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991.
在选择三元共聚尼龙(PA)、聚氯乙烯(PVC)、丁腈橡胶(NBR)为主体材料,制备PA/PVC/NBR(10/30/60)三元共混弹性体的工作基础上,进一步探讨了填料品种和用量,共混温度,加料顺序等因素PA/PVC/NBR三元共混弹性体的影响。试验结果表明:在PA/PVC/NBR(10/30/60)共混体系中,补强型填料的补强效果优于非补强型的填料,6种填料补强效果依次是:快压出炭黑>半补强炭黑>白炭黑>活性重质,CaCO3>陶土>滑石粉,快压出炭黑的适宜用量是20-50份。在制备PA/PVC/NBR三元共混物时,适宜的共混温度是122-140℃,并且采用二段法混工艺制得的共混物性能优于采用一段法共混工艺。 相似文献
992.
改性BMI微孔轴承保持器材料研究 总被引:1,自引:0,他引:1
采用改性双马来酰亚胺树脂制备微孔轴承保持器材料,探讨了制备工艺和最佳工艺参数,得到性能优良的改性双马来酰亚胺微孔轴在保持器材料。 相似文献
993.
A. Amara A. Ferdi A. Drici J.C. Bernde M. Morsli M. Guerioune 《Catalysis Today》2006,113(3-4):251-256
Co-evaporation technique from three sources was used to prepare Cu(In, Ga)Se2 polycrystalline thin films for photovoltaic conversion. Their conductivity was studied in the range 20–300 K. The grain boundary scattering mechanism is mainly responsible for the diffusion process in the latter materials. In the low temperature region, we interpret the data in terms of Mott law and the analysis is very consistent with the variable range hopping. However, thermoionic emission is predominant at high temperatures. When the conductivity deviates from the classical grain boundary conduction models, inhomogeneity is then considered and parameters such as the standard deviation and the mean potential barrier height are derived. Transmittance measurements yielded band gap values of 1.07 and 1.64 eV for CuInSe2 and CuGaSe2, respectively. 相似文献
994.
Summary Copolymeric poly(acrylic acid-co-methyl methacrylate) hydrogels for three different compositions: (90/10), (80/20) and (60/40),
have been studied. Drug release has been examined as a function of the hydrogel composition by HPLC (High Pressure Liquid
Cromatography). The release experiments were carried out at 37 °C. The fraction of available drug release was linear in t1/2. The values of the diffusional coefficient (0.50<n<1.0) indicate that the nafcillin release mechanism from the hydrogels
in study is non-Fickian. The diffusion coefficients for this drug release have been calculated. The molecular diffusion of
nafcillin through hydrogels is controlled by the swelling. 相似文献
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Polylactide (PLA) has been melt spun to produce multifilament continuous yarns. The thermal characteristics of PLA filaments have been investigated using modulated differential scanning calorimetry (MDSC). With MDSC, it is possible to separate the different thermal events and to analyze them more precisely. The influence of hot drawing on thermal properties of PLA filaments has been studied. Hot drawing promotes an increase of glass transition temperature (Tg) and a decrease of heat capacity. The cold crystallization spreads on a larger range of temperature and the peak occurs at a lower temperature. The initial degrees of cristallinity of PLA filaments have been calculated thanks to the reversing and non reversing curves of MDSC. Tensile properties of PLA filaments are also investigated. 相似文献
1000.
X‐ray diffraction methods, DSC thermal analysis, and polarized light microscopy (PLM) were used to investigate the structural changes of nylon 66/clay nanocomposites. PA 66/clay nanocomposites were prepared by the method of melt intercalation. The results indicate that the addition of the intercalated organo‐montmorillonite (OMMT) can induce generation of the β‐form crystal of PA 66 and substantially affect the arrangement of molecules in the α‐form crystal, although the crystallinity scarcely changes. Also, the DSC results indicate that the addition of OMMT in the PA 66 matrix leads to increases of crystallization temperatures and the full width at half maximum (FWHM) of the exothermic peaks. Moreover, the viscosity factor is the main influence on FWHM of the exothermic peaks of PA 66/clay nanocomposites. The results of nonisothermal crystallization kinetics show that OMMT has the effect of heterogeneous nucleation and leads to the decrease of the size of the spherocrystal. The heterogeneous nucleation effects of OMMTs influence the mechanism of crystallization and the growth mode of PA 66 crystals. PLM photographs verify that the size of spherocrystal is decreased and visually confirm the theory of crystallization kinetics. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 95: 756–763, 2005 相似文献