不同叔醇胺对硅酸盐水泥的性能影响研究

采用不同叔醇胺,探讨其对不同矿渣掺量的硅酸盐水泥的助磨、需水量和强度的影响。研究发现,四种叔醇胺的粉磨能力大小为DEIPA＞EDIPA≈TEA＞TIPA;叔醇胺的加入会增加水泥稠需水量,其中增加最大的是EDIPA;当矿渣掺量为0%时,DEIPA提高3 d和28 d抗压强度最好;当矿渣掺量为25%和50%时,TEA提高3 d强度最佳。DEIPA提高28 d强度最佳。即针对矿渣硅酸盐体系将TEA和DEIPA复合使用可得到最佳助磨和早后期强度。     

碳碳双键亲电加成反应的启发式教学

本文以碳碳双键的亲电加成反应为例,从诱导启发、解决问题、问题延伸及讨论总结四个方面,探讨了如何将启发式教学方法运用于有机化学教学过程中,从而达到引导学生独立思考、独立分析问题和解决问题,最终变被动学习为主动学习的目的。     

卤代烃亲核取代和消除反应影响因素教学思考

卤代烃可以发生亲核取代反应、消除反应、与金属反应及还原反应,其中学生在学习亲核取代反应及影响因素、消除反应及影响因素,以及判断反应为取代反应还是消除反应时,感觉知识很多,容易混淆在一起,为了让学生学习起来更容易理解并记住,能快速判断出反应的类型,为此,我们对该部分知识采用了探究式教学,先强调重要基本概念,再对影响因素进行了对比归纳,在教学中取得了较好的教学效果。     

无机卤化物对不溶性硫稳定性的影响

在液相法制备不溶性硫(IS)的过程中,以无机卤化物KCl、KBr、KI作为稳定剂,采用单因素法确定了适宜的稳定剂用量、反应温度和反应时间。实验结果表明,稳定剂KCl的适宜用量为0.6%,反应时间1h,反应温度260℃,IS收率为17.09%;稳定剂KBr适宜用量为0.8%,反应时间90min,反应温度280℃,IS收率为28.5%;稳定剂KI适宜用量为0.6%,反应时间1h,反应温度240℃,IS收率为29.30%。在研究IS热稳定性的过程中,对用三种稳定剂所制备的IS进行充环烷油、脂肪烃油、芳烃油处理,比较了工艺油的品种和稳定剂的协同作用对IS的受热影响。在105℃下15min内,三种工艺油中,以IS充芳烃油的热稳定性为最高;三种稳定剂中,以KI制备的IS充油后的热稳定性最好;以KCl、KBr、KI为稳定剂所制备的IS充芳烃油的热稳定性顺序依次为76.3%、87.5%、96.0%,同时初步讨论了工艺油种类和无机卤化物对抑制IS还原的作用机理。     

钯和铜促进的芳香C-H键转化为碳卤键的最新研究进展

卤代芳烃是一类重要的化合物,合成此类化合物的方法一直是化学家们研究的热点。C-H键直接转化为碳卤键为芳基卤代物的合成提供了一种便捷的方法。最近,钯和铜促进的C-H键活化转化为C-X（X=F,Cl,Br,I）键得到很大发展,在很大程度上解决了低的区域选择性,低毒性的问题。     

腐植酸对叔胺萃取铀的影响

简要叙述了腐植酸的主要性能,论述了腐植酸对叔胺-煤油溶液萃取铀和反萃取铀过程的影响。腐植酸与腐植酸铀酰盐对叔胺-煤油溶液萃取铀将降低萃取效率,并形成乳化。在反萃取铀过程中,实践表明,采用腐植酸脱除剂Na2CO3作为反萃取剂进行反萃取,可以有效把叔胺-煤油溶液中负载的铀、腐植酸铀酰盐以及腐植酸反萃取下来,铀的反萃取率达98%以上,腐植酸的脱除率达99%以上;且两相之间无乳化膜。     

残留高碳醇对烷基多苷性能的影响

用德国Ｈｅｎｋｅｌ公司及国内一些厂家和科研单位生产的同 烷烷基多苷产品,首次从表面张力,起泡性能,增溶性能、乳化性能和分散性能等几个方面研究了残留醇对它们的影响。结论是少量残留醇的存在,对烷基多苷乳化性能影响不大,起泡性能降低,但泡沫的稳定性增加,表面张力降低,增溶性和分散性能均有提高;随着残留醇含量的过量增加,所有性能均有下降的趋势。     

Influence of Covalent Bonds on the Adhesion Energy at Elastomer-Glass Interfaces

The aim of this study was to analyze the effect of interfacial covalent bonds on the adhesive behavior of an elastomer, a crosslinked polydimethylsiloxane, and a glass substrate. These covalent bonds were created by applying to both materials an appropriate surface treatment by means of plasma polymerization. Adhesion measurements were carried out by analyzing the contact area between a rubber hemisphere and a flat rigid glass plate. The contact was forced under a given compressive loading for different times t_c, then the load was removed and the fracture propagation at the interface was recorded as a function of relaxation time t_r. Finally, adhesion energies were also determined by means of a probe test using a tensile testing machine.     

Influence of Surface Topography on Strengths of Thermal Bonds

The influence of the initial topography of fiber surfaces on the strength of thermally-induced autohesive bonds between thermoplastic fibers, such as those found in heat-bonded non-woven textiles, has been studied for flat polypropylene monofilaments having imposed surface scratches. These monofilaments were bonded in various combinations using a laser beam to produce localized melting and bonding. Bond breaking strengths were measured in shear under tensile loading, and the resultant fracture surfaces were examined using scanning electron microscopy. Bonds were strongest when the scratches were aligned; furthermore, for the same alignment pattern, bonds were strongest when the degree of scratching was least. In no case was interfacial failure observed by microscopy. Moreover, more material was torn away from the failing fiber bonds of higher strength than was observed for lower strength bonds. The results are interpreted in terms of the effects on bond strength of the number and distribution of surface flaws present during bonding, which is determined by the initial pattern of surface roughness.     

Influence of Tertiary Alkanolamines on Portland Cement Hydration

The physical and chemical effects of small additions of two different tertiary alkanolamines to portland cement were investigated. The strengths of standard test mortars moist cured for more than 1 day were found to be enhanced in some cases by addition of triisopropanolamine, but not by similar amounts of triethanolamine. Thermogravimetric and X-ray diffractometric data indicate that the increased mortar strengths resulted from an increased degree of hydration of the cement. Calorimetry and aqueous-phase analysis show that the higher alkanolamine, triisopropauo-lamine, remains in solution for a sufficient time to catalyze hydration of C₄ AF after all of the free gypsum has been consumed to form calcium sulfoaluminate hydrates, In contrast, the lower alkanolamine, triethanolamine, is mostly adsorbed by the cement within the first hours of hydration. It is hypothesized that the catalytic mechanism involves facilitated transport of ferric ions through the aqueous phase in the form of ferric-alkanolamine complexes.     

不同工艺条件对卤化银乳剂颗粒粒径分布的影响

实验研究了乳化过程中,各种工艺条件的不同变化对乳剂颗粒粒径分布及性能的影响。通过扫描电镜及粒径分布测试设备的测定,对不同条件乳化后的颗粒分布及大小变化状态进行了观察、测试及数据分析,结果表明,不同工艺条件的变化,对颗粒分布、大小产生了明显的变化,对感光度及性能均产生一定的影响。     

烷基糖苷组成分析研究

采用高效液相色谱法、气相色谱法和液相色谱-电喷雾质谱法对烷基糖苷组成进行了分析。结果表明,气相色谱法可以分离烷基单糖苷、二糖苷、三糖苷及四糖苷;高效液相色谱法可以将烷基单糖苷、烷基多糖苷分离,并计算烷基糖苷各组分的含量;液相色谱-电喷雾质谱法是分析烷基糖苷组成最有效的方法,既可以定性也可以定量。     

考虑水温影响的多水管对垃圾土温度影响分析

垃圾土在填埋场降解过程中产生的热量会使垃圾土自身温度不断升高,而过高的温度对填埋气、衬垫系统以及垃圾填埋场的安全都会产生影响,因此填埋场现场常通过水循环对垃圾土温度进行控制。本文首先通过作用面积相等的原则对多水管梅花形和矩形排列进行简化,然后建立了考虑水温升高的多水管对垃圾土降温模型,推求模型解答,并用工程实例现场参数拟合,计算结果符合实际情况。该模型提供了计算水管降温的一种新方法。     

Alkyl Xylosides: Physico‐Chemical Properties and Influence on Environmental Bacteria Cells

A group of four selected non‐ionic surfactants based on carbohydrates, namely octyl d ‐xyloside (C₈X), nonyl d ‐xyloside (C₉X), decyl d ‐xyloside (C₁₀X) and dodecyl d ‐xyloside (C₁₂X), have been investigated to accomplish a better understanding of their physico‐chemical properties as well as biological activities. The surface‐active properties, such as critical micelle concentration (CMC), emulsion and foam stability, the impact of the compounds on cell surface hydrophobicity and cell membrane permeability together with their toxicity on the selected bacterial strains have been determined as well. The studied group of surfactants showed high surface‐active properties allowing a decrease in the surface tension to values below 25 mN m^?1 for dodecyl d ‐xyloside at the CMC. The investigated compounds did not have any toxic influence on two Pseudomonas bacterial strains at concentrations below 25 mg L^?1. The studied long‐chain alkyl xylosides influenced both the cell inner membrane permeability and the cell surface hydrophobicity. Furthermore, the alkyl chain length, as well as the surfactant concentration, had a significant impact on the modifications of the cell surface properties. The tested non‐ionic surfactants exhibited strong surface‐active properties accompanied by the significant influence on growth and properties of Pseudomonas bacteria cells.     

Adsorption of Alkanethiols on Gold Surfaces: PM-IRRAS Study of the Influence of Terminal Functionality on Alkyl Chain Orientation

The present paper focuses on a simplified method to study the orientation and the anisotropy of two different alkanethiols self-assembled monolayers on gold surfaces. The alkanethiols of interest vary only by their terminal functionalities (COOH and COOCH₃), thus allowing one to highlight the influence of these ending chemical groups on the final orientation of the adsorbed molecules. 11-Mercaptoundecanoic acid [HS-(CH₂)₁₀-COOH] and the methyl-11-mercaptoundecanoate [HS-(CH₂)₁₀-COOCH₃] were grafted under adequate conditions to obtain a high grafting density on gold substrates. These latter, before and after the alkanethiol adsorption, were analyzed mainly by the polarization-modulation infrared reflection-absorption spectroscopy (PM-IRRAS) technique to access orientation angles, and by atomic force microscopy (AFM) to check the homogeneity of the grafted layer.

By applying an original PM-IRRAS simplified method, the results showed an orientation closer to the normal of the surface plane in the case of the acid thiol compared with the ester one, which is probably because of the lateral hydrogen bonds established between the adjacent COOH functions. This method offers a direct and simple way to quantify the orientation angles in the alkanethiol nanofilms.     

Influence of Fillers on Sizing Efficiency and Hydrolysis of Alkyl Ketene Dimer

The influence of various fillers on sizing efficiency, adsorption and hydrolysis of alkyl ketene dimer (AKD) has been investigated. Results indicated that the precipitated calcium carbonate (PCC) improved AKD retention, both bound and unbound. The sizing efficiency was reduced as PCC contents increased, which might be attributed to the decrease in the relative AKD dosage to fibres and AKD hydrolysis promoted by PCC. Less amount of AKD was adsorbed on PCC, compared with calcined clay and TiO₂ fillers under the same conditions. Hydrolysis studies indicated that PCC had a more detrimental effect on AKD hydrolysis than clay and TiO₂.     

一种氧化叔胺化合物在热敏材料体系中的作用

利用双氧水将无色结晶紫分子中的叔胺基团氧化,得到含三个氧化叔胺基团的结晶紫氧化物(OLCV),并通过TGA和DSC测试其热稳定性。将OLCV作为助剂添加到一种基于酚醛树脂的热敏树脂体系中,发现其具有很强的阻溶性,并测定加入量对热敏树脂的碱溶性影响,研究了该种氧化叔胺化合物的在热敏体系中的可能应用。     

Influence of Processing on the Physical Stability of Multiple Emulsions Containing a Green Solvent

The influence of the emulsification process on the microstructure and physical stability of model water‐in‐oil‐in‐water (W/O/W) emulsions formulated with a green solvent and a mixture of amphiphilic copolymers as emulsifiers was investigated. Emulsions were prepared by applying a homogenization step with a rotor‐stator device followed by high‐pressure homogenization. Viscous flow tests, transmitted light optical microscopy, globule size distribution (GSD), and multiple light scattering (MLS) measurements were carried out. The GSDs obtained were the result of a recoalescence due to overprocessing and the coalescence of inner droplets with the outer water phase. MLS detected a main destabilization mechanism by creaming. The passing of the emulsion through a high‐pressure homogenizer (HPH) significantly delayed the creaming process.     

芳纶热拉伸处理过程对氢键影响的研究

研究了热处理过程对聚对苯二甲酰对苯二胺(PPTA)结构与性能的影响。通过对PPTA纤维升温红外光谱分析可以看出:在较低的热处理温度下,随着温度的升高,发现在3 300 cm~(-1)处—NH—伸缩振动峰向高波数方向移动,峰型变宽,吸收峰强度减弱。采用傅里叶变换红外光谱仪和单丝强度仪、比浓对数黏度等研究发现:经热拉伸处理后的PPTA纤维内部分子间氢键作用力增加,自由氢键数减少,游离的—NH_2含量却增加,纤维比浓对数黏度和强度降低,说明纤维的拉伸强度是由分子间作用力以及分子链段的长度共同作用的。     

Analysis of the Effects of Hydrocarbon Chain on Foam Properties of Alkyl Polyglycosides

The influence of surfactant structure on foam properties of different alkyl polyglycosides (APGs) in aqueous solutions was studied. Foamability, foam stability, and foam morphology were analyzed using the FoamScan method. Results showed that the foamability, foam stability, and the liquid carrying ability of long-chain APGs are higher than those of short-chain APGs. Foam morphology analysis showed that the foam produced by short-chain APGs is more unstable than the foam generated by long-chain APGs. Long-chain APGs have stronger intermolecular cohesion force, stringency, and ductility than short-chain APGs.