虫胶包覆硝酸铵工艺研究

利用物理化学包覆的相分离原理,以虫胶为包覆剂、正丁醇为溶剂、正己烷为沉淀剂包覆硝酸铵,降低其吸湿性,用硝酸铵的吸湿率表征包覆效果。对正丁醇与正己烷配比、混合溶剂用量、沉淀剂滴加速度、虫胶用量等影响吸湿性的因素进行了研究。结果表明,正丁醇与正己烷体积比为1:3,混合溶剂与硝酸按配比为5.0 mL/g,沉淀剂滴加速度为6s/滴,虫胶用量与粒径成反比。在较佳包覆条件下,虫胶包覆硝酸铵可使吸湿率下降55%。     

溶剂法回收聚苯乙烯泡沫塑料工艺的研究

研究了溶剂法回收聚苯乙烯泡沫塑料(EPS)的操作方法和优化工艺条件.通过单因素实验考察了以甲苯/二氯乙烷为混合溶剂溶解EPS,然后通过沉淀法制备聚苯乙烯(PS)颗粒.结果表明,优化的工艺条件为甲苯/二氯乙烷混合溶剂中甲苯的体积分数为85％,溶解温度为50℃,溶解时间为30 min,以体积分数为95％乙醇为沉淀剂.PS回收率可达94％以上.     

用改性直链烷烃改善硝酸铵的吸湿性

以改性直链烷烃为包覆材料,用熔融包覆方法对硝酸铵(AN)的表面进行包覆。用红外分析仪、扫描电子显微镜、接触角测定、吸湿性对其结构和表面性质进行了表征。结果表明,包覆AN颗粒的表面缝隙显著减少;改性直链烷烃质量分数为0.5%时可满足成膜要求,质量分数2.5%时包覆均匀且完整,包覆AN颗粒的表面张力从9.04×10-2 N/m降到1.883×10-2 N/m,24h后吸湿量下降了88%,包覆效果较好。     

微胶囊技术在硝酸铵改性中的应用

提出了用聚苯乙烯包覆硝酸铵制备硝酸铵微胶囊的新方法 ,采用电子能谱仪研究了包覆效果 ,并对包覆前后的硝酸铵进行吸湿性测量 ,分析了改性后的硝酸铵吸湿结块性降低的原因和机理。     

包覆硝酸铵发射药吸湿性和安定性研究

为研究包覆硝酸铵(AN)发射药的吸湿问题,用硝化棉(NC)对不同AN含量的AN发射药进行了不同层数的包覆,然后对未包覆和包覆试样进行了平衡干燥器法吸湿测试和真空安定性试验。结果表明:在温度为30℃、相对湿度为90%的条件下,AN发射药的吸湿量随着AN含量的增加而增加;包覆层有效抑制了吸湿性,提高了AN发射药的安定性。     

表面活性剂改善硝酸铵吸湿性研究

用表面活性剂对硝酸铵进行表面改性处理 ,测定了改性硝酸铵的吸湿性。结果表明 ,表面活性剂能有效地降低硝酸铵的吸湿率 ,改性硝酸铵的吸湿率比普通硝酸铵降低约 30 % ,并得出了较为理想的硝酸铵改性表面活性剂。     

PS/POE/功能化石墨烯纳米复合材料的制备和性能研究

利用马来酸酐接枝聚烯烃(POE-g-MAH)弹性体为增韧剂,乙二胺功能化石墨烯(G-EDA)为纳米填料,经熔融共混法制备了聚苯乙烯(PS)/POE-g-MAH/G-EDA纳米复合材料,并对填料和所得纳米复合材料的结构和性能进行了全面的表征。红外光谱(FTIR)、扫描电子显微镜(SEM)、力学性能、维卡软化温度和熔融指数测试表明:乙二胺(EDA)已成功接枝于石墨烯的表面上;共混过程中,POE-g-MAH的酐基与EDA的氨基发生反应改善了共混体系的界面相容性;G-EDA在熔融共混过程中均匀分散于PS基体中;随着G-EDA含量的增加,复合材料的拉伸强度先增大后降低,当G-EDA质量分数为0.5%时,复合材料的拉伸强度达到最大值,比PS/POE-g-MAH提高了12.3%,比纯PS提高了15.5%;而当G-EDA质量分数为0.75%时,复合材料的冲击强度达到最大值,比PS/POE-g-MAH提高了22%,比纯PS提高了22.4%。因此,当G-EDA的质量分数在0.5%~0.75%之间时,复合材料的综合力学性能最好。G-EDA的加入,纳米复合材料的邵氏A硬度、维卡软化温度等都逐渐增大,而熔融指数逐渐降低。     

Purification of cholesterol from lanolin by column chromatography

采用柱层析法分离羊毛脂中的胆固醇,以胆固醇与杂质羊毛甾醇的分离度为判定依据来筛选吸附剂及优化层析工艺,同时对吸附剂进行了再生考察。实验表明,当以200～300目粗孔硅胶为吸附剂、丙酮/正己烷混合溶剂（体积比4∶96）为流动相、35 ℃下胆固醇上载量为2.4%（质量分数）时,胆固醇的分离效果较好,所得胆固醇含量可达84.36%,收率为85.67%。另外选用丙酮/正己烷混合溶剂（体积比50∶50）对吸附剂进行再生处理,硅胶经7次使用再生循环,分离效果未降低。     

用于SLS的表面Tg可控PS球形颗粒的制备

以外形不规则的聚苯乙烯粉末颗粒为原料,通过诱导成球法制备了聚苯乙烯(PS)微球。其粒径16.5μm,可供选择性激光烧结使用。再以上述聚苯乙烯(PS)微球为原料,通过丙烯酸乙酯与微球中残存的苯乙烯共聚,得到表面玻璃化温度(Tg)可控的聚苯乙烯微球。实验结果表明,以质量分数0.08%的过硫酸铵为引发剂,反应温度80℃,丙烯酸乙酯与苯乙烯体积比9:10,当共聚反应时间为3 h时,产物的玻璃化温度可降至最低值74.8℃。     

石墨烯/聚苯乙烯导热复合材料的制备

以偶氮二异丁脒盐酸盐(AIBA)为引发剂,采用分散聚合的方法合成了表面带正电荷、粒径在600 nm的聚苯乙烯(PS)微球,通过自组装将氧化石墨烯包覆于PS微球表面,用化学还原法将氧化石墨烯还原为石墨烯,制备了石墨烯包覆聚苯乙烯微球的复合分散体和压制成型制备的石墨烯/聚苯乙烯导热复合材料。结果表明,随着初始氧化石墨烯投料量的增大,制备得到的石墨烯/聚苯乙烯复合材料的导热系数逐渐增大,投料量为20%时,复合材料的导热系数达到0.41 W/(m·K),相比纯PS本体提高了116%。     

Characterization of iron(III) oxide nanoparticles prepared by using ammonium acetate as precipitating agent

The effect of precipitating agent on the preparation of iron(III) oxide particles was investigated. Iron(III) oxide particles were prepared by precipitation of aqueous ferric nitrate solution by using ammonium acetate and ammonium hydroxide as precipitating agents. Particle size, shape, chemical composition, crystalline formation rate, crystallinity and magnetic property were measured for Fe₂O₃ particles obtained by precipitating with ammonium acetate, and compared with those of particles formed by using ammonium hydroxide. TGA, DTA, IR, XRD, TEM and VSM were used to characterize the particles. The nanoparticles synthesized with ammonium acetate showed a narrow size distribution, spherical shape, fast crystalline formation rate, high crystallinity and complete hysteresis loop. The better properties of particles formed by using ammonium acetate were originated from the chelating effect of carboxylate ions and higher crystallinity than those synthesized with ammonium hydroxide.     

聚(N-乙烯基异丁酰胺)接枝聚苯乙烯微球的合成研究

合成了数均相对分子质量为 35 0 0和 6 30 0的两种聚 (N 乙烯基异丁酰胺 ) (PNVIBA)大分子单体 ,并以此大分子单体与苯乙烯 (St)在V(乙醇 )∶V(水 ) =7∶3的混合溶剂中进行自由基分散共聚 ,得到了稳定分散的PNVIBA接枝聚苯乙烯 (PSt)高分子微球。研究发现微粒的粒径随聚合体系中大分子单体相对分子质量和质量浓度的增加而减小 ,并发现当混合溶剂中水的体积分数增加到 ρ(水 ) =35 %时 ,微球的形态发生明显变化。     

11-溴代十一酸的合成

以10-十一烯酸和溴化氢为原料合成11-溴代十一酸,考察了引发剂、溶剂、反应温度、后处理方法、熟化时间等因素对反应和产品的影响。结果表明,较佳的工艺条件为:以n(苯)∶n(甲苯)=1∶0.83的苯/甲苯混合物作为溶剂,m(10-溴代十一酸)∶m(溶剂)=1∶4,引发剂为过氧化苯甲酰,反应温度为5~20℃,熟化时间为6 h。在此工艺条件下,11-溴代十一酸的收率可达91%。     

氧化铝负载Co-Mo双金属氧化物的共沉淀制备

采用双溶剂体系(硝酸铝和硝酸钴的乙醇溶液与钼酸铵的碳酸铵水溶液)共沉淀制备了氧化铝负载Co-Mo双金属氧化物。研究了双溶剂体系中乙醇和水的体积比对共沉淀的影响,考察了老化时间对氧化物结构参数的影响,研究了焙烧温度对氧化物还原性能的影响。结果表明:乙醇和水体积比对钼酸根离子的沉淀有重要影响,为了保证钼酸根离子的完全沉淀,乙醇的体积要随着MoO3负载量的增加而提高;随着老化时间的增加,氧化物的比表面积先增加后下降,6 h老化的样品具有最大的比表面积;低温焙烧制得的氧化物较容易还原。     

Moisture Proofing of Spray Dried Particles Comprising Ammonium Nitrate/Potassium Nitrate/Polymer

The aim of this study was to fabricate moisture‐proof, phase‐stabilized, ammonium nitrate/potassium nitrate (AN/PN) particles, with a polymer used as the moisture‐proofing agent. The particles were prepared with a spray drying technique. Water solutions (or water dispersions) containing AN/PN and one of five different types of polymer were spray‐dried, which produced white powders with particle diameters of approximately 20–40 μm. Scanning electron microscopy and energy‐dispersive X‐ray spectroscopy indicated that each component was homogeneously distributed throughout the particles. The particles exhibited little aggregation compared to the reagent AN, even when left for 7 d or more. In addition, the moisture absorption of the particles at less than 40 % relative humidity (RH) was lower than that of the polymer‐free particles. Even under high‐moisture conditions (83 % RH), the particles did not deliquesce immediately, and they retained their original shape for 30–60 min, whereas the polymer‐free particles were transformed into droplets within 5 min.     

烷基多苷硫酸酯铵盐的合成及性能

以烷基多苷为原料,用氨磺酸为硫酸化试剂,合成了烷基多苷硫酸氨。通过正交实验及优化实验确定了反应温度、反应时间、原料配比、溶剂、催化剂种类、催化剂用量等因素对产率的影响。得出了最佳合成条件为:以V(甲苯)∶V(吡啶)=7∶3为溶剂,以尿素为催化剂,m(APG)∶m(NH2SO3H)=1∶1.10,反应温度105℃;反应时间3.5 h。该条件下的烷基多苷硫酸铵收率达到86.6%。产品的水溶性、起泡性、增溶性较烷基多苷显著提高。     

PVC制品中增塑剂DEHA的快速检测方法

分别以异丙醇、正己烷、异辛烷为主萃取剂,以二氯甲烷为辅助萃取剂,考察了主萃取剂种类、主辅萃取剂体积比、萃取时间等因素对聚氯乙烯(PVC)制品中己二酸二(2–乙基己酯)(DEHA)萃取率的影响,并与传统萃取方法进行了比较。结果表明:以正己烷为主萃取剂,在正己烷/二氯甲烷的体积比为5:1时,PVC样品中DEHA的相对提取率最高,回收率和相对标准偏差分别为85.3%～94.6%、1.02%～2.74%;与传统提取方法相比,该提取方法简便、快速,提取效率高。     

Stabilization of ammonium azide particles through its microencapsulation with some organic coating agents

This work is devoted to reduce spontaneous sublimation of ammonium azide at ambient and elevated temperatures by means of two microencapsulation techniques involving solvent/non-solvent and solvent evaporation methods in which stearic acid, Viton and nitrocellulose (NC) have been tested as coating agents. Scanning electron microscopy (SEM) was employed to examine the coating morphology. The thermal behavior of pure and coated ammonium azide samples have been studied by using simultaneous thermogravimetery-differential thermal analysis (TG-DTA) and differential scanning calorimetry (DSC). The results showed that ammonium azide microparticle could be effectively coated with nitrocellulose through a solvent/non-solvent experiment in which the coating quality depends on some experimental factors such as coating agent to NH₄N₃ weight ratio and volume and addition time of non-solvent. The effect of these factors on coating quality and thermal properties of NH₄N₃ has been revealed by results of SEM and thermal experiments. The most stabilized coated ammonium azide was achieved by using 4.5% (w/w) of NC as stabilizer, and by addition of 30 ml n-hexane as non-solvent within 75 min, where the maximum sublimation temperature increases about 30 °C with respect to uncoated sample and reaches to 145.5 °C. The influence of the heating rate (5, 10, 15 and 20 °C/min) on the DSC behavior of the pure and coated ammonium azide particles at the optimum condition was verified, whereas sublimation temperature of the NH₄N₃ was increased as the heating rate was increased. Also, the kinetic parameters such as the activation energy and frequency factor of the sublimation processes for pure and coated ammonium azide were obtained from the DSC data by non-isothermal methods proposed by Kissinger and Ozawa. The results showed that, activation energy for sublimation of completely coated NH₄N₃ particles is considerably higher than (nearly 1.5 times) that of the pure one. Also, the first order rate constant of sublimation of completely coated sample is noticeably lower than that of pure sample (). The kinetic results led us to conclude that the applied microencapsulation technique caused efficient stabilization of volatile NH₄N_3.     

化学沉淀法处理高浓度硫酸铵废水的研究

采用化学沉淀法处理了高浓度硫酸铵废水,以Ca(OH)2为沉淀剂除去废水中的硫酸根离子,以MgCl2.6H2O和Na2HPO4.12H2O为沉淀剂除去铵根离子,重点研究了不同工艺条件对铵根离子去除效果的影响。实验结果表明,反应体系的pH=9.5,n(Mg2+)∶n(PO34-)∶n(NH4+)=1.05∶1∶1时,氨氮的去除率达到最佳,在不同的磷酸盐作为沉淀剂的对比中,最经济的沉淀剂为Na2HPO4.12H2O。     

Low temperature complete combustion of dilute toluene and methyl ethyl ketone over Mn‐doped ZrO2 (cubic) catalysts

Combustion of dilute toluene and methyl ethyl ketone over Mn‐doped ZrO₂ catalysts prepared using different precipitating agents, such as tetra‐alkyl ammonium hydroxides and NH₄OH, having Mn/Zr ratios from 0.05 to 0.67, and calcined at different temperatures has been thoroughly investigated. The Mn‐doped ZrO₂ catalyst shows high toluene or methyl ethyl ketone combustion activity, particularly when its ZrO₂ is in cubic form, when its Mn/Zr ratio is close to 0.2, and when it is prepared using tetra‐methyl ammonium hydroxide as a precipitating agent and calcined at 773 K. Copyright © 2005 Society of Chemical Industry