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Full-Text Articles in Engineering
Fluorescent Molecular Probe Technique For Assessing The Interaction Between Sulfonated Polystyrene And Poly(Ethyl Acrylate-Co-4-Vinylpyridine) Ionomers In Tetrahydrofuran, William Macknight, Kirill N. Bakeev
Fluorescent Molecular Probe Technique For Assessing The Interaction Between Sulfonated Polystyrene And Poly(Ethyl Acrylate-Co-4-Vinylpyridine) Ionomers In Tetrahydrofuran, William Macknight, Kirill N. Bakeev
William MacKnight
The interaction between sulfonated polystyrene (SPS) and poly(ethy1 acrylate-eo-4-vinylpyridine)
(EtAc4VP) ionomers was investigated over a wide range of concentrations in the nonpolar solvent,
tetrahydrofuran (THF), using a fluorescent molecular probe technique. The acid-base interaction between
the sulfonate groups of SPS and the pyridine groups of EtAcVP and the miscibility of these ionomers are
evident for pyridine contents of 7.8 and 4.5 mol 5% in EtAc4VP and are not detectable for EtAc4VP with
1.7 mol % pyridine groups. Concentration-dependent excimer fluorescence from SPS and EtAc4VP mixtures
indicates the occurrence of polar interactions as a result of proton transfer from the styrenesulfonic …
Mechanism Of The Dicyandiamide/Epoxide Reaction, William Macknight, Michael D. Gilbert, Nathan S. Schneider
Mechanism Of The Dicyandiamide/Epoxide Reaction, William Macknight, Michael D. Gilbert, Nathan S. Schneider
William MacKnight
A mechanism is proposed for the dicyandiamide (dicy) cure of epoxy resins based on the
analysis of products formed by the reaction of a monofunctional epoxide with dicy and with cyanamide.
Products were isolated from the uncatalyzed reaction mixtures using preparatory liquid chromatography and
were characterized by FTIR, NMR, mass spectrometry, and elemental analysis. Both linear dicy/epoxide
adducts and cyclical species were identified and the mechanism of the cyclization reaction was delineated.
A mechanism for carbonyl generation during the later stages of cure was also found.
Thermal, Dielectric, And Mechanical Relaxation In Poly(Benzimidazole)/Poly(Etherimide) Blends, William Macknight, Kuiming Liang, Gyorgy Banhegyi, F. E. Karasz
Thermal, Dielectric, And Mechanical Relaxation In Poly(Benzimidazole)/Poly(Etherimide) Blends, William Macknight, Kuiming Liang, Gyorgy Banhegyi, F. E. Karasz
William MacKnight
Thermal, dielectric, and mechanical relaxation measurements on miscible blends of poly-
benzimidazole(PBI)and a polyetherimide (PEI, Ultem 1000)prepared by solution casting
from dimethylacetamide (DMAc) reveal a number of structurally related features. Annealing
below the glass transition temperature induces an enthalpy relaxation process typical of
single-phase glasses of nonequilibrium structure. Dielectric relaxation experiments on
samples annealed at ambient conditions reveal two relaxation processes below 400°C.At
lower temperatures (50-2OO0C), the desorption of water is observed. Above 200°C in the
first run, a composition-dependent relaxation is seen at the highest frequencies ( 100 kHz)
while a relaxation approximately independent of composition appears in the …