نتایج جستجو برای: polymer viscosity
تعداد نتایج: 125524 فیلتر نتایج به سال:
Plasticizers are small molecules with low molecular weight. These compounds typically have an esteric structure. The plasticizers reduce the glass transition temperature and the viscosity of the polymer to enhance the flexibility and processability of polymer materials. The main problem with these additives is that, over time, they migrate from the polymeric matrix and exude to the surface of p...
Various solubilizers were tried during preformulation study. Propylene glycol and Transcutol were selected as solubilizers for further study. Poloxamer 407 gives gelation temperature in nasal temperature range 280 to 350 in 18% w/v concentration. Addition of bioadhesive polymer from 0.2% to 0.7% further lowered the gelation temperature from 340 to 290. Gelation temperatures obtained using two d...
Rodlike polymer particles could have interesting properties and could find many practical applications; however, few methods for the production of such particles are available. We report a systematic study of a droplet shearing process for the formation of polymer rods with micrometer or submicrometer diameter and a length of up to tens of micrometers. The process is based on emulsification of ...
Objective of the present study was to develop and evaluate vaginal films with essential in vitro studies. Films were developed using hydroxypropyl methylcellulose as a polymer and formulations were coded. The developed films were evaluated with Fourier transform infrared spectroscopy, drug content, viscosity, surface pH, thickness, mechanical characterisation and in vitro drug release study. Fo...
Assessment of the potential of a polymer flood for mobility control requires an accurate model on the viscosities of displacement fluids involved in the process. Because most polymers used in EOR exhibit shear-thinning behavior, the effective viscosity of a polymer solution is a highly nonlinear function of shear rate. A reservoir simulator including the model for the shear-rate dependence of v...
Glycoprotein concentrations (0) were measured by a modification of the method of Mantle & Allen (1978). Viscosities were measured with an Ostwald viscometer at 25OC within 5min of collection of samples in order to minimize the observed fall in viscosity due to peptic action. Specific (v,,,, 0) and reduced specific viscosities (vred., A) are illustrated. Each point is an observation on a pooled ...
Polymer nanostructures were directly written onto substrates in ultra-high vacuum. The polymer ink was coated onto atomic force microscope (AFM) probes that could be heated to control the ink viscosity. Then, the ink-coated probes were placed into an ultra-high vacuum (UHV) AFM and used to write polymer nanostructures on surfaces, including surfaces cleaned in UHV. Controlling the writing speed...
The slurry polymerization of ethylene was studied by employing a (TiCl4/Mg(OEt)2/TEA) catalyst system in hexane. The effects of triethylaluminum concentration and temperature on polymer yield and polymer viscosity average molecular weight, Mv, were investigated. The maximum polymer yield was obtained at an Al/Ti molar ratio of 124. The highest yield and Mv were achieved at 60 °C. The concentrat...
Momen Abad mining district is a part of Eastern Iranian bentonite zone, located in Eocene-Oligocene volcanic belt. Mineralogical study of bentonites by XRD method introduced smectite and cristobalite as major mineralogical phases and plagioclase, alkali feldspar, paragonite, zeolite (heulandite and clinoptilolite), mica-illite, and quartz as minor phases. SEM imaging of bentonites shows that pl...
The Rubinstein-Duke model for polymer reptation is analyzed by means of density matrix renormalization techniques. It is found that the crossover in the scaling behavior of polymer renewal time (or viscosity) arises from the competing effect of the contribution due to tube length fluctuations and higher-order corrections, which are of opposite sign. Experiments which ought to emphasize both con...
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