Wiley
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Superstructure in segmented polyether–urethanes
Wiley - Tập 13 Số 3 - Trang 455-476 - 1975
AbstractThe morphology of several series of segmented polyether–urethanes was
studied. The “hard” segments contained urethane and urea linkages formed by
4,4′‐dicyclohexylmethane diisocyanate (Hylene W) and selected aliphatic and
aromatic monomeric diamines (DA). The “soft” segments were composed of
oligomeric poly(ethylene oxide) (PEO), poly(propylene oxide) (PPO), or both PEO
and PPO. For studyi...
Melting studies of poly(vinylidene fluoride) and its blends with poly(methyl methacrylate)
Wiley - Tập 20 Số 12 - Trang 2243-2259 - 1982
AbstractBlends of poly(vinylidene fluoride) (PVF2) and poly(methyl methacrylate)
exhibit complex melting behavior when crystallized at low undercoolings. Three
crystals comprised of two different PVF2 forms grow. Hoffman‐Weeks plots of the
observed melting points Tm of these crystals versus crystallization temperatures
are constructed. The lowest‐melting‐point species, the α form, shows a change i...
Macromolecular nucleation
Wiley - Tập 12 Số 2 - Trang 255-263 - 1974
AbstractThe rate‐determining step of crystallization of macromolecules from melt
and solution is shown to be molecular nucleation. Molecular nucleation is
described by using classical nucleation theory. Good agreement is found between
the molecular nucleus size and the critical length of the rejected species.
Molecular nucleation has a higher free‐energy barrier than secondary nucleation;
it might...
An analysis of the crystallization behavior of poly(ethylene oxide)/poly(methyl methacrylate) blends by spectroscopic and calorimetric techniques
Wiley - Tập 22 Số 7 - Trang 1331-1342 - 1984
AbstractInfrared spectra in conjunction with calorimetric measurements have been
used to follow the crystallization process and microstructural changes of
poly(ethylene oxide) (PEO) in poly(ethylene oxide) and poly(methyl methacrylate)
(PMMA) blends. We have given particular attention to compositions containing low
PEO concentrations. The crystallization behavior and the resultant
microstructures ...
The heat of fusion of 66 nylon
Wiley - Tập 22 Số 9 - Trang 1615-1621 - 1984
AbstractThe heat of fusion ΔHf of 66 nylon has been determined by use of the
Clapeyron equation. Measurements of ΔHf and the unit‐cell parameters on molding
pellets show that this material contains the α2 crystal phase, which is less
dense than the α1 phase obtained by crystallization from solution. The value of
ΔHf‐45–46 cal/g, is in good agreement with earlier reports.
Hydrogen bonding in nylon 66 and model compounds
Wiley - Tập 23 Số 3 - Trang 537-555 - 1985
AbstractFourier‐transform infrared spectroscopy was used to study the hydrogen
bond‐breaking process in nylon 66 and two model compounds. The resulting
enthalpy and entropy values indicated that while there is no interaction between
adjacent amide groups in the polymer chain, there is, nevertheless, a
substantial cooperative effect in the transverse hydrogen bond direction. We
have also establishe...
A model for permeation of mixed gases and vapors in glassy polymers
Wiley - Tập 19 Số 10 - Trang 1513-1530 - 1981
AbstractA model is discussed which explains reported complex effects of feed
composition and pressure on component permeabilities in high‐pressure gas
separators based on glassy polymer membranes. A special form of Fick's law which
accounts for the fact that penetrants in glassy polymers sorb into and diffuse
through two different molecular environments provides the basis for the analysis
of gas m...
Diffusion‐controlled formation of porous structures in ternary polymer systems
Wiley - Tập 17 Số 3 - Trang 477-489 - 1979
AbstractWe propose a theory for the appearance of two‐phase structures during
the formation of polymer membranes from a casting solution immersed in a
coagulant bath. Our model is based on diffusion induced phase separation at the
spinodal in the ternary nonsolvent‐solvent‐polymer system. A simplified
treatment of the interdiffusion process by the diffusion layer method permits
the formulation of ...
Synthesis and solution properties of linear, four‐branched, and six‐branched star polyisoprenes
Wiley - Tập 12 Số 12 - Trang 2521-2533 - 1974
AbstractA number of linear, four‐ and six‐branched regular star polyisoprenes
were synthesized by anionic polymerization techniques in benzene using lithium
as the counterion and polyfunctional silicon chloride compounds as the coupling
agents. Light‐scattering measurements in dioxane were performed in order to
establish Θ solvent conditions. Determinations of the radius of gyration of the
polymer...
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