专利专栏

专利名称:聚氨酯弹性体／蒙脱土纳米复合材料及其制备方法专利申请号:02129016.4公开号:1398921申请人:中国科学院长春应用化学研究所本发明属于聚氨酯弹性体／蒙脱土纳米复合材料及其制备方法。这类聚氨酯弹性体／蒙脱土纳米复合材料由聚氨酯弹性体、增容剂、有机化蒙脱土和功能性防老剂组成。其制备方法是将蒙脱土经过阳离子交换反应后,再与增容剂进行熔融插层,并借助增容剂增容聚氨酯弹性体和有机化蒙脱土。本发明的纳米复合材料不仅具有蒙脱土均匀分散在聚合物基质中的结构,而且力学性能相对于纯聚氨酯弹性体有明显提高。     

聚丙烯／有机蒙脱土复合材料的制备、结构及性能

以改性聚丙烯作增容剂，用熔融插层法制备了聚丙烯／有机蒙脱土复合材料，研究了有机蒙脱土对复合材料力学性能的影响，并用X射线衍射研究了复合材料的结构。结果表明：增容剂增加了聚丙烯与蒙脱土片层之间的作用力，使蒙脱土片层间距增大，在聚丙烯基体中分散更好，因而使聚丙烯／有机蒙脱土复合材料的缺口冲击强度大幅度提高，当蒙脱土含量达5％时，缺口冲击强度提高120％，并且拉伸性能下降不大，约下降5％，其中有机蒙脱土TJ4的增韧效果最好。     

有机蒙脱土改性PC/ABS合金材料的力学性能研究

以有机蒙脱土、相容剂为改性材料,采用熔融插层法制备了有机蒙脱土/聚碳酸酯(PC)/丙烯腈-苯乙烯-丁二烯共聚物(ABS)复合材料,研究了增容剂用量、有机蒙脱土用量对复合材料力学性能的影响。结果表明:相容剂和有机蒙脱土的加入不仅使PC/ABS合金材料的韧性显著增加,而且其刚性也有所增强。     

聚氯乙烯／蒙脱土纳米复合材料的制备与性能

对钠基蒙脱土进行有机化处理,XRD表明有机阳离子已同钠离子发生离子交换。熔融法制备聚氯乙烯／蒙脱土插层复合材料,用X－射线衍射研究复合材料的结构,聚氯乙烯不能插层于钠基蒙脱土,但能插层于有机蒙脱土,形成剥离型纳米复合材料。采用DSC研究了聚氯乙烯／有机蒙脱土复合材料的玻璃化转变温度,研究结果表明,聚氯乙烯／有机蒙脱土比聚 乙烯／钠基蒙脱土复合材料的力学性能优异。     

季铵盐插层剂对高密度聚乙烯性能的影响

采用季铵盐阳离子作为插层剂与钠基蒙脱土层间的无机阳离子进行离子交换,制备系列有机化蒙脱土,利用红外光谱对蒙脱土的结构进行表征,结果表明,插层剂已进入蒙脱土的层间.同时将有机化蒙脱土与HDPE进行熔融插层,制备了纳米聚乙烯复合材料,研究了插层剂对其部分力学性能的影响.     

聚丙烯／聚苯乙烯／蒙脱土纳米复合材料的制备

通过对钠基蒙脱土的有机化处理，有机土与聚苯乙烯的复合，聚苯惭烯／蒙脱土复合材料与聚丙的复合等三个步骤制备出了聚丙烯／聚苯乙烯／蒙脱土纳米复合材料。     

PET／蒙脱土纳米复合材制的增韧研究

以聚对苯二甲酸乙二酯（PET）为基体，以（甲基丙烯酸甲酯／丙烯腈／丁二烯／苯乙烯）共聚物为增韧剂，采用熔融共混法制备了PET／蒙脱土纳米复合材料。用广角X射线衍射仪、透射电子显微镜研究了复合材料的微观结构，并测试了力学性能。结果表明，所制得的纳米复合材料具有剥离型和插层型结构；增韧剂及增容剂的引入都较大程度地提高了复合材料的缺口冲击强度，而拉伸强度和弯曲强度基本不变；纳米蒙脱土及增容剂的加入提高了纳米复合材料结晶性能。     

PVC／蒙脱土复合材料的制备与结构研究

采用钠基蒙脱土及经有机化处理后的蒙脱土分别通过纳米粒子直接填充分散法和熔融插层法与PVC混合制备PVC/蒙脱土纳米复合材料。对有机蒙脱土的结构进行了表征；对上述两类纳米复合材料的结构及力学性能进行了研究。此外，考察了采用硅烷偶联剂KH570处理钠基蒙脱土后与PVC熔融混合制备的纳米复合材料的力学性能。结果表明，经硅烷偶联剂处理后，纳米复合材料的拉伸强度和冲击强度均有明显的提高。     

蒙脱土含量对PP/PP-g-MMA/MMT复合材料性能影响的研究

以福建省武平县蒙脱土作原料,经过提纯和钠化后用十八烷基三甲基溴化铵(TMSAB,Trimethyl stearyl ammonium Bromide)作有机改性剂对蒙脱土进行有机化改性处理,得到有机蒙脱土(TMSAB蒙脱土)。以自制界面改性剂PP-g-MMA为增容剂,改变有机蒙脱土含量,经挤出造粒、注塑成型,制成PP/PP-g-MMA/OMMT复合材料的标准试样。通过测试复合材料的力学性能,并用XRD、DSC、DMA、TG进行表征,当有机蒙脱土含量低于2%时,在复合材料的抗拉强度和冲击强度不下降的情况下,拉伸模量得到较大的提高,达33.3%。     

HDPE/层状硅酸盐复合材料阻隔性能研究

研究了不同层状硅酸盐包括普通蒙脱土、云母以及有机化蒙脱土对HDPE／层状硅酸盐复合材料的阻隔性能影响。结果表明：HDPE／云母(质量配比100／30)共混体系中云母作为分散相提高复合材料的阻隔性能最明显，40份分散剂TXT的加入显著提高复合材料的阻隔性能达到15倍，层状硅酸盐改进了复合材料的加工性能。     

Polymorphism of LiGa5O8 and of LiGa5O8-MgGa2O4Solid Solutions

High-temperature X-ray diffraction and differential thermal analyses showed that LiGa₅O₈ exists in two polymorphs related by the first-order transition at 1138°±3°C of the low-temperature simple-cubic form, space group (probably) O⁷, to the high-temperature spinel (fcc) form, space group O _h ⁷. The transition is rapid, and the high-temperature form in pure LiGa₅O₈ could not be quenched to room temperature under the conditions used. However, the high-temperature polymorph can be quenched under equilibrium conditions when 40 mol% or more MgGa₂O₄ is present. The subsolidus equilibrium relations in the system MgGa₂O₄-LiGa₅O₈ are discussed.     

Activation and characterization of Fe---Mn---SO4/ZrO2 catalysts

Changes in Fe---Mn---SO₄²⁻/ZrO₂ catalyst formulations during activation have been observed. In air or an inert gas, the added salt, such as iron and/or manganese nitrate, decomposes over a temperature range of about 200–400°C to produce nitric oxide, oxygen and iron and/or manganese oxide. The crystallization of zirconia occurs at 450°C; when the sample contains sulfate the exothermic event occurs at a temperature that is about 200°C higher. Heating in the presence of hydrogen causes the evolution of nitric oxide to occur over a narrow temperature range and at a lower temperature than when the sample is heated in helium or air. It appears that the nitrate ions associated with Fe, Mn and Zr decompose to produce nitric oxide, and presumably water, at different temperatures when the sample is heated in the presence of hydrogen. Heating samples of sulfated zirconia containing iron and/or manganese in hydrogen causes sulfur evolution at a lower temperature, and a significant fraction of it in the form of H₂S.     

The structures of VOx/MOx and alkali-VOx/MOx catalysts and their catalytic performances for soot combustion

Vanadium oxides supported on γ-Al₂O₃, SiO₂, TiO₂, and ZrO₂ were studied on their molecular structures and reactive performances for soot combustion. To investigate the effect of different alkali metals on the structures and reactivities of supported-vanadium oxide catalysts, they were doped into the V₄/TiO₂ catalyst which had the best intrinsic activity for soot combustion in the selected supported vanadium oxide catalysts. The experimental results demonstrated that the catalytic properties of these catalysts depended on the vanadium loading amount, support nature, and the presence or the absence of alkali metals. The spectroscopic analysis (FT-IR and UV–vis) and H₂-TPR results revealed that the higher activity of alkali-promoted vanadium oxide catalysts could be related to the ability of alkali metal promoting the redox cycle of the active vanadyl species. TG results showed that adding alkali to V_m/TiO₂ catalyst was beneficial to lowering their melting points. Low melting points could ensure the good surface atom migration ability, which would improve the contact between the catalyst and soot. Due to the alkali metal components promoting the redox ability and the mobility of the catalysts, alkali-modified vanadium oxide catalysts could remarkably improve their catalytic activities for soot combustion. The catalytic activity order for soot combustion followed Li > Na > K > Rb > Cs in the catalyst system of alkali-V₄/TiO₂, and the reason why it followed this sequence was discussed.     

Magnetoresistance of CuxCo1-xFe2O4 Ferrites

Magnetoresistance measurements (Δ/R) were carried out on Cu _x Co_{1- x} Fe₂O₄ samples with x =1, 0.75, 0.50, 0.25 and cobalt ferrite in the range of magnetic intensity (H) from 1.0 to 4.5 kG. Linear plots were obtained between log (Δ/R) and log H for all compositions except that of cobalt ferrite. The values of n at x =0.5 do not agree with the results of some authors. The discrepancy may be attributed to the value of magnetic field intensity at which such measurements were carried out. The similarity of features of n and μ_D with composition leads us to believe that the magnetoresistance may arise from the scattering of conduction electrons by localized electrons involving the s-d exchange interaction.     

Compact Swelling in Bi1.4Pb0.6Sr2Ca2Cu3.6Oy During the Formation of High-Tc Superconducting Phase

Compact swelling in Pb-doped Bi-Sr-Ca-Cu-O superconductor has been studied by observing the effects of the size of calcined powders, volatilization of materials, and sintering of high- T _c (2223) powders. The bulk density increases at the early stage of sintering, for about 20 h, and then decreases. Densification occurs when the low- T _c (2212) phase and a liquid phase exist, whereas dedensification occurs with the formation of the 2223 phase regardless of the presence of the liquid. Gas evolution from specimens does not appear to be responsible for compact swelling. Compact swelling is explained by anisotropic growth of thin, platelike 2223 grains in random orientation. When 2223 grains grow in a preferred direction, compact swelling is suppressed.     

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.     

Effects of metal-support interactions on the hydrogenation of CO over PdSiO2 and PdLa2O3

A study of CO hydrogenation over $\text{Pd}\text{SiO}{}_2$ and $\text{Pd}\text{La}{}_2\text{O}{}_3$ has been carried out for the purpose of identifying the effects of Pd dispersion, Pd morphology, and support composition on the catalytic activity of supported Pd. The specific activity of each catalyst for methanol and methane synthesis was determined from microreactor studies carried out at a fixed set of reaction conditions. Palladium dispersion was measured by H₂O₂ titration, and the morphology of the Pd crystallites, as expressed by the distribution of Pd(100) and Pd(111) planes, was determined from in situ infrared spectra of adsorbed CO. The crystallite morphology of the $\text{Pd}\text{SiO}{}_2$ catalysts is the same, independent of Pd weight loading: 90% of the surface is comprised of Pd(100) planes and 10% of the surface is comprised of Pd(111) planes. By contrast, the crystallite morphology of the $\text{Pd}\text{La}{}_2\text{O}{}_3$ catalysts changes with Pd loading. Primarily Pd(100) planes are exposed at low-weight loadings while Pd(111) planes are exposed at high-weight loadings. The Pd dispersion has little effect on the methanol turnover frequency over both $\text{Pd}\text{SiO}{}_2$ and $\text{Pd}\text{La}{}_2\text{O}{}_3$, for dispersions between 10 and 20%. On the other hand, the methane turnover frequency is independent of Pd dispersion over $\text{Pd}\text{SiO}{}_2$, but increases with decreasing dispersion over $\text{Pd}\text{La}{}_2\text{O}{}_3$. It is further observed that the Pd morphology influences the specific activity of $\text{Pd}\text{La}{}_2\text{O}{}_3$ for methanol synthesis: Pd(100) is nearly threefold more active than Pd(111). For a fixed morphology, the specific methanol synthesis activity of $\text{Pd}\text{La}{}_2\text{O}{}_3$ is a factor of 7.5 greater than that of $\text{Pd}\text{SiO}{}_2$.     

Oxidation of Ba2YCu3Ox at High Po2

Dense large-grain ceramic samples of Ba₂YCu₂O_x have been oxidized at 400° to 500°C in 10 to 30 MPa of oxygen for 1 to 10 d. The high-pressure treatment has increased the equilibrium content x slightly above 7 but there is no concomitant increase in T_c. At x = 7.03 the superconducting transition, measured by ac susceptibility, has an onset temperature of ∼91 K and ΔT∼4 K and no change in lattice parameter is observed. High oxygen pressure increases the rate of oxidation.