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振动筛压框改造及合理使用 总被引:1,自引:0,他引:1
1.特迹系列振动筛的激振原理和特点
特迹系列振动筛的激振器由轮毂、连杆机构、压簧压盖和主副偏心块组成。激振器安装在振动轴两端,激振器的旋转中心即为振动轴的轴心线。当振动轴的转速小于440r/min或处于静止状态时,由于压簧的作用,主副偏心块处于闭合位置,此时激振器的重心与旋转中心重合,不产生离心力,因此筛箱不振动。当振动轴的转速大于440r/min时主副偏心块开始张开,激振器的重心开始旋转产生离心力,筛箱开始振动。随着振动转速的增加,主副偏心块张开的角度也随之增大,离心力也逐步增大,筛箱振动加剧。当振动轴的转速达到580r/min时,主副偏心块张开最大位置。当振动轴的转速达到额定转速(1052r/min)时,激振器的离心力达到最大值,筛箱处于稳定振动状态,开始正常工作。 相似文献
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A novel class of xanthan-maleic anhydride (Xan-MA)/poly(N-isopropylacrylamide) hybrid hydrogels was designed and synthesized
by solution polymerization. The xanthan-based precursor (Xan-MA) was prepared by substituting the hydroxyl groups in Xan by
MA. This Xan-MA precursor was then polymerized with a known temperature sensitive precursor (N-isopropylacrylamide, NIPAAm)
to form hybrid hydrogels with a series range of composition ratio of Xan-MA to NIPAAm precursors. These smart hydrogels were
characterized by Fourier transform infrared spectroscopy for structural determination, differential scanning calorimertry
for thermal property. And maximum swelling ratio, swelling kinetics and temperature response kinetics were studied. The data
obtained clearly show that these smart hydrogels are responsive to the external changes of temperature as well as pH value.
The magnitudes of smart and hydrogel properties of these hybrid hydrogels depend on the feed composition ratio of the two
precursors. With the increase of the content of Xan-MA the maximum swelling ratio, reswelling ratio and thermo-sensitivities
increase, and the feed composition ratio of Xan-MA/NIPAAm increases the maximum swelling ratio augment from 13.88 to 23.21.
From XMN0, XMN1, XMN3 to XMN5, the lower critical solution temperatures (LCSTs) are 33.02, 36.15, 40.28 and 41.92 °, respectively.
By changing the composition ratio of these two precursors, the LCST of the hybrid hydrogels could also be adjusted to be or
near the body temperature for the potential applications in bioengineering and biotechnology fields. 相似文献
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N-异丙基丙烯酰胺(NIPA)和丙烯酸甲酯(MA)通过自由基共聚形成线型大分子P(NIPA-MA),再用联胺取代MA嵌段上的甲氧基,得到一种多官能团的温敏大分子聚(N-异丙基丙烯酰胺-丙烯酸甲酯-丙烯酰肼)(PNMH),用它交联氧化的海藻酸钠(OSA),得到可生物降解的温敏凝胶PNMH-OSA。研究了PNMH的取代度(DS)、海藻酸钠的氧化程度(DO)、pH值和离子强度对PNMH-OSA凝胶降解性能的影响,同时以次甲基蓝(MB)和牛血清蛋白(BSA)为模拟药物,采用包埋法将药物载入凝胶中,研究了凝胶的释药行为。结果表明,凝胶降解速率随海藻酸钠的氧化程度、pH值增加而增加,随PNMH的取代度、离子强度增加而减慢;药物释放速率与药物的分子量和凝胶的降解速率有关。 相似文献
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聚丙烯酰胺-co-2-丙烯酰胺基-2-甲基丙磺酸凝胶催化合成乙酸正丁酯 总被引:1,自引:0,他引:1
采用聚丙烯酰胺-co-2-丙烯酰胺基-2-甲基丙磺酸(AAm-co-AMPS)凝胶代替传统酸性催化剂催化酯化反应,期望能够在反应过程中分离副产物-水,提高酯化率。考察凝胶在纯水中的溶胀性能,并以.乙酸正丁酯合成为模板来考察凝胶的催化性能和在反应过程中分离水的作用。研究表明:凝胶相对于氨基磺酸具有较好的催化活性;反应的酯化率主要弓凝胶的加入量有关,在100℃,催化剂加入量为1.8g,反应3.6h,酯化率达到78.2%。该凝胶催化剂通过简单的处理霞复利用4次,催化活性几乎不变。 相似文献
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