (81%-97%) poly(styrene-b-isobutylene-b-styrene) polymer were exchanged with a variety of cations: Cu, Ba, Zn, Cs, Ag, Ca, and Mg. Absorption levels of the cation-exchanged materials was determined for water, methanol, and an equimolar water/methanol mixture, measured using a gravimetric technique. Proton conductivity of the membranes was measured in a dry state, as well as swollen in water, methanol, and the equimolar water /methanol ... |
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| Hybrid Helmet Cure Cycle Optimization |
FEB 2008 |
17 pages |
| Authors:
David M. Spagnuolo; Eugene Napadensky; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD WEAPONS AND MATERIALS RESEARCH DIRECTORATE
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| Some of the recent work involving the use of thermoplastic materials for combat helmets has shown significant weight savings and improved protection. Unfortunately, the change to thermoplastic materials brings with it some important concerns. First, the stiffness is compromised with these materials so a hybrid type of helmet (a thermoplastic shell with thermoset inner or outer skins) is needed to reduce the deflection properties. This brings us to the second ... |
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| Thermo Stability of Highly Sulfonated Poly(Styrene-Isobutylene-Styrene) Block Copolymers: Effects of Sulfonation and Counter-Ion Substitution |
JAN 2008 |
20 pages |
| Authors:
James M. Sloan; David Suleiman; Eugene Napadensky; Dawn M. Crawford; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD WEAPONS AND MATERIALS RESEARCH DIRECTORATE
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| In this study, poly(styrene-isobutylene-styrene) (SIBS) block copolymers were characterized by thermogravimetry as a function of sulfonation level (53% to 97%) and counter-ion substitution (Mg+2, Ca+2, Ba+2). Sulfonated samples showed an additional minor loss of mass at ~290 plus/minus 2 deg. C, which was not observed in the unsulfonated polymer. At this temperature, desulfonation or a cleavage reaction of the aromatic carbon-sulfur bond occurs. The counter-ion substituted membranes did not show ... |
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| Multiscale Modeling of Polymer Membranes for Soldiers Protective Clothing |
NOV 2006 |
34 pages |
| Authors:
Jan Andzelm; James Sloan; Eugene Napadensky; Rick Beyer; James Snyder; Steven McKnight; Peter W. Chung; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD WEAPONS AND MATERIALS RESEARCH DIRECTORATE
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| The development of protective and breathable clothing is a very important goal set for the Future Force. Recently, a new polymer membrane made of an ionic triblock (A-B-A) copolymer was developed at the U.S. Army Research Laboratory (ARL) that provides an excellent selective barrier for soldier s protective clothing. We have used multiscale modeling to gain an understanding of the static and dynamic properties of this polymer membrane at detailed ... |
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| Transport Properties of N-Methyloated Nylon-6: Chitosan Blend Membranes |
SEP 2006 |
22 pages |
| Authors:
Eugene Napadensky; Yossef A. Elabd; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD WEAPONS AND MATERIALS RESEARCH DIRECTORATE
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| A series of N-Methylolated Nylon-6 chitosan blend membranes was evaluated for their potential use as breathable (high water transport) barriers (low chemical agent transport) for military and civilian protective clothing apparel. Nylon-6 was methylolated and subsequently blended with chitosan at different compositions and processing conditions (room temperature, 100 C, and 200 C). Vapor transport rates of water (breathability) and dimethyl methylphosphonate (protection) (a simulant of the nerve agent Sarin) were ... |
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| Thermogravimetric and Spectroscopic Characterization of Sulfonated Poly(Styrene-Isobutylene-Styrene) Block Copolymers: Effects of Processing Conditions |
MAY 2006 |
20 pages |
| Authors:
James M. Sloan; David Suleiman; Yossef A. Elabd; Eugene Napadensky; Dawn M. Crawford; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD WEAPONS AND MATERIALS RESEARCH DIRECTORATE
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| In this study, sulfonated poly(styrene-isobutylene-styrene) (S-SIBS) block copolymers were characterized by thermogravimetry as a function of four different processing conditions: sulfonation level, annealing temperature, film formation, and casting solvent. Sulfonated samples showed an increase in degradation temperature from 432 to 450 degrees C compared to the unsulfonated polymer, regardless of sulfonation level or other processing condition. Sulfonated samples also showed an additional minor loss of mass at -290 degrees C, ... |
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| Characterization of Polyamide 66 Obturator Materials by Differential Scanning Calorimetry and Size-Exclusion Chromatography |
DEC 2005 |
24 pages |
| Authors:
Frederick L. Beyer; Eugene Napadensky; Christopher R. Ziegler; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
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| Samples of two polyamide 6/6 materials used to make obturation were characterized by differential scanning calorimetry (DSC) and by size-exclusion chromatography (SEC). The two materials. commercially available DuPont Zytel 42A and Zytel 101, have been used in obturators. but an increase in undesired part failures occurred when Zytel 101 was replaced with the newer Zytel 42A. DSC analysis of these materials revealed very little variation in the nature of the ... |
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| Transport Properties of Sulfonated Poly (Styrene-b-isobutylene-b-styrene) Triblock Copolymers at High Ion-Exchange Capacities |
20 OCT 2005 |
11 pages |
| Authors:
Karen I. Winey; Yossef A. Elabd; Eugene Napadensky; Charles W. Walker; PENNSYLVANIA UNIV PHILADELPHIA
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| Transport properties of sulfonated poly(styrene-b-isobutylene-b-styrene) (S-SIBS) triblock copolymers were examined as a function of ion-exchange capacity (IEC), specifically at high IECs (up to -2 mequiv/g). The proton conductivity of S-SIBS was -1 order of magnitude higher than sulfonated polystyrene at similar IECs and 3-fold higher than Nafion 117 at an IEC of 2 mequiv/g. However, all polymers in this study possessed similar selectivities (i.e., proton conductivity/methanol permeability) regardless of chemistry ... |
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| Characterization of Highly Sulfonated SIBS Polymer Partially Neutralized With Mg(+2) Cations |
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30 pages |
| Authors:
Eugene Napadensky; James M Sloan; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD WEAPONS AND MATERIALS RESEARCH DIRECTORATE
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| In the search for selective membranes capable of separating protons from methanol for direct methanol fuel cells or chemical and biological toxins from water in chemical protective clothing, block copolymer ionomer membranes emerge. They are highly ordered sequence of both ionic and nonionic blocks, in which the ionic groups are randomly arranged along the polymer chain. This investigation studied one of these block copolymer ionomers, sulfonated poly(styrene-b-isobutylene-b-styrene). In this study, ... |
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