硅酸盐水泥基胶凝材料体系水化热计算研究

基于传统水化热模型计算水泥水化热,建立矿物掺合料水化热计算公式;采用直接法测定掺粉煤灰、矿渣条件下普通硅酸盐水泥和低热水泥基胶凝材料体系1~7 d水化热。计算结果与实测结果对比表明:矿物掺和料水化热双指数计算公式可表征普通硅酸盐水泥和低热水泥基胶凝材料体系下粉煤灰和矿渣1~7 d水化热,可采用此法结合水泥水化热计算方法进行以水化热作为目标函数的胶凝材料体系优化设计。     

聚葡萄糖对冻藏面筋蛋白水合及结构的影响

为提高面筋蛋白的冻藏稳定性,采用核磁共振仪、傅里叶红外光谱仪、差示扫描量热仪、动态流变仪和扫描电子显微镜,研究冻藏条件下添加聚葡萄糖对面筋蛋白体系中水分分布、二级结构、热力学特性、流变学特性及微观结构的影响。结果表明,随冻藏时间延长,添加6%(质量分数)聚葡萄糖的面筋蛋白中弱结合水向自由水的转化量显著减少,抑制了面筋蛋白二级结构中α-螺旋下降及无规则卷曲增大,提高了面筋蛋白的热力学稳定性;冻藏7周时,添加6%(质量分数)聚葡萄糖的面筋蛋白,储能模量和耗能模量下降显著小于对照,且面筋蛋白三维网络结构较均匀,孔径较小,连续性较好。结果表明,聚葡萄糖能有效减弱冻藏对面筋网络的破坏,提升面筋蛋白的冻藏稳定性。     

CO2辅助挤压对马铃薯渣可溶性膳食纤维的影响

以马铃薯渣为原料,研究CO2辅助挤压各工艺条件对马铃薯渣可溶性膳食纤维的影响。结合马铃薯渣颜色、持水力、持油力和膨胀力的变化,得出CO2辅助挤压最佳工艺参数为:CO2发生剂柠檬酸与碳酸氢钠添加质量比为1∶1、添加量30%(质量分数)、挤压温度185℃、物料含水量25%(质量分数)、螺杆转速170 r/min。在此工艺条件下,挤压所得马铃薯渣可溶性膳食纤维含量较高,色泽较好,水合特性得到较好地保持,可为马铃薯渣膳食纤维的改性提供参考。     

马来酸三乙醇胺酯对水泥水化的影响

为克服三乙醇胺早强剂对水泥抗折强度和后期强度的影响,合成了马来酸三乙醇胺酯,并通过背散射电子成像(BSE)和BET分析,研究了马来酸三乙醇胺酯对水泥水化程度、C-S-H含量和水泥水化28 d分形维数的影响。结果表明:马来酸三乙醇胺酯可促进水泥水化尤其是水泥中硅酸盐相的水化;复掺马来酸三乙醇胺酯和聚羧酸减水剂,可显著提高水泥水化产物中C-S-H的含量;三乙醇胺降低了水泥石28 d的分形维数,马来酸三乙醇胺酯单掺及与聚羧酸减水剂复掺则使水泥石28 d的分形维数提高。由此可见,马来酸三乙醇胺酯作为增强型水泥早强剂具有广阔的应用前景。     

Thermodynamic parameters of amitriptyline hydrochloride–additives at cloud point: effects of the ethanol–water mixed media

Abstract

Addition of organic solvents is known to change the properties of amphiphiles through modification of bulk phase. Amitriptyline hydrochloride (AMT) is a tricyclic amphiphilic drug which is usually used as an antidepressant. In drug delivery, the cloud point (CP) of the drug is an important parameter. This article discusses the effects of ethanol–water (EtOH–WR) compositions on the energetic parameters, such as changes in Gibbs energy of clouding (Δ_sG⁰), enthalpy of clouding (Δ_sH⁰), and entropy of clouding (TΔ_sS⁰) of AMT-additive systems. Monovalent alkali halide salts, cationic conventional surfactants, and gemini surfactants were used as additives in the EtOH–WR mixed media whose compositions were varied between 0 and 15% (w/w). The Δ_sG⁰ values are positive for all the additives and the values decrease with the rise in mole fractions of the additives. The Δ_sH⁰ and TΔ_sS⁰ were noted to be positive except for KF in 15% EtOH–WR mixed media.     

Preparation of CaO granules using the granulation method

ABSTRACT

Improving the hydration resistance of CaO particle in manufacturing and application of free CaO-containing materials has practical significance. In this study, CaO granules was made from Ca(OH)₂ particles, which were fabricated by the granulation method. The results showed that the hydration resistance of the CaO granules which was prepared under 1700?r?min^?1 was the best, the CaO granules was sintered well in calcination process, the shell of CaO granules was relatively dense, which improves the hydration resistance of CaO granules, and the rate of hydration weight increment was 0.58% after placed in the air for 20 days under a temperature of 10–14°C and a relative humidity of 57–81%.     

Effect of titanium chelating compound on hydration resistance of CaO material

The hydration resistance of CaO materials prepared by Ca(OH)₂ calcination with titanium chelating compounds is investigated in this paper. The crystalline phases and microstructure characteristics of sintered specimens were studied by X-ray diffraction (XRD), define FTIR spectroscopy, scanning electron microscopy (SEM), and energy dispersive spectrometer (EDS). The results showed that the hydration resistance of CaO samples was improved significantly, especially for samples with 9 wt% Ti chelating compound. The specimens with Ti chelating compound showed an increase in bulk density and a decrease in apparent porosity after heating when compared to the specimens without additive. The grain surface of CaO grain and the gaps between the CaO grain boundaries were covered with calcium phosphate glass phase, calcium phosphate showed two different shapes: irregular shape and rod shape. The formation and distribution of these two forms were the key factors that affecting the hydration resistance of CaO samples.     

Evolution of elastic behavior of alite paste at early hydration stages

Elastic behavior is an important aspect of fresh cement-based materials. In this paper, the elasticity development of fresh pure alite paste within 5 hours was monitored in situ by small amplitude oscillation shear. Isothermal microcalorimetry, X-ray diffraction, scanning electronic microscopy, ¹H nuclear magnetic resonance, zeta potential measurements were used to investigate the underlying mechanisms. It was found that the evolution of storage modulus can be characterized by three different stages. The first stage stems from the compression of electrical double layer and the slight increase of solid volume fraction; the second stage is only controlled by the colloidal interaction; and the third stage is associated to the significant growth of solid volume fraction, the enhancement of short-range attraction and the rigidification of calcium silicate hydrate (CSH) network. Moreover, the relationship between the formation of CSH and the growth of elasticity was also quantified.     

环己烯水合生产精己二酸提质提量的研究

为提高己二酸生产负荷和产品质量,在对环己醇与硝酸反应机理进行研究的基础上,发现环己烯水合生成环己醇、环己醇与硝酸反应生成己二酸的氧化反应产生的热量及NOx气量较大,制约了氧化反应负荷的提升。通过调整NOx总管压力以及吸收塔吸收液输送阀自控条件,提高氧化反应的空气补入量,同时稳定输送吸收塔吸收液,实现了己二酸装置高负荷连续运行。另外,通过增加原料过滤设施,控制己二酸中丁二酸、戊二酸含量等措施,提高了己二酸产品质量。