疏水改性胍胶稠化剂的制备及结构与性能的相关性

以胍胶为原料,溴代十二烷（C12H25Br）为醚化剂,在碱的催化作用下通过悬浮聚合制备出疏水改性胍胶,并制备了改性胍胶的水溶液及冻胶。通过红外、X射线衍射（XRD）、热重（TGA）测试对改性胍胶结构与性能进行了研究。测定了溶液表观黏度,并对冻胶耐剪切、耐温性能及粘弹性进行了研究。红外和XRD分析表明,疏水长链被成功引入...     

基于相分离法制备聚丙烯微孔膜性能的研究

基于相分离法以对二甲苯为溶剂,2-丁酮为非溶剂制备出了具有超疏水性的聚丙烯(PP)微孔膜,用傅里叶红外光谱、接触角、扫描电镜、分别表征了微孔膜的化学组成、润湿性能及表面形貌。通过改变聚丙烯初始浓度、2-丁酮体积比、处理温度等条件,获得不同微观形貌的PP膜,通过分析可知微观形貌对微孔膜的疏水性能有很大影响。通过系统探讨工艺条件对微孔膜疏水性能的影响规律,得出:随着2-丁酮的体积比、PP初始浓度的增加,PP膜的疏水性能改善,且处理温度越低PP膜的疏水性越好。     

溶胶-凝胶法制备疏水型SiO-2气凝胶

以正硅酸乙酯 (TEOS)为硅源 ,用三甲基氯硅烷 (TMCS)为疏水试剂 ,通过溶胶 凝胶法在室温下制备出疏水型SiO2 气凝胶。用傅立叶变温红外 (FT IR)、扫描电镜 (SEM)、透射电镜 (TEM)和吸水性能对疏水型SiO2气凝胶的结构和性能进行了研究     

相分离法制备多孔聚合物超疏水涂层EI北大核心CSCD

以1,4-丁二醇(BDO)和环己醇为致孔剂,甲基丙烯酸丁酯(BMA)为反应性单体、乙二醇二甲基丙烯酸酯(EDMA)为交联单体,偶氮二异丁腈(AIBN)为引发剂进行原位自由基聚合,利用相分离法制备了具有超疏水性能的多孔聚合物涂层。考察了EDMA和BDO用量对涂层性能的影响。通过接触角(CA)、扫描电镜(SEM)和原子力显微镜(AFM)对涂层的疏水性和结构进行了表征。结果表明,涂层的疏水性分别随着EDMA和BDO用量的增加先升高后下降,当ω(EDMA)=25%及ω(BDO)=25%时,涂层表面具有微/纳米复合结构,其静态水接触角(CA)和滚动角(SA)分别为153.8°和4°,不同pH条件下涂层均显示良好的耐酸碱盐效果。     

聚-3-羟基丁酸酯及其共聚物的合成与表征

合成一种环烷氧锡化合物,用氢谱、元素分析和质谱对其结构进行表征确认,并以其作为β-丁内酯开环聚合的引发剂制备聚-3-羟基丁酸酯,考察了单体引发剂配比、聚合时间和聚合温度等聚合条件对聚合产物特性粘度的影响.由丁内酯与丙交酯、己内酯共聚制备聚(丁内酯-丙交酯)和聚(丁内酯-己内酯)共聚物,并用FT-IR、1H-NMR、DSC等手段对聚合物的结构及性能进行了表征.     

溶胶-凝胶法制备超疏水PMHS-SiO2涂膜

通过溶胶-凝胶法制备了二氧化硅(SiO_2)溶胶,并以含氢硅油(PMHS)为改性剂,对SiO_2粒子表面进行疏水化处理,然后在玻璃基片上提拉成膜和加热凝胶化,制备出超疏水PMHS-SiO_2涂膜。通过接触角测定、红外光谱、透射电镜、扫描电镜、湿热老化等手段对涂膜的制备条件、结构与性能进行了研究。结果表明,在PMHS/SiO_2质量比为1:1、改性时间为4 h、涂膜热处理温度170℃、热处理时间3 h的条件下,可制得具有优良超疏水性的PMHS-SiO_2涂膜,其水接触角可达163°,滚动角可低至3°-5°,且具有优异的耐湿热老化性能。对改性前后的SiO_2溶胶和PMHS-SiO_2涂膜的结构形态研究发现,PMHS与SiO_2表面产生了化学结合,形成了PMHS-SiO_2杂化交联材料;涂膜表面被疏水性PMHS包覆,同时较均匀地分布着许多粒径为50-400 nm的微米-纳米双重粗糙度的微凸体,这是产生优异的超疏水性能的主要原因。     

炭膜表面疏水改性及老化性能研究

采用溶胶凝胶法,以正硅酸乙酯(TEOS)和甲基三乙氧基硅烷(MTES)为混合硅源,合成疏水硅溶胶,将其浸渍涂覆在卷式炭膜上,经干燥、热处理制备了具有高疏水性能的疏水炭膜.考察了硅溶胶制备工艺和膜热处理工艺对所制备炭膜疏水性能的影响.采用水接触角测试仪、TG、FTIR、AFM、SEM和TEM等测试手段,对疏水炭膜的表面结构和疏水性能进行了表征.结果表明,通过硅溶胶表面改性,在炭膜表面引入了甲基化的二氧化硅的表面结构,提高了其疏水性能.硅溶胶的制备工艺对所制备疏水炭膜的表面化学结构、形貌及粗糙度有较大的影响.其中硅溶胶合成反应温度对提高膜表面疏水性能的影响最为显著;膜表面甲基基团含量对改善炭膜表面的疏水性能起到决定性作用.通过控制硅溶胶合成和膜的热处理工艺可以有效地调控疏水炭膜的表面疏水性能;在最佳条件下制备的疏水炭膜,其表面粗糙度为34.263nm;水接触角达到138°左右,表现出良好的疏水性能.气体渗透性能测试表明,炭膜疏水改性对炭膜的气体渗透性能影响较小,但明显地提高了炭膜的抗老化性能.     

聚苯乙烯-丙烯酸复合粒子/乙二醇体系的流变性能研究

通过无皂乳液聚合法制备了聚苯乙烯-丙烯酸(PS-AA)纳米粒子,产物粒子呈球状,且具有核壳结构;通过高能球磨法将其分散在乙二醇中,得到一种新型有机高分子体系的剪切增稠液(STF),分别采用动态流变仪和扩散波谱仪(Diffusing Wave Spectroscopy,DWS)对其机械流变性能和微流变性能进行了测试,经对比分析,双层论证了体系剪切增稠的特性。     

Poly(VBMIMPF_6)/BMIMPF_6离子凝胶的制备与性能

以1-乙烯基-3-丁基咪唑六氟磷酸盐(VBMIMPF6)为单体,1-丁基-3-甲基咪唑六氟磷酸盐(BMIMPF6)为溶剂和电解质,并以聚乙二醇二丙烯酸酯(PEGDA)为交联剂,采用原位紫外交联的方法制备出了一种新型聚离子液体基离子凝胶电解质。通过扫描电子显微镜、流变性能、力学拉伸和电化学交流阻抗等手段,考察了离子凝胶电解质的微观结构、流变性能、力学性能和电学性能。流变性能测试结果表明,离子凝胶具有很高的储能模量(10~4~10~5 Pa),且温度200℃内储能模量基本保持不变。拉伸性能测试结果表明,体系具有很强的力学性能且拉伸强度达到10~5 Pa数量级。电学性能测试结果表明室温下离子凝胶具有很高的电导率(10~(-4)~10~(-3)S/cm),且电导率随BMIMPF6含量的增加而增大。     

3,3',5,5'-四甲基-4,4'-二氨基二苯甲烷及其聚酰亚胺的制备及其性能研究

以2,6-二甲基苯胺为原料,通过一步反应制备了3,3′,5,5′-四甲基-4,4′-二氨基二苯甲烷(TMDDM),并对其结构进行表征。将TMDDM、4,4′-二氨基二苯醚(ODA)与4,4′-氧双邻苯二甲酸酐(ODPA)以不同的配比进行三元共聚,通过热亚胺化合成了6种TMDDM/ODA/ODPA-聚酰亚胺(PI)薄膜,随后对6种薄膜进行了结构表征和性能研究。结果表明:6种PI薄膜具有优良的热性能、疏水性、紫外-可见光透过率、机械性能和溶解性。     

Rheological behavior of gel of xanthan with seed galactomannan: Effect of hydroalcoholic–ascorbic acid

The rheological properties of a physically linked hydroalcoholic gel obtained from a binary system consisting of xanthan and of galactomannan from the seeds of Mimosa scabrella (X:GB) with a low Man:Gal ratio of 1.1:1 were compared to those of guar gum (Man:Gal ratio 1.5:1, X:GG). The rheological analysis demonstrated an improvement of strength of X:GB and X:GG hydrogels after dispersion of the polysaccharides in buffer with 1,2-propanediol. The addition of ascorbic acid to these hydrogel formulations resulted in a slight decrease of gel strength. Both hydrogels presented rheological stability over 12 weeks at ambient temperature.     

醇对瓜尔胶高分子水溶液黏度的影响

潮定了异丙醇和乙二醇对瓜尔胶高分子水溶液黏度的影响,发现随着异丙醇的加入,瓜尔胶高分子水溶液的特性黏数逐渐减小,Huggins相互作用参数会逐渐增加;与此相反,随着乙二醇的加入,瓜尔胶高分子水溶液的特性黏数逐渐增加,Huggins相互作用参数却逐渐减小.醇和瓜尔胶高分子之间缔合导致高分子链疏水性质和空间位阻效应的改变,...     

瓜尔胶-g-聚丙烯酸/OMMT纳米复合吸水性树脂的制备与表征

以瓜尔胶(GG)、季按盐改性的蒙脱土(OM-MT)和丙烯酸(AA)为原料,N,N'-亚甲基双丙烯酰胺(MBA)为交联剂,在水溶液中通过接枝聚合反应制备了瓜尔胶-g-聚丙烯酸/OMMT纳米复合吸水性树脂.研究了OMMT的含量、MBA的浓度对产物吸水倍率的影响,考察了OMMT的引入对产物反复溶胀性能的影响.并用傅利叶变换红...     

Investigations of the properties of the manganese dioxide suspensions in the presence of guar gum and carboxymethylcellulose

Properties of manganese dioxide suspensions in the presence of two polysaccharides: non-ionic guar gum (GG) and anionic carboxymethylcellulose (CMC) were investigated using NaCl as a background electrolyte. The colloidal stability of MnO₂ suspensions in the presence and absence of these two polymers was measured. It was found that both polymers improve stability of measured suspensions. This fact results from steric stabilization (low polymer concentrations) and depletion stabilization (high polymer concentrations) for MnO₂ particles covered with macromolecules. Next the kinetics of the adsorption of these two polymers on MnO₂ as well as the heats of GG and CMC adsorption processes were measured. The obtained data proved that CMC is adsorbed more effectively on the manganese dioxide surface than guar gum. To obtain more information about the changes of adsorption of these polymers on MnO₂ some factors influencing this process (pH, ionic strength of the background electrolyte) were investigated. The data obtained from the surface charge density and the zeta potential measurements allowed the analysis of the structure of the electric double layer created by polymers on the solid surface.     

包装用三元共聚树脂的合成及其吸水与 热降解特性

以2-丙烯酰胺基-2-甲基丙磺酸(AMPS)、丙烯酸(AA)、瓜尔胶(GG)为原料,N,N-亚甲基双丙烯酰胺(NMBA)为交联剂,通过超声辐射合成AMPS/AA/GG三元共聚树脂,借助热重曲线(TG)对树脂的热降解特性进行分析。实验结果表明:在优化条件下,树脂的吸水率最大,而且树脂具有良好的耐热性能和保水性能;热分解动力学分析结果显示树脂热降解活化能为164.29 kJ/mol,lg A为13.84,反应级数n=1/6,树脂的热降解遵循44号随机成核和随后生长机理。     

Geotechnical properties of problematic expansive subgrade stabilized with guar gum biopolymer

Clean Technologies and Environmental Policy - This article presents a comprehensive study on the geotechnical behavior of problematic expansive subgrade stabilized by guar gum (GG) biopolymer. In...     

pH敏感瓜胶/聚丙烯酸半互穿网络水凝胶的溶胀动力学

考察了瓜胶(GG)、丙烯酸(AA)的起始加料量和溶胀介质pH对瓜胶/聚丙烯酸半互穿网络水凝胶溶胀机理及溶胀动力学的影响。结果表明:在pH=3.0时,将GG用量从0增加到25 g/L,最大溶胀率从9.93下降到2.83,对应的溶胀特征指数n由0.600减小到0.203,水的扩散趋于F ick ian模式;将AA用量从125 g/L增加到375 g/L,最大溶胀率从3.14增加到4.30,n从0.484增加到0.609,水的扩散趋于non-F ick ian模式;GG/PAA半互穿网络水凝胶的溶胀行为满足Schott二级动力学方程。将溶胀介质pH从3.0提高到7.4,水凝胶的溶胀率、扩散特征指数n均明显增加。因此调整GG、AA用量以及溶胀介质pH可改变体系的溶胀性能。     

Flow and Consistency Index Dependence of Pseodoplastic Guar Gum Solutions

Abstract

The flow and consistency index values for aqueous solutions of guar gum have been shown. The effects of particle size, ionic strength and pH variations on rheological parameters were investigated. The rheograms generated in this study were fitted to the power law with a correlation coefficient greater than 0.99 in all cases. From a practical point of view, the flow index of gum solutions is a useful parameter in designing a gum system for a given formulation. This study used guar gum as a model to point out the utility of flow and consistency index in formulation work.     

Polysaccharide matrices for microbially triggered drug delivery to the colon

Matrix tablets were prepared using xanthan gum (XG) and guar gum (GG) in varying proportions, and the suitability of the prepared tablets was evaluated for colon specific drug delivery. Indomethacin was used as a model drug. The ability of the prepared matrices to retard drug release in the upper gastrointestinal tract (GIT) and to undergo enzymatic hydrolysis by the colonic bacteria was evaluated. For this, drug release studies were carried out in the presence of rat cecal content. Further cecal content of rats with induced enzymatic activity were used. To ascertain the role of bacterial flora in carrying out the hydrolysis of the tablet, cecal content of rats treated with antibiotics were used in the dissolution media. Presence of XG in combination with GG in the tablets could retard drug release in the conditions of the upper GIT. However, the presence of GG and starch made these matrices microbially degradable. Guar gum alone as a drug release-retarding excipient in the matrices does not achieve the desired retardation. Presence of XG in the tablets not only retards the initial drug release from the tablets, but due to high swelling, makes them more vulnerable to digestion by the microbial enzymes in the colon.