脲醛树脂包覆聚硫密封剂微胶囊的制备和性能EI北大核心CSCD

以脲醛树脂为壁材、聚硫密封剂为芯材,采用原位聚合制备出聚硫密封剂微胶囊,并使用红外光谱、扫描电镜等手段表征了微胶囊的结构和形貌。为了研究微胶囊化过程对密封剂固化胶膜力学性能的影响,将聚硫密封剂微胶囊与一定比例的硫化剂均匀混合分别制备成标准螺母试件或胶膜试片,依据相关标准系统考察了聚硫密封剂包覆前后破坏力矩、拆卸力矩和拉伸性能以及硬度的变化。结果表明,基于脲醛原位聚合可制备出形貌规则、粒径均一、表面相对粗糙、包覆膜致密的聚硫密封剂微胶囊,与未包覆密封剂相比包覆后聚硫密封剂胶膜的力学性能大幅度提高。     

微胶囊铜粉对铜复合浆料性能的影响

为提高铜浆料的导电性,利用微胶囊技术在铜粉表面包覆液体石蜡,增强铜粉的抗氧化性,并添加少量导电性能优异的碳纳米管作为导电增强相,制备碳纳米管-铜复合浆料.利用四探针测试仪、扫描电镜等测试方法研究了液体石蜡含量对包覆铜粉性能的影响以及微胶囊铜粉作为主导电相,碳纳米管作为导电增强相对浆料导电性能的影响.结果表明:液体石蜡包覆含量为4 wt%的微胶囊铜粉具有良好的导电性和抗氧化性,其电导率为44.32%IACS;微胶囊铜粉作为碳纳米管-铜浆料的主导电相,制备浆料膜层电阻率为22.59 mΩ·cm,相比于未包覆的铜粉为主导电相制备的浆料膜层电阻率降低了12.44%;碳纳米管作为导电增强相所制备的浆料相比于纯铜浆料,电阻率降低31.74%.     

石蜡微胶囊的制备与表征

利用一步原位聚合法,制备了以脲醛树脂为壁材的石蜡微胶囊.采用扫描电子显微镜、激光共聚焦显微镜和红外光谱分析技术表征了微胶囊的表面形貌和结构组成.使用差示扫描量热仪(DSC)考察了石蜡微胶囊的热性能.结果表明,石蜡被脲醛树脂成功包覆;石蜡微胶囊呈圆球状、包覆完整、分散均匀,粒径在100μm左右;表面粗糙,壁厚约为4μm,...     

反相乳液聚合法制备负载缓蚀剂的纳米SiO2粒子

采用反向乳液聚合方法,以环己烷作为连续相,缓蚀剂钨酸钠的水溶液作为分散相,Span80/OP-10作为复合乳化剂,四乙氧基硅烷(TEOS)作为单体,氨水作为催化剂进行反向乳液聚合,制备了包覆缓蚀剂钨酸钠的纳米SiO2粒子。采用动态光散射(DLS)及扫描电镜(SEM)表征了微胶囊粒子的粒径及分布。结合扫描电镜-能谱法(SEM-EDS)和扫描透射电镜-能谱法(STEM-EDS)表征了微胶囊表面和内部的元素组成。     

相变储热微胶囊的研制

采用原位聚合法用三聚氰胺甲醛树脂包覆一种相变点为24C相变材料A，制得相变储热微胶囊。利用激光粒径分布仪、SEM、DSC和TG分别研究了微胶囊的粒径分布、表面形态及热性能的影响因素．实验结果表明．所得微胶囊粒径分布均匀，表面光洁，具有很好的致密性和一定的强度。其中当乳化速度大于3500r／min、乳化时间为5min、壁材滴加速度小于0．5mL／min且系统调节荆为芯材的30％～40％时，微胶囊的粒径分布集中DSC显示微胶囊包覆相变材料不影响其相变点，相变储热明显，此种微胶囊中由于含有相变材料，而相变材料在发生相变时具有调温功能，应用于室内墙体材料中，可使墙体材料具有自调温作用．     

石墨烯对微胶囊铜电子浆料导电性能的影响

以丙烯酸树脂作为微胶囊壁材溶液包覆铜粉,石墨烯作为导电增强相,制备了石墨烯-微胶囊铜复合电子浆料。利用金属电导率测试仪、X射线衍射仪、四探针测试仪和扫描电子显微镜分别研究了微胶囊铜粉的电导率及其抗氧化性能,分析了石墨烯对石墨烯-微胶囊铜复合电子浆料导电性能的影响。结果表明:微胶囊铜粉与未包覆铜粉相比,电导率明显提高,且当增重率为4%(wt,质量分数)时,电导率达到最大值41.30%IACS,且不存在CuO或Cu_2O;石墨烯的加入对铜复合电子浆料的导电性能有增强作用,但不同类型石墨烯的增强效果不同,导电性能主要与石墨烯的片径、厚度、纯度相关,其中片径约5μm,厚度为1～5nm的石墨烯纳米片作为导电增强相制备的铜复合电子浆料导电性能最优。     

脲醛树脂包覆α-烯烃减阻聚合物微胶囊的制备与性能

在阐述了尿素与甲醛聚合制备微胶囊壁材反应原理的基础上,以尿素与甲醛为壁材原料,运用原位聚合法研究了包覆α-烯烃减阻聚合物微胶囊的制备工艺,利用粒度分析仪、红外光谱仪、同步热分析仪和模拟环道油品减阻率评价系统等,对微胶囊制备、储存稳定和溶解性能进行了研究。结果表明:在酸性条件下,以尿素与甲醛为微胶囊化原料,采用原位聚合法制备包覆石油减阻聚合物颗粒的微胶囊,制备工艺具有反应温和、缩聚反应可控,可有效缩短反应时间等特点。制备的脲醛树脂包覆α-烯烃减阻聚合物微胶囊粒度分布主要集中在200μm处,微胶囊可长期保持较好的圆润小球状态,具有良好的热力学稳定性。静压耐压储存稳定性和热力学稳定性研究结果表明,微胶囊可完全满足储存稳定性的要求。脲醛树脂包覆α-烯烃减阻聚合物微胶囊在输送油品中具有优良的溶解性,与未包覆的减阻聚合物颗粒减阻率接近,微胶囊溶解后减阻率较未包覆时略有延迟,但减阻率峰值依然与未包覆时相当,可满足现场工程实际应用。     

疏水阻燃微胶囊的制备及其在牛皮纸中的应用

目的为改善聚磷酸铵的阻燃性及热稳定性,降低其对纸材物理性能的影响,制备一种疏水阻燃微胶囊。方法以聚磷酸铵、季戊四醇、铜改性4A分子筛为芯材,以海藻酸钠和氯化钙为原料制备壁材,在外壳包覆SiO₂微粒,并制备阻燃牛皮纸。采用极限氧指数（LOI）测试、垂直燃烧测试（VBT）、烟密度测试（SDT）、微型量热仪（MCC）和热重分析（TG）表征阻燃纸的阻燃性和热稳定性,采用场发射扫描电镜（SEM）、透射电镜（TEM）表征疏水阻燃微胶囊的微观形貌,用傅里叶变换红外光谱（FTIR）表征试样的官能团特征,并根据国标测定纸张试样的抗张强度和撕裂度。结果涂布疏水阻燃微胶囊的牛皮纸试样的极限氧指数达到了36.3%,与空白组相比,烟释放总量、热释放速率峰值和热释放总量分别降低了42.44%、52.4%、36.1%,抗张强度和撕裂度分别提高了8.2%、177.1%,疏水阻燃微胶囊的表面形貌特征、元素分析结果以及红外光谱分析结果可表明,阻燃剂被成功包覆,并且SiO2微粒成功沉积在微胶囊壁材的表面。结论疏水阻燃微胶囊能有效改善阻燃剂的阻燃性、抑烟性和热稳定性,提高了基材的力学强度,降低了微胶囊的...     

原位聚合法制备石蜡微胶囊的工艺研究

考察了助剂类型和后处理工艺对微胶囊制备的影响。结果表明，表面活性剂的加入会影响微胶囊形成，加入4．0％的表面活性剂得不到微胶囊，而在不加助剂或加入聚乙烯醇时能够得到较高微胶囊化率的微胶囊。制备石蜡微胶囊必须考虑后处理工艺的影响，需依次用热水、乙醇和热石油醚洗涤才能除去未包覆石蜡。通过对微胶囊合成过程的分析表明，要形成石蜡微胶囊，必须使生成的物质具有在石蜡液滴表面富集的能力。尿素和甲醛反应生成的缩聚产物具有一定的表面活性，逐渐移动到两相界面，在水相中进一步反应、沉积，包覆石蜡形成微胶囊。     

溶剂挥发法制备苯乙烯微胶囊

采用简单易控制的溶剂挥发法成功制备了聚砜材料包覆苯乙烯的自修复微胶囊,通过核磁共振氢谱(1H-NMR)、扫描电子显微镜(SEM)、元素分析仪和热重分析仪(TGA)对微胶囊的化学结构、表面形貌及其热性能进行了研究.结果表明,选择0.5％的聚乙烯醇表面活性剂,700 r/min乳化转速、芯壁比2∶1时制得的微胶囊表面光滑,体积平均粒径为120μm,并且分布比较窄,微胶囊在室温下具有一定缓释性.     

The influence of carbon on the phases in the copper-titanium system and their precipitation

The influence of carbon on the phases occurring in the copper-titanium system has been experimentally investigated. Samples were fabricated from elemental copper and titanium. Carbon was added in the form of graphite or as titanium carbide. The samples were encapsulated, heat-treated at 1173 or 1373 K for 24 h and subsequently quenched in brine. The phases present at the treatment temperature were identified, as well as the phases occurring during solidification. The microstructure indicates the presence of a miscibility gap. The composition of the phases were determined using EDS-analysis. The composition of the copper phase was found to show a great variation caused by the precipitation sequence during quenching of the melts. The complex precipitation also caused both TiCu₄ and the meta-stable TiCu₃ to form. The composition of TiCu was found to show a wider compositional interval than earlier found. The variation of its composition with the nominal composition suggests that TiCu can dissolve carbon. The pure Ti phases also showed larger solubility of copper than earlier found. An outline of the precipitation sequence is made.     

Surface-enhanced infrared absorption (SEIRA) of adsorbates on copper nanoparticles synthesized by galvanic displacement

Copper nanoparticles (Cu NPs) were made by electroless deposition on Ge disks as substrates for surface-enhanced infrared absorption (SEIRA). Previous X-ray photoelectron spectra had shown that elemental copper is deposited on the Ge substrate and that the nanoparticulate film remains resistant to oxidation even after several days of air exposure at room temperature. SEIRA spectra of p-nitrothiophenol (p-NTP) adsorbed on the copper nanoparticles were measured. Freshly made substrates made by electroless deposition gave higher enhancements than both the 12-day-old oxidized substrates and substrates made by physical vapor deposition. The intensity of the antisymmetric NO(2) stretching band of p-NTP relative to that of the symmetric stretch was significantly higher for p-NTP adsorbed on copper than on silver nanofilms, indicating that the C(2) axis of the aromatic ring is tilted with respect to the copper surface.     

X-ray absorption spectroscopy study of a copper-containing material after thermal treatment

Thermal immobilization of copper contaminant in a copper-containing solid material collected from local copper smelting and foundry area is investigated in the present work. X-ray absorption spectroscopy (XAS) and X-ray diffraction (XRD) are employed for copper speciation. XAS results indicate that cupric hydroxide is the major copper species in the solid material dried at 105 degrees C. After being subjected to a 500 degrees C thermal process, cupric hydroxide still remains as the main copper species, but some Cu(II) is chemically reduced to Cu(I). More cupric hydroxide is progressively converted to Cu(I) as the sample was heated at 1100 degrees C than that heated at 500 degrees C. The sample heated at 500 degrees C is in its original powder form. However, thermal treatment at 1100 degrees C transforms the powder into a hardened granule-like form that is much bigger in size and difficult to be ground into powders. The sample is sintered with the sparingly soluble cuprous oxide and elemental copper being encapsulated inside. Toxicity characteristic leaching procedure (TCLP) results depict that amount of copper leached from the sample (containing 133,000 mg copper kg-1) heated at 1100 degrees C for 2 h is considerably minor, being 367 mg copper kg-1.     

尤加利精油制备微胶囊抗菌纤维素薄膜

用β-环糊精包埋尤加利精油制备微胶囊抗菌剂,添加到纤维素溶液中制备抗菌性纤维素薄膜,测试了微胶囊包埋率、添加不同质量分数微胶囊的抗菌纤维素薄膜的最低抑菌质量分数以及薄膜中的精油含量。实验结果表明:制得的微胶囊最大包埋率为72.0%,抗菌纤维素薄膜中微胶囊质量分数为2.0%时抗菌率达到100%,此时抗菌纤维素薄膜中精油质量分数为薄膜质量的1.16%。     

微米级铜粉化学镀银及抗氧化性分析

采用化学镀的方法在微米级铜粉表面镀银.用X射线衍射法(XRD)和热重分析法(TG)测定了铜-银粉的物相和抗氧化性,比较了由镀前有无活化的铜粉所制备的两种金属粉体的性能,最后用X射线荧光光谱仪对两种粉体的表面元素和含量进行测定.结果表明镀银能明显提高铜粉抗氧化性,而镀前经活化的铜粉具有更好的活性,银在铜粉表面含量达到93.27%.     

Current sensor in PCB technology

A novel DC/AC current sensor works on the fluxgate principle. The core in the form of a 7/10-mm ring made of electrodeposited permalloy is sandwiched in the middle of a printed circuit board (PCB), whereas the sensor excitation winding is also integrated in the copper layers of the PCB. To lower the sensor power consumption, the excitation winding was tuned by a parallel capacitor. The peak-peak/rms ratio of 5.2 was achieved for the excitation frequency of 25 kHz. The open-loop sensor has 100-mV/A sensitivity; the characteristics have a linearity error of 10% and hysteresis below 0.1% in the 1-A range.     

可伐合金与无氧铜复合材料的研制

采用外皮为可伐合金(4J29)内芯为无氧 Cu(UT_1),经热加工、冷加工和扩散退火等工艺复合制成的复合材料。Cu 芯是圆形的,复合界面形成固溶体并牢固地结合在一起。轴向平均线膨胀系数α_(20)—400℃=(4.9-5.5)×10~(-6)/℃。外径为1.5mm,内芯径为0.6mm 复合线,其电阻率ρ=8.3×10~(-8)Ω·m;复合界面漏气率小于6.67×10~(-8)Pa·L/S。     

铜合金增材制造技术研究进展

增材制造技术的迅速发展,给铜合金制造技术提供了新的发展动力。主要综述了近年来国内外不同铜合金增材制造工艺的方法,分析了增材制造研究过程中遇到的增材制造试样晶粒易粗大、易形成裂纹及易引入杂质等问题,对比了不同增材制造工艺方法下,制备的铜合金试样的微观组织和力学性能。在此基础上,着重综述了铜合金增材制造技术研究在不同增材制造工艺方法方面的进展,并对增材制造试样与传统铸造试样的微观组织和力学性能进行对比。最后,对铜合金增材制造技术研究进展进行总结,并对其发展前景和发展方向进行展望。     

Development of a pulsed radio frequency glow discharge for three-dimensional elemental surface imaging. 1. Application to biopolymer analysis

Glow discharge optical emission spectrometry has cemented itself as an important surface elemental analysis technique in part because of its superb depth resolution (on the order of single nanometers). However, very few studies have explored the ability of the glow discharge to provide laterally resolved elemental information. In the present study, an end-on-viewed pulsed radio frequency glow discharge is coupled to a monochromatic imaging spectrometer to provide lateral surface imaging. The performance of the technique is demonstrated with etched copper circuits on fiber-glass substrates, and it is shown how several operating parameters including pressure, pulsed mode operation, and time-resolved detection affect the lateral surface resolution. In addition, because a pulsed radio frequency glow discharge offers elemental information on nonconducting samples, the technique is applied to the three-dimensional elemental analysis of proteins on blotting substrates. Several alternative sample types are also examined, including photographic film and glass.     

Investigation of shock-wave phenomena in composite materials

We propose a complex experimental-theoretical approach to the investigation and development of high-energy and composite materials for the conditions of high-velocity throwing and interaction with the application of nanotechnologies. We have obtained data on the character of the high-velocity interaction of strikers made from tungsten composites by different technologies with a steel obstacle. A nanostructured material based on copper with higher strength characteristics has been developed. The conditions for increasing the muzzle velocity of a barrel throwing installation due to the application of nanocomposite fuels have been investigated and realized. A computing-experimental method for investigating the processes of high-velocity collision of bodies has been elaborated.