MgO/CaZrO3和MgO/ZrO2复合物的工艺、烧结和性能

白云石-氧化锆和氧化镁-氧化锆两批料成比例配制了用于各种高温环境下的MgO/CaZrO3和MgO/ZrO2复合物。这些批料是在不同烧结温度下所制备的,即1400、1500和1600℃。用XRD和具有EDAX的扫描电子显微镜对所制备试样的晶相成分进行了研究分析。对烧成参数(体积密度和显气孔率),常温耐压强度和耐火性能(永久线变化PLC),抗热震性(TC),耐火度和荷软(RUL)也进行了研究。这两种复合物都具有良好的烧结性、机械和耐火性能。不过,白云石-氧化锆混合物还具有独特的性能。除了这些复合物(特别是白云石-氧化锆)具有完全致密的显微结构外,还具有良好的烧结性、机械和耐火性能,可以用作工程材料和用于高温环境下,特别是用于烧制石灰、白云石、镁砂和波特兰水泥的回转窑和竖窑中。     

Cu_2O/Fe_2O_3复合物的制备及其光催化性能研究

采用电子束辐照技术制备了不同Cu_2O含量的Cu_2O/Fe_2O_3复合物。通过X射线粉末衍射(XRD)、X射线光电子能谱(XPS)、透射电子显微镜(TEM)、紫外-可见(UV-vis)等表征方法对复合物的结构和表面物性进行了研究。结果表明,随着Cu_2O含量的增加,Cu_2O各晶面的衍射强度增强,峰也逐渐宽化;合成的复合物为正八面体,粒径尺寸在50~175 nm之间;复合物的紫外-可见吸收光谱蓝移。将复合物用于金橙Ⅱ的可见光催化降解反应,当Cu_2O含量为90%时其催化活性最好,经过30 min的降解,染料的降解率超过90。     

AgBr/ZnO/GO复合物的制备及其光催化降解和抗菌性能研究

采用水热法制备AgBr/ZnO/GO复合物,采用XRD、UV-Vis、SEM、TEM、EDS及XPS对复合物进行表征;以亚甲基蓝(MB)为模型研究复合物在可见光照射下的光催化降解性能,以大肠杆菌(E.coli)和金黄色葡萄球菌(S.aureus)为模型研究复合物的抗菌性能;通过比较ZnO、ZnO/GO及AgBr/ZnO/GO的光催化降解性能和抗菌性能,研究AgBr及GO在催化过程中的作用,探究AgBr/ZnO/GO复合物的光催化机理。结果表明,AgBr及ZnO能很好地沉积在GO上,AgBr、ZnO、GO发挥协同作用使得AgBr/ZnO/GO复合物的光催化降解性能和抗菌性能显著提高;AgBr及GO的加入能够增强ZnO的吸光强度、拓宽ZnO的吸光范围、促进光生电子-空穴的分离;与ZnO、ZnO/GO比较,AgBr/ZnO/GO复合物在可见光照射下具有更优的MB降解性能,且对E.coil及S.aureus表现出更佳的抗菌性能,有望在水污染处理中得到应用。     

聚苯胺/纳米Al_2O_3复合材料的制备及其防腐性能研究

在纳米Al_2O_3粒子存在的情况下,以苯胺单体为原料,过硫酸铵为氧化剂,采用化学氧化聚合法制备了聚苯胺/纳米Al_2O_3,复合物。分别用扫描电子显微镜(SEM)、X射线衍射仪(XRD)、紫外-可见分光光度计(UV-vis)和傅里叶变换红外光谱(FTIR)对产物进行形貌观察和结构表征。将涂覆含有聚苯胺和聚苯胺/纳米Al_2O_3,复合物涂层的碳钢片,浸泡于质量分数为3.5%的NaCl溶液中,通过开路电位、极化曲线和交流阻抗来评价涂层的防腐性能。结果表明,涂层中含有聚苯胺/纳米Al_2O_3复合物的碳钢片抗腐蚀能力强于含聚苯胺的碳钢片,腐蚀电位最高,腐蚀电流密度最小;而裸钢片腐蚀电位最小,腐蚀电流密度最大。     

石墨烯/S掺杂TiO_2复合物的制备及其光催化活性

采用水热法首先合成S掺杂TiO_2(S-TiO_2),然后S-TiO_2与氧化石墨烯(GO)经水热反应制备了石墨烯/S掺杂TiO_2复合物(GR/S-TiO_2)。所得样品通过扫描电子显微镜(SEM)、X射线衍射(XRD)、拉曼光谱(Raman)、傅里叶红外光谱(FTIR)和光致发光光谱(PL)对形貌和结构性能进行了表征,并在可见光下进行了光催化降解亚甲基蓝性能测试。结果表明,与S-TiO_2相比,GR/S-TiO_2对污染物的吸附性能有较大提高,光生电子-空穴对复合率大大降低,可见光下催化降解亚甲基蓝的速率提高了近1倍。     

石墨烯/S掺杂TiO_2复合物的制备及其光催化活性

采用水热法首先合成S掺杂TiO_2(S-TiO_2),然后S-TiO_2与氧化石墨烯(GO)经水热反应制备了石墨烯/S掺杂TiO_2复合物(GR/S-TiO_2)。所得样品通过扫描电子显微镜(SEM)、X射线衍射(XRD)、拉曼光谱(Raman)、傅里叶红外光谱(FTIR)和光致发光光谱(PL)对形貌和结构性能进行了表征,并在可见光下进行了光催化降解亚甲基蓝性能测试。结果表明,与S-TiO_2相比,GR/S-TiO_2对污染物的吸附性能有较大提高,光生电子-空穴对复合率大大降低,可见光下催化降解亚甲基蓝的速率提高了近1倍。     

添加剂对ABS/APP/PETA体系协同阻燃作用的研究

为了提高膨胀型阻燃体系聚磷酸胺(APP)/聚对苯二甲酰乙二胺(PETA)对苯乙烯-丁二烯-丙烯腈共聚物(ABS)的阻燃效果,并研究一些常用添加剂的协效阻燃机理,采用极限氧指数法、垂直燃烧法、热失重探讨了添加剂4A分子筛、次磷酸铝、有机蒙脱土(OMMT)和双噁唑啉(BOZ)对ABS/APP/PETA膨胀型阻燃复合物的协效...     

石墨烯/聚苯胺水性硅酸钾富锌防腐涂层的制备及性能研究

水性硅酸钾富锌防腐涂层因具有安全环保、耐热性好、耐酸碱性强等特点被广泛研究。但其较高的锌含量降低了涂层的力学性能、增加了施工难度，同时锌粉对施工者健康有害。以实验室化学气相沉积法制备的石墨烯为基底，采用原位聚合法制备了石墨烯/聚苯胺复合物。通过扫描电子显微镜、显微共焦激光拉曼光谱仪、X射线衍射仪及红外光谱仪等对石墨烯/聚苯胺复合物的表面形貌与结构进行了表征。研究了石墨烯/聚苯胺复合物对水性硅酸钾富锌防腐涂层性能的影响。结果表明：当锌粉与基料质量比为1∶1，石墨烯/聚苯胺复合物添加量为2%时，涂层的附着力为1级，硬度为5H，自腐蚀电位(E_corr)为-0.533 V，自腐蚀电流密度(i_corr)为4.788×10^-7 A/cm²，低频区阻抗模值(|Z|_{0.01 Hz})为4.25×10⁴Ω·cm²，静态水接触角为89.8°。石墨烯/聚苯胺复合物不仅能提高涂层的防腐性能和力学性能，还能提高锌粉的有效利用率，从而降低锌粉含量。     

聚苯胺-木质素磺酸纳米复合物的制备及吸附性能

以木质素磺酸(LS)为分散剂,采用静态聚合法制备了聚苯胺-木质素磺酸(PANI-LS)纳米复合物。通过扫描电子显微镜、透射电子显微镜、红外光谱、紫外可见光谱和广角X射线衍射对纳米复合物的形貌、结构和性能进行了表征。同时,研究了该纳米复合物对银离子的吸附性能。在银离子初始浓度为0.03 mol·L^-1时,PANI-LS纳米复合物对银离子的最大吸附容量为500 mg·g^-1。对吸附后纳米复合物的透射电子显微镜和广角X射线衍射的研究表明,PANI-LS纳米复合物对银离子具有还原作用,吸附后纳米复合物表面有直径为2～7 nm的单质银纳米粒子生成。     

聚乳酸/纤维素纳米晶纳米复合物的结晶性能

通过溶液混合,将纤维素纳米晶(CNC)与聚乙二醇(PEG)复合得到了改性的CNC-PEG纳米粒子,然后将其与PLA熔融共混得到PLA/CNC-PEG纳米复合物.采用扫描电子显微镜(SEM)表征了纳米复合物的形貌,结果表明,PLA/CNC-PEG复合物中纳米粒子的分散效果更均匀.采用示差扫描量热仪(DSC)研究了PLA、...     

Preparation and properties of poly(Nε,Nε-dicarboxymethyl-l-lysine)

A new ampholytic homopolypeptide, $\text{poly}\text{(N}{}^{\mathrm{\epsilon }}\text{,N}{}^{\mathrm{\epsilon }}\text{-}\text{dicarboxy-methyl-}\text{l}\text{-lysine}\text{)}$, which has one tertiary amino and two carboxyl groups in the side chain has been derived from a hydrochloride salt of poly(L-lysine). The polymer in aqueous solution seems to be in the coil form with locally extended structure (LES) at neutral pH. In both the acidic and alkaline regions, the molar ellipticity of the polymer changes as a result of change in net charge on the side chain. The conformational changes may be from the coil with LES to other coiled forms. 5–7 M NaClO₄ and 80% aqueous methanol induce the α-helix in the polymer at neutral pH. Divalent cations, Cu²⁺ and Ca²⁺, do not induce any remarkably ordered structures such as α-helix or β-structure in the polymer in aqueous solution at any pH. Ultraviolet absorption studies show an absorption peak of the polymer-Cu²⁺ complex near 240 nm. Dependence of the peak intensity on pH at various q values ($\text{q =}\text{[}\text{Cu}{}^{\mathrm{2+}}\text{]}\text{[}\text{residue}\text{]}$) indicates the two steps of the complex formation. At q less than 0.64, the formation is described only with the first step. An average coordination number for Cu²⁺ at the first step was calculated to be about 2 by the method of Mandel and Leyte. The association constant of Cu²⁺ with the residue at the step was determined from the absorption data to be far smaller than that for the Cu²⁺-EDTA complex. The second step of the formation occurs in the case of large q but the absorption data for the second step cannot be obtained exactly due to precipitation.     

Wet Milling of Fe/Al/Al2O3 and Fe2O3/Al/Al2O3 Powder Mixtures

Wet milling of Al₂O₃-aluminide alloy (3A) precursor powders in acetone has been investigated by milling Fe/Al/Al₂O₃ and Fe₂O₃/Al/Al₂O₃ powder mixtures. The influence of the milling process on the physical and chemical properties of the milled powders has been studied. Particle refinement and homogenization were found not to play a dominant role, whereas plastic deformation of the metal particles leads to the formation of dislocations and a highly disarranged polycrystalline structure. Although no chemical reactions among the powder components in Fe₂O₃/Al/Al₂O₃ powder mixtures were observed, the formation of a nanocrystalline, ordered intermetallic FeAl phase in Fe/Al/Al₂O₃ powder mixtures caused by mechanical alloying was detected. Chemical reactions of Fe and Al particle surfaces with the atmosphere and the milling media lead to the formation of highly porous hydroxides on the particle surfaces. Hence the specific surface area of the powders increases, while the powder density decreases during milling. The fraction of Fe oxidized during milling was determined to be 0.13. The fraction of Al oxidized during milling strongly depends on the metal content of the powder mixture. It ranges between 0.4 and 0.8.     

Participation of lewis base on vinyl chloride polymerization with Al(C2H5)3CCl4 catalyst system

The polymerization of vinyl chloride has been investigated using an $\text{Al}\text{(}\text{C}{}_2\text{H}{}_5\text{)}{}_3\text{CCl}{}_4$ catalyst system in the presence of various Lewis bases. Effective Lewis bases are γ-butyrolactone, diglyme and diethylenetriamine which are multidentate. The rate of polymerization is dependent not only on the basicity of the Lewis base used but also on a coordination number of one. The latter is the predominant factor. For the effect of polymeric amines, a tentative hypothesis is discussed.     

Sintering of Si3N4-Y2O3-Al2O3

Sintering kinetics of the system Si₃N4-Y2O₃-Al₂O3 were determined from measurements of the linear shrinkage of pressed disks sintered isothermally at 1500° to 1700°C. Amorphous and crystalline Si₃N₄ were studied with additions of 4 to 17 wt% Y₂O₃ and 4 wt% A1₂O₃. Sintering occurs by a liquid-phase mechanism in which the kinetics exhibit the three stages predicted by Kingery's model. However, the rates during the second stage of the process are higher for all compositions than predicted by the model. X-ray data show the presence of several transient phases which, with sufficient heating, disappear leaving mixtures of β ' -Si₃N₄ and glass or β '-Si₃N₄, α '-Si₃N₄, and glass. The compositions and amounts of the residual glassy phases are estimated.     

Synthesis and Characterization of Ti0.33Ta0.33Nb0.33C and Ti0.33Ta0.33Nb0.33CxN1-x Whiskers

Ta_0.33Ti_0.33Nb_0.33C and Ta_0.33Ti_0.33Nb_0.33C _x N_{1− x} whiskers were synthesized via a carbothermal vapor-liquid-solid growth mechanism in the temperature range 900°-1450°C in Ar or N₂. The optimum temperature was 1250°C. Whiskers were obtained in a yield of 70-90 vol%. The whiskers were 0.5–1 µm in diameter and 10–30 µm in length. The starting materials that produced the highest whisker yield were: TiO₂, Ta₂O₅, Nb₂O₅, C, Ni, and NaCl. C was added to reduce the oxides, and Ni to catalyze whisker growth. NaCl was used as a source of Cl for vapor-phase transportation of Ta and Nb oxochlorides and Ti chlorides to the catalyst. The catalyst metal was recycled several times during the synthesis and was transported as NiCl₂( g ) according to thermodynamic calculations. The rate of formation and the chemical composition of the whiskers depended on the synthesis temperature, the choice of catalyst, and the atmosphere. At low temperatures, the whiskers were enriched in Nb and Ta, whereas the Ti content increased with increased synthesis temperature.