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1.
采用十二氟庚醇通过醚化-闭环的两步法合成了十二氟庚基缩水甘油醚,考察了反应时间以及催化剂用量、加碱量对产物收率的影响,通过FTIR及13C-NMR表征了合成产物.结果表明,低温长时间的醚化反应有利于提高产物收率,碱用量的摩尔份敷为醇的1.2倍时,产物有较高的收率,达到86%.  相似文献   

2.
以马铃薯淀粉为原料,乙醇为溶剂,用溶剂法制备高取代度羧甲基淀粉。应用正交设计法研究了影响淀粉羧甲基化反应的各种因素,确定了制取高取代度(DS>1.3)羧甲基淀粉制的反应条件是:醚化温度50℃,醚化时间120min,原料最佳摩尔比:n(淀粉):n(氯乙酸)=1:3,n(氢氧化钠):n(氯乙酸)=2.5:1。  相似文献   

3.
采用乙醇和水的混合溶液为介质,用锌粉还原2,5-二甲氧基-4-氯硝基苯制备中间体2,5-二甲氧基-4-氯苯胺.最佳反应条件如下:2,5-二甲氧基-4-氯硝基苯与锌粉的摩尔比为1:4;2,5-二甲氧基-4-氯硝基苯与冰醋酸的摩尔比为1:0.1;混合溶剂中乙醇和水的体积比为3:2;以氯化铵为电解质,2,5-二甲氧基-4-氯硝基苯与氯化铵的摩尔比为1:0.06.在此反应条件下得到的还原产物收率可达91.45%、熔点为116~117℃、胺基值为97.33%.  相似文献   

4.
以3,3’,5,5’-四甲基联苯二酚(TMBP)和2-氯乙醇为原料两步法合成了3,3’,5,5’-四甲基联苯-4,4’-二羟乙基醚。探讨了反应物物质的量比、碱用量、催化剂及反应温度对转化率的影响。结果表明,在n(TMBP)∶n(NaOH)∶n(2-氯乙醇)=1∶3.0∶2.5,反应时间为10h,反应温度为110℃条件下,总转化率达95.9%,纯度达99.1%。并用红外、质谱以及核磁等方法对产物结构进行了表征。  相似文献   

5.
玉米淀粉接枝丙烯腈制备高吸水性树脂   总被引:10,自引:0,他引:10  
用硝酸铈铵作引发剂,通过水溶液聚合法制得了玉米淀粉接枝丙烯腈高吸水性树脂.研究了引发剂用量、碱用量、反应温度以及反应时间等对吸水率的影响.得到的最佳反应条件为:引发剂与丙烯腈的摩尔比为4.5×10-3,碱与丙烯腈的摩尔比为1.32,反应温度25℃,反应时间3h.制得的高吸水性树脂在室温下30min每克吸蒸馏水和自来水分别约为其自身质量的1000倍和200g倍.  相似文献   

6.
以1-烯丙基-3-甲基咪唑乙酸鎓盐([AMIM]Ac)为反应介质,3-氯-2-羟丙基三甲基氯化铵(CTA)、氯乙酸钠、环氧丙烷为改性剂,创新性的一步制备了阳离子羧甲基羟丙基瓜尔胶(CCMHPG)。研究了3种改性剂用量、碱用量、反应温度、反应时间对产物取代度和粘度的影响,确定了最佳制备条件。经测定,反应产物的阳离子取代度为0.24,羧甲基取代度为0.41,羟丙基取代度为0.36,产物水溶性较好,1%水溶液粘度达1 072 mPa·s。CCMHPG的红外谱图和~1H NMR谱表明季铵基团、羧甲基和羟丙基均已成功接枝到瓜尔胶分子上,电镜照片显示颗粒表面出现了褶皱及鳞片状裂纹。将CCMHPG/PAC二元微粒体系用于脱墨废纸浆,PAC添加量为0.8%、CCMHPG添加量为0.04%时的留着率为94.3%,打浆度为43°SR。  相似文献   

7.
采用无毒高活性的氯甲基辛基醚(CMOE)作为氯甲基化试剂,对聚醚酰亚胺(PEI)进行氯甲基化。考察了各种因素对氯甲基化反应的影响规律,优化了反应条件。溶剂用量、催化剂用量、反应温度等因素对反应有显著影响,最佳反应条件为:PEI∶CMOE∶C2H4Cl2∶ZnCl2=2.0 g∶4 mL∶50 mL∶1.0 g,反应温度60℃。在该条件下控制反应时间,成功合成了一系列不同取代度的氯甲基化PEI,取代度为21%~110%。  相似文献   

8.
高取代度阳离子淀粉的制备   总被引:7,自引:0,他引:7  
以玉米淀粉及 3 氯 2 羟丙基三甲基氯化铵 (CHPTMA)为原料 ,运用改进常温干法—预干燥干法制备了高取代度季铵型阳离子淀粉。考察了水的质量分数、氢氧化钠用量醚化剂用量、反应温度和反应时间对取代度和反应效率的影响 ,确定了反应配方和反应条件 ,并对产物进行了性能测定。结果表明 ,产物具有良好的分散性和溶解性 ,具有一定的工业应用价值。  相似文献   

9.
新型磷酸单酯PVA聚阴离子电解质膜材料的合成及性能   总被引:4,自引:0,他引:4  
采用磷酸和聚乙烯醇(PVA)在尿素存在下发生单酯化反应,合成了一种新型聚阴离子电解质磷酸单酯PVA(PMPVA).考察了反应时间、反应温度、磷酸用量、尿素用量对取代度的影响.利用傅立叶变换红外光谱(FT-IR)、扫描电镜(SEM)对PMPVA的结构进行了表征,PMPVA的导电和耐热性随取代度的增大而提高.将PMPVA及PMPVA/季铵化聚阳离子PVA(QAPVA)复合物制备的渗透汽化复合膜,用于乙醇/水体系进行渗透汽化分离.PMPVA对水的分离因子α为637,渗透通量J为3903g/(m2·h);PMPVA/QAPVA复合物膜对水的分离因子α为1890、渗透通量J为520g/(m2·h).  相似文献   

10.
刘云飞  陈煜  史亮  姚维尚  陈洋 《材料工程》2012,(7):20-23,28
通过将月桂胺(DA)与环氧氯丙烷发生开环反应所得的氯醇分子进一步在KOH-H2O溶液中进行闭环反应,制备得到具有良好反应活性的表面活性剂中间体N,N-二-2,3-环氧丙基月桂胺(EDA)。采用FTIR,1 H-NMR,13 C-NMR等表征手段对产物的结构进行了表征。研究了闭环反应温度、碱的用量、环氧氯丙烷的用量、碱的种类和闭环反应时间等反应条件对产物中EDA含量的影响,在此基础上确定了N,N-二-2,3-环氧丙基月桂胺的最优化反应条件。  相似文献   

11.
Alkali activation of a slag at ambient and elevated temperatures   总被引:3,自引:0,他引:3  
Strength development of alkali activated slag (AAS) mortars, activated using alkali hydroxide and sodium silicate, was investigated at room and elevated temperatures. Heat evolution at room temperature was measured using isothermal calorimetry. Important differences were observed between critical activation parameters. Heat cured specimens gain strength rapidly, humid oven conditions being favorable, but given sufficient time room temperature curing yields comparable strengths. Both activators are needed for high strength at room temperature, NaOH solution is more critical and its concentration greatly influences strength. At 80 °C however, sodium silicate is essential and even sufficient. KOH is more effective than NaOH at 80 °C, but not at room temperature. Lower water-to-slag ratios give higher strength at early ages. AAS hydration evolves less heat than Portland cement hydration. Time to significant strength gain of mixtures can be predicted using their time and heat evolution at setting. Twenty eight-day strength of AAS mortars is roughly related to total evolved heat and increases nearly linearly with the amount of NaOH activator for fixed water glass content.  相似文献   

12.
The effect of alkali treatment on the wetting ability and coherence of sisal-epoxy composites has been examined. Treatment of sisal fibre in a 0.5N solution of sodium hydroxide, resulted into more rigid composites with lower porosity and hence higher density. The treatment has been shown to improve the adhesion characteristics, due to improved work of adhesion because it increases the surface tension and surface roughness. The resulting composites showed improvements in the compressive strength and water resistance. It has been suggested that the removal of intracrystalline and intercrystalline lignin and other surface waxy substances by the alkali substantially increases the possibility for mechanical interlocking and chemical bonding. The alkali treatment is simple and is recommended to precede other sophisticated surface modification treatments on plant fibres similar to sisal fibre.  相似文献   

13.
《Materials Letters》2005,59(14-15):1871-1875
Submicron- to nanometer-sized particles of single phase lead titanate have been prepared in stoichiometric proportion under mild hydrothermal conditions employing either potassium or sodium hydroxides as alkali mineralizers. In conjunction with reaction temperature and time, these variables played a crucial role in determining the habit of crystalline particles. The feasibility of using sodium hydroxide as an alternative for potassium hydroxide in the preparation of nanopowders of lead titanate was demonstrated. The influence of the preparative conditions, e.g. reaction temperature and time, on phase formation, morphology, the habit of crystalline particles, size and size distribution, was investigated.  相似文献   

14.
研究了AgInSbTe相变薄膜作为一种新的热刻蚀材料的腐蚀特性。采用射频磁控溅射的方法在室温下制备了非晶态AgInSbTe薄膜,经真空加热退火晶化.以氢氧化钠溶液作为腐蚀剂,研究了退火温度、腐蚀剂浓度、腐蚀时间对晶态、非晶态AgInSbTe薄膜腐蚀特性的影响.结果表明:以非晶态形式存在的沉积态AgInSbTe薄膜在0.001 mol/L氢氧化钠溶液中腐蚀速度小于0.04 nm/min,退火晶化后,薄膜的腐蚀速度大幅度提高,晶态和非晶态薄膜的腐蚀选择比随退火温度的升高而增大.当腐蚀时间为20 min时,经300℃真空退火的晶态AgInSbTe薄膜比相应非晶态的腐蚀速度高45倍以上.腐蚀后薄膜表面质量良好(粗糙度<1 nm,10μm×10μm区域).并对AgInSbTe相变薄膜的腐蚀机理进行了讨论.  相似文献   

15.
Modified softwood sawdust as adsorbent of heavy metal ions from water   总被引:2,自引:0,他引:2  
The sawdust of deciduous softwood-poplar, and coniferous softwood-fir, have been found to possess some adsorption capacities for heavy metal ions. Their adsorption capacities can be increased by previous treatment with a sodium hydroxide solution. Adsorption capacities of alkali modified adsorbents were higher than for unmodified ones from 2.5 to 5 times for copper ions, and about 15 times for zinc ions. Also, for modification can be used solution of sodium carbonate, but that alkaline solution is less efficient than sodium hydroxide solution. The 1% sodium hydroxide solution is suggested for modification of softwood sawdust. It was established that the ion exchange is not only adsorption mechanism, than microprecipitation of metal-hydroxide in the pore liquid was happened, too. At the same time, the leaching of organic matters from modified softwood sawdust were less than from unmodified ones for about 7% for poplar and 23% for fir.  相似文献   

16.
Coconut fiber-reinforced wheat gluten (WG) biocomposites were fabricated. The coconut fibers (CCFs) were chemically modified by either sodium hydroxide or silane treatment, as well as following the alkali surface treatment with a silane treatment. (3-triethoxysilylpropyl)-t-butylcarbamate (carbamate silane), which is a masked isocyanate functional silane, was used for the first time to improve interfacial adhesion between WG and natural fibers. X-ray photoelectron spectroscopy (XPS) and gas chromatography/mass spectroscopy (GC/MS) analyses were employed to prove the presence of the silane on silane-treated coconut fiber (SCCF) and alkali-followed by silane-treated fiber (ASCCF). It was found that ASCCF has more silane content on the fiber surface than SCCF. The mechanical properties of composites with 15 mass% fiber loading were assessed by three-point bending tests. Moreover, scanning electron microscopy (SEM) was used to investigate fracture surface characteristics of composites. The WG/ASCCF composite provided an 80% increase in strength, and showed superior fiber–matrix interfacial adhesion.  相似文献   

17.
The zeolite A was synthesized from the mechanically activated solid mixtures of metakaolin, sodium hydroxide and aluminum oxide. The stages of both thermal treatment and hydrothermal crystallization were investigated and optimized. The size of zeolite A particle was directly measured by scanning electron microscopy as well as calculated using the X-ray diffraction spectroscopy data. The thermal stability of the zeolite A was studied by the differential thermal analysis. It was shown that the optimum thermal treatment temperature providing the zeolite A yield of about 65 wt% and the particle size in the range of 0.2–0.3 μm is 600 °C. The furthermore increase in the thermal treatment temperature results in decreasing amount of zeolite A crystalline phase as well as in the formation of nepheline. It was also found that the optimum NaOH concentration providing the zeolite A yield of about 90 wt % and the particle size more than 0.7 μm after the hydrothermal crystallization stage is 2–4 mol/l. The higher alkali concentrations result decreasing amount of the zeolite A phase and cause the recrystallization into the sodalite. The use of KOH in the hydrothermal crystallization stage allows one to obtain the potassium-containing zeolite A by direct synthesis.  相似文献   

18.
In this study, the physical and mechanical behaviors of geopolymers prepared by using different amounts of silica fume and calcium hydroxide as binding materials, acidic pumice as fine aggregate and waste aluminium particles as air-entraining agent were investigated. Test results showed that binder types, amount of binders and alkali activator (sodium hydroxide) significantly affected the physical and mechanical behavior of geopolymer specimens. Bulk density, compressive and flexural strength decreased with the higher alkali activator content. Addition of waste aluminium particles led to decrease in bulk density and strength due to the some extent of entrained air. In the case of same alkali activator content, compressive and flexural strength increased with increase in silica fume and calcium hydroxide up to a certain level.  相似文献   

19.
Kenaf fibre reinforced polypropylene composites were manufactured by compression moulding. The kenaf fibre was considered in three forms; untreated, treated with sodium hydroxide solution and treated with sodium hydroxide solution followed by three-aminopropyltriethoxysilane. The effects of these chemical treatments on the tensile and flexural properties of the composites were investigated. Mechanical test results show that alkali treatment followed by three-aminopropyltriethoxysilane treatment (alkali–silane treatment) significantly improves the tensile and flexural properties of short fibre non-woven kenaf polypropylene composites. In particular, the specific tensile and flexural strengths of alkali–silane treated kenaf composites with 30% fibre mass fraction are, respectively, only 4% and 11% lower than those of composites made using glass fibre. Scanning electron microscopy examination shows that the improvements in the tensile and flexural properties resulting from alkali–silane treatment can be attributed to better bonding between the fibres and matrix.  相似文献   

20.
Basalt and glass fibers were treated with sodium hydroxide and hydrochloric acid solutions respectively for different periods of time. Both the mass loss ratio and the strength maintenance ratio of the fibers were examined after the treatment. The morphologies of the fiber surfaces were characterized using scanning electron microscopy and their compositions were analyzed using energy dispersive X-ray spectroscopy. For the basalt fibers, the acid resistance was much better than the alkali resistance. Nevertheless, for the glass fibers, the acid resistance was nearly the same as the alkali resistance. Based on the experimental results, possible corrosion mechanisms are addressed.  相似文献   

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