Viscoelastic properties of amorphous solids deformed under uniform shear stress were studied using a kind of sandwich method with utilizing a sensitive optical technique. Time-dependent deformation data were analyzed on the basis of a mechanical model of anelasticity plus viscosity. Experiments were performed to determine the temperature dependence of viscosity for several kinds of inorganic gl...

We report measurements of turbulent drag reduction of two different polyelectrolyte solutions: DNA and hydrolyzed Polyacrylamide. Changing the salt concentration in the solutions allows us to change the flexibility of the polymer chains. For both polymers the amount of drag reduction was found to increase with the flexibility. Rheological studies reveal that the elongational viscosity of the so...

Cationic waterborne polyurethane as a new dispersing polymer was synthesized by using relatively hydrophilic polyols. Dispersing cationic polyurethane (DCPU) nanocomposites were prepared using isophorone diisocyanate (IPDI), polyethylene glycol (PEG) with different molecular weights (Mn=200, 400, 600,and1000 g/mol), N-methyl diethanolamine (MDEA), dibutyltin dilaurate (DBTDL) and different perc...

The curing of fluid resins is performed by pouring the polymer-monomer mixture into molds made of hydrocolloid[1] or special plaster investment[2], before the fluidity of resin mixture disappears. Therefore, it can be said that the fluidity of resin mixture is an important factor which not only determines the pouring time but also is much related to the quality of the products. The viscosity of...

Hyaluronic acid (HA) is a naturally occurring biodegradable polymer with a variety of applications in medicine including tissue engineering, dermatological fillers, and viscosupplementation for osteoarthritis treatment. The cytotoxicity of crosslinking techniques for scaffold fabrication and the high viscosity of viscosupplements have been issues impeding the development of products from HA. Th...

Floating dosage forms of acetylsalicylic acid, used for its antithrombotic effect, were developed to prolong gastric residence time and increase bioavailability. In the two-layer tablet formulation, hydroxypropyl methylcellulose (HPMC) of high viscosity and an effervescent mixture of citric acid and sodium bicarbonate formed the floating layer. The release layer contained the drug, direct table...

bis(indenyl)zirconium dichloride as a catalyst was synthesized using a modified method at the room temperature. polymerization of ethylene and copolymerization of ethylene and propylene were carried out by this metallocene catalyst. ethylene propylene (p/e) feed ratios of 0.25, 0.5, 1, and 2 were employed into the copolymerization systems. copolymerization conditions like cocatalyst/catalyst ra...