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991.
992.
993.
采用二烯丙基双酚A(DP)与乙烯基橡胶对两种结构类型双马树脂进行增韧。探讨了乙烯基橡胶用量对改性树脂的力学性能、耐热性能及玻璃化转变温度的影响,确定当乙烯基橡胶用量为5%(占双马树脂)时,改性树脂具有较好的综合性能,较未增韧前有大幅提高。此时,冲击强度为23.17kJ/m2,GIC值为338.5J·m-2,玻璃化转变温度为241℃,5%热失重温度约在420℃。同时,通过SEM观察其断面的微观形貌为典型的韧性破坏。 相似文献
994.
The effects of grain size, space velocity, temperature and reactant concentration on the kinetics of NOx reduction with propane over Co-β-zeolite catalyst were investigated. The external mass transfer phenomenon was examined by varying the space velocity. The results show that the transfer can be negligible when the space velocity is greater than 60000 h-1 in low temperature range. However, the transfer exists at high temperatures even when the space velocity reaches a high level.Variation of the catalyst grain size from 0.05 to 0.125 mm does not change the conversion rate of NOx. The concentrations of components, NOx, C3H8 and O2, were also investigated to have a better understanding of mechanism. Based on the experimental data, the selectivity formula was proposed. The results shows that lower temperature is helpful to get higher selectivity as the activation energy of hydrocarbon oxidation, Ea,2, is greater than that of NOx reduction, Ea,1, (Ea,2>Ea,1). High NOx concentration and low C3H8 concentration are beneficial to high selectivity. However in order to maintain high activity simultaneously, the temperature and C3H8 concentration should be high enough to promote NOx reduction. 10%(ψ) H2O and 75×10-6(ψ) SO2 were introduced into the reaction system, and Co-β-zeolite shows strong resistance to water and SO2. 相似文献
995.
996.
997.
998.
Experiments of gas mixing between two half-beds were performed in a dual-leg circulating fluidized bed(DL-CFB)240 mm in width,40 mm in depth and 2000 mm in height by using glass beads with diameter of 0.25-0.28 mm as bed material.SO2 and CO as the gas tracers entering the left and right distributors separately were used to simulate the gas mixing between the two legs.MSD(mean square displacement)model was adopted to calculate the gas dispersion coefficient(Dw)which was used to investigate the effect of fluidization velocity and bed material inventory on gas mixing in the DL-CFB.The experimental results showed that Dw was about 50-300 cm2穝-1 at different fluidization velocities and bed material inventories.A higher fluidization velocity benefited particles exchange between two half-beds,which intensified the gas-solids interactions at the region with higher solids volume fraction.The gas mixing in the lower region of the DL-CFB was stronger than that in the upper region of the bed.A higher bed inventory was helpful to gas mixing at a lower fluidization velocity,while a higher fluidization velocity weakened gas mixing because of higher solids concentration in the center of the bed that prevented gas mixing. 相似文献
999.
1000.
用1,5-萘二异氰酸酯(NDI)和聚四氢呋喃醚二醇(PTMG)为原料合成了聚氨酯预聚体,以三羟基聚醚多元醇(330N)作为交联剂,1,4-丁二醇(BDO)作为扩链剂制备了NDI型聚氨酯弹性体,讨论了交联剂与扩链剂的不同羟基摩尔比对NDI型聚氨酯弹性体性能的影响。结果表明,随着三羟基聚醚多元醇含量的增加,NDI型聚氨酯弹性体软段玻璃化转变温度有所提高;三羟基聚醚多元醇的加入虽然使得聚氨酯弹性体的滞后损失峰值增加,但对常用温度范围的滞后损失影响不大,0~150℃温度范围内的储能模量降低;聚氨酯弹性体的拉伸强度与断裂伸长率随着三羟基聚醚多元醇含量的增加,呈先增加后下降的趋势变化,硬度则呈下降趋势。 相似文献