| Synthesis, Cure Kinetics, and Physical Properties of a New Tricyanate Ester with Enhanced Molecular Flexibility |
03 MAY 2011 |
1 pages |
| Authors:
Andrew J. Guenthner; Matthew C. Davis; Kevin R. Lamison; Gregory R. Yandek; Lee R. Cambrea; Thomas J. Groshens; Lawrence C. Baldwin; Joseph M. Mabry; AIR FORCE RESEARCH LAB EDWARDS AFB CA PROPULSION DIRECTORATE
|
 | 1,2,3-Tris(4-cyanatophenyl)propane, a new tricyanate ester monomer analogous to cyanated novolac or "phenolic triazine (PT) resin" that features more flexible chemical linkages at the central branch point, was synthesized in nine steps with an overall yield of 26%. The highly purified monomer exhibited an activation energy of 110 kJ/mol for auto-catalytic cure at temperatures of 210 deg C to 290 deg C, modestly lower than the comparably measured activation energy of ... |
|
| Fluoroalkyl-functionalized Silica Particles: Synthesis, Characterization, and Wetting Characteristics (Preprint) |
03 MAY 2011 |
35 pages |
| Authors:
Raymond Campos; Andrew J. Guenthner; Timothy S. Haddad; Joseph M. Mabry; AIR FORCE RESEARCH LAB EDWARDS AFB CA PROPULSION DIRECTORATE
|
| Fluoroalkyl-functionalized silica particles for use in non-wetting surfaces were prepared by treatment of silica particles with fluoroalkyl-functional chlorosilanes. Both fumed and precipitated silica were studied, as well as the efficiency of surface coverage using mono-, di-, and tri-functional chlorosilanes. The most-effective surface treatment was accomplished via the surface grafting of mono-functional-chlorosilanes in the presence of pre-adsorbed dimethylamine under anhydrous conditions at room temperature. Confirmation of covalent attachment was accomplished via ... |
|
| The Role of Concurrent Chemical and Physical Processes in Determining the Maximum Use Temperature of Thermosetting Polymers for Aerospace Applications |
04 APR 2011 |
3 pages |
| Authors:
Andrew J. Guenthner; Kevin R. Lamison; Gregory R. Yandek; Kenneth C. Masurat; Josiah T. Reams; Lee R. Cambrea; Joseph M. Mabry; AIR FORCE RESEARCH LAB EDWARDS AFB CA PROPULSION DIRECTORATE
|
| Herein we report on our efforts to better determine the maximum use temperatures of thermosetting polymers through a combination of alternative thermo-mechanical analyses. We show that thermal cycling and attention to heating rates can often provide more reliable results with a minimum of additional effort. |
|
| Fluoroalkyl Polyhedral Oligomeric Silsesquioxane (F-POSS) Based Monomers and Polymers |
04 APR 2011 |
4 pages |
| Authors:
Sean M. Ramirez; Raymond Campos; Yvonne Diaz; Timothy S. Haddad; Joseph M. Mabry; ENGINEERING RESEARCH AND CONSULTING INC (ERC INC) EDWARDS AFB CA
|
| Fluorinated Polyhedral Oligomeric SilSesquioxanes (F-POSS), which contain silicon-oxygen cores and a periphery of long chain fluorinated alkyl groups, were functionalized with methyl methacrylate (MMA) and acrylate (A) to produce F-POSS monomers (F-POSS-MMA and F-POSS-A). Structures were confirmed with multinuclear NMR (1H, 13C, and 29Si) and found to be soluble in non-fluorinated solvents such as diethyl ether. |
|
| Asymmetric Aryl Polyhedral Oligomeric SilSesquioxanes (ArPOSS) with Enhanced Solubility (Preprint) |
23 MAR 2011 |
16 pages |
| Authors:
Brian M. Moore; Sean M. Ramirez; Gregory R. Yandek; Timothy S. Haddad; Joseph M. Mabry; AIR FORCE RESEARCH LAB EDWARDS AFB CA PROPULSION DIRECTORATE SPACE AND MISSILE PROPULSION DIV/PROPULSION MATERIALS APPLICATIONS BRANCH
|
| Four new asymmetric Polyhedral Oligomeric SilSesquixoanes (POSS) with the formula (Aryl)Phenyl7Si8O12, where Aryl = 1-naphthyl, 2-naphthyl, 9-phenanthrenyl, and 1-pyrenyl, have been synthesized in reasonable yield and high purity. These compounds were characterized with 1H, 13C, 29Si NMR and elemental combustion analysis. These compounds possess polycyclic aromatic functionality, which disrupts symmetry to improve solubility in organic solvents and aromatic polymers, without significant impact on thermal stability. |
|
| Solution Spraying of Poly(methyl methacrylate) Blends to Fabricate Micro-textured, Superoleophobic Surfaces (PREPRINT) |
2011 |
28 pages |
| Authors:
Siddarth Srinivasan; Shreerang S. Chhatre; Joseph M. Mabry; Robert E. Cohen; Gareth H. McKinley; AIR FORCE RESEARCH LAB EDWARDS AFB CA PROPULSION DIR/SPACE AND MISSILE PROPULSION DIV
|
| We describe a simple technique to prepare superhydrophobic and superoleophobic micro-textured surfaces by spray coating a blend of poly(methyl methacrylate) (PMMA) and the low surface energy molecule 1H,1H,2H,2H-heptadecafluorodecyl polyhedral oligomeric silsesquioxane (fluorodecyl POSS, gamma(sv) approximately equal to 10 mN/m) using an air brush with a pressurized nitrogen stream. Scanning electron micrographs show the formation of micro-textured surfaces possessing re-entrant curvature; a critical feature for obtaining liquid repellency with low surface ... |
|
| Reduced Cost Fabrication of Large Composite Aerospace Structures Through Nanoparticle Modification of Thermoplastics (Preprint) |
08 MAY 2007 |
15 pages |
| Authors:
Gregory R. Yandek; Darrell Marchant; Joseph M. Mabry; Mark B. Gruber; Mark Lamontia; Sandra Cope; ENGINEERING RESEARCH AND CONSULTING INC (ERC INC) EDWARDS AFB CA
|
| To achieve superior mechanical properties and environmental durability in semi-crystalline engineering thermoplastic composites an intermediate degree of molecular ordering is required. While many thermoplastics achieve their potential crystallinities with autoclave processing, only a fraction of that which is desired is developed with lower cost manufacturing processes, viz. automated fiber placement and tape laying featuring polymer chilling from the melt in seconds. Implementation of such processes for the manufacture of large ... |
|
| Synthesis and Characterization of Space-Survivable POSS-Kapton (Trademark) Polyimides (Preprint) |
06 MAR 2007 |
15 pages |
| Authors:
Sandra J. Tomczak; Timothy K. Minton; Amy L. Brunsvold; Vandana Vij; MIcheal E. Wright; Brian J. Petteys; Andrew J. Guenthner; Steven A. Svejda; Joseph M. Mabry; AIR FORCE RESEARCH LAB EDWARDS AFB CA PROPULSION DIRECTORATE
|
| Kapton(Registered) is used extensively in spacecraft thermal blankets, solar arrays, and space inflatable structures. This material is chosen due to its thermal and physical properties, however it is degraded severely in low Earth orbit (LEO) by atomic oxygen (AO). SiO2 coatings impart remarkable oxidation resistance to Kapton(Registered), yet imperfections in the SiO2 application process and micrometeoroid debris impact in orbit may damage the SiO2 coating and lead to Kapton(Registered) erosion. ... |
|
| Ultrahydrophobic Fluorinated Polyhedral Oligomeric Silsesquioxanes (F-POSS) (Preprint) |
25 JAN 2007 |
11 pages |
| Authors:
Joseph M. Mabry; Scott T. Iacono; Brent D. Viers; Ashwani Vij; AIR FORCE RESEARCH LAB EDWARDS AFB CA PROPULSION DIRECTORATE
|
| Recently, significant attention has been drawn to preparing low surface energy materials inspired by naturally evolved biological systems possessing a high degree of ultrahydrophobicity. Specifically, the lotus leaf exhibits an inherent self-cleaning mechanism resulting from micron-sized waxy nodes protruding from its surface so that water is naturally repelled removing any foreign debris. This remarkable cleansing mechanism, coined the "lotus effect," has been artificially mimicked to produce materials with pronounced ultrahydrophobicity. ... |
|
| Comparisons of Polyhedral Oligomeric Silsesquioxane (POSS) Polyimides as Space-Survivable Materials (Postprint) |
15 NOV 2006 |
14 pages |
| Authors:
Sandra J. Tomczak; Vandana Vij; Timothy K. Minton; Amy L. Brunsvold; Darrell Marchant; Michael E. Wright; Brian J. Petteys; Andrew J. Guenthner; Joseph M. Mabry; AIR FORCE RESEARCH LAB EDWARDS AFB CA PROPULSION DIRECTORATE
|
| Kapton(registered name) is used extensively in spacecraft thermal blankets, solar arrays, and space inflatable structures. Atomic oxygen (AO) in low Earth orbit (LEO) causes severe degradation of Kapton. SiO2 coatings impart remarkable oxidation resistance to Kapton, yet imperfections in the SiO2 application process and micrometeoroid / debris impact in orbit damage the SiO2 coating leading to Kapton erosion. Polyhedral oligomeric silsesquioxane (POSS) is a silicon and oxygen cage-like structure surrounded ... |
|
| Hydrophobic Silsesquioxane Nanoparticles and Nanocomposite Surfaces (POSTPRINT) |
04 MAY 2006 |
13 pages |
| Authors:
Joseph M. Mabry; Darrell Marchant; Brent D. Viers; Ashwani Vij; Wade Grabow; Patrick N. Ruth; Isha Vij; AIR FORCE RESEARCH LAB EDWARDS AFB CA PROPULSION DIRECTORATE
|
| Fluorinated Polyhedral Oligomeric Silsesquioxanes are hydrophobic nanoparticles. One compound, FD8T8, is ultrahydrophobic, possessing a water contact angle of 154 deg. This is believed to be the most hydrophobic and lowest surface tension crystalline substance known. Analysis of the x-ray crystal structure indicates a large number of Si...F contacts may lead to ultrahydrophobicity. |
|
| Determination of Mechanical and Surface Properties of Semicrystalline Polyhedral Oligomeric Silsesquioxane (POSS) Nanocomposites |
11 OCT 2005 |
25 pages |
| Authors:
Laura E. Moody; Darrell Marchant; Wade W. Grabow; Andre Y. Lee; Joseph M. Mabry; AIR FORCE RESEARCH LAB EDWARDS AFB CA PROPULSION DIRECTORATE
|
| INTRODUCTION: (1) Nanomodification of semicrystalline polymers -- unequalled thermal, mechanical and surface properties at low volume fractions that cannot be obtained using conventional fillers; (2) Blending POSS molecules into polymers can increase the thermal and mechanical properties as well as the surface properties; (3) The objective of this study is to examine the effect of blending various POSS molecules into a variety of appropriate semicrystalline polymers. |
|
| Determination of Mechanical and Surface Properties of Semicrystalline Polyhedral Oligomeric Silsequioxane (POSS) Nanocomposites |
02 AUG 2005 |
12 pages |
| Authors:
Laura E. Moody; Darrell Marchant; Wade W. Grabow; Andre Y. Lee; Joseph M. Mabry; AIR FORCE RESEARCH LAB EDWARDS AFB CA PROPULSION DIRECTORATE
|
| Polyhedral Oligomeric Silsesquioxanes are three dimensionally precise silicon/oxygen nanoparticles. These nanoparticles can be tailored to maximize the interactions between the POSS compounds and the polymer by the modification of the organic groups surrounding the inorganic cage. This study examines the ability of POSS to improve the mechanical and surface properties of three semicrystalline polymers, fluorinated ethylene-propylene (FEP), poly(vinylidene fluoride) (PVDF) and isotactic polypropylene (PP). The POSS materials used included methyl(sub-8)T(sub-8) ... |
|
Reports by Author
