Exploitation of introducing of catalytic centers into layer galleries of layered silicates and related epoxy nanocomposites. I. Epoxy nanocomposites derived from montmorillonite modified with catalytic surfactant‐bearing carboxyl groups

Montmorillonite (MMT) was modified with the acidified cocamidopropyl betaine (CAB) and the resulting organo‐montmorillonite (O‐MMT) was dispersed in an epoxy/methyl tetrahydrophthalic anhydride system to form epoxy nanocomposites. The intercalation and exfoliation behavior of the epoxy nanocomposites were examined by X‐ray diffraction and transmission electron microscopy. The curing behavior and thermal property were investigated by in situ Fourier transform infrared spectroscopy and DSC, respectively. The results showed that MMT could be highly intercalated by acidified CAB, and O‐MMT could be easily dispersed in epoxy resin to form intercalated/exfoliated epoxy nanocomposites. When the O‐MMT loading was lower than 8 phr (relative to 100 phr resin), exfoliated nanocomposites were achieved. The glass‐transition temperatures (T_g's) of the exfoliated nanocomposite were 20 °C higher than that of the neat resin. At higher O‐MMT loading, partial exfoliation was achieved, and those samples possessed moderately higher T_g's as compared with the neat resin. O‐MMT showed an obviously catalytic nature toward the curing of epoxy resin. The curing rate of the epoxy compound increased with O‐MMT loading. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 1192–1198, 2004     

Problem of the free oscillations of a capillary bridge

The free oscillations of a capillary bridge whose equilibrium shape is determined by the surface tension forces and the static gravity field are investigated. The values of 25 “lower” levels of the spectrum of natural oscillations of the capillary bridge are found for various control parameters in accordance with the experimental conditions.     

Ferromagnetic material CdGeP2:Mn for spintronics

Solid solutions Cd_1?x Mn_xGeP₂ (x=0?0.19) have been synthesized and identified. In these solutions, the unit cell parameters decrease with an increase in the manganese content. The solid solution Cd_0.81Mn_0.19GeP₂ is a ferromagnet with the Curie temperature T _C ≈ 311 K. The paramagnetic moment of Mn²⁺ ions equal to 5.8 μ_B, as well as the spontaneous magnetization constituting 76% of the total magnetization of a crystal, has been determined with the use of the Langevin function. The origin of ferromagnetism in CdGeP₂:Mn is exchange mediated by charge carriers (holes). These holes are caused by cationic defects in the structure of chalcopyrite.     

Measurement of the spin and temperature dependence of ddµ molecule formation rate in solid and liquid deuterium

The ddµ molecule formation rate is experimentally measured for the two hyperfine states of the dµ-atom in the temperature range of 5–30 K. Results are consistent with a preliminary measurement by the TRIUMF group and contradict theoretical predictions. The work has been performed on the JINR phasotron (Dubna).     

钒、铬、锰磷桥络合物中31P NMR化学位移的研究

ISSIe山和W6flSChllh山子1960年首次用pdCI。和二苯基磷合成出黄色的二聚络合物，后被H。yieY＊确认为具有pRZ的桥式结构．此后一系列该类结构的化合物被合成并引起了广泛的兴趣．磷可以和两个甚至多个金属原子络合构成多核金属络合物，在催化反应中有重要应用．磷原子存在多种电子态，其3d空轨道也能参与成键．P乃1的NMR谱是研究含磷化合物立体结构的有力工具．P－31与其它核素之间的耦合常数以及P－31的化学位移对阐明化合物的立体构象以及电子结构具有重要作用．近年来，West饲用计算机神经网络技术预测P－：if的化学位移，但仅…     

增容剂对聚丙烯/粘土纳米复合材料热分解动力学的影响

采用三单体固相接枝聚丙烯作为增容剂制备了聚丙烯粘土纳米复合材料.通过XRD和TEM表征了其纳米结构.利用动态TGA方法研究了聚丙烯和纳米复合材料的热稳定性.分别采用Flynn Wall Ozawa和Kissinger法研究了聚丙烯及其纳米复合材料的热分解动力学.结果都表明,蒙脱土的加入明显提高了聚丙烯的起始热分解温度,纳米复合材料热失重10%时的温度比聚丙烯提高40K左右;纳米复合材料的热分解温度区间明显比聚丙烯的窄;纳米复合材料热分解表观活化能明显增大,与聚丙烯相比提高50%以上.     

季铵盐固相催化使聚氯乙烯脱HCl

通过将季铵盐与聚氯乙烯(PVC)混溶成膜,使其在固相脱HCl,研究了催化剂对PVC脱HCl反应速度和产物结构的影响以及固相反应与温度、时间的关系.发现在催化性能上下基铵盐比乙基铵盐好得多,根据实验结果提出了季铵盐通过分解成叔胺实现催化的机理.     

不同类型聚合物溶液对采油残余油的作用机理研究

通过实验测定了HPAM溶液和黄原胶溶液的流变性、在多孔介质中的流变性和残余阻力系数 ,计算了衰竭层效应 .用不同的浓度和注入速度进行了驱油实验 .提出聚合物分子缠结作用的增强不仅引起表观粘度增加或衰竭层厚度降低 ,而且使平行于油水界面的拉动残余油的力增加 ,从而使残余油饱和度降低 ,采收率提高 .随浓度增加 ,HPAM溶液的表观粘度和残余阻力系数增加 ,衰竭层厚度减小 ;黄原胶溶液的浓度高于缠结浓度时 ,衰竭层厚度和表观粘度变化不大 .注入速度增加时 ,两种聚合物溶液的衰竭层厚度均降低 ,HPAM溶液的残余阻力系数不变 ,粘弹性增加 ;而黄原胶溶液的残余阻力系数下降 .不同浓度和注入速度情况下两种聚合物溶液的驱油结果证实了文中提出的聚合物分子缠结作用和衰竭层效应对残余油的作用机理 .分子结构的不同是造成两种聚合物溶液在多孔介质中渗流规律和对残余油作用机理的差别的根本原因 .     

A NEW PEAK (T_4) IN THE ~(13)C-NMR SPECTRUM OF POLYBUTADIENE

A new peak at 39.0 ppm in the ~(13)C-NMR spectrum of polybutadiene (PBD) was discovered. This peak is assigned to the fourth peak (T_4) of trans-1,4-sequence marked with an asterisk as shown in Fig. 3 in the text.The occurrence of T_4 carbon nuclei is strongly affected by their neighboring 1,2-units. So long as both contents of trans-1,4- and 1,2-units attain their proper amounts the peak (T_4) with appear in the ~(13)C-NMR spectrum of PBD.