In this paper six new copoly(amide-imide)s (7a-f) were synthesized through the direct polycondensation reaction of N,N'-(4,4'-diphenylsulfone)bistrimellitimide (1) with 4,4'-diamino diphenylsulfone (2), 4,4'-diamino diphenylether (3), in the presence of adipic acid (4), fumaric acid (5) or terephthalic acid (6) as the second diacid in a medium consisting of N-methyl-2-pyrrolidone, triphenyl pho...

29Si NMR spectroscopy of concentrated silicate sols, prepared by acid-catalyzed hydrolysis of TEOS in ethanol with H20/Si ratios, r -1.5 or 1.7, followed by alcohol evaporation, shows that the polysilicate species responsible for spinnability are not simple rigid-rod, ladder polymers or linear polymers. Instead a distribution of silicate species is observed consistent with the products of a sta...

Motivated by turbulent drag reduction by minute concentrations of polymers we study the effects of minor viscosity contrasts on the stability of hydrodynamic flows. The key player is a localized region where fluctuations are produced by interactions with the mean flow (the "critical layer"). We show that a layer of weakly space-dependent viscosity placed near the critical layer has a very large...

in this article six new copoly(amide-imide)s (11a-c) were synthesized through the directpolycondensation reaction of 1,3-bis[4,4'-(trimellitimido) phenoxy] propane (6) with 3,3'-diamino diphenyl sulfone (7), 4,4'-diaminodiphenyl ether (8) and 1,5-naphtalene (9) in thepresence of fumaric acid (10) as a second diacid in a medium consisting of n-methyl-2-pyrrolidone, triphenyl phosp...

In order to study the effects of extensional viscosities on turbulent drag reduction, experimental studies using two-dimensional turbulence have been made. Anisotropic structures and variations of energy transfer induced by polymers are considered. Polyethyleneoxide and hydroxypropyl cellulose having different flexibility, which is due to different characteristics of extensional viscosity, are ...

In this study, effects of multi walled carbon nanotubes and temperature on rheological behavior of engine oil (10W40) have been examined. For this purpose, the experiments were carried out in the temperature range of 5-55°C for several suspensions with solid volume fractions of 0.025%, 0.05%, 0.1%, 0.25%, 0.5% and 0.75%. The viscosity of all samples was measured in the shear rate range of 666s-...

One method of reducing styrene emissions from vinyl ester (VE) and unsaturated polyester resins (UPE) is to replace some or all of the styrene with fatty acid-based monomers. Methacrylated fatty acid (MFA) monomers are ideal candidates because they are inexpensive, have low volatilities, and free-radically polymerize with vinyl ester. The viscosity of VE resins using these fatty acid monomers r...

Motivated by the large effect of turbulent drag reduction by minute concentrations of polymers, we study the effects of a weakly space-dependent viscosity on the stability of hydrodynamic flows. In a recent paper [Phys. Rev. Lett. 87, 174501, (2001)], we exposed the crucial role played by a localized region where the energy of fluctuations is produced by interactions with the mean flow (the "cr...

We propose a simple dynamic model of polymers under shear with an anisotropic mobility tensor. We calculate the shear viscosity, the rheo-dielectric response function, and the parallel relaxation modulus under shear flow deduced from our model. We utilize recently developed linear response theories for nonequilibrium systems to calculate linear response functions. Our results are qualitatively ...

This paper describes an experimental study of the stability of a hydrolyzed polyacrylamide (HPAM) polymer and an HPAM-2acrylamido-tertbutylsulfonic acid (ATBS) terpolymer in the presence of varying initial levels of dissolved oxygen (0 to 8,000 ppb), Fe2þ (0 to 220 ppm), and Fe3þ (0 to 172 ppm). A special method was developed to attain and confirm dissolved-oxygen levels. Stability studies were...