نتایج جستجو برای: polymers viscosity index

تعداد نتایج: 497165  

2008
R. K. Wanchoo A. Thakur

Blends of chitosan with hydrophilic polymers were investigated for miscibility. Chitosan/poly (vinyl alcohol) (CS/PVA), chitosan/poly vinylpyrollidone (CS/PVP) and chitosan/poly (ethylene oxide) (CS/PEO) blends were prepared in dilute aqueous acetic acid ( = 1 %) and found to be miscible over the entire composition range by dilute solution viscosity and rheological measurements. The miscibility...

2017
Nejib Kasmi Martina Roso Nadia Hammami Mustapha Majdoub Carlo Boaretti Paolo Sgarbossa Chiara Vianello Giuseppe Maschio Michele Modesti Alessandra Lorenzetti

In order to prepare thermally stable isosorbide-derived thermoplastic polyurethane, the synthesis of two new chiral exo-exo configured diols, prepared from isosorbide, and two types of diphenols (bisphenol A and thiodiphenol) was described. The synthesis conditions were optimized under conventional heating and microwave irradiations. To prove their suitability in polymerization, these monomers ...

Journal: :Journal of chromatography. A 2003
Galina E Kassalainen S Kim Ratanathanawongs Williams

Thermal field-flow fractionation (ThFFF) is capable of separating a wide molecular mass range of polymers by their molecular mass (Mr) and chemical composition. However, retention and resolution decrease significantly for polymers with Mr<20 kDa. Various approaches for increasing the retention of low Mr (<15 kDa) polymers were investigated. Our results showed that temperature conditions and sin...

Currently available polymers as a component of in-situ gels are unsuitable for treating high-temperature/high-salinity reservoirs due to their chemical and thermal degradation. In this study, a new copolymer-based gel system including high molecular weight nanostructured polymers (NSPs) was developed to address the excessive water production problem in reservoirs under harsh conditions. The sta...

2014
Alok S. Tayi E. Thomas Pashuck Christina J. Newcomb Mark T. McClendon Samuel I. Stupp

Electrospinning is a high-throughput, low-cost technique for manufacturing long fibers from solution. Conventionally, this technique is used with covalent polymers with large molecular weights. We report here the electrospinning of functional peptide-based supramolecular polymers from water at very low concentrations (<4 wt %). Molecules with low molecular weights (<1 kDa) could be electrospun ...

2010
Saeed Zahmatkesh Mohammad Reza Vakili

Ethyl L-lysine dihydrochloride was reacted with three different dianhydrides to yield the poly (ethyl L-lysinimide)s (PI(1-3)); it was also reacted with two different diacyl chlorides to yield the poly (ethyl L-lysinamide)s (PA(4-5)). The resulting polymers have inherent viscosities in the range of 0.15 to 0.42 dL g(-1). These polymers are prepared from an inexpensive starting material and are ...

Journal: :Journal of agricultural and food chemistry 2009
Jerome V Diaz Gordon E Anthon Diane M Barrett

It is well-known that an irreversible decrease in serum viscosity occurs when tomato juice is concentrated by evaporation into paste. Several studies have suggested that the loss in serum viscosity is due to pectin depolymerization, caused by the high temperatures used during industrial tomato paste production. This study demonstrates that conformational changes in pectin may play a more import...

Journal: :International journal of toxicology 2014
Lillian C Becker Wilma F Bergfeld Donald V Belsito Ronald A Hill Curtis D Klaassen Daniel C Liebler James G Marks Ronald C Shank Thomas J Slaga Paul W Snyder F Alan Andersen

The safety of 6 modified terephthalate polymers as cosmetic ingredients was assessed. These ingredients mostly function as exfoliants, bulking agents, hair fixatives, and viscosity-increasing agents-nonaqueous. Polyethylene terephthalate (PET) is used in leave-on products up to 100% and in rinse-off products up to 2%. The Cosmetic Ingredient Review Expert Panel (Panel) considered that the PET u...

Journal: :Journal of the American Chemical Society 2006
Taiho Park Steven C Zimmerman

A supramolecular network polymer consisting of a pair of immiscible polymers, poly(butyl)methacrylate (PBMA) and polystyrene (PS), is described. A urea of guanosine (1, UG) and 2,7-diamido-1,8-naphthyridine (2, DAN), which form an exceptionally strong quadruply hydrogen-bonding complex, are displayed at 1-10 mol % along the main backbone of PBMA and PS, respectively. (1)H NMR studies show heter...

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