Swelling of superabsorbents polymers in an aqueous medium

The polymers studied are superabsorbents materials. They were synthesized by inverse suspension polymerisation of acrylic acid. The polymers studied, X10 and X5, are different in their degree of ionisation. In fact, our objective was to increase the amount of water that may be stored by the polymer. In this article, we investigated not only the effect of temperature and pH on the satured water absorbency of polymers X10 and X5, but also various swelling behaviours of polymer X10 in different saline solutions. The results show that for temperature ranging from 10 to 90°C, the effect of temperature on the satured water absorbency is rather limited when the superabsorbent is swelled by distilled water. Further, water absorbency of X10 and X5 is strongly affected by the pH value. The results also indicate that saline solutions can weaken the swelling abilities of the polymer X10. Water absorbency of polymer X10 in aqueous chloride salt solutions has the following order: Na⁺ = K⁺= NH > Ca²⁺ = Mg²⁺ all through the range of investigated concentration. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

微波法合成淀粉-丙烯酸高吸水性树脂的研究

研究了微波法合成玉米淀粉-丙烯酸高吸水性树脂的工艺条件,测定了树脂对去离子水、自来水、模拟尿、模拟血、生理盐水的吸液倍率以及产物的吸水速率和保水性能。较佳的工艺条件为：丙烯酸用量30 mL,淀粉3 g,去离子水18 mL,25%NaOH溶液30 mL,质量浓度为2.0 g/L的K_2S_2O_8溶液3.5 mL,1 g/L的N,N′-亚甲基双丙烯酰胺溶液1 mL,初始聚合温度为常温,微波功率160 W,在氮气保护下反应5 min,真空干燥温度60℃,所得产物1 g能吸收去离子水1036.0 g。     

四烯丙基氯化铵交联的耐高温吸水树脂的研究

采用水溶液聚合法,以丙烯酸(AA)、2-丙烯酰胺基-2-甲基丙磺酸(AMPS)为单体,四烯丙基氯化铵(TAAC)为交联剂,过硫酸铵(APS)为引发剂,制备了耐高温吸水树脂,考察了单体配比、引发剂和交联剂用量对吸水树脂在高温下吸水性能的影响,并对吸水树脂结构进行扫描电镜分析。研究结果表明,所合成的吸水树脂具有良好的耐高温性能,最佳合成条件:AMPS与AA的质量比为0.22,引发剂、交联剂与单体的物质的量比分别为0.11%、0.14%,此条件下合成的吸水树脂在300℃蒸馏水中的吸水倍率为248g/g。     

冲击荷载循环作用下砂岩动态力学性能的围压效应研究

利用带围压装置的霍普金森压杆设备对砂岩在不同围压等级、不同应变率下的动态力学性能进行试验研究,分析了砂岩在冲击荷载循环作用下的累积比能量吸收值,损伤度与围压等参量之间的关系.研究结果表明:在围压作用下,砂岩的应力-应变曲线出现较明显的屈服平台,具有明显的脆性-延性转化特征.随着冲击荷载循环作用次数的增加,材料的弹性模量...     

纳秒级强激光对多晶硅片光吸收性能的影响

采用兆瓦级TEA CO2激光器输出的纳秒级强红外激光脉冲照射太阳能多晶硅片,用红外光谱仪测试了硅片的吸收谱,发现经激光脉冲照射后的太阳能多晶硅片对光的吸收能力大为增强,并对实验结果做出了初步的分析。     

常用印刷纸张对油墨吸收特性的实验研究

在室温20-25℃、湿度60%-65%条件下,采用IGT印刷适性仪(AIC2-5型)对常用印刷用纸(胶版纸、铜版纸)的吸墨性能进行了实验研究.结果表明,在不同印刷速度下保证纸张最佳吸墨性的压力值是不同的,胶版纸的吸墨性对印刷压力比较敏感;在相同条件下,铜版纸对印刷压力的要求低于胶版纸.     

U-PVC型材专用低吸油值纳米碳酸钙制备

采用鼓泡搅拌釜液相合成纳米碳酸钙,用电导率仪和pH计监控整个碳化过程,用TEM、BET等方法对所得纳米碳酸钙进行表征。研究表明:控制碳化反应温度在20~25℃,选择合适的总通气量以控制反应时间,添加剂的加入时间选择在碳酸钙晶核形成后,可制备出低吸油值、粒径均匀、形貌规整的纳米碳酸钙产品,适用作U-PVC型材的填充剂。     

聚丙烯酸钠缓释作用及其在砂土中吸液性能的探讨

探讨了砂土和溶液中水量、时间、pH值、温度、肥料对聚丙烯酸钠吸液倍率的影响以及聚丙烯酸钠对肥料的缓释作用。实验表明,在砂土中,聚丙烯酸钠的吸液倍率比溶液中降低105g;吸液饱和时间比溶液中延长60min;pH值(4～10),温度(20℃～80℃)对聚丙烯酸钠吸液倍率影响不大;非电解质肥料对吸液倍率影响很小,电解质肥料对吸液倍率影响较大。经过96小时,吸收1.0%KCl和1.0%尿素溶液的聚丙烯酸钠对钾和氮素累积释放率分别不到25.0%和80.0%,说明聚丙烯酸钠对尿素和KCl均有一定的缓释作用。     

Two in One: Modified Polyurethane Foams by Dip‐Coating of Halloysite Nanotubes with Acceptable Flame Retardancy and Absorbency

Poor flame retardancy of polyurethane foam (PUF) limits its practical application in many fields. Here, flame‐retardant performance of PUF is improved by a simple dip‐coating method. Halloysite nanotube (HNT) coating can be uniformly bonded to PUF surfaces via hydrogen‐bonding interactions, which is confirmed by element mapping and X‐ray photoelectron spectra. Density and mechanical properties of PUF increase with the concentration of HNT suspension, while porosity of the foam decreases with HNT loading. Weight ratio of HNTs to PUF in the composite can be achieved as high as 65.2%. Surfaces of PUF transfer from hydrophobic to super‐hydrophilic after HNT coating, and the water contact angle decreases from 116° to 0° after HNT coating. As a result, methylene blue adsorption capacity of HNTs‐coated PUF increases from 0.02 to 0.15 mg g^?1, and adsorption efficiency can reach 98% after 10 s. HNT coating can prevent PUF from burning and dripping, which suggests that flame‐retardant performance of PUF is significantly improved by HNTs. This work establishes a general procedure for improving flame retardancy and dye absorbency of polymer materials by simple dip‐coating of environmental‐friendly clay nanotubes, which shows great potential in high‐performance polymer and functional composite materials.     

基于单片机的半自动生化分析仪系统设计

介绍一种以C8051F120单片机为控制器的半自动生化分析仪的系统设计.仪器采用吸光光度法测量原理,在测量方法上避免了模拟对数放大与运算;用步进电机控制选择8种波长的滤光片;用串行16位模/数转换器AD7715实现了高精度的数据采集;温度控制采用无触点的开关控制,并实现了PID调节.