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21.
不同类型聚合物溶液对采油残余油的作用机理研究 总被引:6,自引:0,他引:6
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 . 相似文献
22.
增容剂对聚丙烯/粘土纳米复合材料热分解动力学的影响 总被引:12,自引:0,他引:12
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. 相似文献
23.
Ju Gu Qiang Xiong Demin Jia Yuanfang Luo Rongshi Cheng 《Frontiers of Chemistry in China》2009,4(1):75-82
A modified nano-calcium carbonate (R-CCR) was prepared by coating a layer of unsaturated hydroxylfatty acid on the surface
of CCR powders using a solid state method; the latter were commercial nano-CaCO3 modified with stearic acid. FTIR studies indicate that the modifier is combined on the surface of CaCO3. PP/EPDM/nano-CaCO3 ternary composites were prepared by a melt-mixing method. SEM and TEM were utilized to examine the morphology of the composites.
The tensile fractured surface of PP/EPDM/R-CCR showed a fibroid morphology and large-scale yield deformation. The impact fractured
surface showed that the amount of cavities in the PP/EPDM/R-CCR system was increased, however their size diminished obviously.
R-CCR particles were dispersed uniformly in the PP matrix, and their compatibility was distinctly improved as compared to
CCR when the amount of R-CCR was 15 h−1. The tensile strength remained nearly constant (reduced from 27.6 MPa to 27.5 MPa), while the impact strength increased from
9.6 kJ/m2 to 15.4 kJ/m2 as CCR was replaced by R-CCR. Meanwhile, the bending strength and bending modulus also increased correspondingly. Furthermore,
the impact strength of PP/EPDM/R-CCR was maintained at a high level (15.4 kJ/m2), which was more than the sum of that of PP/EPDM and PP/R-CCR (6.6 kJ/m2 and 6.1 kJ/m2 respectively). This indicates that the R-CCR and EPDM have a significant synergistic toughening effect on PP while maintaining
the strength and modulus of virgin PP. Both the storage modulus G′ and loss modulus G″ of PP/EPDM and PP/EPDM/R-CCR composites increase with increasing frequency, but the values of G′ and G″ of the tertiary composite are relatively higher than those of the binary system. The loss factor and viscosity decrease with
increasing frequency, but there is little difference between tertiary and binary composites. The apparent viscosity η of the tertiary system containing R-CCR is lower than that of the tertiary system containing CCR and virgin PP. The viscosity
of the composites sig-nificantly decreases with increasing shear rate. The mea-sured mechanical properties of the composites
indicate that replacing CCR with R-CCR for binary composites could simultaneously enhance the toughness and strength of PP.
__________
Translated from Acta Polymerica Sinica, 2008, 4 (in Chinese) 相似文献
24.
Trubetskaya OE Shaloiko LA Demin DV Marchenkov VV Proskuryakov II Coelho C Trubetskoj OA 《Analytica chimica acta》2011,(2):263-268
Polyacrylamide gel electrophoresis of chernozem soil humic acids (HAs) followed by observation under UV (312 nm) excitation light reveals new low molecular weight (MW) fluorescent fractions. Ultrafiltration of HAs sample in 7 M urea on a membrane of low nominal MW retention (NMWR, 5 kDa) was repetitively used for separation of fluorescent and non-fluorescent species. Thirty ultrafiltrates and the final retentate R were obtained. Fluorescence maxima of separate ultrafiltrates were different and non-monotonously changed in the range of 475–505 nm. Fluorescence maxima of less than 490 nm were detected only in the four first utrafiltrates. For further physical–chemical analyses all utrafiltrates were combined into a fraction called UF < 5 (NMW < 5 kDa). Retentate R demonstrated very weak fluorescence under 270 nm excitation, while fluorescence intensity of UF < 5 was about six times higher than of the bulk HAs. Fraction UF < 5 was further ultrafiltrated on membranes of MNWR 3 kDa and 1 kDa, yielding three subfractions UF3-5, UF1-3 and UF < 1 with NMW 3–5 kDa, 1–3 kDa and <1 kDa, respectively. The validation of the UF procedure was performed by size exclusion chromatography on Sephadex G-25 column. The fluorescence maxima were found to be at 505, 488 and 465 nm for UF3-5, UF1-3 and UF < 1, respectively, with increasing of fluorescence intensity from UF3-5 to UF1-3 to UF < 1 fraction. EPR analysis showed that the amount of free radicals was the largest in retentate R and drastically decreased in fluorescent ultrafiltrates. The results demonstrate that more than one fluorophore is present in chernozem soil HAs complex. 相似文献
25.
26.
Electron paramagnetic resonance spectroscopy is used to determine the concentration of excited (singlet) molecular oxygen photosensitized by silicon nanocrystals. The generation of singlet oxygen in the porous silicon layers is studied quantitatively at various oxygen pressures and exciting light intensities with the use of the technique proposed. The experimental results indicate that silicon nanoclusters as the photosensitizers of singlet oxygen are promising for biomedical applications. 相似文献
27.
An integro-differential equation is written down that contains terms responsible for nonlinear absorption, visco-heat-conducting dissipation, and relaxation processes in a medium. A general integral expression is obtained for calculating energy losses of the wave with arbitrary characteristics—intensity, profile (frequency spectrum), and kernel describing the internal dynamics of the medium. It is shown that for weak waves, the general integral leads to well-known results of a linear approximation. Profiles of stationary solutions are constructed both for an exponential relaxation kernel and for other types of kernels. Energy losses at the front of week shock waves are calculated. General integral formulas are obtained for energy losses of intense noise, which are determined by the form of the kernel, the structure of the noise correlation function, and the mean square of the derivative of realization of a random process. 相似文献
28.
29.
The effect of vertical high-frequency vibration on steady-state binary-mixture flows in connected channels is studied theoretically.
Mixtures with both positive and negative thermal diffusion are considered. It is shown that the convection excitation mode
changes with the sign of the thermal diffusion. The dependence of the flow amplitude on the supercriticality is analytically
obtained for various vibrational Rayleigh numbers. 相似文献
30.
V. P. Krasnov A. M. Demin G. L. Levit A. N. Grishakov L. Sh. Sadretdinova V. A. Ol’shevskaya I. V. Glukhov V. N. Kalinin V. N. Charushin 《Russian Chemical Bulletin》2008,57(12):2535-2539
A determination of enantiomeric purity of 1-substituted (Me, Ph, and Pri) 3-amino-1,2dicarba-closo-dodecaboranes by HPLC on chiral Chiralcel OD-H and Chiralpac AD stationary phases involving preliminary phthaloylation of
3-aminocarboranes has been suggested as a general method. 相似文献