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William MacKnight

Selected Works

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Property-Structure Relationships In Poly-Urethanes: Infrared Studies, William Macknight, M. Yang Dec 1972

Property-Structure Relationships In Poly-Urethanes: Infrared Studies, William Macknight, M. Yang

William MacKnight

No abstract provided.

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Dielectric And Mechanical Relaxations In Ethylene-Acrylic Acid And Ethylene-Methacrylic Acid Copolymers, William Macknight, F. A. Emerson Dec 1971

Dielectric And Mechanical Relaxations In Ethylene-Acrylic Acid And Ethylene-Methacrylic Acid Copolymers, William Macknight, F. A. Emerson

William MacKnight

The dielectric relaxation behavior of ethylene-carboxylic acid copolymers has been studied over the frequency ° range of °SO Hz to 10 f Hz and over the temperature range of -160 C to+ 100 C. The copolymers studied consisted of four acrylic acid and two methacry­lic acid copolymers of varying acid content. In the temperature and frequency region investigated, two dielectric dispersions occur and these are labelled B' and yin order of decreasing temperature. The B' dispersion may be quantitatively accounted for on the basis of the orientation of free carboxylic acid groups. The concentra­tion of these groups is assessed from …

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Physical Properties Of The System: Poly(2,6-Dimethylphenylene Oxide)-Polystyrene, William Macknight, J. Stoelting, F. E. Karasz Dec 1970

Physical Properties Of The System: Poly(2,6-Dimethylphenylene Oxide)-Polystyrene, William Macknight, J. Stoelting, F. E. Karasz

William MacKnight

No abstract provided.

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Dynamic Mechanical Behavior Of Partially Hydrolyzed Ethylene-Vinyl Acetate Copolymers, William Macknight, R. J. Tetreault Dec 1970

Dynamic Mechanical Behavior Of Partially Hydrolyzed Ethylene-Vinyl Acetate Copolymers, William Macknight, R. J. Tetreault

William MacKnight

No abstract provided.

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Infrared Dichroism Studies Of The Relaxation Of Ethylene-Methacrylic Acid Copolymers And Their Salts, William Macknight, Y. Uemura, R. S. Stein Dec 1970

Infrared Dichroism Studies Of The Relaxation Of Ethylene-Methacrylic Acid Copolymers And Their Salts, William Macknight, Y. Uemura, R. S. Stein

William MacKnight

The change in infrared dichroism with elongation has been observed at a series of temperatures for several infrared bands of ethylene-methacrylic acid copolymers and their salts. The orientation functions of hydrocarbon and meth­acrylic acid parts of the molecule were calculated as a function of the temperature of stretching. It is found that the orienta­tion function-strain coefficient for the un-ionized acid decreases uniformly with temperature, but that for the ionized salt passes through a maximum at about 40° where the strain-optical coefficient has been observed to pass through a maximum. Maxima are observed for the dichroism-strain coefficients for both the hydrocarbon …

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Mechanical And Thermal Properties Of Phosphorylated Polyethylene, William Macknight, P. J. Phillips Dec 1969

Mechanical And Thermal Properties Of Phosphorylated Polyethylene, William Macknight, P. J. Phillips

William MacKnight

No abstract provided.

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Thermal Properties Of Partially Hydrolyzed Ethylene-Vinyl Acetate Copolymers, William Macknight, R. J. Tetreault, Roger S. Porter Dec 1969

Thermal Properties Of Partially Hydrolyzed Ethylene-Vinyl Acetate Copolymers, William Macknight, R. J. Tetreault, Roger S. Porter

William MacKnight

No abstract provided.

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Dielectric Relaxation In Ethylene-Methacrylic Acid Copolymers And Their Salts, William Macknight, P. J. Phillips Dec 1969

Dielectric Relaxation In Ethylene-Methacrylic Acid Copolymers And Their Salts, William Macknight, P. J. Phillips

William MacKnight

No abstract provided.

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Dynamic And Steady-Shear Melt Rheology Of An Ethylene-Methacrylic Acid Copolymer And Its Salts, William Macknight, Kunisuke Sakamoto, Roger S. Porter Dec 1969

Dynamic And Steady-Shear Melt Rheology Of An Ethylene-Methacrylic Acid Copolymer And Its Salts, William Macknight, Kunisuke Sakamoto, Roger S. Porter

William MacKnight

No abstract provided.

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Dielectric Properties Of Poly(2, 6-Dimethyl Phenylene Oxide), William Macknight, F. E. Karasz, J. Stoelting Dec 1969

Dielectric Properties Of Poly(2, 6-Dimethyl Phenylene Oxide), William Macknight, F. E. Karasz, J. Stoelting

William MacKnight

No abstract provided.

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Structure And Properties Of Polyethylene Modified With Phosphonic Acid Side Groups. Ii. Dielectric Properties, William Macknight, P. J. Phillips, F. A. Emerson Dec 1969

Structure And Properties Of Polyethylene Modified With Phosphonic Acid Side Groups. Ii. Dielectric Properties, William Macknight, P. J. Phillips, F. A. Emerson

William MacKnight

No abstract provided.

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Birefringence Studies Of The Relaxation Of Ethylene-Methacrylic Acid Copolymers And Their Salts, William Macknight Dec 1969

Birefringence Studies Of The Relaxation Of Ethylene-Methacrylic Acid Copolymers And Their Salts, William Macknight

William MacKnight

The strain-optical coefficient of ethylene-methacrylic acid copolymers is measured in static and dynamic experiments as a function of temperature and degree of ionization. An alpha optical loss peak which cor­responds to a mechanical loss peak is found for the ionized salt but not for the un-ionized acid. This peak is associated with mobility of an ionized domain. Birefringence relaxation curves are found to be super­posable using horizontal and vertical shift factors. A plot of the logarithmic shift factor against (1/T) gives a broken curve exhibiting two activation energies for the salt indicating contributions by two processes. 

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Structure And Properties Of Polyethylene Modified With Phosphonic Acid Side Groups. I. Mechanical And Thermal Studies, William Macknight, P. J. Phillips Dec 1969

Structure And Properties Of Polyethylene Modified With Phosphonic Acid Side Groups. I. Mechanical And Thermal Studies, William Macknight, P. J. Phillips

William MacKnight

A sample of low-density polyethylene containing 1.4 long chain branches per 100 carbon atoms was chemically modified by the inclusion of phosphonic acid side groups. Dynamic mechanical and differential scanning calorimetry (dsc) studies were carried out on the unmodified polyethylene and on samples containing 0.8, 1.8, 2.8, and 7.4 phosphonic acid side groups per 100 carbon atoms. The dsc results show that the weight per cent crystallinity is a decreasing function of the phosphonic acid concentration, no crystallinity being detectable by dsc in the material with highest phosphonic acid content. The effect is partly kinetic as illustrated by the fact …

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Thermal Properties Of Polyurethanes. Enthalpies And Entropies Of Fusion, William Macknight, T. Kajiyama Dec 1969

Thermal Properties Of Polyurethanes. Enthalpies And Entropies Of Fusion, William Macknight, T. Kajiyama

William MacKnight

Enthalpies and entropies of fusion have been determined for two series of scmicrystalline polyurethanes. The H series is based on 1,6-hexamethylene diiso­cyanate and various a, 01-diols containing from 2 to 10 methylene units. The DP series is based on 4,4'-methylene diphenyl diisocyanate and various a, m-diols containing from 2 to 10 methylene units. Differential Scanning Calorimetry (DSC) was used in con­j unction with X-ray analysis (X-ray method) and low molecular-weight diluents (diluent method) to determine the enthalpies of fusion. Agreement between the X-ray method and the diluent method was good. 
Differences between the enthalpies and entropies of fusion of the …

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Dynamic Mechanical Properties Of Poly(2, 6-Dimethyl-1,4-Phenylene Ether)-Polystyrene Blends, William Macknight, J. Stoelting, F. E. Karasz Dec 1969

Dynamic Mechanical Properties Of Poly(2, 6-Dimethyl-1,4-Phenylene Ether)-Polystyrene Blends, William Macknight, J. Stoelting, F. E. Karasz

William MacKnight

Blends of poly(2,6-dimethyl-l,4-phenylene ether) (FPO) and a tactic polystyrene (PS) have been prepared by mechan­ically mixing powders of the two polymers and subjecti􀀇ng the mixtures to three different thermal treatments. Three different 
compositions were studied by the dynamic m􀀋echaniac􀀌l and DSC techniques. The weight fractions of FPO m the mixtures 
were 0.25, 0.50 and 0.75. The dynamic mechanical measure­
ments indicate that partial mixing took place but that two 
distinct phases, one rich in PS and the other in FPO, exis􀀕 􀀖n all the mixtures studied. Each phase exhibits a charactenstlc 
relaxation peak associated with the glass transition of that  …

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Structure And Properties Of Ethylene-Methacrylic Acid Copolymers And Their Sodium Salts: Dielectric And Proton Magnetic Relaxation Studies, William Macknight, B. E. Read, E. A. Carter, T. M. Connor Dec 1968

Structure And Properties Of Ethylene-Methacrylic Acid Copolymers And Their Sodium Salts: Dielectric And Proton Magnetic Relaxation Studies, William Macknight, B. E. Read, E. A. Carter, T. M. Connor

William MacKnight

No abstract provided.

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Relaxation In Polyurethanes In The Glass Transition Region, William Macknight, T. Kajiyama Dec 1968

Relaxation In Polyurethanes In The Glass Transition Region, William Macknight, T. Kajiyama

William MacKnight

A study has been made of the relaxation phenomena in three series of poly­urethanes in the neighborhood of their glass transition temperatures and above. The technique of dynamic mechanical relaxation was used in the investigation at various frequencies up to 110 Hz. Differential Scanning Calorimetry (DSC) was also used as a supplement to the mechanical measurements. The series are: (1) H series based on polymerization of hexamethylene diisocyanate and various diols, (2) DP series based on polymerization of 4,4' diphenylmethane diisocyanate and various diols, and (3) 4M series based on polymerization of 4-methyl meta pheny lene diisocyanate and various diols. …

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Low Angle X-Ray Scattering From Ethylene-Methacrylic Acid Copolymers And Their Salts, William Macknight, B. W. Delf Dec 1968

Low Angle X-Ray Scattering From Ethylene-Methacrylic Acid Copolymers And Their Salts, William Macknight, B. W. Delf

William MacKnight

No abstract provided.

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Low-Temperature Relaxations In Polyurethans, William Macknight, T. Kajiyama Dec 1967

Low-Temperature Relaxations In Polyurethans, William Macknight, T. Kajiyama

William MacKnight

A study has been made of the relaxation phenomena in three series of glassy polyurethans in the temperature range from -190 to 100° and at various frequencies up to 110 Hz using dynamic mechanical and dielectric relaxation. The structures of the repeat units of the three series are given in eq 1-3. Several overlapping relaxation peaks are discernible in the temperature and frequency region investigated. All of these relaxations arise largely from motion in the amorphous phase. The following assignments of the various relaxation peaks to specific molecular motions have been made on the basis of comparisons both within and …

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Viscous And Elastic Behavior Attributed To Polymer Entanglements, William Macknight, Roger S. Porter, Julian F. Johnson Dec 1967

Viscous And Elastic Behavior Attributed To Polymer Entanglements, William Macknight, Roger S. Porter, Julian F. Johnson

William MacKnight

No abstract provided.

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Properties Of Ethylene - Methacrylic Acid Copolymers And Their Sodium Salts: Infrared Studies, William Macknight, L. W. Mckenna, B. E. Read Dec 1966

Properties Of Ethylene - Methacrylic Acid Copolymers And Their Sodium Salts: Infrared Studies, William Macknight, L. W. Mckenna, B. E. Read

William MacKnight

An infrared spectroscopic investigation of ethylene-methacrylic acid copolymers and their sodium salts has been carried out. All the copolymers studied were based on a parent copolymer containing 4.1 mol % of methacrylic acid groups. This was then neutralized to various e;d;ents (from O to 78%) with sodium hydroxide. The per cent ionization was determined from the integrated absorbance of the 1700 cm -1 un-ionized carbonyl stretching band. Temperature-dependent infrared studies showed that the behavior of the un-ionized acid groups over the entire range of ionization is quantitatively comparable to that of low molecular weight car­boxylic acids in nonpolar solvents. A …

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Effect Of S(Pi) On The Polymerization Of Liquid Sulfur And The Nature Of S(Pi), William Macknight, J. A. Poulis, C. H. Massen Dec 1966

Effect Of S(Pi) On The Polymerization Of Liquid Sulfur And The Nature Of S(Pi), William Macknight, J. A. Poulis, C. H. Massen

William MacKnight

The Tobolsky-Eisenberg theory serves to explain the equilibrium polym­erization of sulfur in terms of the dependence of S8 (ring) concentration on temperature and the dependence of number-average degree of polymeri­zation on temperature. The predictions of the theory are completely in accord with experiment. In this paper it is shown that it is possible to take the presence of another component in the melt, S,,, into account, using a slightly modified version of the Tobolsky-Eisenberg theory. When this is done it is found that the earlier conclusions remain valid. The molecular complexity and structure of Sw is also discussed.

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Chemical Stress Relaxation, William Macknight Dec 1966

Chemical Stress Relaxation, William Macknight

William MacKnight

No abstract provided.

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Volume Changes Accompanying The Extension Of Rubber-Like Materials, William Macknight Dec 1965

Volume Changes Accompanying The Extension Of Rubber-Like Materials, William Macknight

William MacKnight

No abstract provided.

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Properties Of Polymeric Sulfur, William Macknight, A. V. Tobolsky Dec 1964

Properties Of Polymeric Sulfur, William Macknight, A. V. Tobolsky

William MacKnight

No abstract provided.

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Relaxation Of Disulfide And Tetrasulfide Polymers, William Macknight, A. V. Tobolsky, M. Takahashi Dec 1963

Relaxation Of Disulfide And Tetrasulfide Polymers, William Macknight, A. V. Tobolsky, M. Takahashi

William MacKnight

The chemorheology of cross-linked polyethylene disulfide, polyethylene tetrasulfide, and mixtures of these polymers with elemental sulfur is investigated. It is shown that stress decay in the disulfide polymer occurs by scission of the small quantities of higher poly­sulfide linkages present in the network. It is also shown that elemental sulfur decreases the chemical relaxation time in cross-linked polyethylene disulfide in a predictable manner.

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Cleavage Reactions In Crosslinked Urethane Elastomers, William Macknight, A. V. Tobolsky Dec 1963

Cleavage Reactions In Crosslinked Urethane Elastomers, William Macknight, A. V. Tobolsky

William MacKnight

A study of network cleavage in a crosslinked poJ.yurethane elastomer was ma.de using the technique of stress relaxation. 
It was found that the data could be well represented by a sum 
of two exponential decay terms, and a theoretical explanation for this is presented. stress relaxation in the. polyurethane sample investigated is discussed in terms of the reversible cleavage 
of various linkages formed by isocyanate reactions. It is possible to identify two different decay processes and obtain activation energies for these processes. These are identified with cleavage of two different linkages. It is not possible at present to give a …

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Physical Chemistry Of Crosslinked Polysulfide Elastomers, William Macknight, G. E. Leroi, A. V. Tobolsky Dec 1963

Physical Chemistry Of Crosslinked Polysulfide Elastomers, William Macknight, G. E. Leroi, A. V. Tobolsky

William MacKnight

No abstract provided.

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Urethane Elastomers Containing Disulfide And Tetrasulfide Linkages, William Macknight, G. D. T. Owens, A. V. Tobolsky Dec 1962

Urethane Elastomers Containing Disulfide And Tetrasulfide Linkages, William Macknight, G. D. T. Owens, A. V. Tobolsky

William MacKnight

The chemorheology of two cross-linked polyurethane elastomers containing (1) disulfide groups and (2) tetrasulfide groups was investigated by stress relaxation experiments. It was found that the tetrasulfide-containing elastomer underwent stress decay at a rate 10 times faster than the disulfide-containing elastomer, showing that the tetrasulfide linkage undergoes bond interchange much more rapidly than the disulfide linkage. Spectroscopic evidence is cited tending to confirm the greater stability of the disulfide linkage. The behavior of a cross-linked polyurethane elastomer without polysulfide linkages is presented for comparison. 

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The Glass Transition Temperature Of Polymeric Sulfur, William Macknight, A. V. Tobolsky, R. B. Beevers, V. D. Gupia Dec 1962

The Glass Transition Temperature Of Polymeric Sulfur, William Macknight, A. V. Tobolsky, R. B. Beevers, V. D. Gupia

William MacKnight

No abstract provided.

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