Open Access. Powered by Scholars. Published by Universities.®

Engineering Commons™

Open Access. Powered by Scholars. Published by Universities.®

1988

Selected Works

Discipline
Institution
Keyword
Publication
File Type

Articles 31 - 39 of 39

Full-Text Articles in Engineering

Transport Processes In Random Arrays Of Cylinders. I. Thermal Conduction, Ashok S. Sangani, C. Yao Jan 1988

Transport Processes In Random Arrays Of Cylinders. I. Thermal Conduction, Ashok S. Sangani, C. Yao

Ashok S. Sangani

A numerical method is developed that takes into account the many particle interactions in a rigorous manner to determine the effective thermal conductivity of Km of a composite medium consisting of parallel circular cylinders of thermal conductivity ak suspended in a matrix of conductivity k. Numerical results for Km are presented for a wide rane of a and o, the area fraction of the cylinders, after averaging over several computer-generated random arrays of cylinders. The results obtained via this exact method are compared with those of various approximate analystical methods to assess their utility in predicting Km.

Go to article

Fourier Transform Infrared Spectroscopy Of Some Miscible Polybenzimidazole/Polyimide Blends, William Macknight, Gaetano Guerra, Soonja Choe, David J. Williams, F. E. Karasz Dec 1987

Fourier Transform Infrared Spectroscopy Of Some Miscible Polybenzimidazole/Polyimide Blends, William Macknight, Gaetano Guerra, Soonja Choe, David J. Williams, F. E. Karasz

William MacKnight

The IR spectra of representative miscible aromatic polybenzimidazole/aromatic polyimide (PBI/PI) blends have been studied. Composition-dependent frequency shifts of up to 55 cm-1 in the N-H stretching band of PBI and up to 6 cm-1 in the carbonyl stretching bands of Pl were observed. These shifts were removed by thermally induced phase separation. The results suggest that the miscibility of these blends derives from specific intermolecular interactions involving the > NH and carbonyl groups. 

Go to article

Sans From Sulfonate Ionomer Solutions 1. Associating Polymer Behavior, William Macknight, C. W. Lantman, J. S. Higgins, D. G. Peiffer, S. K. Sinha, R. D. Lundberg Dec 1987

Sans From Sulfonate Ionomer Solutions 1. Associating Polymer Behavior, William Macknight, C. W. Lantman, J. S. Higgins, D. G. Peiffer, S. K. Sinha, R. D. Lundberg

William MacKnight

No abstract provided.

Go to article

The Preparation And Properties Of Zinc Coordination Complexes Of Poly(4-Vinylpyridine-Co-N-Butyl Methacrylate) Copolymers, William Macknight, Mihailo Jacovic, Ivan Perovic, R. W. Lenz Dec 1987

The Preparation And Properties Of Zinc Coordination Complexes Of Poly(4-Vinylpyridine-Co-N-Butyl Methacrylate) Copolymers, William Macknight, Mihailo Jacovic, Ivan Perovic, R. W. Lenz

William MacKnight

Two poly(4-vinylpyridine-co-n-butyl methacrylate) copolymers containing 14.2 and 30.0 mo!% of 4-vinylpyridine residues were prepared by free radical copolymerization reactions. Insoluble complexes were obtained for each copolymer by reaction with zinc chloride. The coordination complexes obtained had a molar ratio of 4-vinylpyridine residues to zinc atoms close to 2 in both cases. The rheological behavior of each of these complexes has been compared to that of the corresponding metal-free copolymers, which were recovered by decomplexation. The metal com­plexed polymers exhibited much higher glass transition temperatures and much longer high temperature relaxation times than the corresponding uncomplexed copolymers. 

Go to article

Miscible Polybenzimidazole Blends With A Benzophenone-Based Polyimide, William Macknight, Gaetano Guerra, David J. Williams, F. E. Karasz Dec 1987

Miscible Polybenzimidazole Blends With A Benzophenone-Based Polyimide, William Macknight, Gaetano Guerra, David J. Williams, F. E. Karasz

William MacKnight

No abstract provided.

Go to article

Molecular Motions In Model Network Polymers, William Macknight, L. Charles Dickinson, P. Morganelli, C. W. Chu, Z. Petrovic, James C. W. Chien Dec 1987

Molecular Motions In Model Network Polymers, William Macknight, L. Charles Dickinson, P. Morganelli, C. W. Chu, Z. Petrovic, James C. W. Chien

William MacKnight

No abstract provided.

Go to article

Miscibility And Phase Behaviour In Poly(2,6-Dimethyl-1,4-Phenylene Oxide) And Poly(Fluorostyrene-Co-Bromostyrene) Blends, William Macknight, R. Vukovic, G. Bogdanic, Vjera Kuresevic, F. E. Karasz Dec 1987

Miscibility And Phase Behaviour In Poly(2,6-Dimethyl-1,4-Phenylene Oxide) And Poly(Fluorostyrene-Co-Bromostyrene) Blends, William Macknight, R. Vukovic, G. Bogdanic, Vjera Kuresevic, F. E. Karasz

William MacKnight

Copolymers of or tho (para )fluorostyrene and ortho(para )bromostyrene with a range of copolymer compositions were prepared by free radical polymerization in toluene solution using azobis­(isobutyronitrile). The miscibility and phase behaviour of these copolymers in blends with poly(2,6-dimethyl-l,4-phenylene oxide) (PPO) have been studied by differential scanning calorimetry. Of the four possible copolymer systems, miscibility was observed only for PPO/poly(o-fluorostyrene­co-p-bromostyrene) blends in which the copolymer contains between 11 and 73 mo!% p-bromostyrene. High temperature phase separation in the miscible blends is a function of copolymer composition and of the thermal history. The results can be explained on the basis of the …

Go to article

Distribution Of Interactions In Binary Polymer Mixtures: A Monte Carlo Simulation Study, William Macknight, P. Cifra, F. E. Karasz Dec 1987

Distribution Of Interactions In Binary Polymer Mixtures: A Monte Carlo Simulation Study, William Macknight, P. Cifra, F. E. Karasz

William MacKnight

Phase transitions from miscibility to immiscibility were observed in simulations of binary polymer mixtures on a planar square lattice using reptation sampling techniques. The relationship between the phenomenological interaction parameter, x, and the true molecular interaction energy was followed, and the dependence of the number and distribution of heterocontacts in the mixture on the applied heterosegment interaction energy was determined. Deviations from the results of mean-field treatments, which overestimate the number of heterocontact.s, were observed even for athermal mixtures. Kinetically driven hysteresis governed by a temperature equilibration time scale was examined for the phase transitions. An important prediction of expansion …

Go to article

Miscible Blends Of Polybenzimidazole And A Diisocyanate-Based Polyimide, William Macknight, Slavka Stankovic, Gaetano Guerra, David J. Williams, F. E. Karasz Dec 1987

Miscible Blends Of Polybenzimidazole And A Diisocyanate-Based Polyimide, William Macknight, Slavka Stankovic, Gaetano Guerra, David J. Williams, F. E. Karasz

William MacKnight

No abstract provided.

Go to article

First Prev