The effect of C3S on the early hydration of C3A

Journal of Thermal Analysis and Calorimetry - The hydration of C3A, C3S and C3A+C3S mixtures was examined by thermogravimetry, differential thermogravimetry and calorimetry. The results showed the...     

Catalysis of heteropoly acidic salts for synthesis of diethylene glycol ethyl ether with diethylene glycol and ethanol

Ag₃PW₁₂O₄₀ and Ag₄SiW₁₂O₄₀ showed high activity and stability in the synthesis of diethylene glycol ethyl ether with diethylene glycol and ethanol, on which the conversion is 80.2% and 78.4%, respectively, and the selectivity of diethylene glycol ether is 75.4% and 80.6%, respectively. After the third reaction cycle, Ag₃PW₁₂O₄₀ and Ag₄SiW₁₂O₄₀) still showed higher activity and selectivity, on which the conversion is 72. 6% and 77.5% respectively. But the activity of Ag₃PMo₁₂O₄₀ is lower, the conversion is only 21.0%. IR, XRD, TG and n‐butylamine titrimetry showed that the catalysis may be connected with two kinds of acidic centers owned by heteropoly acidic salt.     

Ternary diffusion coefficients of diethylene glycol and lithium chloride in aqueous solutions containing diethylene glycol and lithium chloride

In this work, ternary diffusion coefficients of diethylene glycol and lithium chloride in aqueous solutions containing diethylene glycol and lithium chloride were reported for temperatures (303.2, 308.2, and 313.2 K) using the Taylor dispersion method. The investigated ternaries contained total glycol–salt concentrations of 10, 15, and 20 wt%. The main diffusion coefficients (D₁₁ and D₂₂) and the cross-diffusion coefficients (D₁₂ and D₂₁) were discussed as function of temperature and concentration. A modified equation originally proposed by Batchelor [1] for mixture of hard spheres in a continuum solvent was used to correlate the present diffusion coefficient data and the results are satisfactory.     

Gas-chromatographic determination of propylene- and diethylene glycol ethers in urine

Summary In order to reduce the health risks in solvent technology, produced by the largely used ethylene glycol ethers, these are getting more and more substituted by glycol ethers derived from propylene glycol. According to the current knowledge these also called 1-alkoxy-2-propanols are to a considerable amount excreted unmetabolized in urine; so these substances themselves might be used for the estimation of health risks. The sensitive analysis consists of a special extraction step using diatomaceous earth. The extract is then concentrated for further gas-chromatographic investigation (FID). Using this technique, 17 in part widely used glycol ethers in urine were determined.     

Contact line dynamics in the late-stage coalescence of diethylene glycol drops

We investigated the contact line dynamics of a composite drop formed as a result of the coalescence during the condensation of two diethylene glycol (DEG) drops at -4 degrees C on a silicon surface. The composite drop relaxes exponentially toward equilibrium with a typical relaxation time, tc, which depends on the equilibrium radius, R, of the composite drop. The value of tc is found to be in the range of 10-100 s for R approximately 1-4 microm. The relaxation dynamics is found to be larger by 6 orders of magnitude than that predicted by bulk hydrodynamics because of high dissipation in the contact line vicinity. Similar to low viscous liquids (water), this high dissipation can be attributed to an Arrhenius factor resulting from the phase change in the contact line vicinity and to the influence of surface defects that pin the contact line.     

Application of differential thermogravimetry to the hydration of expansive cement pastes

Differential thermogravimetric analysis was used to determine the hydration kinetics of expansive cement and its products at various ages of hydration. Analytical grade reagents, kaolin and Portland cement were used to prepare an expansive cement on the basis of calcium sulphoaluminate. Two mix compositions having the stoichiometric composition of trisulphate and monosulphate were synthesized from pure reagents. Three clinkers were also prepared from kaolin, gypsum and calcium carbonate with different compositions.The hydration of expansive cement prepared from the stoichiometric composition of trisulphate and Portland cement gives ettringite as the stable phase after seven days of hydration. The presence of more CaO than the stoichiometric composition of trisulphate favours the conversion of some ettringite to the monosulphate hydrate. The hydration of expansive cement prepared from the stoichiometric composition of monosulphate and Portland cement shows the presence of ettringite and the monosulphate phase. Ettringite is formed initially, and then transformed to the monosulphate form.     

酸性离子液体催化合成二甘醇双丙烯酸酯

二甘醇双丙烯酸酯(Diethylene glycol diacrylate,简称DEGDA),是重要的丙烯酸多官能酯类单体之一,作为紫外光固化树脂的活性稀释剂,广泛用于光固化涂料、印刷油墨、感光树脂版、印刷线路版等领域[1].目前,合成DEGDA多用浓硫酸为催化剂,其反应底物一般可形成均相分散体系,有利于反应物间充分接触,反应速度快.缺点是浓硫酸的脱水性和强氧化性,导致反应中副反应多,设备腐蚀严重,大量"三废"的排放给环境保护造成极大的压力[2].     

The kinetics of diethylene glycol formation in the preparation of polyethylene terephthalate

For revealing diethylene glycol (DEG) formation in poly(ethylene terephthalate) (PET) synthesis, this research focused on finding the stage most critical for DEG formation. It is found that the esterification stage was the most critical stage for DEG formation during production of PET through the direct esterification process. In addition, the kinetics of the formation of DEG (ether bond), which is mainly produced from hydroxyl end groups of ethylene glycol (EG) and bis-hydroxyethyl terephthalate (BHET) oligomer, was investigated. The results show that the reactivity of BHET-OH functional group is greater than that of EG-OH functional group in the reaction to produce ether bonds. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 3073–3080, 1998     

Polyester polyols: Synthesis and characterization of diethylene glycol terephthalate oligomers

The composition of polyester polyols derived from terephthalic acid (TPA) and diethylene glycol (DEG) was examined. The synthesis of individual oligomers 1 , n is described. The compounds were characterized with ¹H and ¹³C NMR, mass spectrometry, and elemental analyses. The resonance signals arising from aromatic protons in 1 , n = 1–3 were identified in ¹H NMR spectra of TPA‐DEG condensates. From ¹H NMR studies and chromatographic separation, it was concluded that the condensation of TPA and DEG in a 1:2 molar ratio results in a mixture of linear oligomers 1 with the average ñ varying from 1.1 to 2.2, and containing about 2% of cyclic oligomer 2 . © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 1114–1123, 2003     

Simultaneous measurements of heat of hydration and chemical shrinkage on hardening cement pastes

Isothermal calorimetry and chemical shrinkage measurements are two independent techniques used to study the development of hydration in cementitious systems. In this study, calorimetry and chemical shrinkage measurements were combined and simultaneously performed on hydrating cement paste samples. Portland cement pastes with different water to cement ratios and a cement paste containing calcium sulfoaluminate clinker and anhydrite were studied. The combined calorimetry/chemical shrinkage test showed good reproducibility and revealed the different hydration behavior of sealed samples and open samples, i.e., samples exposed to external water during hydration. Large differences between sealed and open samples were observed in a Portland cement paste with low water to cement ratio and in the calcium sulfoaluminate paste; these effects are attributed to self-desiccation of the sealed pastes. Once the setup is fully automatized, it is expected that combined calorimetry/chemical shrinkage measurements can be routinely used for investigating cement hydration.     

Viscosimetric and ultrasonic studies of intermolecular interactions of 2-methoxyethanol with diethylene glycol,triethylene glycol and tetraethylene glycol binary mixtures

The viscosities at T = (293.15, 298.15 and 303.15) K and ultrasonic speeds at T = 298.15 K in the binary liquid mixtures of 2-methoxyethanol with diethylene glycol, triethylene glycol and tetraethylene glycol have been measured over the entire mixture compositions. From the experimental data, deviations in the viscosity (Δη), ultrasonic speed (Δu), and excess energies of activation for viscous flow (ΔG* ^E ) have been calculated. The viscosity data were correlated with equations of Hind et al., Grunberg and Nissan, Frenkel, and McAllister. The results are discussed in terms of intermolecular interactions and structure of studied binary mixtures.     

Relative permittivity of the binary mixtures of 2-methoxyethanol with diethylene glycol,triethylene glycol,tetraethylene glycol,and polyethylene glycol 200 at various temperatures

Relative permittivities at T = (293.15, 298.15, and 303.15) K in the binary liquid mixtures of 2-methoxyethanol with diethylene glycol, triethylene glycol, tetraethylene glycol, and polyethylene glycol 200 have been measured over the entire mixture compositions. The relative permittivity deviations (Δε) were calculated from these experimental data. The results are discussed in terms of intermolecular interactions and structure of studied binary mixtures.     

Effect of microcrystalline and microfibrillated cellulose on the evolution of hydration of cement pastes by thermogravimetry

Journal of Thermal Analysis and Calorimetry - The interest in the use of cellulose fibers of increasingly smaller sizes in cementitious materials has increased in recent years. This paper brings...     

网络型聚醚酯弹性体聚柠檬酸二甘醇酯的合成与性能

用一缩二乙二醇(二甘醇)和柠檬酸通过熔融缩聚的方法,合成了一种新型的网络型聚醚酯弹性体—po-ly(diethylene glycol citrate)(PDGC).用FTIR初步表征了预聚物的结构;通过ATR-FTIR、DSC、XRD等表征了PDGC的结构;测试了材料的静态水接触角、力学性能以及体外降解性能,考察了单体的摩尔比以及后期交联时间对材料上述性能的影响.     

Influence of superabsorbent polymers on hydration of cement pastes with low water-to-binder ratio

Internal curing with superabsorbent polymers (SAP) is a method for promoting hydration of cement and limiting self-desiccation, shrinkage and cracking in high-performance, and ultra high-performance concrete with low water-to-binder ratio. SAP are introduced in the dry state during mixing and form water-filled inclusions by absorbing pore solution. The absorbed solution is later released to the cement paste during hydration of the cement. In this paper, cement pastes with low water-to-binder ratios incorporating superplasticizer and different dosages of SAP and corresponding additional water were prepared. Reference cement pastes without SAP but with the same amount of water and superplasticizer were also mixed. Isothermal calorimetry was used to measure hydration heat flow. Water entrainment by means of SAP increased the degree of hydration at later hydration times in a manner similar to increasing the water-to-binder ratio. Addition of SAP also delayed the main calorimetric hydration peak compared to the reference pastes, however, in a less prominent manner than the increase in water-to-cement ratio.     

Investigation of the hydration of nonfouling material poly(ethylene glycol) by low-field nuclear magnetic resonance

The strong surface hydration layer of nonfouling materials plays a key role in their resistance to nonspecific protein adsorption. Poly(ethylene glycol) (PEG) is an effective example of materials that can resist nonspecific protein adsorption and cell adhesion. Thus, the strong interaction between water molecules and PEG was investigated through each T(2) component in water/PEG mixtures using multiexponential inversion of T(2) relaxation time measured by the Carr-Purcell-Meiboom-Gill (CPMG) sequence of low-field nuclear magnetic resonance (LF-NMR). Results show that about one water molecule is tightly bound with one ethylene glycol (EG) unit, and additional water molecules over 1:1 ratio mainly swell the PEG matrix and are not tightly bound with PEG. This result was also supported by the endothermic behavior of water/PEG mixtures measured by differential scanning calorimetry (DSC). It is believed that the method developed could be also applied to investigate various interactions between macromolecules and other small molecules without using deuterium samples, which might open a novel route to quantitatively measure guest-host interactions in the future.