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采用聚乙二醇、聚乙烯吡咯烷酮、CaCO3等不同材料作致孔剂合成多孔聚丙烯酰胺(PAAm)水凝胶,以图提高凝胶的溶胀响应速率。研究结果表明,采用PEG20000、PVP-K30,PEG600作致孔剂对PAAm凝胶响应速率影响不大。用PEG300作致孔剂,凝胶溶胀率随致孔剂浓度的升高,先升高后又逐渐降低,当其浓度为0.045mol/L时,溶胀3.5h,凝胶室温溶胀率提高了15.2%。采用CaCO3作致孔剂可在一定程度上加快凝胶响应速率,随着CaCO3用量的增加,溶胀率先升高后又有所降低。当CaCO3/AAM为5.6%(质量分数)时,溶胀3h后,溶胀率提高了40.3%。 相似文献
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首次以丙烯酸(AA)和尿素(U)为原料,N,N′-亚甲基双丙烯酰胺(MBAA)为交联剂,亚硫酸氢钠-过硫酸铵为引发剂,采用水溶液聚合法制备聚丙烯酸钠/尿素多孔材料(PAA/U)。研究了中和度、尿素含量等聚合条件对其吸湿性能的影响。由正交实验确定了最佳反应条件,其吸湿率最高达0.975 g/g。应用SigmaStat3.5进行多元线性回归分析得到各因素与吸湿率的数学关联式。红外光谱(FT-IR)和热重(TGA)分析表明,添加尿素后,形成了新的吸湿基团异氰酸根。扫描电镜(SEM)观察到PAA/U表面出现孔洞,增加了有效吸湿比表面积,其吸湿性能明显提高。 相似文献
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本文报导的烯丙基三甲基氯化胺合成新方法及它的丙烯酰胺类单体共聚制备的水溶性阳离子高分子聚合物,用作造纸增强剂,干纸页强度提高45%以上;湿纸页强度提高384%,施胶度提高56%,未见国内外相同的专科和技术报导。 相似文献
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制备了多孔聚氨酯-聚丙烯酸/丙烯酰胺(PU-PAA/AM)复合材料,并研究了其恒湿性能.结果表明:在30℃,100%RH环境下预吸湿0.5~6h后,20g多孔PU-PAA/AM复合材料可迅速自动吸湿或放湿,特6L密闭容器内的相对湿度恒定在43%RH~59%RH之间的某个值.在25~53℃高低温交变环境下,40g多孔PU-PAA/AM复合材料可将6L密闭容器内的湿度恒定在50%RH.多孔PU-PAA/AM复合材料还具有优异的拉伸性能和回弹性能,并且具有网状开孔结构,可将防震缓冲和恒湿性能有机结合起来,在武器装备的存储包装防潮领域和其它民用领域具有很大的应用价值. 相似文献
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两性聚丙烯酰胺纸张增强剂的合成和应用 总被引:20,自引:0,他引:20
研究了两性聚丙烯酰胺的合成、结构和性能。这种两性聚丙烯酰胺和纸纤维能够通过离子键和配位络合结合,形成较均一的交联网络,使纸张干强度明显增加,是一种新型和优异的纸张干强剂。 相似文献
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粉状阳离子聚丙烯酰胺的研制 总被引:2,自引:0,他引:2
黄祥虎 《高分子材料科学与工程》1992,8(4):120-122
用聚丙烯酰胺胶体,在≥20%浓度的硫酸盐溶液中,进行Mannich反应,经真空干燥后,制取水溶性阳离子型高分子。初步探讨了盐浓度、温度、时间、配比对产物的阳离子度、溶解性的影响。 相似文献
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镁基多孔材料的研究现状与展望 总被引:1,自引:0,他引:1
介绍了镁基多孔材料的主要制备方法,包括熔模铸造法、触融压铸法、固/气共晶凝固法、真空发泡法、粉末冶金法、熔体直接发泡法、渗流铸造法.分析了现有研究的主要特点,并着重对熔体直接发泡法制备镁基多孔材料的工艺进行了讨论,给出了该种方法的原则工艺流程. 相似文献
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分散聚合法聚丙烯酰胺微球调剖剂的研究 总被引:1,自引:0,他引:1
以过硫酸铵和亚硫酸氢钠为氧化还原引发剂,N,N-亚甲基双丙烯酰胺为交联剂,乙醇/去离子水为分散介质,聚乙烯吡咯烷酮(PVP)为分散剂,将丙烯酰胺和苯乙烯磺酸钠进行分散聚合制备了聚丙烯酰胺微球调剖剂,考察了乙醇/去离子水体积比、丙烯酰胺用量、引发剂用量、分散剂用量、交联剂用量、苯乙烯磺酸钠含量和反应温度对聚丙烯酰胺微球调剖剂的粒径和凝胶强度的影响。结果表明所合成的聚合物微球调剖剂粒径可调,平均粒径为1.0~8.5μm,具有较好的分散性和凝胶强度。FTIR谱图初步证实丙烯酰胺微球聚合物的结构。 相似文献
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为改善树脂吸湿性能,充分发挥树脂在吸湿领域的实际应用,本文系统分析了多孔聚丙烯酸钠树脂的吸湿过程及吸湿机理.通过测定多孔树脂在不同湿度下的吸湿量,得到其吸湿等温线,并确定其吸附类型;测定树脂在80%相对湿度下的吸湿曲线,采用动力学理论分析树脂吸湿速率,并与无孔聚丙烯酸钠树脂吸湿速率进行比较;测定树脂在不同温度下的吸湿量计算其吸湿热力学参数,研究树脂吸湿所能到达的程度.结果表明:树脂满足Ⅲ型吸附等温线,对吸附等温线进行线性拟合,树脂吸湿过程可用Freundlich吸附等温式进行描述;树脂吸湿符合二级吸附动力学模型,且多孔聚丙烯酸钠树脂的吸湿速率明显高于无孔聚丙烯酸钠树脂;树脂吸湿过程的焓变、熵变、吉布斯自由能变化均小于零,说明树脂吸湿过程是放热自发的.研究发现:树脂吸湿过程同时包含物理吸附和化学吸附,且以化学吸附为主;多孔结构的存在有利于提高树脂吸湿速率;降低温度有利于树脂吸湿. 相似文献
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以丙烯酸、丙烯酰胺和甲基丙烯酸为单体,N,N’-亚甲基双丙烯酰胺为交联剂,过硫酸钾为引发剂制备P(AA-AM-MA)高分子吸湿材料。系统研究单体浓度、单体配比等因素对其吸湿性能影响。根据正交实验,P(AA-AM-MA)最高吸湿率达0.95g/g。应用Sigma Stat 3.5进行多元线性回归分析得各因素与吸湿率的数学关联式,吸湿量直观分析表明,六因素影响吸湿性的主次顺序:脲含量>中和度>单体浓度>单体配比>交联剂浓度>引发剂浓度。 相似文献
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A method for measuring the coupled influences of temperature and moisture on the linear thermal expansion of porous materials is proposed. The method is based on length measurements using a comparator and on application of the superposition principle to the relative elongation due to temperature and moisture changes. The application of the proposed method is illustrated on the heat-insulating building material Dekalit P. Measured results show a significant influence of the rate of moistening and drying as well as the moistening method itself on the linear expansion. The differences in the linear moisture expansion coefficient caused by these effects can achieve several hundreds percent. The thermal expansion behavior of Dekalit P is found to be regular, the linear thermal expansion coefficient being constant in the temperature range of -30 to 180°C Generally, for Dekalit P, the influence of moisture on linear expansion is more important than the influence of temperature.Paper presented at the Twelfth Symposium on Thermophysical Properties, June 19 24, 1994, Boulder, Colorado, U.S.A. 相似文献
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Existing methods for determining heat and moisture transport properties in porous media are briefly reviewed, and their merits and deficiencies are discussed. Emphasis is placed on research in developing new transient methods undertaken in China during the recent years. An attempt has been made to relate the coefficients in the heat and mass transfer equations with inherent properties of the liquid and matrix and then to predict these coefficients based on limited measurements.Invited paper presented at the Tenth Symposium on Thermophysical Properties, June 20–23, 988, Gaithersburg, Maryland, U.S.A. 相似文献
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分层多孔材料吸声结构的性能分析 总被引:2,自引:0,他引:2
利用声波在分层介质中的传播方程,给出了由不同种吸声材料复合而成的多层吸声结构吸声系数的递推计算公式。继而以由多孔吸声材料复合而成的双层吸声结构为基础,通过数值仿真,深入分析了内外层材料的厚度、孔隙率、和微孔半径变化对吸声系数的影响。以导出的递推计算公式为基础,通过仿真实验研究了分层吸声结构的参数优化设计。结果表明:由多孔材料复合而成的分层吸声结构具有良好的吸声效果,通过合理配置各层材料结构参数,可以在较宽的频段上达到较为满意的吸声效果,从而为相应产品的开发提供了理论依据 相似文献
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B E Rama Chandran N Balasubramanian G V Subba Rao G Aravamudan 《Bulletin of Materials Science》1981,3(3):333-339
High silica fabric with a silica content >98% can be prepared by removing the non-siliceous ions from the E-glass fabric using
HCl as the leachant. The presence of Si-OH groups makes the material hydrophilic. The extent of moisture absorption depends
on the extent of leaching. The moisture present in the leached fabric decreases the volume and surface resistivity values. 相似文献
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Ninghu Su 《Materials Letters》2009,63(28):2483-2485
Absorption is a very common process which takes place on various types of materials ranging from porous media to new nano-materials and biological tissues. The majority of studies reported on absorption to date are concentrated on “rigid” porous media, which contradict the properties of real porous media which undergo swelling and shrinking changes. Here we present new absorption equations derived from a fractional diffusion-wave equation (fDWE) for absorption onto swelling porous media in a material coordinate. We show that the cumulative anomalous absorption is I(t) = Stβ/2 and the absorption rate , where S is the anomalous sorptivity and β the order of fractional derivative in fDWE. Using published data on cumulative absorption against time, the two adsorption parameters are determined: β = 1.2448 and S = 2.7775 cm2/h. The value of β = 1.2448 implies that absorption onto this swelling porous media belong to the category of super-diffusion, which is a phenomenon unknown to us before. In comparison, the traditional absorption equations do not have such features. When S is determined, the anomalous diffusivity, Dm, is calculated using its relation with S. We expect that the proposed new absorption equations will be valuable for explaining new phenomena and processes encountered in broader disciplines of science and engineering applications. 相似文献