本体法合成HDI-TMP加成物工艺

本体法合成了六亚甲基二异氰酸酯(HDI)与三羟甲基丙烷(TMP)的加成物作为聚氨酯胶粘剂的固化剂。通过对反应产物-NCO含量和粘度的测定,考察了反应温度、催化剂二月桂酸二丁基锡(DBTDL)用量、HDI与TMP物质的量比对加成产物性能的影响,并由凝胶渗透色谱(GPC)和红外光谱(FT-IR)表征了产物组成和结构特征,获得本体法合成物HDI-TMP加成较佳工艺:n(HDI)∶n(TMP)=9∶1(即n(-NCO)∶n(-OH)=6∶1),催化剂DBTDL用量为0.05%(按TMP质量计),反应温度80℃,反应时间3h,即可制备出HDI-TMP理想加成物含量占总加成物52.66%的低粘度产物。     

浅析催化剂对聚氨酯合成的影响

研究了在TDI-TMP加成物合成过程中甲苯二异氰酸酯（TDI）与三羟甲基丙烷（TMP）摩尔比、三种常用的催化剂以及不同反应温度、时间对产物合成的影响。试验表明,TDI与TMP质量比在3.89-3.91范围、反应温度60-90℃、反应时间2.5-4h为宜;有机金属类催化剂可用于催化本体系,而胺类的催化剂不合适,综合而言,辛酸亚锡最适合。     

水杨酸乙酯双封端异氰酸酯产物的合成及鉴定

研究了水杨酸乙酯双封端1,6 六亚甲基二异氰酸酯(HDI)的反应。讨论了温度、催化剂用量、加料方式、加料时间及反应时间对该反应的影响。用正交实验设计方法,优选了反应条件:n(水杨酸乙酯)/n(HDI)=2 4,反应温度85℃,反应时间10h,催化剂用量为HDI质量的1 0%。双封端产物产率(相对于合成粗产物而言)达到90 25%。用熔点和薄层色谱分析定性验证了产物质量。用红外光谱和气质联机分析证实了产物的结构。用热重分析(TG/DTA)测定产物热分解温度为116℃。     

钠离子对三羟甲基丙烷的应用性能的影响

本文以甲酸钠的方式把钠引进三羟甲基丙烷(TMP)中,对不同量钠的TMP进行应用评价,通过合成TDI-TMP来评价钠的影响并确定钠含量,在TDI-TMP加成物中,钠含量应不超过25×10-6。     

三羟甲基丙烷产品质量改进研究

本文对三羟甲基丙烷(TMP)及其加成物的黄变进行小试研究,发现影响TMP质量和黄变的主要因素是钠离子和微量水存在。并进行微量水存在和黄变机理的探讨。通过合成TDI-TMP来评价钠的影响并确定钠含量,在TDI-TMP加成物中,钠含量应不超过25×10-6。     

低TMP残留乙氧基(3)三羟甲基丙烷的合成研究

简要介绍了以三羟甲基丙烷为起始剂在氢氧化钠条件下与环氧乙烷进行加成反应,合成了TMP残留低的乙氧基(3)三羟甲基丙烷产品;本文主要考察了反应温度、反应时间、EO加成数、催化剂用量对起始剂残留的影响,得出最佳合成工艺。     

一种新型固化剂的合成

合成了一种新型的聚氨酯固化剂 ,并讨论了在 TDI- DMP加成物合成过程中甲苯二异氰酸酯 ( TDI)与 2 .2 -二甲基 - 1 .3-丙二醇 ( DMP)或三羟甲基丙烷 ( TMP)投料比 ,反应温度 ,时间、酸、碱度 ,不同催化剂等对产物性能影响。试验结果表明 ,NCO/OH质量比在 ( 1 .2～ 2 .0 ) /1 .0 ( mol)范围内 ,反应温度为 70°C,反应时间为 2 .5～ 3.0 h,二月桂酸二丁基锡催化剂可用于催化本体系     

甲基环戊二烯基三羰基锰的合成

甲基环戊二烯基三羰基锰(MMT)是一种有机锰油品抗爆添加剂,被认为是有机铅的最好替代物。国内对其研究较少,本文对MMT的合成工艺进行了详细研究。研究了反应温度、反应时间及原料摩尔比对反应收率的影响。用气相色谱分析了产物含量,用FT-IR表征了产物结构。实验结果表明:反应温度160~170℃,反应时间2小时,甲基环戊二烯钠摩尔数∶二氯化锰摩尔数=1∶0.55为适宜的反应条件。在此条件下,该反应收率接近80%,气相色谱法分析产物中对甲基环戊二烯基三羰基锰含量99%以上。     

碳酸酯系溶剂体系下TDI-TMP的固化剂合成

研究了在碳酸酯体系下,TDI-TMP加成物合成过程中m(TDI)/m(TMP)、反应温度和保温温度、反应时间、不同降低游离TDI的方法对产物性能的影响。试验表明,TDI与TMP质量比至少在3.5以上、3.89左右适宜,反应温度60℃左右、保温温度70℃,总反应时间3~4 h左右,固含量在60%~65%为宜。     

非光气法合成六亚甲基二异氰酸酯的研究

六亚甲基二异氰酸酯（HDI）是聚氨酯合成的重要的原料之一。对六亚甲基二氨基甲酸甲酯（HDU）热分解合成六戚甲基二异氰酸酯（HDI）进行了研究,考察了催化剂、反应温度、反应时间、物料浓度、催化剂甩量等对反应的影响。优化后反应条件为：以HSFE为催化剂,反应温度260℃,催化剂用量为溶剂质量的0．30％,HDU浓度7．50％。此条件下反应35min,HDI收率为66．51％。     

Quantification of Phospholipids Classes in Human Milk

Phospholipids are integral constituents of the milk fat globule membranes and they play a central role in infants’ immune and inflammatory responses. A methodology employing liquid chromatography coupled with evaporative light scattering detector has been optimized and validated to quantify the major phospholipids classes in human milk. Phospholipids were extracted using chloroform and methanol and separated on C18 column. Repeatability, intermediate reproducibility, and recovery values were calculated and a large sample set of human milk analyzed. In human milk, phospholipid classes were quantified at concentrations of 0.6 mg/100 g for phosphatidylinositol; 4.2 mg/100 g for phosphatidylethanolamine, 0.4 mg/100 g for phosphatidylserine, 2.8 mg/100 g for phosphatidylcholine, and 4.6 mg/100 g for sphingomyelin. Their relative standard deviation of repeatability and intermediate reproducibility values ranging between 0.8 and 13.4 % and between 2.4 and 25.7 %, respectively. The recovery values ranged between 67 and 112 %. Finally, the validated method was used to quantify phospholipid classes in human milk collected from 50 volunteers 4 weeks postpartum providing absolute content of these lipids in a relatively large cohort. The average content of total phospholipids was 23.8 mg/100 g that corresponds to an estimated mean intake of 140 mg phospholipids/day in a 4-week old infant when exclusively breast-fed.     

The hydration of reactive cement-in-polymer dispersions studied by nuclear magnetic resonance

The behaviour of two novel cement-in-polymer (c/p) dispersions, namely cement-in-poly(vinyl acetate) and cement-in-poly(vinyl alcohol) upon exposure to water at room temperature was investigated by a combination of various NMR methods. The swelling, cracking, and the water ingress were monitored non-destructively using ¹H single point imaging. The hydration of the cement matrix was investigated using ²⁹Si NMR whilst ¹³C CPMAS NMR spectra allowed the quantification of the kinetics of the hydrolysis reaction of poly(vinyl acetate) into poly(vinyl alcohol). The polymer controls the rate of water ingress and swelling which in turn determines the behaviour of the c/p dispersions upon exposure to water. For the cement-in-poly(vinyl alcohol), the rates of water ingress and swelling are much faster than the hydration of the clinker whilst for the cement-in-poly(vinyl acetate) the slow rates of the two processes allow the formation of a cementious matrix which assures the stability of the sample.     

Interactions between shrinkage reducing admixtures (SRA) and cement paste's pore solution

Shrinkage reducing admixtures (SRA) have been developed to combat shrinkage cracking in concrete elements. While SRA has been shown to have significant benefits in reducing the magnitude of drying and autogenous shrinkage, it has been reported that SRA may cause a negative side effect as it reduces the rate of cement hydration and strength development in concrete. To examine the influence of SRA on cement hydration, this study explores the interactions between SRA and cement paste's pore solution. It is described that SRA is mainly composed of amphiphilic (i.e., surfactant) molecules that when added to an aqueous solution, accumulate at the solution-air interface and can significantly reduce the interfacial tension. However, these surfactants can also self-aggregate in the bulk solution (i.e., micellation) and this may limit the surface tension reduction capacity of SRA. In synthetic pore solutions, SRA is observed to form an oil-water-surfactant emulsion that may or may not be stable. Specifically, at concentrations above a critical threshold, the mixture of SRA and pore fluid is unstable and can separate into two distinct phases (an SRA-rich phase and an SRA-dilute phase). Further, chemical analysis of extracted pore solutions shows that addition of SRA to the mixing water depresses the dissolution of alkalis in the pore fluid. This results in a pore fluid with lower alkalinity which causes a reduction in the rate of cement hydration. This may explain why concrete containing SRA shows a delayed setting and a slower strength development.     

Design and function of novel superplasticizers for more durable high performance concrete (superplast project)

In this article we shall describe our quest and ultimate success in furthering our understanding of the action of superplasticizers on the rheology of cement and concrete. By specifically producing superplasticizers with varied architectures, we have been able to show the important structural features of the macromolecules that lead to a successful superplasticizer or water reducing agent. Both polycarboxylate and lignosulfonate polymers have been investigated. Using both non-reactive model MgO powders, three different types of cement blends, the adsorption behaviour and the effect on the rheological properties of these two important superplasticizer families have been used to further develop a conceptual model for superplasticizer — cement behaviour. This paper will deal mainly with the conceptual model, the materials and methods used to asses the polymer adsorption behaviour and rheological properties of the systems studied. We shall briefly describe the adsorption of the polymers onto the different surfaces and their influence on surface charge and rheology and the influence of the various ionic species found in cement pore solutions that may influence polymer-cement affinity. The key factors are shown to be the effective adsorbed polymer thickness and the induced surface charge which can be influenced by the polymer architecture, the pore solution composition and the initial particle surface charge.     

Study of the hydration of CaO powder by gas–solid reaction

Hydration of CaO powders by reaction with water vapor has been studied in isothermal and isobaric conditions. Experimental tests were performed within the temperature range of 70 °C–420 °C and with a water vapor pressure from 5 to 160 hPa by means of a thermogravimetric device. Two powders, exhibiting slight differences in their physical properties, were studied. However, for one of the powders and under some temperature and pressure conditions, the reaction is not complete. The difference of behavior between both CaO powders was interpreted by considering the effect of the morphological properties on the mechanism of growth of Ca(OH)₂.     

The influence of water removal techniques on the composition and microstructure of hardened cement pastes

The removal of water from hardened cement paste for analysis or to arrest ongoing hydration has been reported to affect the composition of hydrated phases and microstructure. The effect that arresting the hydration of hardened cement paste by replacing the pore water with acetone before drying, and by removing the water by freeze, vacuum and oven drying has on the hardened cement paste has been investigated. Two pastes were studied, a cemented iron hydroxide floc where a high proportion of ordinary Portland cement (OPC) had been replaced by pulverised fuel ash, and a pure hydrated OPC. The results showed that none of the water removal techniques caused any major deterioration in the composition and microstructure of the hardened cement pastes studied, but the pores appeared better preserved after arresting hydration using acetone quenching. Freeze drying appeared to cause more cracking of the microstructure than the other water removal techniques.     

2-(2'-咪唑偶氮)萘酚-4-磺酸的合成及其分析性质的研究

合成了新显色剂咪唑偶氮－２－萘酚－４－磺酸（ＩＡＮ－４Ｓ）,研究了试剂的离解常数及其与金属离子的显色反应。     

Influence of bleed water reabsorption on cement paste autogenous deformation

The effects of bleed water reabsorption and subsequent early age expansion on observed autogenous deformation are investigated in this research. Bleeding was induced by varying superplasticizer and shrinkage-reducing admixture dosages and by increasing the water-to-cement ratio. This research revealed that significant early age expansion occurs with increasing chemical admixture dosages and higher water-to-cement ratios, as expected, due to increasing bleeding of those samples. When samples were rotated, negligible early age expansion was observed. Thus, bleed water reabsorption is shown to be the primary mechanism causing initial expansion in sealed autogenous deformation samples. Thermal dilation and ettringite growth appear to have a minimal influence on the observed expansion. Rotating the samples during setting eliminates the potential for bleed water reabsorption and is recommended for all autogenous deformation testing.     

Comparison between surface and bulk hydrophobic treatment against corrosion of galvanized reinforcing steel in concrete

The effectiveness of bulk hydrophobic treatment against corrosion of galvanized steel reinforcement in concrete specimens with w/c = 0.45 and w/c = 0.75 was compared with that of surface treatment, even in the presence of cracks 0.5 and 1 mm wide in the concrete cover. In this case surface hydrophobic treatments were applied both before and after cracking as a preventive and a restorative method against reinforced concrete deterioration, respectively. The obtained results in terms of water absorption, electrochemical measurements, chlorides penetration, and visual observations carried out on reinforced concrete specimens during the exposure to wet–dry cycles in 10% NaCl solution showed that bulk hydrophobization is the most effective treatment in improving the corrosion resistance of galvanized steel reinforcements in concrete also in the presence of cracks. Surface hydrophobization is very effective just in the first few exposure cycles to the aggressive environment and when used as a restorative method which is able to cancel the deleterious effect of cracks only 0.5 mm wide.     

Effect of plasma treatment of polymeric tape carriers on wetting behaviour of aqueous ceramic tape casting slurry

Due to environmental and health aspects, aqueous ceramic slurries are preferred to traditional organic solvent systems in tape casting. An important obstacle associated with the high surface energy of water is poor wetting of aqueous ceramic slurries on polymeric tape carriers. Therefore, we measured the contact angles of an aqueous epoxy-based ceramic slurry on polyethylene terephtalate (PET), polypropylene (PP), polymethyl methacrylate (PMMA), and aluminium-coated polyethylene terephtalate (PET-Al) films and investigated approaches to improving their wetting. We evaluated the effect of plasma treatment of the tape carrier surface on the wetting behaviour and compared it with the effect of adding non-ionic amphiphilic surfactants to the ceramic slurry. The treatment of the tape carrier surface by low-temperature plasma substantially improved the wetting behaviour of aqueous ceramic slurry. The lowest contact angle of 31° was obtained on the PET film. Although the addition of non-ionic surfactants improved both the wetting behaviour of the slurry and the detachment of the polymeric carrier from the ceramic tape even better than the plasma treatment of the carrier surface did, the plasma-treated carriers still present a useful alternative to the surfactants. In the case of the plasma-treated PET carrier the surfactants could be fully eliminated and potential drawbacks related to the use of surfactants could be prevented.