Characterization of the water uptake and electrolyte uptake of organic coatings and the consequences by means of electrochemical impedance spectroscopy and UV–vis spectroscopy

A new method to the investigation of the electrolyte uptake in a coating is presented. By means of UV–vis spectroscopy without nitrogen atmosphere in the region of 189 nm the concentration change of the overlaying electrolyte over a coating could be defined. In combination with the analysis of the water/electrolyte uptake by means of the electrochemical impedance spectroscopy (EIS) the resulting electrolyte uptake could be defined on a qualitative level. Furthermore a simple analysis of EIS spectra by a graphical interpretation of the Nyquist spectra has been developed. With the EIS spectra analysis in the same timeline as the water/electrolyte uptake a model for the processes inside a coating during corrosive stress has been obtained. It shows that the fast water uptake is followed by a slow ion uptake and this causes the initiation of a corrosion process at the interface.     

Emulsion microgel particles: Novel encapsulation strategy for lipophilic molecules

BackgroundLipophilic molecules such as flavours, essential oils, vitamins and fatty acids are difficult to deliver in food matrices owing to their limited solubility, rapid oxidation and degradation during physiological transit. Among the technologies available to deliver lipophilic molecules, emulsion microgel particles are a relatively new class of soft solid particles of discrete size, shape, and interesting release properties.Scope and approachRelevant literature concerning the processing of emulsion gels and emulsion microgel particles has been reviewed. Factors affecting the mechanical properties of protein-stabilised emulsion gels with key emphasis on the role of “active” and “inactive fillers” are discussed. Technologies for creation of emulsion gel particles using top-down and bottom-up approaches has been covered. Special attention was dedicated to the release mechanisms from emulsion microgel particles via swelling and erosion.Key findings and conclusionsEmulsion gels with “active fillers” offer the potential to create emulsion microgel particles using top-down approach. Polymer extrusion, multiple emulsion templating, fluid gels are few routes for creating emulsion microgel particles using bottom-up approaches. Although whey protein has been well researched, modified starch, plant proteins need to be investigated for design of new emulsion microgel particles that can act as surfactant and bulk gelling agents in their own right through intelligent tuning of processing conditions. If designed carefully with an end goal of “controlled delivery” in mind, responsiveness to oral temperature, gastric enzymes, intestinal pH etc, can be built into emulsion microgel particles so that they may find novel applications in food, pharmaceutical and personal care industries.     

Study of release kinetics and diffusion coefficients in swellable cellulosic thin films by means of a simple spectrophotometric technique

Measurement of diffusion in gel is an essential task for pharmaceutic technology and biochemical engineering. In this work we investigate diffusion coefficients and release kinetics of colored substances loaded in polymeric thin strips, by extending a simple spectrophotometric technique from catalysis science to swellable polymer matrices. Absorbance can be a measure of the average solute concentration in the swollen gel so that the time decay of film absorbance can be a quantitative measure of the release kinetics and henceforth of the diffusion coefficient in the swollen gel. Thin film dissolution is carried out in a newly proposed microfluidic continuous flow-through device. Hydroxypropyl methylcellulose (HPMC) is used as filming polymer. Film thickness, uniformity of content and swelling time-scales are accounted for in the estimation of the effective diffusion coefficient.     

Preparation of cellulose-based conductive hydrogels with ionic liquid

Conductive hydrogel composed of microcrystalline cellulose (MCC) and polypyrrole (PPy) was prepared in ionic liquid; and the resulting hydrogel was characterized with FT-IR, SEM, XRD and TGA. By doping with TsONa, the MCC/PPy composite hydrogels showed relatively high electrical conductivity, up to 7.83 × 10⁻³ S/cm, measured using a four-probe method. The swelling kinetics of the composite hydrogels indicated that the swelling process was mainly influenced by the cellulose content; and the equilibrium swelling ratio decreased as the increasing of MCC content in the hydrogels. In addition, the MCC/PPy composite hydrogels exhibited significantly enhanced mechanical property in contrast to MCC hydrogel.     

Swelling Behavior of Hydrogels within Auxetic Polytetrafluoroethylene Jacket

An acrylamide type hydrogel consisting of 2-acrylamido-2-methyl-1-propanesulfonic acid was synthesized using free radical suspension polymerization. Hydrogel particles were then loaded within an auxetic polytetrafluoroethylene jacket. It was found that the swelling ratio of the hydrogels within the jacket can be controlled by changing the loaded particle’s amount and size without the wear and tear of jacket due to the auxetic effect. Increasing swelling ratio with finer hydrogel particles was observed due to higher surface area. On the other hand, increasing hydrogel particle amount resulted in a decrease in water absorption due to diminished free volume for swelling within the jacket.     

辐射和热作用对高庙子膨润土膨胀能力影响的研究

以高庙子天然钙基膨润土和其改性钠基膨润土为研究对象,利用X-射线衍射对电子辐照-热顺序老化作用和γ-射线辐照-热顺序作用前后的样品进行了吸水膨胀能力大小测试,结果表明,在本试验条件下,两种不同类型的辐照-热顺序老化作用对高庙子膨润土膨胀能力的影响微弱,老化后的样品基本保持了原始样品的吸水膨胀能力。     

具正氮离子乙烯基化合物DMAPA制备及同丙烯酰胺共聚制备阳离子聚合物

本文叙述了丙烯酰胺，环氧氯丙烷，二甲胺通过三组份不对称缩合反应制备Ｎ—（３—二甲胺基、２—羟基）丙基丙烯酰胺盐酸盐，即ＤＭＡＰＡ，并同丙烯酰胺进行水溶液自由基共聚合，获得一定阳离子度的阳离子聚合物．对该聚合物作了红外光谱图，确认聚合物具有正氨离子的结构。并用此阳离子聚合物进行粘土防膨及絮凝性评价，实验表明，不同阳离子度，不同分子量的该阳离子聚合物皆具有良好使用性能。     

溶胀热重分析法研究腈纶纤维的侧序结构

本文用溶胀热重分析法(溶胀TGA)研究了影响腈纶纤维的各种因素,如纤维的化学组成,热处理条件,纺丝方法等。发现一般的溶胀TGA曲线都有三个增重峰,分别对应三种侧序结构,即无定形纸序区、中序区,和蕴晶高序区,化学组成中第二单体和第三单体含量增加都使纤维的序态降低,三单作用比二单更加敏感,热定型使纤维的低序区向高序区转化,蒸汽热定型比干热定型作用显著。     

锌锰干电池隔膜

运用高分子电化学最新理论,系统的研究并改进了纸板电池用的浆层纸。采用特种纤维,制成带有毡状纤维层的片基、(?)布含有非水溶性万能糊料的膜层,制出具有三层结构的新型电池隔膜。与传统的浆层纸相比,在保液能力、抗胶化能力和抗结晶能力方面显示了巨大的质量优势。     

超载卸除后地基变形的研究

本文探讨了在不同超载情况下土体变形的室内试验规律,旋出了计算超载预压地基变形的方法。该方法综合考虑了土体的主固结变形、吸水膨胀变形、回胀变形和次固结变形,其计算结果与试验实测值吻合尚好。 研究表明,卸去超载前地基的平均固结度和超载比是决定卸载后地基残余变形的关键因素,文中提出了有效应力面积比的概念以综合反映这两个因素的影响。本文建议采用有效应力面积比作为堆载预压设计和卸载决定的根据。文章最后简要报告了在宁波机场工程软土地基处理实践时应用本文研究成果的情况。