Michael Covitch - Profile on Academia.edu (original) (raw)

Papers by Michael Covitch

Review of Data on Contact Fatigue

Rubber Chemistry and Technology, Nov 1, 1972

Interpenetrating polymer networks (IPN's) of polybutadiene (PB) and polystyrene (PS) were prepare... more Interpenetrating polymer networks (IPN's) of polybutadiene (PB) and polystyrene (PS) were prepared using both random (containing 36% cis, 55% trans, and 9% 1,2 vinyl) PB and high-cis PB. For both series, a wide range of PB/PS compositions were synthesized. Using samples stained with osmium tetroxide, electron microscope studies revealed an irregular cellular structure of a few hundred Angstrom diameter with the first component, PB, making up the cell walls. The size of the cells was found to depend on the PB crosslink density for the random materials. Modulus-temperature data revealed two distinct glass transitions, confirming the microscopy finding of two phases. However, the transition temperature and transition slope varied with composition, and with the microstructure of the polybutadiene, giving evidence of significant molecular mixing. Stress-strain data on the IPN's showed that materials rich in PB behave like self-reinforced elastomers. Charpy impact resistance experiments on materials rich in PS indicated values of 5 ft-lb/in. of notch, which compares well with graft-type polyblends of similar PB/PS composition. The results were interpreted in the light of the recent theoretical work of Bragaw, who considered the importance of the distances between domain boundaries with respect to crack acceleration mechanics. Although the IPN's considered herein exhibited somewhat less than the predicted optimum phase dimensions, the arrangement of the domains is different from ordinary impact resistant plastics.

Non-steady and Mixed Friction Problems

An Improved Method for Calculating Viscosity Index (VI) of Low Viscosity Base Oils

Journal of Testing and Evaluation, Oct 31, 2017

The phenomenon of “VI droop” has been observed for many years for low viscosity oils within a giv... more The phenomenon of “VI droop” has been observed for many years for low viscosity oils within a given family of base oils. Whereas base oils with 100°C kinematic viscosity greater than 4 mm2/s (cSt) easily conform to the nominal API base oil group of its family, 2 and 3 mm2/s products often do not. For example, the low viscosity members of the NEXBASE® API Group III family are technically Group II oils because their viscosity index values fall below the 120 minimum established for Group III. Although it might appear that the low viscosity oils are of lower quality than their higher viscosity siblings, all are produced by the same refining technique and share the same rheological profile. As formulated engine oils evolve into lower SAE viscosity grades in the future to meet OEM demands for greater fuel economy, lighter base oils will become increasingly important formulating components. Therefore, a study to understand the underlying cause(s) of VI droop for low viscosity base oils was undertaken.

Journal of The Electrochemical Society, Jun 1, 1984

Birdwell et al.

Olefin Copolymer Viscosity Modifiers

Chemical industries, Jan 29, 2003

Thermal Crosslinking of a Chemically-Modified Ionomer

Polymeric Separation Media, 1982

Perfluorosulfonic acid ionomer resins have received considerable attention by the chlor-alkali in... more Perfluorosulfonic acid ionomer resins have received considerable attention by the chlor-alkali industry as chemically inert polymers suitable for use as cation exchange membranes in sodium chloride electrolysis cells. A paper by Hora and Maloney1 reported that the low cation selectivity of standard perfluorosulfonic acid membranes is improved by amine modification of the sulfonyl halide form with ethylenediamine (EDA). Several related patents2 describe this reaction and its consequences on membrane selectivity. In addition to direct amidation, the patents refer to the process of post heat treatment which results in crosslinking by the difunctional amine. This paper summarizes an investigation of the chemistry of this thermal crosslinking reaction.

Elastohydrodynamic Lubrication by Formulated Lubricants That Undergo Stress-Induced Degradation

Modern Mechanics and Mathematics, 2010

Kinetics approach to modeling of polymer additive degradation in lubricants

A kinetics problem for a degrading polymer additive dissolved in a base stock is studied. The pol... more A kinetics problem for a degrading polymer additive dissolved in a base stock is studied. The polymer degradation may be caused by the combination of such lubricant flow parameters as pressure, elongational strain rate, and temperature as well as lubricant viscosity and the polymer characteristics (dissociation energy, bead radius, bond length, etc.). A fundamental approach to the problem of modeling mechanically induced polymer degradation is proposed. The polymer degradation is modeled on the basis of a kinetic equation for the density of the statistical distribution of polymer molecules as a function of their molecular weight. The integrodifferential kinetic equation for polymer degradation is solved numerically. The effects of pressure, elongational strain rate, temperature, and lubricant viscosity on the process of lubricant degradation are considered. The increase of pressure promotes fast degradation while the increase of temperature delays degradation. A comparison of a nume...

Rheology of Lubricating Oils

Modern Mechanics and Mathematics, 2010

Asymptotic and Numerical Analysis of Lightly and Heavily Loaded Fluid Lubricated Contacts of Elastic Solids

Non-steady and Mixed Friction Lubrication Problems

Sequence IID Crankcase Pressure - Investigation of Condenser Plugging by Emulsion Formation

SAE Technical Paper Series, 1989

Porous thermoresin structures

Coated porous substrate formation by solution coating

Method for making a porous fluorinated polymer structure

Method for making linings and coatings from soluble cross-linkable perfluorocarbon copolymers

Kinetics Approach to Modeling of Stress-Induced Degradation of Lubricants Formulated with Star Polymer Additives

Tribology Transactions, 2005

ABSTRACT The kinetics of stress-induced degradation of a star polymer additive dissolved in a min... more ABSTRACT The kinetics of stress-induced degradation of a star polymer additive dissolved in a mineral oil lubricant was modeled. Polymer degradation was modeled based on a new system of kinetic integrodifferential equations for the distribution densities of star polymer molecules with different numbers of arms and arm chain lengths. Some properties of the solution were established. A numerical method for solution of the problem was proposed and realized. Some of the numerically simulated molecular weight distributions were compared with the independently obtained experimental ones. The lubricant viscosity losses due to polymer degradation were determined and compared with the experimentally measured ones. The theoretical and experimental data are in very good agreement.

Polymer Engineering and Science, 1972

Interpenetrating polymer networks (IPN's) of polybutadiene (PB) and polystyrene (PS) were prepare... more Interpenetrating polymer networks (IPN's) of polybutadiene (PB) and polystyrene (PS) were prepared using both random (containing 36% cis, 55% trans, and 9% 1,2 vinyl) PB and high-cis PB. For both series, a wide range of PB/PS compositions were synthesized. Using samples stained with osmium tetroxide, electron microscope studies revealed an irregular cellular structure of a few hundred Angstrom diameter with the first component, PB, making up the cell walls. The size of the cells was found to depend on the PB crosslink density for the random materials. Modulus-temperature data revealed two distinct glass transitions, confirming the microscopy finding of two phases. However, the transition temperature and transition slope varied with composition, and with the microstructure of the polybutadiene, giving evidence of significant molecular mixing. Stress-strain data on the IPN's showed that materials rich in PB behave like self-reinforced elastomers. Charpy impact resistance experiments on materials rich in PS indicated values of 5 ft-lb/in. of notch, which compares well with graft-type polyblends of similar PB/PS composition. The results were interpreted in the light of the recent theoretical work of Bragaw, who considered the importance of the distances between domain boundaries with respect to crack acceleration mechanics. Although the IPN's considered herein exhibited somewhat less than the predicted optimum phase dimensions, the arrangement of the domains is different from ordinary impact resistant plastics.

Modeling of Kinetics of Strain Induced Degradation of Polymer Additives in Lubricants

Mathematical Models and Methods in Applied Sciences, 2002

A kinetics problem for a degrading polymer additive dissolved in a fluid lubricant is studied. Th... more A kinetics problem for a degrading polymer additive dissolved in a fluid lubricant is studied. The polymer degradation may be caused by the combination of such lubricant flow parameters as pressure, strain rate, and temperature as well as lubricant viscosity and the polymer characteristics (dissociation energy, bead radius, bond length, etc.). A fundamental approach to the problem of modeling stress-induced polymer degradation is proposed. The polymer degradation is modeled on the basis of a kinetic equation for the density of the statistical distribution of polymer molecules as a function of their molecular weight. The existence and uniqueness of the solution to the initial-value problem for the kinetic equation is proven. Moreover, some properties of the solution are established. The integrodifferential kinetic equation for polymer degradation is solved numerically for a number of different input data. The effects of pressure, strain rate, temperature, and lubricant viscosity on t...

Review of Data on Contact Fatigue

Rubber Chemistry and Technology, Nov 1, 1972

Interpenetrating polymer networks (IPN's) of polybutadiene (PB) and polystyrene (PS) were prepare... more Interpenetrating polymer networks (IPN's) of polybutadiene (PB) and polystyrene (PS) were prepared using both random (containing 36% cis, 55% trans, and 9% 1,2 vinyl) PB and high-cis PB. For both series, a wide range of PB/PS compositions were synthesized. Using samples stained with osmium tetroxide, electron microscope studies revealed an irregular cellular structure of a few hundred Angstrom diameter with the first component, PB, making up the cell walls. The size of the cells was found to depend on the PB crosslink density for the random materials. Modulus-temperature data revealed two distinct glass transitions, confirming the microscopy finding of two phases. However, the transition temperature and transition slope varied with composition, and with the microstructure of the polybutadiene, giving evidence of significant molecular mixing. Stress-strain data on the IPN's showed that materials rich in PB behave like self-reinforced elastomers. Charpy impact resistance experiments on materials rich in PS indicated values of 5 ft-lb/in. of notch, which compares well with graft-type polyblends of similar PB/PS composition. The results were interpreted in the light of the recent theoretical work of Bragaw, who considered the importance of the distances between domain boundaries with respect to crack acceleration mechanics. Although the IPN's considered herein exhibited somewhat less than the predicted optimum phase dimensions, the arrangement of the domains is different from ordinary impact resistant plastics.

Non-steady and Mixed Friction Problems

An Improved Method for Calculating Viscosity Index (VI) of Low Viscosity Base Oils

Journal of Testing and Evaluation, Oct 31, 2017

The phenomenon of “VI droop” has been observed for many years for low viscosity oils within a giv... more The phenomenon of “VI droop” has been observed for many years for low viscosity oils within a given family of base oils. Whereas base oils with 100°C kinematic viscosity greater than 4 mm2/s (cSt) easily conform to the nominal API base oil group of its family, 2 and 3 mm2/s products often do not. For example, the low viscosity members of the NEXBASE® API Group III family are technically Group II oils because their viscosity index values fall below the 120 minimum established for Group III. Although it might appear that the low viscosity oils are of lower quality than their higher viscosity siblings, all are produced by the same refining technique and share the same rheological profile. As formulated engine oils evolve into lower SAE viscosity grades in the future to meet OEM demands for greater fuel economy, lighter base oils will become increasingly important formulating components. Therefore, a study to understand the underlying cause(s) of VI droop for low viscosity base oils was undertaken.

Journal of The Electrochemical Society, Jun 1, 1984

Birdwell et al.

Olefin Copolymer Viscosity Modifiers

Chemical industries, Jan 29, 2003

Thermal Crosslinking of a Chemically-Modified Ionomer

Polymeric Separation Media, 1982

Perfluorosulfonic acid ionomer resins have received considerable attention by the chlor-alkali in... more Perfluorosulfonic acid ionomer resins have received considerable attention by the chlor-alkali industry as chemically inert polymers suitable for use as cation exchange membranes in sodium chloride electrolysis cells. A paper by Hora and Maloney1 reported that the low cation selectivity of standard perfluorosulfonic acid membranes is improved by amine modification of the sulfonyl halide form with ethylenediamine (EDA). Several related patents2 describe this reaction and its consequences on membrane selectivity. In addition to direct amidation, the patents refer to the process of post heat treatment which results in crosslinking by the difunctional amine. This paper summarizes an investigation of the chemistry of this thermal crosslinking reaction.

Elastohydrodynamic Lubrication by Formulated Lubricants That Undergo Stress-Induced Degradation

Modern Mechanics and Mathematics, 2010

Kinetics approach to modeling of polymer additive degradation in lubricants

A kinetics problem for a degrading polymer additive dissolved in a base stock is studied. The pol... more A kinetics problem for a degrading polymer additive dissolved in a base stock is studied. The polymer degradation may be caused by the combination of such lubricant flow parameters as pressure, elongational strain rate, and temperature as well as lubricant viscosity and the polymer characteristics (dissociation energy, bead radius, bond length, etc.). A fundamental approach to the problem of modeling mechanically induced polymer degradation is proposed. The polymer degradation is modeled on the basis of a kinetic equation for the density of the statistical distribution of polymer molecules as a function of their molecular weight. The integrodifferential kinetic equation for polymer degradation is solved numerically. The effects of pressure, elongational strain rate, temperature, and lubricant viscosity on the process of lubricant degradation are considered. The increase of pressure promotes fast degradation while the increase of temperature delays degradation. A comparison of a nume...

Rheology of Lubricating Oils

Modern Mechanics and Mathematics, 2010

Asymptotic and Numerical Analysis of Lightly and Heavily Loaded Fluid Lubricated Contacts of Elastic Solids

Non-steady and Mixed Friction Lubrication Problems

Sequence IID Crankcase Pressure - Investigation of Condenser Plugging by Emulsion Formation

SAE Technical Paper Series, 1989

Porous thermoresin structures

Coated porous substrate formation by solution coating

Method for making a porous fluorinated polymer structure

Method for making linings and coatings from soluble cross-linkable perfluorocarbon copolymers

Kinetics Approach to Modeling of Stress-Induced Degradation of Lubricants Formulated with Star Polymer Additives

Tribology Transactions, 2005

ABSTRACT The kinetics of stress-induced degradation of a star polymer additive dissolved in a min... more ABSTRACT The kinetics of stress-induced degradation of a star polymer additive dissolved in a mineral oil lubricant was modeled. Polymer degradation was modeled based on a new system of kinetic integrodifferential equations for the distribution densities of star polymer molecules with different numbers of arms and arm chain lengths. Some properties of the solution were established. A numerical method for solution of the problem was proposed and realized. Some of the numerically simulated molecular weight distributions were compared with the independently obtained experimental ones. The lubricant viscosity losses due to polymer degradation were determined and compared with the experimentally measured ones. The theoretical and experimental data are in very good agreement.

Polymer Engineering and Science, 1972

Interpenetrating polymer networks (IPN's) of polybutadiene (PB) and polystyrene (PS) were prepare... more Interpenetrating polymer networks (IPN's) of polybutadiene (PB) and polystyrene (PS) were prepared using both random (containing 36% cis, 55% trans, and 9% 1,2 vinyl) PB and high-cis PB. For both series, a wide range of PB/PS compositions were synthesized. Using samples stained with osmium tetroxide, electron microscope studies revealed an irregular cellular structure of a few hundred Angstrom diameter with the first component, PB, making up the cell walls. The size of the cells was found to depend on the PB crosslink density for the random materials. Modulus-temperature data revealed two distinct glass transitions, confirming the microscopy finding of two phases. However, the transition temperature and transition slope varied with composition, and with the microstructure of the polybutadiene, giving evidence of significant molecular mixing. Stress-strain data on the IPN's showed that materials rich in PB behave like self-reinforced elastomers. Charpy impact resistance experiments on materials rich in PS indicated values of 5 ft-lb/in. of notch, which compares well with graft-type polyblends of similar PB/PS composition. The results were interpreted in the light of the recent theoretical work of Bragaw, who considered the importance of the distances between domain boundaries with respect to crack acceleration mechanics. Although the IPN's considered herein exhibited somewhat less than the predicted optimum phase dimensions, the arrangement of the domains is different from ordinary impact resistant plastics.

Modeling of Kinetics of Strain Induced Degradation of Polymer Additives in Lubricants

Mathematical Models and Methods in Applied Sciences, 2002

A kinetics problem for a degrading polymer additive dissolved in a fluid lubricant is studied. Th... more A kinetics problem for a degrading polymer additive dissolved in a fluid lubricant is studied. The polymer degradation may be caused by the combination of such lubricant flow parameters as pressure, strain rate, and temperature as well as lubricant viscosity and the polymer characteristics (dissociation energy, bead radius, bond length, etc.). A fundamental approach to the problem of modeling stress-induced polymer degradation is proposed. The polymer degradation is modeled on the basis of a kinetic equation for the density of the statistical distribution of polymer molecules as a function of their molecular weight. The existence and uniqueness of the solution to the initial-value problem for the kinetic equation is proven. Moreover, some properties of the solution are established. The integrodifferential kinetic equation for polymer degradation is solved numerically for a number of different input data. The effects of pressure, strain rate, temperature, and lubricant viscosity on t...