交联型水性硝化纤维乳液的制备及应用研究

以甘油为交联剂、硝化纤维(NC)为基体和邻苯二甲酸二丁酯(DBP)为增塑剂,制备了交联型水性硝化纤维(WNC)乳液。探讨了Tri-IPDI(异佛尔酮二异氰酸酯三聚体)、甘油及DBP对WNC乳液及其胶膜性能的影响。研究结果表明:当n(Tri-IPDI)∶n(NC)=0.54∶1.00、w(甘油)=1.0%和w(DBP)=1.5%(均相对于总物料质量而言)时,WNC乳液的储存稳定性良好,WNC胶膜的耐水性和力学性能明显提高,其断裂伸长率由无增塑剂时的85.3%增至356.2%、拉伸强度由1.52 MPa降至1.30 MPa。     

环氧氯丙烷改性水性硝化纤维乳液的制备及性能

以硝化纤维(NC)、异佛尔酮二异氰酸酯(IPDI)和二羟甲基丙酸(DMPA)等为主要原料,制得自乳化型WNC(水性硝化纤维)乳液;然后以环氧氯丙烷(ECH)为交联改性剂,制成改性WNC乳液胶粘剂。研究结果表明:当w(DMPA)=3.5%、w(ECH)=7%时,改性WNC乳液具有优良的储存稳定性,其胶膜耐水性(吸水率为9.1%)、T型剥离强度(7.1 N/mm)、拉伸强度(14.9 MPa)和断裂伸长率(529.3%)俱佳,柔韧性和耐热性优异。     

水性硝化纤维/聚乙烯醇复合乳液的制备与性能

将水性硝化纤维(WNC)乳液与聚乙烯醇(PVA)溶液共混制备了WNC/PVA复合乳液。用傅里叶变换红外光谱(FT-IR)和透射电镜(TEM)表征了材料的相容性,并通过万能材料试验机、吸水率测试和热重分析等方法研究了PVA含量对复合材料力学性能、耐水性和热性能的影响。实验结果表明:WNC与PVA之间存在分子间氢键作用,两者相容性较好。当PVA含量为15%时,复合乳液具有优异的稳定性,涂膜拉伸强度为4.0 MPa,断裂伸长率为299.0%,吸水率为18.4%。     

KH560改性水性硝化纤维乳液的制备及性能

以硝化纤维(NC)、异佛尔酮二异氰酸酯(IPDI)、二羟甲基丙酸(DMPA)等为主要原料,制得自乳化型水性硝化纤维乳液,再加入可水解自交联的硅烷偶联剂KH560,其分子中的环氧基与羧基反应,从而制备出KH560改性水性硝化纤维乳液。通过傅里叶变换红外光谱(FT-IR)、透射电子显微镜(TEM)、热重分析(TGA)法等测试手段,研究了KH560和DMPA的含量对乳液及其涂膜性能的影响。结果表明:当w(KH560)=7%,w(DMPA)=3.5%时,改性后的乳液具有良好的稳定性,涂膜的耐水性、耐乙醇性、热性能、力学性能均得到明显改善。     

含有磺酸基团的水性硝化纤维乳液的制备

采用1,5-二氨基-3-戊磺酸钠为亲水扩链剂,以异佛尔酮二异氰酸酯(IPDI)、硝化纤维素(NC)为主要原料,通过自乳化法制备磺酸盐型水性硝化纤维(SWNC)乳液。探索了IPDI与1,5-二氨基-3-戊磺酸钠摩尔比、硝化纤维用量对乳液粒径及涂膜性能的影响,利用FTIR、TEM、TGA和XPS等测试手段对聚合物结构与性能进行表征。结果表明,1,5-二氨基-3-戊磺酸钠已接枝到硝化纤维上,并未破坏硝化纤维分子原有结构,SWNC乳液平均粒径较小,且乳液的贮存稳定性及水分散性较好,SWNC涂膜的热稳定性与硝化纤维相比有所提高。     

含有磺酸基团的水性硝化纤维乳液的制备

采用1,5-二氨基-3-戊磺酸钠为亲水扩链剂,以异佛尔酮二异氰酸酯(IPDI)、硝化纤维素(NC)为主要原料,通过自乳化法制备磺酸盐型水性硝化纤维(SWNC)乳液。探索了IPDI与1,5-二氨基-3-戊磺酸钠摩尔比、硝化纤维用量对乳液粒径及涂膜性能的影响,利用FTIR、TEM、TGA和XPS等测试手段对聚合物结构与性能进行表征。结果表明,1,5-二氨基-3-戊磺酸钠已接枝到硝化纤维上,并未破坏硝化纤维分子原有结构,SWNC乳液平均粒径较小,且乳液的贮存稳定性及水分散性较好,SWNC涂膜的热稳定性与硝化纤维相比有所提高。     

有机硅改性水性硝化纤维乳液的研究

以甲基硅油对水性硝化纤维(WNC)进行改性,制备了改性水性硝化纤维乳液。通过傅里叶变换红外光谱(FT-IR)、粒径分析和热重分析(TGA)等测试手段,研究了IPDI三聚体(TriIPDI)、甲基硅油的含量对WNC乳液及其涂膜性能的影响。结果表明:当n(Tri-IPDI)∶n(NC)为0.50左右,w(甲基硅油)=7%时,乳液贮存稳定性良好,涂膜的耐水性、表面疏水性和热稳定性较未改性乳液涂膜都得到提高。     

含氟丙烯酸酯改性水性硝化纤维乳液的制备及其性能

以硝化纤维(NC)、异佛尔酮二异氰酸酯(IPDI)、丙烯酸(AA)、丙烯酸羟乙酯(HEMA)、全氟辛基乙基丙烯酸酯(FA)、三乙胺(TEA)为主要原料,采用自乳化法制备含氟丙烯酸酯改性水性硝化纤维乳液(WNC)。通过傅里叶变换红外光谱(FTIR)、透射电子显微镜(TEM)、纳米粒度仪、动态流变仪以及视频光学接触角测定仪对所制乳液及薄膜进行了结构和性能表征,并考察了单体聚合温度、n(AA)∶n(HEMA)、含氟丙烯酸酯质量分数(占反应物AA、HEMA、NC、IPDI总质量的百分数)对乳液及其薄膜性能的影响。结果表明,所得WNC乳液性能稳定,乳液胶粒呈球形,具有核-壳结构。当单体聚合温度为60℃,n(AA)∶n(HEMA)=3∶1,含氟丙烯酸酯用量为1.0%时,所得乳液粒径较小且分布窄,平均粒径和分散系数分别是54 nm和0.023;改性后的乳液薄膜吸水率降低至2.0%,薄膜接触角增加至120°,相比较未改性的WNC乳液,改性后的WNC乳液薄膜具有优异的耐水性。     

阳离子聚合物乳液制备方法

综述了阳离子聚合物乳液制备方法 ,着重总结了近年来在无皂阳离子乳液聚合方面的研究成果     

切片石蜡乳液的制备

石蜡一直存在难乳化、乳液稳定性差等问题。研究了以切片石蜡为原料,采用种子乳液聚合法,选择复配型乳化剂;讨论了乳化剂用量,乳化时间,乳化温度以及搅拌速度等因素对石蜡乳液稳定性和分散性的影响。结果表明:在乳化剂用量为乳液总量的10%,乳化时间为70 m in,乳化温度控制在(85±5)℃,搅拌速度为1500 r/m in的反应条件下,可制备出稳定的切片石蜡乳液。     

One-step fabrication superhydrophobic sand filter for capillary-driven separation of water-in-oil emulsions

The efficient separation of water-in-oil emulsion is of significance in environment and energy filed, and it has become a world-wide challenge. Herein, we have presented a one-step, facile and low-cost approach to prepare superhydrophobic sands for efficient separation of water-in-oil emulsion. The as-prepared sand layers possessed a water contact angle higher than 151°, demonstrating their superior superhydrophobic property. Besides, the as-prepared sand layers could separate water-in-emulsions with separation efficiency up to 99.7%, which is superior to both traditional and superwettable filtration membranes. The effect of thickness of sand layer on separation performance was also investigated. The results showed that the filtration flux decreased with the increased of filtration thickness while the separation efficiency increased. The as-prepared sand layer proposed by this study is a processing candidate for separating water-in-oil emulsion in practical industry. Additionally,the as-prepared superhydrophobic sand fabrication method also provides an alternative for desert water storage.     

Alcogel and aerogel of nitrocellulose formed in nitrocellulose/acetone/ethanol ternary system

Nitrocellulose (NC) alcogels were formed in NC/acetone/ethanol ternary system and NC aerogels were prepared from NC alcogels after drying under supercritical CO₂ (scCO2). NC alcogel with lower modulus was formed in the ternary system with a higher ethanol ratio. The densities and porosities of NC aerogels were related directly to the initial ethanol content. The NC aerogels clearly retained the crystalline structure of NC powder. NC aerogels that were formed in the system with higher ethanol content had larger pore size distribution range, larger average pore diameter, and larger mesopore and macropore volume. The thermal decomposition of NC aerogel was more accelerated and more acute compared with NC powders.     

电晕场作用于棉纤维素对硝化纤维素性能的研究

采用直流电晕场预处理精制棉纤维素，将N2O5-HNO3硝化电晕场作用后的棉纤维素，测定硝化纤维素的黏度和含氮量。结果表明电晕场对棉纤维素的作用时间从3min到720min时，硝化纤维素的黏度从0．320Pa．s降至0．0312Pa．s，含氮量保持不变。棉纤维素电晕场作用时间与硝化纤维素黏度之间的关系为η=30＋883／t。在硝化和电晕场条件一定时，电晕场作用时间对硝化纤维素的含氮量及氮量均匀性没有影响。     

Comparison of fuel properties and emission characteristics of two- and three-phase emulsions prepared by ultrasonically vibrating and mechanically homogenizing emulsification methods

Emulsions have long been considered as an alternative fuel for combustion equipment in order to achieve better fuel economy and pollution reduction. While a mechanical homogenizing method is frequently used to prepare emulsions, the use of an ultrasonic emulsification method to do so is still rather limited, and is mostly applied to two-phase emulsions only. Hence, two-phase W/O and three-phase O/W/O emulsions, prepared by a mechanical homogenizer and an ultrasonic vibrator, respectively, were prepared and used as engine fuel. The emulsion properties, engine performance, and engine emission characteristics between these two emulsification methods were measured and compared. The potential of the ultrasonic emulsification method was also evaluated. The experimental results show that the emulsions prepared by the ultrasonic vibrator appeared to have more favorable emulsification characteristics such as smaller dispersed water droplets that were distributed more uniformly in the continuous oil phase, lower separation rate of water droplets from the continuous phase of diesel fuel and thus a lower separating rate of the dispersed water droplets from the emulsion, larger emulsion stability, and larger emulsion viscosity than the emulsions produced using a mechanical homogenizer. In addition, a larger content of water was emulsified when the emulsion was prepared using the ultrasonic vibrator than the mechanical homogenizer. The emulsions prepared by the ultrasonic vibrator also had a lower fuel consumption rate, lower bsfc, and significantly lower CO emission while at the same time having a larger black smoke opacity. When comparing the two-phase W/O and the three-phase O/W/O emulsions prepared by either the ultrasonic vibrator or the mechanical homogenizer, the two-phase W/O emulsions appeared to have a lower fuel consumption rate, bsfc, CO, and a lower black smoke opacity than the three-phase O/W/O emulsions, regardless of whether they were prepared by ultrasonic vibrator or mechanical homogenizer.     

乳液法制备聚合物纳米复合材料研究进展

介绍了近年来国内外学者采用微乳液聚合、常规乳液聚合、种子乳液聚合 ,核壳乳液聚合、辐射乳液聚合、可聚合的乳化剂和聚合物乳化剂聚合等多种乳液聚合法制备聚合物纳米材料所作的研究工作。     

核壳型聚丙烯酸酯乳液的耐水性能研究

采用种子乳液二阶段聚合法,制备了经丙烯酸(AA)/丙烯酰胺(AM)交联、具有核壳结构的甲基丙烯酸甲酯(MMA)/丙烯酸丁酯(BA)/丙烯腈(AN)复合乳液,研究了核壳软硬单体比、AN及壳层中交联单体AM含量对乳胶膜吸水率的影响。结果表明:乳胶膜吸水率主要受壳层软硬单体比例的影响,软硬单体比值越小,乳胶膜的吸水率越低;丙烯酸/丙烯酰胺复合交联剂对乳胶膜吸水率的影响不明显;功能单体丙烯腈可明显降低乳胶膜的吸水率,乳胶膜吸水率随丙烯腈含量的增加而逐渐降低,最低达到9.40%。     

有机／无机纳米复合材料的制备方法

综述了近年来国内外有机/无机纳米复合材料的制备方法及其最新进展情况。     

Hydrate formation from high water content-crude oil emulsions

Methane hydrate formation and dissociation studies from high water content ( water) - crude oil emulsions were performed. The hydrate and emulsion system was characterized using two particle size analyzers and conductivity measurements. It was observed that hydrate formation and dissociation from water-in-oil (W/O) emulsions destabilized the emulsion, with the final emulsion formulation favoring a water continuous state following re-emulsification. Hence, following dissociation, the W/O emulsion formed a multiple o/W/O emulsion (60 vol% water) or inverted at even higher water cuts, forming an oil-in-water (O/W) emulsion (68 vol% water). In contrast, hydrate formation and dissociation from O/W emulsions ( water) stabilized the O/W emulsion.     

Stability and settling characteristics of solvent-diluted bitumen emulsions

When bitumen emulsions are diluted with aliphatic solvents at solvent-to-bitumen ratios above a certain value, water droplets, solids, and precipitated asphaltenes tend to form clusters that are much larger than the individual components. This work demonstrates that bitumen emulsions diluted with aliphatic solvent exhibit settling behavior distinctly different from that of bitumen emulsions diluted with aromatic solvent. The aliphatic system exhibits a zone settling mode with sharp interfaces. A characteristic interface appears as a discontinuity between the clean oil phase and the hindered settling zone. Laboratory techniques have been developed for measuring settling rates by tracking the interface positions with time. As an example, an experimentally observed settling curve was modeled by solving the conservation law hyperbolic equations.     

SiC晶须制备方法研究进展

碳化硅晶须的制备已有众多研究。目前,国内制备SiC晶须的方法主要可分为两大类:气相反应法和固体材料法,每种制备方法都有其各自的特点。本文重点介绍了这两种制备方法的合成机理,以及相关制备方法取得的一些实验研究成果。