Kennard Wilson - Academia.edu (original) (raw)

Papers by Kennard Wilson

Journal of Macromolecular Science: Part A - Chemistry, 1989

The solubilities and viscosities of four novel symmetric tri-n-alkyltin fluorides in various orga... more The solubilities and viscosities of four novel symmetric tri-n-alkyltin fluorides in various organic solvents were studied. It is shown that these compounds do behave as transient polymers. Increasing the length of the n-alkyl chain beyond n-butyl imparts considerable solubility to this class of associative polymers and offers no steric hindrance to polymer chain formation. The effects of concentration, solvent type, temperature, and brine on the solution viscosities were also studied. These associative polymers effectively viscosify compressed gases (having liquid-like densities), such as propane and n-butane. They can therefore be used in enhanced oil recovery operations as well as in fracturing of oil wells.

Industrial & Engineering Chemistry Product Research and Development, 1985

... Dlleep K. Dandge,' John P. Heller, and Kennard V. Wilson New Mexico Petroleum Recove... more ... Dlleep K. Dandge,' John P. Heller, and Kennard V. Wilson New Mexico Petroleum Recovery Research Center, New Mexico Institute of Mining ... and Josendal, 1982; Stalkup, 1983), supercritical fluid chro-matography (SFC) (Giddings et al., 1968; Lauer et al., 1983; Wasen et al ...

Transactions of the American Nuclear Society

Based on the agreement between the gravimetric, calculated, and LOI measurements for the high-pur... more Based on the agreement between the gravimetric, calculated, and LOI measurements for the high-purity surrogate oxides and the divergence of these measurements for the PuOâ samples, we conclude that (a) LOI measurements are not a reliable indicator for the determination of hydrogenous material in plutonium oxides, and (b) supercritical fluid extraction can be used as an alternative analytical method for the determination of absolute water content in these inorganic oxide matrices. Future experiments will focus on surrogate and plutonium oxides containing organic compounds to verify the efficiency of supercritical fluid extraction for their quantitative determination.

Separation Science and Technology

The N,N{prime}-tetraalkylmalonamides are a class of compounds under development for transuranic (... more The N,N{prime}-tetraalkylmalonamides are a class of compounds under development for transuranic (TRU) separations under high nitric acid conditions. There are several issues that challenge the further development of these ligands. One is the development of improved synthetic procedures that lend themselves to commercial scale-up. Another major issue is the third-phase formation that occurs when the N,N{prime}-tetraalkylmalonamides are contacted with medium-to-high nitric acid concentrations in hydrocarbon solvents. To address the synthesis issue, the authors have developed a new synthetic approach for preparing these materials. Third-phase formation can be eliminated by addition of diluent modifiers such as tributylphosphate (TBP). TBP is inappropriate if a nonphosphate-containing process stream is required. Amides have been proposed as alternatives for TBP in a variety of applications because of their ease of synthesis and the variety of substituents that can be generated. The auth...

Silica and bridged polysilsesquioxane aerogels are low-density materials that are attractive for ... more Silica and bridged polysilsesquioxane aerogels are low-density materials that are attractive for applications such as thermal insulation, porous separation media or catalyst supports, adsorbents, and cometary dust capture agents. However, aerogels are notoriously weak and brittle making it difficult to handle and machine monoliths into desired forms. This complication prevents the development of many applications that would otherwise benefit from the use of the low-density materials. Here, we will describe our efforts to chemically modify and mechanically enhance silica-based aerogels using chemical vapor techniques without sacrificing their characteristic low densities. Monolithic silica and organic-bridged polysilsesquioxane aerogels were prepared by sol-gel polymerization of the respective methoxysilane monomers followed by supercritical carbon dioxide drying of the gels. Then the gels were reactively modified with silylating agents to demonstrate the viability of CVD modificatio...

High Internal Phase Emulsion polystyrene foams have been made at Los Alamos National Laboratory f... more High Internal Phase Emulsion polystyrene foams have been made at Los Alamos National Laboratory for the past decade. As target designs become more complex the demands placed on the foams are more stringent. Parts need to be machined from 30 mg/cm{sup 3} foams to a thickness of 50 {micro}m within a couple of microns. Containing upwards of 97% air, these foams are to withstand extraction with ethanol to remove the wax utilized as a machining aid yet retain their dimensional stability. At low densities, less than 50 mg/cm{sup 3}, voids are a problem. To determine a formulation that reduces void content and allows minimum shrinkage, experimental design was utilized. We also developed image analysis techniques that allow us to quantify the amount of voids in the system and the surface finish of the foam. In order to machine these low density foams to the tolerance required with an optimum surface finish, the foams are backfilled with Brij{reg_sign} 78, an alcohol soluble wax. After a par...

At the Los Alamos Plutonium Facility, various isotopes of plutonium along with other actinides ar... more At the Los Alamos Plutonium Facility, various isotopes of plutonium along with other actinides are handled in a glove box environment. Weapons-grade plutonium consists mainly in Pu-239. Pu-238 is another isotope used for heat sources. The Pu-238 is more aggressive regarding gloves due to its higher alpha-emitting characteristic (â300 times more active than Pu-239), which modifies the change-out intervals for gloves. Optimization of the change-out intervals for gloves is fundamental since Nuclear Materials Technology (NMT) Division generates approximately 4 m³/yr of TRU waste from the disposal of glovebox gloves. To reduce the number of glovebox glove failures, the NMT Division pro-actively investigates processes and procedures that minimize glove failures. Aging studies have been conducted that correlate changes in mechanical (physical) properties with degradation chemistry. This present work derives glovebox glove change intervals based on mechanical data of thermally aged Hypalon...

ABSTRACT Silica and bridged polysilsesquioxane aerogels are low density materials that are attrac... more ABSTRACT Silica and bridged polysilsesquioxane aerogels are low density materials that are attractive for applications such as, thermal insulation, porous separation media or catalyst supports, adsorbents. However, aerogels are notoriously weak and brittle making it difficult to handle and machine monoliths into desired forms. This prevents the development of many applications that would otherwise benefit from the use of the low density materials. We will describe our efforts to chemically modify and mechanically enhance silica-based aerogels using chemical vapor techniques without sacrificing their characteristic low densities. Monolithic silica and organically bridged polysilsesquioxane aerogels were prepared by sol-gel polymerization of the respective methoxysilane monomers followed by supercritical carbon dioxide drying of the gels. Reactive modification of the gels with volatile silylating compounds during and after the drying process and these effects on the mechanical properties and density of the aerogels will be described.

The Journal of Physical Chemistry C, 2008

The kinetics of LiH powder/water reactions indicate a corrosion resistant layer can readily be ge... more The kinetics of LiH powder/water reactions indicate a corrosion resistant layer can readily be generated on LiH by exposure to a mixture of CO2 and H2O. Specifically, LiH powder corrodes very rapidly even in low ppm concentration of water, but samples pretreated in ...

MRS Proceedings, 2004

... INFLUENCE OF THE BRIDGING GROUP LENGTH Douglas A. Loy,* James H. Small, Kimberly A. DeFriend,... more ... INFLUENCE OF THE BRIDGING GROUP LENGTH Douglas A. Loy,* James H. Small, Kimberly A. DeFriend, Kennard V. Wilson, Jr., McKenzie Minke,1 Brigitta M. Baugher,1 Colleen R. Baugher,1 Duane A. Schneider,1 and Kenneth J. Shea2 ...

MRS Proceedings, 2004

ABSTRACT Aging of silica gels before drying is known to result in significant changes in xerogel ... more ABSTRACT Aging of silica gels before drying is known to result in significant changes in xerogel morphology, porosity and properties. In this study, the influence of aging gels on the porosity and morphology of alkylene-bridged polysilsesquioxane xerogels was examined. ...

The eight average molecular weights, as well as other characteristics such as the second virial c... more The eight average molecular weights, as well as other characteristics such as the second virial coefficients and root-mean-square (RMS) radii of gyration of poly (ethyleneimine) (PEI) and various derivatives, have been determined in solution light scattering studies. The solution dynamics of PEI and carboxylated and phosphorylated derivatives were studied a pH of 3.3, 7.0 and 10.0. Measurements were made in

This is the final report of a one-year, Laboratory Directed Research and Development (LDRD) proje... more This is the final report of a one-year, Laboratory Directed Research and Development (LDRD) project at Los Alamos National Laboratory (LANL). The objectives of this project were (1) to develop an enhanced fundamental understanding of the coordination chemistry of hazardous-metal-ion complexation with water-soluble metal-binding polymers, and (2) to exploit this knowledge to develop improved separations for analytical methods, metals processing, and waste treatment. We investigated features of water-soluble metal-binding polymers that affect their binding constants and selectivity for selected transition metal ions. We evaluated backbone polymers using light scattering and ultrafiltration techniques to determine the effect of pH and ionic strength on the molecular volume of the polymers. The backbone polymers were incrementally functionalized with a metal-binding ligand. A procedure and analytical method to determine the absolute level of functionalization was developed and the results correlated with the elemental analysis, viscosity, and molecular size.

Separation Science and Technology, 1997

The N,N′-tetraalkylmalonamides are a class of compounds under development for transuranic (TRU) s... more The N,N′-tetraalkylmalonamides are a class of compounds under development for transuranic (TRU) separations under high nitric acid conditions. There are several issues that challenge the further development of these ligands. One is the development of improved synthetic procedures that lend themselves to commercial scale-up. Another major issue is the third-phase formation that occurs when the N,N′-tetraalkylmalonamides are contacted with medium-to-high nitric acid concentrations in hydrocarbon solvents. To address the synthesis issue we have developed a new synthetic approach for preparing these materials. Third-phase formation can be eliminated by addition of diluent modifiers such as tributylphosphate (TBP). TBP is inappropriate if a nonphosphate-containing process stream is required. Amides have been proposed as alternatives for TBP in a variety of applications because of their ease of synthesis and the variety of substituents that can be generated. We have been able to develop an amide phase-modified system that extends the working process range of alkylmalonamides (0.5 M) in dodecane (unbranched hydrocarbon) from 3.5 M to 7.5 M nitric acid and in Isopar H (branched hydrocarbon) from 4.0 M to 10.0 M nitric acid using 1.0 M di-2-ethylhexylacetamide/0.5 M alkylmalonamide. The Kd values were comparable to extraction with alkylmalonamide in Isopar H or hydrogenated tetrapropylene (TPH) solvents. The overall extraction system was more robust than the phase-unmodified system allowing for greater temperature and acid concentration fluctuations without third-phase formation.

Polymer Degradation and Stability, 2004

Attenuated total reflection (ATR) infrared spectra have been analyzed using multivariate curve re... more Attenuated total reflection (ATR) infrared spectra have been analyzed using multivariate curve resolution (MCR) to capture the chemistry of the thermal degradation in the aging of chlorosulfonated polyethylene (Hypalon Ò ) glove samples. The analysis demonstrates the primary degradation pathways to be oxidation (formation of ketones and carboxylic acids), dehydrochlorination with formation of eC]Ce groups, and polymer crosslinking with changes in the CeH functional groups. From the multivariate analysis, the dominant degradation pathway involves carbonecarbon double bond formation and oxidation to form ketones. The tensile properties (modulus and elongation at break) demonstrate stiffening of the material with aging time. The dynamic mechanical data show that the storage modulus and mechanical loss tangent are also strongly affected with aging due to a hardening of the material. Taken together the mechanical and ATR data indicate that in thermal aging hypalon degrades by dehydrochlorination and loss of eSO 2 Cl functionality with eC]Ce formation, oxidation, and crosslinking causing the material to harden and become brittle. Published by Elsevier Ltd.

Journal of Non-Crystalline Solids, 2011

... Enhancing mechanical properties of silica aerogels. Kimberly AD Obrey a , low asterisk , E-ma... more ... Enhancing mechanical properties of silica aerogels. Kimberly AD Obrey a , low asterisk , E-mail The Corresponding Author , Kennard V. Wilson b and Douglas A. Loy c. ... In turn, polymer-silica composites have been made by Boday, Loy, DeFriend, et.al. [28]. ...

Journal of Applied Polymer Science, 1983

Due to the high chain transfer to monomer, the homopolymerization of methacrylamide yields polyme... more Due to the high chain transfer to monomer, the homopolymerization of methacrylamide yields polymers of extremely low molecular weight. On partial alkaline hydrolysis, the viscosities of these polymers in aqueous solution are much inferior to those of partially hydrolyzed polyacrylamide (HPAM). However, polymethacrylamides prepared by room temperature, persulfate-initiated polymerization in the presence of small amounts of N,N'-methylenebisacrylamide demonstrate posthydrolysis reduced

Journal of Applied Polymer Science, 1986

ABSTRACT Several poly-1-hexene samples were prepared using different Ziegler-Natta catalysts, and... more ABSTRACT Several poly-1-hexene samples were prepared using different Ziegler-Natta catalysts, and their solubilities in dense carbon dioxide (CO2) were studied. Despite the varied molecular weight distributions (MWD) in the polymers, a surprising correlation was found between intrinsic viscosity and dense CO2 solubility. Due to the ability of dense CO2 to extract low-molecular weight fractions preferentially, it is recommended that narrow MWD polymers be used, as far as possible, for dense CO2 solubility determinations.

Journal of Applied Polymer Science, 1986

Kinetics of 1-hexene polymerization was studied by following the amount of unreacted monomer usin... more Kinetics of 1-hexene polymerization was studied by following the amount of unreacted monomer using gas chromatography. The Ziegler-Natta catalyst system used was comprised of TiC1,-AlEt, with A1 : Ti ratio of 0.85. The sampling and monomer analysis techniques developed can be applied to study the kinetics of higher a-olefins polymerizations, in general. Also, with minor modifications in this technique, a precise profile of molecular weight can be obtained during polymerization.

Journal of Macromolecular Science: Part A - Chemistry, 1989

The solubilities and viscosities of four novel symmetric tri-n-alkyltin fluorides in various orga... more The solubilities and viscosities of four novel symmetric tri-n-alkyltin fluorides in various organic solvents were studied. It is shown that these compounds do behave as transient polymers. Increasing the length of the n-alkyl chain beyond n-butyl imparts considerable solubility to this class of associative polymers and offers no steric hindrance to polymer chain formation. The effects of concentration, solvent type, temperature, and brine on the solution viscosities were also studied. These associative polymers effectively viscosify compressed gases (having liquid-like densities), such as propane and n-butane. They can therefore be used in enhanced oil recovery operations as well as in fracturing of oil wells.

Industrial & Engineering Chemistry Product Research and Development, 1985

... Dlleep K. Dandge,' John P. Heller, and Kennard V. Wilson New Mexico Petroleum Recove... more ... Dlleep K. Dandge,' John P. Heller, and Kennard V. Wilson New Mexico Petroleum Recovery Research Center, New Mexico Institute of Mining ... and Josendal, 1982; Stalkup, 1983), supercritical fluid chro-matography (SFC) (Giddings et al., 1968; Lauer et al., 1983; Wasen et al ...

Transactions of the American Nuclear Society

Based on the agreement between the gravimetric, calculated, and LOI measurements for the high-pur... more Based on the agreement between the gravimetric, calculated, and LOI measurements for the high-purity surrogate oxides and the divergence of these measurements for the PuOâ samples, we conclude that (a) LOI measurements are not a reliable indicator for the determination of hydrogenous material in plutonium oxides, and (b) supercritical fluid extraction can be used as an alternative analytical method for the determination of absolute water content in these inorganic oxide matrices. Future experiments will focus on surrogate and plutonium oxides containing organic compounds to verify the efficiency of supercritical fluid extraction for their quantitative determination.

Separation Science and Technology

The N,N{prime}-tetraalkylmalonamides are a class of compounds under development for transuranic (... more The N,N{prime}-tetraalkylmalonamides are a class of compounds under development for transuranic (TRU) separations under high nitric acid conditions. There are several issues that challenge the further development of these ligands. One is the development of improved synthetic procedures that lend themselves to commercial scale-up. Another major issue is the third-phase formation that occurs when the N,N{prime}-tetraalkylmalonamides are contacted with medium-to-high nitric acid concentrations in hydrocarbon solvents. To address the synthesis issue, the authors have developed a new synthetic approach for preparing these materials. Third-phase formation can be eliminated by addition of diluent modifiers such as tributylphosphate (TBP). TBP is inappropriate if a nonphosphate-containing process stream is required. Amides have been proposed as alternatives for TBP in a variety of applications because of their ease of synthesis and the variety of substituents that can be generated. The auth...

Silica and bridged polysilsesquioxane aerogels are low-density materials that are attractive for ... more Silica and bridged polysilsesquioxane aerogels are low-density materials that are attractive for applications such as thermal insulation, porous separation media or catalyst supports, adsorbents, and cometary dust capture agents. However, aerogels are notoriously weak and brittle making it difficult to handle and machine monoliths into desired forms. This complication prevents the development of many applications that would otherwise benefit from the use of the low-density materials. Here, we will describe our efforts to chemically modify and mechanically enhance silica-based aerogels using chemical vapor techniques without sacrificing their characteristic low densities. Monolithic silica and organic-bridged polysilsesquioxane aerogels were prepared by sol-gel polymerization of the respective methoxysilane monomers followed by supercritical carbon dioxide drying of the gels. Then the gels were reactively modified with silylating agents to demonstrate the viability of CVD modificatio...

High Internal Phase Emulsion polystyrene foams have been made at Los Alamos National Laboratory f... more High Internal Phase Emulsion polystyrene foams have been made at Los Alamos National Laboratory for the past decade. As target designs become more complex the demands placed on the foams are more stringent. Parts need to be machined from 30 mg/cm{sup 3} foams to a thickness of 50 {micro}m within a couple of microns. Containing upwards of 97% air, these foams are to withstand extraction with ethanol to remove the wax utilized as a machining aid yet retain their dimensional stability. At low densities, less than 50 mg/cm{sup 3}, voids are a problem. To determine a formulation that reduces void content and allows minimum shrinkage, experimental design was utilized. We also developed image analysis techniques that allow us to quantify the amount of voids in the system and the surface finish of the foam. In order to machine these low density foams to the tolerance required with an optimum surface finish, the foams are backfilled with Brij{reg_sign} 78, an alcohol soluble wax. After a par...

At the Los Alamos Plutonium Facility, various isotopes of plutonium along with other actinides ar... more At the Los Alamos Plutonium Facility, various isotopes of plutonium along with other actinides are handled in a glove box environment. Weapons-grade plutonium consists mainly in Pu-239. Pu-238 is another isotope used for heat sources. The Pu-238 is more aggressive regarding gloves due to its higher alpha-emitting characteristic (â300 times more active than Pu-239), which modifies the change-out intervals for gloves. Optimization of the change-out intervals for gloves is fundamental since Nuclear Materials Technology (NMT) Division generates approximately 4 m³/yr of TRU waste from the disposal of glovebox gloves. To reduce the number of glovebox glove failures, the NMT Division pro-actively investigates processes and procedures that minimize glove failures. Aging studies have been conducted that correlate changes in mechanical (physical) properties with degradation chemistry. This present work derives glovebox glove change intervals based on mechanical data of thermally aged Hypalon...

ABSTRACT Silica and bridged polysilsesquioxane aerogels are low density materials that are attrac... more ABSTRACT Silica and bridged polysilsesquioxane aerogels are low density materials that are attractive for applications such as, thermal insulation, porous separation media or catalyst supports, adsorbents. However, aerogels are notoriously weak and brittle making it difficult to handle and machine monoliths into desired forms. This prevents the development of many applications that would otherwise benefit from the use of the low density materials. We will describe our efforts to chemically modify and mechanically enhance silica-based aerogels using chemical vapor techniques without sacrificing their characteristic low densities. Monolithic silica and organically bridged polysilsesquioxane aerogels were prepared by sol-gel polymerization of the respective methoxysilane monomers followed by supercritical carbon dioxide drying of the gels. Reactive modification of the gels with volatile silylating compounds during and after the drying process and these effects on the mechanical properties and density of the aerogels will be described.

The Journal of Physical Chemistry C, 2008

The kinetics of LiH powder/water reactions indicate a corrosion resistant layer can readily be ge... more The kinetics of LiH powder/water reactions indicate a corrosion resistant layer can readily be generated on LiH by exposure to a mixture of CO2 and H2O. Specifically, LiH powder corrodes very rapidly even in low ppm concentration of water, but samples pretreated in ...

MRS Proceedings, 2004

... INFLUENCE OF THE BRIDGING GROUP LENGTH Douglas A. Loy,* James H. Small, Kimberly A. DeFriend,... more ... INFLUENCE OF THE BRIDGING GROUP LENGTH Douglas A. Loy,* James H. Small, Kimberly A. DeFriend, Kennard V. Wilson, Jr., McKenzie Minke,1 Brigitta M. Baugher,1 Colleen R. Baugher,1 Duane A. Schneider,1 and Kenneth J. Shea2 ...

MRS Proceedings, 2004

ABSTRACT Aging of silica gels before drying is known to result in significant changes in xerogel ... more ABSTRACT Aging of silica gels before drying is known to result in significant changes in xerogel morphology, porosity and properties. In this study, the influence of aging gels on the porosity and morphology of alkylene-bridged polysilsesquioxane xerogels was examined. ...

The eight average molecular weights, as well as other characteristics such as the second virial c... more The eight average molecular weights, as well as other characteristics such as the second virial coefficients and root-mean-square (RMS) radii of gyration of poly (ethyleneimine) (PEI) and various derivatives, have been determined in solution light scattering studies. The solution dynamics of PEI and carboxylated and phosphorylated derivatives were studied a pH of 3.3, 7.0 and 10.0. Measurements were made in

This is the final report of a one-year, Laboratory Directed Research and Development (LDRD) proje... more This is the final report of a one-year, Laboratory Directed Research and Development (LDRD) project at Los Alamos National Laboratory (LANL). The objectives of this project were (1) to develop an enhanced fundamental understanding of the coordination chemistry of hazardous-metal-ion complexation with water-soluble metal-binding polymers, and (2) to exploit this knowledge to develop improved separations for analytical methods, metals processing, and waste treatment. We investigated features of water-soluble metal-binding polymers that affect their binding constants and selectivity for selected transition metal ions. We evaluated backbone polymers using light scattering and ultrafiltration techniques to determine the effect of pH and ionic strength on the molecular volume of the polymers. The backbone polymers were incrementally functionalized with a metal-binding ligand. A procedure and analytical method to determine the absolute level of functionalization was developed and the results correlated with the elemental analysis, viscosity, and molecular size.

Separation Science and Technology, 1997

The N,N′-tetraalkylmalonamides are a class of compounds under development for transuranic (TRU) s... more The N,N′-tetraalkylmalonamides are a class of compounds under development for transuranic (TRU) separations under high nitric acid conditions. There are several issues that challenge the further development of these ligands. One is the development of improved synthetic procedures that lend themselves to commercial scale-up. Another major issue is the third-phase formation that occurs when the N,N′-tetraalkylmalonamides are contacted with medium-to-high nitric acid concentrations in hydrocarbon solvents. To address the synthesis issue we have developed a new synthetic approach for preparing these materials. Third-phase formation can be eliminated by addition of diluent modifiers such as tributylphosphate (TBP). TBP is inappropriate if a nonphosphate-containing process stream is required. Amides have been proposed as alternatives for TBP in a variety of applications because of their ease of synthesis and the variety of substituents that can be generated. We have been able to develop an amide phase-modified system that extends the working process range of alkylmalonamides (0.5 M) in dodecane (unbranched hydrocarbon) from 3.5 M to 7.5 M nitric acid and in Isopar H (branched hydrocarbon) from 4.0 M to 10.0 M nitric acid using 1.0 M di-2-ethylhexylacetamide/0.5 M alkylmalonamide. The Kd values were comparable to extraction with alkylmalonamide in Isopar H or hydrogenated tetrapropylene (TPH) solvents. The overall extraction system was more robust than the phase-unmodified system allowing for greater temperature and acid concentration fluctuations without third-phase formation.

Polymer Degradation and Stability, 2004

Attenuated total reflection (ATR) infrared spectra have been analyzed using multivariate curve re... more Attenuated total reflection (ATR) infrared spectra have been analyzed using multivariate curve resolution (MCR) to capture the chemistry of the thermal degradation in the aging of chlorosulfonated polyethylene (Hypalon Ò ) glove samples. The analysis demonstrates the primary degradation pathways to be oxidation (formation of ketones and carboxylic acids), dehydrochlorination with formation of eC]Ce groups, and polymer crosslinking with changes in the CeH functional groups. From the multivariate analysis, the dominant degradation pathway involves carbonecarbon double bond formation and oxidation to form ketones. The tensile properties (modulus and elongation at break) demonstrate stiffening of the material with aging time. The dynamic mechanical data show that the storage modulus and mechanical loss tangent are also strongly affected with aging due to a hardening of the material. Taken together the mechanical and ATR data indicate that in thermal aging hypalon degrades by dehydrochlorination and loss of eSO 2 Cl functionality with eC]Ce formation, oxidation, and crosslinking causing the material to harden and become brittle. Published by Elsevier Ltd.

Journal of Non-Crystalline Solids, 2011

... Enhancing mechanical properties of silica aerogels. Kimberly AD Obrey a , low asterisk , E-ma... more ... Enhancing mechanical properties of silica aerogels. Kimberly AD Obrey a , low asterisk , E-mail The Corresponding Author , Kennard V. Wilson b and Douglas A. Loy c. ... In turn, polymer-silica composites have been made by Boday, Loy, DeFriend, et.al. [28]. ...

Journal of Applied Polymer Science, 1983

Due to the high chain transfer to monomer, the homopolymerization of methacrylamide yields polyme... more Due to the high chain transfer to monomer, the homopolymerization of methacrylamide yields polymers of extremely low molecular weight. On partial alkaline hydrolysis, the viscosities of these polymers in aqueous solution are much inferior to those of partially hydrolyzed polyacrylamide (HPAM). However, polymethacrylamides prepared by room temperature, persulfate-initiated polymerization in the presence of small amounts of N,N'-methylenebisacrylamide demonstrate posthydrolysis reduced

Journal of Applied Polymer Science, 1986

ABSTRACT Several poly-1-hexene samples were prepared using different Ziegler-Natta catalysts, and... more ABSTRACT Several poly-1-hexene samples were prepared using different Ziegler-Natta catalysts, and their solubilities in dense carbon dioxide (CO2) were studied. Despite the varied molecular weight distributions (MWD) in the polymers, a surprising correlation was found between intrinsic viscosity and dense CO2 solubility. Due to the ability of dense CO2 to extract low-molecular weight fractions preferentially, it is recommended that narrow MWD polymers be used, as far as possible, for dense CO2 solubility determinations.

Journal of Applied Polymer Science, 1986

Kinetics of 1-hexene polymerization was studied by following the amount of unreacted monomer usin... more Kinetics of 1-hexene polymerization was studied by following the amount of unreacted monomer using gas chromatography. The Ziegler-Natta catalyst system used was comprised of TiC1,-AlEt, with A1 : Ti ratio of 0.85. The sampling and monomer analysis techniques developed can be applied to study the kinetics of higher a-olefins polymerizations, in general. Also, with minor modifications in this technique, a precise profile of molecular weight can be obtained during polymerization.