Basic Research of Improving the Mortar Flow by Thermal Stimulation to Superplasticizer

Polycarboxylic acid-based superplasticizers are being used for various fields of concrete work, however little has reported on changing basic performance by thermal fluctuation. In this study, heating superplasticizers itself is hereinafter as referred to as “thermal stimulation”, the effect of thermal stimulation and heat retention of superplasticizer on the fresh mortar, moreover the influence of molecular structural changed of superplasticizer by thermal stimulation were investigated. As the result, it was confirmed that improving fluidity of the mortar flow on this condition the highly heat temperature and heat over a long time by thermal stimulation of superplasticizer. In addition, it turned out that this phenomenon was caused molecular structural changed by thermal stimulation, and the result was revealed that the effect of thermal stimulation varies according to the type of polymer

Thermophoresis of cyclic oligosaccharides in polar solvents

Cyclodextrins are cyclic oligosaccharides which are interesting as drug delivery systems, because they can be used as containers for pharmaceutical substances. We studied the Ludwig-Soret effect of $\alpha$-, $\beta$-, $\gamma$- and methyl-$\beta$-cyclodextrin in water and formamide by infrared thermal diffusion forced Rayleigh scattering (IR-TDFRS).In water the Soret coefficient, $S_{\mathrm{T}}$, of $\alpha$-, $\beta$- and $\gamma$-cyclodextrin increases with increasing temperature and shows a sign change from negative to positive around $T=35^\circ$C, while $S_{\mathrm{T}}$ of methyl-$\beta$-cyclodextrin is positive in the entire investigated temperature. In formamide $S_{\mathrm{T}}$-values of all cyclodextrins coincide and show a slight decrease with temperature. We discuss the obtained results and relate the $S_{\mathrm{T}}$-values to the different hydrogen bonding capabilities of the cyclodextrins and the used solvents. It turns out that the change of $S_{\mathrm{T}}$ with temperature correlates with the partition coefficient, log~$P$, which indicates that more hydrophilic substances show a more pronounced temperature sensitivity of $S_{\mathrm{T}}$. Additionally we obtained a surprising result measuring the refractive index contrast factor with temperature, $(\partial n/\partial T)_{c,p}$ of cyclodextrins in formamide, which might be explained by a complex formation between cyclodextrins and formamide

Sign change of the Soret coefficient of poly(ethylene oxide) in water/ethanol mixtures observed by thermal diffusion forced Rayleigh scattering

Soret coefficients of the ternary system of poly(ethylene oxide) in mixed water/ethanol solvent were measured over a wide solvent composition range by means of thermal diffusion forced Rayleigh scattering. The Soret coefficient S(T) of the polymer was found to change sign as the water content of the solvent increases with the sign change taking place at a water mass fraction of 0.83 at a temperature of 22 degrees C. For high water concentrations, the value of S(T) of poly(ethylene oxide) is positive, i.e., the polymer migrates to the cooler regions of the fluid, as is typical for polymers in good solvents. For low water content, on the other hand, the Soret coefficient of the polymer is negative, i.e., the polymer migrates to the warmer regions of the fluid. Measurements for two different polymer concentrations showed a larger magnitude of the Soret coefficient for the smaller polymer concentration. The temperature dependence of the Soret coefficient was investigated for water-rich polymer solutions and revealed a sign change from negative to positive as the temperature is increased. Thermodiffusion experiments were also performed on the binary mixture water/ethanol. For the binary mixtures, the Soret coefficient of water was observed to change sign at a water mass fraction of 0.71. This is in agreement with experimental results from the literature. Our results show that specific interactions (hydrogen bonds) between solvent molecules and between polymer and solvent molecules play an important role in thermodiffusion for this system

Basic Research of Improving the Mortar Flow by Thermal Stimulation to Superplasticizer

Polycarboxylic acid-based superplasticizers are being used for various fields of concrete work, however little has reported on changing basic performance by thermal fluctuation. In this study, heating superplasticizers itself is hereinafter as referred to as “thermal stimulation”, the effect of thermal stimulation and heat retention of superplasticizer on the fresh mortar, moreover the influence of molecular structural changed of superplasticizer by thermal stimulation were investigated. As the result, it was confirmed that improving fluidity of the mortar flow on this condition the highly heat temperature and heat over a long time by thermal stimulation of superplasticizer. In addition, it turned out that this phenomenon was caused molecular structural changed by thermal stimulation, and the result was revealed that the effect of thermal stimulation varies according to the type of polymer

How does thermodiffusion of aqueous solutions depend on concentration and hydrophobicity?

The thermal diffusion of aqueous solutions of mono-, di-ethylene glycols, poly(ethylene glycol), methanol, and glycerol is investigated systematically as a function of concentration using the Thermal Diffusion Forced Rayleigh Scattering (TDFRS). For all investigated binary mixtures, the Soret coefficient, S T , decays with increasing concentration of the non-aqueous component showing two regions. For aqueous solution of ethylene glycol, at a very low solute content the decay is steep, while it becomes less steep for higher solute concentration. All mixtures show a sign change of S T with concentration. The sign change concentration is discussed with respect to chemical structures of solute molecules and the partition coefficient, log p . It turns out that the number of hydroxyl groups plays an important role. For the investigated aqueous mixtures, we find empirical linear relations between the sign change concentration and the ratio of the number of hydroxyl groups to the number of carbon atoms as well as the partition coefficient, log p