泡沫冻胶调剖体系的优选及性能评价

优选了泡沫冻胶调驱体系,研究了聚合物、交联剂的用量及温度、pH值、矿化度对泡沫冻胶体系的影响。结果表明,泡沫冻胶体系的组成为0.2%(质量分数,下同)、相对分子质量2000万的部分水解聚丙烯酰胺,0.15%~0.2%交联剂,0.2%表面活性剂发泡剂。在60℃、pH=7、矿化度6000 mg/L条件下,泡沫冻胶体系的黏度达到最大值,成胶强度最大;当黏度达到最大值之前,泡沫冻胶的黏度随着温度的升高、pH和矿化度的增加而增大;当黏度超过最大值后,泡沫冻胶的黏度随着温度的升高、pH和矿化度的增加逐渐降低。     

聚乙烯醇/壳聚糖凝胶的制备及性能研究

通过壳聚糖与聚乙烯醇共混,用戊二醛作交联剂制备了聚乙烯醇/壳聚糖凝胶,并考察了不同质量比、交联剂浓度以及温度对凝胶的硬度和溶胀性能的影响.结果表明:随着聚乙烯醇与壳聚糖的质量比、交联剂浓度的增大,凝胶的硬度增大而溶胀性能减小.随着成胶温度的升高,凝胶的硬度和溶胀性能均先增大后减小.在此基础上,通过两种方法将银粒子分散到凝胶中:(1)在成胶过程中加入硝酸银,成胶后用还原剂硼氢化钠还原;(2)制成凝胶以后,将凝胶依次浸泡在硝酸银和硼氢化钠溶液中.通过XRD和SEM表征,说明两种方法均能将银粒子均匀分散在凝胶中,从而表明壳聚糖凝胶可以作为金属纳米粒子的载体,这将在生物医学方面具有良好的应用前景.     

粉煤灰浮选活性炭对含铬废水的吸附研究

以火电厂的废渣浮选出来的精炭为原料,制备活性炭,用于吸附水溶液中的六价铬。讨论了接触时间、pH值和温度对六价铬吸附过程的影响,并对其速率方程进行拟合。结果表明,随着吸附时间和温度的增大,Cr(Ⅵ)吸附量呈不断增加的趋势,约7 h达到平衡。平衡吸附量随pH值的升高而减小,pH值越低,平衡吸附量越大。吸附速率随浓度升高而增大,且成直线关系,直线方程为r=0.0278c-0.115。     

刺激响应性聚甲基丙烯酸二甲氨基乙酯水凝胶

以二甲基丙烯酸乙二醇酯为交联剂,甲基丙烯酸-N,N-二甲氨基乙酯为单体,分别采用普通自由基聚合和原子转移自由基聚合合成交联聚甲基丙烯酸-N,N-二甲氨基乙酯(PDMAEMA)。由于PDMAEMA同时呈现温度、pH和离子强度敏感性,文中研究了离子强度、pH值对交联PDMAEMA在水溶液中的溶胀比、体积相转变温度(TVPT)的影响。实验结果表明,PDMAEMA水凝胶的溶胀度随着离子强度和pH值的增大而减小;溶液离子强度的改变导致体系中的水状态发生改变,TVPT也随之改变;在酸性条件下TVPT随着pH值的增加而降低。     

碳纳米管/炭黑复配对天然橡胶湿法混炼共沉胶性能的影响

通过制备碳纳米管(CNTs)/炭黑(CB)/天然橡胶(NR)湿法混炼共沉胶,分析碳纳米管与炭黑复配后的共沉胶物理力学性能、硫化性能和动态力学性能,并与传统干法混炼胶进行对比。结果表明,在湿法混炼共沉胶中,随着填料中碳纳米管份数的增大,胶料的焦烧时间及正硫化时间逐渐缩短,其中焦烧时间缩短了11%,正硫化时间缩短了18%。相比于单一填料的补强体系,复配填料体系更有助于2种填料各自的分散。扫描电镜和动态力学性能分析共同显示,复配填料体系在湿法混炼天然胶中分散得更好,且复合材料拉伸强度、撕裂强度和断裂伸长率更高。     

胶原纤维对水中Cr(Ⅵ)的吸附性能研究

胶原纤维(CF)作为吸附剂去除水中Cr(Ⅵ),研究了CF去除Cr(Ⅵ)时溶液pH值、温度、吸附剂用量和Cr(Ⅵ)初始浓度对去除效率的影响。结果显示,CF对Cr(Ⅵ)的去除率随溶液pH值降低而升高,在pH值为2.0时达到最大,随吸附剂用量增大而增大,随Cr(Ⅵ)初始浓度增加而减小,CF对Cr(Ⅵ)的吸附量随吸附剂用量增加而减小;随Cr(Ⅵ)初始浓度增加而增加,最后趋于稳定。吸附平衡时间为6h,最佳吸附温度为40℃。测定了吸附等温线和吸附动力学曲线,结果表明,Freundlich等温方程能更好地描述CF对Cr(Ⅵ)的吸附,吸附动力学符合伪二级吸附速率方程。FT-IR和SEM-EDS分析表明,CF表面含有大量氨基羧基及羟基等活性官能团,CF对Cr(Ⅵ)的吸附过程存在铬酸根阴离子与质子化活性官能团的静电吸附作用和离子交换作用。     

氯化钠对阳离子杂化硅溶胶凝胶化的影响

以正硅酸乙酯(TEOS)为前驱物,无水乙醇为共溶剂,盐酸为催化剂,双十八烷基二甲基氯化铵(DODAC)为添加剂制备阳离子杂化硅溶胶.通过分析溶胶在胶凝之前相关性能的变化,探讨了氯化钠浓度对阳离子杂化硅溶胶凝胶化的作用机理.结果表明氯化钠可以使溶胶体系粘度增大、透光率减小、Zeta电位降低、凝胶化时间缩短.说明氯化钠能使硅溶胶颗粒表面的离子头之间的排斥作用减弱,溶胶颗粒脱离水相的趋势增大,促进了颗粒之间的聚集,虽然氯化钠还能使体系的pH值降低,凝胶速度减慢,但促凝作用比缓凝作用更显著,并且浓度越大促凝作用越强.     

氧化塘污泥流变特性的研究

本文选用聚铁作为絮凝剂,考察了剪切速率、污泥浓度、污泥pH值、聚铁投加量因素对污泥流变性的影响。研究表明:污泥属于非牛顿流体,具有剪切稀化的特性;在实验污泥浓度范围内,污泥表观粘度随着其浓度增大而增大;pH值变化对污泥流变性质影响不同,酸性时体系粘度较小,随着pH的增大,表观粘度增大,碱性表观粘度较大;随着聚铁浓度的增大,污泥的表观粘度减小。这些实验现象可用颗粒的空间结构化理论及絮凝原理予以解释。     

不同pH值下纳米纤维素晶体悬浮液的流变性能研究

研究不同pH值下的棒状纳米纤维素晶体悬浮液体系的细微结构变化与流变行为的关系,探讨了pH调节剂的加入所引起的体系结构变化的机理,并采用线性的流变学方法研究了各体系流动性、蠕变性以及频率响应性等动态粘弹性质,分别利用Power-Law模型、Burger模型对体系的流动曲线、蠕变曲线进行了数据拟合,研究发现,pH=2的悬浮液体系具有典型的液晶结构,呈现三段式＂S＂型流动曲线;随着pH值的增加,体系逐渐形成凝胶结构且凝胶强度越来越强,＂S＂型流动曲线逐渐模糊,蠕变的弹性柔量逐渐增大,粘性柔量逐渐减小,而pH〉9后出现蠕变弹性恢复,体系储能模量G′和损耗模量G″均有明显增加,但损耗角正切tanδ值先减小然后增大,pH=7体系内耗最小。     

pH值对海藻酸钠溶液黏度及体系中氢键的影响规律

为了分析不同pH值下海藻酸钠(SA)溶液黏度的变化规律及其形成机制,首先测试了不同pH值下SA溶液的流变曲线,采用高斯分峰拟合法对各SA溶液的FTIR谱图中羟基的特征吸收峰进了分峰拟合,并根据拟合结果统计了各SA溶液体系中氢键的类型和相对强度。同时研究了储存时间对不同pH值SA溶液的黏度和体系中氢键强度的影响。结果表明,不同pH值下SA溶液均呈现剪切变稀的特性,且随着pH值的增大,SA溶液的黏度下降;各SA溶液体系中存在分子间和分子内氢键,SA溶液中分子间氢键的相对强度随着pH值的增大而降低,同时SA表面的负电荷增加,使得SA分子之间的静电斥力增加,导致黏度下降。冷藏储存24 h后,pH值为5和9的SA溶液体系中分子间氢键的相对强度分别增加4. 22%和20. 13%,导致SA溶液的黏度增大;而pH值为7的SA溶液体系中分子间氢键的相对强度仅增加0. 29%,其溶液的黏度几乎没变。     

Hexavalent chromium reduction with scrap iron in continuous-flow system Part 1: effect of feed solution pH

The reduction of hexavalent chromium by scrap iron was investigated in continuous system, using long-term column experiments, for aqueous Cr(VI) solutions having low buffering capacities, over the pH range of 2.00-7.30. The results showed that the initial pH of Cr(VI) solution significantly affects the reduction capacity of scrap iron. The highest reduction capacity was determined to be 19.2 mg Cr(VI)/g scrap iron, at pH 2.50, and decreased with increasing the initial pH of Cr(VI) solution. A considerable decrease in scrap iron reduction capacity (25%) was also observed at pH 2.00, as compared to pH 2.50, due to the increased contribution of H(+) ions to the corrosion of scrap iron, which leads to a rapid decrease in time of the scrap iron volume. Over the pH range of 2.50-7.30, hexavalent chromium concentration increases slowly in time after its breakthrough in column effluent, until a steady-state concentration was observed; similarly, over the same pH range, the amount of solubilized Cr(III) in treated column effluent decreases in time, until a steady-state concentration was observed. The steady-state concentration in column effluent decreased for Cr(VI) and increased for Cr(III) with decreasing the initial pH of Cr(VI) solution. No steady-state Cr(VI) or Cr(III) concentrations in column effluent were observed at pH 2.00. Over the entire studied pH range, the amount of Fe(total) in treated solution increases as the initial pH of column influent is decreased; the results show also a continuously decrease in time of Fe(total) concentration, for a constant initial pH, due to a decrease in time of iron corrosion rate. Cr(III) concentration in column effluent also continuously decreased in time, for a constant initial pH, over the pH range of 2.50-7.30. This represents an advantage, because the amount of precipitant agent used to remove Fe(total) and Cr(III) from the column effluent will also decrease in time. The optimum pH for Cr(VI) reduction with scrap iron in continuous-flow system was established at the value of 2.50.     

苯丙乳液应用性能的影响因素

以苯乙烯(St)、丙烯酸异辛酯(2-EHA)为主要单体采用预乳化半连续种子乳液聚合工艺合成了苯丙乳液。用激光粒度仪测试了乳胶粒粒径大小及粒度分布, 用差示扫描量热法(DSC)测试了共聚物的玻璃化转变温度, 用流变仪测量了乳液的流变性能, 研究了单体配比、交联剂用量以及乳化剂用量对乳胶粒粒径、乳液的稳定性、流变性、粘结性能的影响。结果表明: 合成的苯丙乳液为假塑型流体; 乳液的粘度随着2-EHA/St配比、交联剂用量和乳化剂用量的增加而升高; 乳液的稳定性随着乳化剂用量的增大而提高, 随着交联剂用量的增大而降低; 乳液胶膜的粘结性随着交联剂用量以及2-EHA/St配比的增大而增强; 乳胶粒的粒径随着乳化剂用量的增加而变小, 随着交联剂用量的增加而变大。     

反应流变性对嵌段聚氨酯结构与性能的影响

利用自行设计的绝热反应流变仪研究了聚氨酯（脲）快速扩链过程的反应流变性，用流变仪同时测得绝热扩链反应过程的温度和粘度对时间的关系，将绝热温升与反应热关联，显示凝胶时官能团反应程度、粘度－时间曲线和凝胶时间，可预示软硬链段微相分离程度、反应程度和微相分离程度影响着嵌段聚氨酯（脲）的结构和力学性能。     

电沉积Ni-Cr合金工艺研究

含有一定量Cr的Ni-Cr镀层具有良好的耐磨、耐腐蚀性能.选取柠檬酸钠作为配位剂,用动电位扫描法研究了电沉积Ni-Cr合金时的阴极行为,同时对镀层的耐腐蚀性进行了试验.试验结果表明:镀液中加入配位剂柠檬酸钠可以提高阴极极化;pH值、阴极电流密度、配位剂对镀层中铬含量影响较大,在一定范围内增大pH值,增加配位剂的用量,提高电流密度,有利于提高镀层中铬的含量,最佳工艺条件为pH值为2.5,阴极电流密度为25A/dm2,镀液中柠檬酸钠的含量为35g/L,镀层中铬质量分数为20%左右时,Ni-Cr合金镀层的耐腐蚀性能最好.     

AIM中橡胶相交联密度对AIM/PMMA共混物性能的影响

采用乳液聚合方法制备了四种不同交联密度且粒径及折光指数可控的丙烯酸酯类冲击改性剂(AIMs),考察了AIMs中橡胶相的交联密度变化对AIM/PMMA共混物力学性能及光学性能的影响。结果表明,AIM/PMMA共混物的冲击强度随AIM中交联剂用量的提高呈先上升后下降趋势,当AIM的橡胶相交联剂含量为2%(质量分数,下同)时,AIM/PMMA共混物的最大裂纹引发能(Kmax)、裂纹增长能(Uprop)及冲击强度均达到最大值,与纯聚甲基丙烯酸甲酯(PMMA)相比较,其冲击强度提高了5倍,且光学性能没有明显下降。结合共混物的冲击强度与形变区的扫描电镜(SEM)观察,可见断裂过程中此种AIM橡胶粒子的空洞化能够有效地促进基体树脂的能量吸收。     

Dynamic cross-linking effect of Mg2+ to enhance sieving properties of low-viscosity poly(vinylpyrrolidone) solutions for microchip electrophoresis of proteins

We report a dynamic cross-linking effect of Mg2+ that enhances the sieving properties of low-viscosity poly(vinylpyrrolidone) (PVP) solutions. A low-viscosity PVP solution was applied to nondenaturing microchip electrophoresis of protein samples using microchips made of poly(methyl methacrylate). The separation resolution of nondenatured protein markers in 1.8% PVP solution was improved by adding 1-20 mM MgCl2. We studied the effect of the ratio of cross-linking agent on mobility of protein samples and showed that protein retardation (ln micro/micro0) is correlated with the ratio of cross-linking agent to PVP ([cMg2+/cPVP]) as ln micro/micro0=A'[cMg2+/cPVP]b'. A' was related to the protein radius (R), and b' was found to be 0.72 for proteins with R=2.4 nm and 0.82 for proteins with R=1.85 nm. A structural study of PVP in semidilute solutions using dynamic light scattering showed that incremental increases of Mg2+ ion concentration from 5 to 20 mM in 1.8% PVP solution increased the hydrodynamic radius of PVP polymers by 20%.     

含铝凝胶燃料的流变特性研究

在庚烷/硝酸异丙酯混合体系中加入不同粒径的无机纳米凝胶剂,实现燃料凝胶化;并在部分样品中添加纳米铝粉,制得一系列凝胶燃料;以此来研究凝胶剂粒径和铝粉含量对凝胶燃料流变性能的影响规律。采用激光共聚焦显微镜、比重杯和氧弹量热仪测试凝胶燃料的微观形貌、密度与燃烧热;利用流变仪测试凝胶燃料的剪切变稀性、蠕变性以及非线性黏弹性等流变性能。结果表明:凝胶化的燃料具有更高的密度和体积燃烧热;大粒径凝胶剂体系的假塑性更明显,网络强度更大,但内部结构易碎;铝粉的加入破坏了絮凝体网络的连续性,增强了凝胶燃料的塑性,降低了蠕变恢复能力,但会提升凝胶燃料的整体强度。添加质量分数20%的铝粉后,凝胶燃料的零切黏度η₀提高了6倍,储能模量G′₀ 提高了3倍,蠕变恢复能力r_c 下降了33%。     

草鱼鱼鳞胶原蛋白的凝胶性能研究

以草鱼鱼鳞为原料,分别提取鱼鳞中的酸溶性胶原蛋白(ASC)和酶溶性胶原蛋白(PSC),利用动态流变仪和物性分析仪开展胶原凝胶形成和凝胶性能的相关研究,并与哺乳动物来源的猪皮胶原(PC)相比较。实验结果表明,制备所得的3种胶原蛋白均为典型的Ⅰ型胶原并具有完整的3螺旋结构;蛋白浓度和体系pH值是影响胶原凝胶形成的重要因素。ASC形成凝胶的临界pH值为4.5,而PSC和PC为5,3种胶原蛋白凝胶形成的临界蛋白浓度均为0.5mg/mL。粘弹性分析和质构分析的实验结果表明,ASC容易形成一种硬度高但脆性大的凝胶,升高温度可导致其凝胶结构发生不可逆的破坏,而PSC和PC更容易形成一种硬度小但韧性好的凝胶,在低于蛋白变性温度的条件下升高温度可以有效提高凝胶硬度;胶原蛋白凝胶质构受蛋白浓度、体系pH值和蛋白的3螺旋结构影响。蛋白浓度越高,体系pH值越接近中性,形成的凝胶硬度越大,但脆性也随之增加;当胶原蛋白因受热而导致其三螺旋结构破坏后,其凝胶形成能力急剧下降。     

疏水缔合两亲聚合物凝胶的形成规律及性能

基于疏水缔合两亲聚合物具有良好的耐温抗盐性能,研究了以其为主剂的新型凝胶体系.利用黏度法筛选出体系的最优配方:两亲聚合物主剂的相对分子质量为750×10<'4>、浓度1000mg/L,交联剂乌洛托品、间苯二酚、助剂柠檬酸的最佳用量分别为0.3%、0.02%、O.3%(质量分数,下同),且最佳体系的储能模量G'大于损耗模...     

Chromium(VI) biosorption by dried Rhizopus arrhizus: effect of salt (NaCl) concentration on equilibrium and kinetic parameters

Some industrial wastewaters contain high quantities of salts besides heavy metal ions. The presence of salt ions leads to high ionic strength, which may significantly affect the performance of the biosorption process so the effect of salts on the biosorption of heavy metal ions should be investigated. In this study the biosorption of chromium(VI) from saline solutions on dried Rhizopus arrhizus was studied as a function of pH, initial chromium(VI) and salt (NaCl) concentrations in a batch system. The biosorption capacity of R. arrhizus strongly depended on solution pH and maximum chromium(VI) sorption capacity of sorbent was obtained at pH 2.0 both in the absence and in the presence of increasing concentrations of salt. Chromium(VI)-salt biosorption studies were performed at this pH value. Equilibrium uptakes of chromium(VI) increased with increasing chromium(VI) concentration up to 250mgl(-1) and decreased considerably by the presence of increasing concentrations of salt. At 100mgl(-1), initial chromium(VI) concentration, dried R. arrhizus biosorbed 78.0mgg(-1) of chromium(VI) in 72h without salt medium. When salt concentration was raised to 50gl(-1), this value dropped to 64.0mgg(-1) of chromium(VI) at the same conditions resulting in 17.9% decrease of biosorption capacity. The equilibrium sorption data were analysed by using Freundlich, Langmuir, Redlich-Peterson and Langmuir-Freundlich (Sips), the two and three parameters adsorption models, using non-linear regression technique and isotherm constants were evaluated depending on salt concentration. The Langmuir-Freundlich (Sips) was the best suitable adsorption model for describing the biosorption of chromium(VI) individually and in salt-containing medium. Pseudo-first-order, pseudo-second-order and saturation type kinetic models described the biosorption kinetics accurately at all chromium(VI) concentrations in the absence and in the presence of changing concentrations of salt. Isotherm and saturation type kinetic constants varied due to the level of salt were expressed as a function of initial salt concentration.