Mixture Design Approach in Wall Material Selection and Evaluation of Ultrasonic Emulsification in Flaxseed Oil Microencapsulation

Flaxseed oil, sensitive to oxidation, was systematically microencapsulated with six triple wall materials combinations [carbohydrate (maltodextrine and two different modified starches (N-Lok® and HiCap® 100)); protein (sodium caseinate, whey protein concentrate); and Arabic gum] for the highest microencapsulation efficiency and oxidation stability. Proportions of the triple wall materials were optimized in mixture design using the quadratic model. Effects of Ultra-Turrax and ultrasonic emulsifications on microencapsulation efficiencies were additionally characterized in the optimized wall material combinations. The microcapsules produced were investigated for particle size distribution, moisture content, water activity, bulk density, and oxidative stability. Results showed that the combination of modified starch (Hi-Cap® 100)/Arabic gum/whey protein concentrate (4/0/1, w/w/w) provided the highest efficiency in flaxseed oil microencapsulation. However, the only successful combination in preventing flaxseed oil oxidation was maltodextrine/Arabic gum/whey protein concentrate (4/0/1, w/w/w). The microcapsules produced by ultrasonic emulsification had higher microencapsulation efficiency than that of Ultra-Turrax emulsification.     

STATE ESTIMATION IN THE BATCH DRYING OF FOODS

ABSTRACT

Measurement of material moisture content is necessary for the control of product quality in batch drying. However, this variable cannot be measured on-line, and state estimation techniques are proposed. A non-linear dynamic model is developed for batch drying of foods. Process disturbances and measurement errors are modeled as stochastic processes and a hybrid extended Kalman filter is employed for state estimation. This filter is based on the local linearization of the process model around the suboptimal filter estimates. The moisture estimation approach was applied to experimental points obtained in a laboratory dryer with quite satisfactory results.     

Improvement of Industrial Drying of Natural Rubber Through Analysis of Heat and Mass Transfers

ABSTRACT

An analysis of convective drying of natural rubber in granule form. Exploitation of the mathematical model developed from analysis of internal transfers requires determination of the ‘drying rate’ and the ‘energy exchange coefficient’ between the material and the drying air. This was performed using a portable laboratory drier at the production site, avoiding the problem of changes in the material during transport. Analysis of the drying kinetics of material in thin layers led to modelling the drying rate at the temperatures, rates and relative humidity values encountered in industrial driers. The energy exchange coefficient was found by measurement of air and granule temperatures. Thick layer trials showed the suitability of the model for simulation of changes in moisture content and temperature of air and granules in a granular environment. The study as a whole led to the development of a computer program for simulating a zone drier. This software can be used to optimise the management of an industrial natural rubber drying installation.     

锂离子电池电极材料SEI膜的研究概况*

综述了锂离子电池电极材料表面的“固体电解质界面膜”（SEI 膜） 的成膜机理及研究概况,并分析了电解液、温度和电流密度对SEI膜形成过程的影响;在此基础上,对SEI膜的改性（主要包括电极材料的改性和添加电解液添加剂）进行了分析,认为SEI膜的研究将对电极材料和电解液添加剂的改进研究产生重要影响。     

软模板法合成多级孔沸石分子筛及其催化性能研究进展

详细介绍了软模板法合成多级孔沸石分子筛及其催化性能。合成多级孔沸石分子筛的软模板主要包括两种类型,一种是含多季铵基团的烷基季铵盐;另一种是双亲有机硅表面活性剂。对采用这两种表面活性剂合成多级孔沸石分子筛的方法以及得到的材料结构特性进行了综述。进一步讨论了这两种方法得到的分子筛的催化性能。关于这些材料的催化性能研究主要有三方面内容:有机大分子化合物合成的活性和选择性,生物质催化热解特性和大分子化合物合成中抗积炭失活性能。     

前驱体二水磷酸铁对磷酸铁锂电化学性能的影响

以钛白生产副产物七水硫酸亚铁为铁源,工业磷酸二氢铵为磷源,双氧水为氧化剂,采用共沉淀法合成了不同粒径和形貌的二水磷酸铁,并以此为前驱体,通过碳热还原法制备了粒径不同的LiFePO₄/C正极材料。经过对样品进行X射线衍射（XRD）、扫描电镜（SEM）以及恒电流充放电测试,研究了二水磷酸铁及LiFePO₄/C的结构、形貌以及电化学性能。结果表明,以较细的二水磷酸铁为铁源,制备得到的LiFePO₄/C颗粒较细,且具有更优异的电化学性能。0.1、0.5、1、2、5、10 C放电比容量分别为154、148、144、140、130、120 mA·h/g。     

硅烷偶联剂在玻纤增强复合材料领域中的应用

介绍了玻纤生产中常用硅烷偶联剂的种类、结构、偶联机理及使用方法。着重介绍了硅烷偶联剂在玻纤增强复合材料中的应用,特别是硅烷结构类型、用量对复合材料性能的影响。同时,对硅烷偶联剂的作用及其在玻纤增强热固性和热塑性树脂中的应用进行了阐述。     

An Overview of Plastics Recycling

In 1980, plastic in the United States has overtaken steel on a volume basis as the dominant material. Though recycling of iron and steel goes back to the early years of United States history, plastics recycling is in its infancy. Today, plastics recycling is an urgent necessity as petrochemical raw materials, energy, and disposal become more costly.     

Interfacial microstructure and properties of carbon fiber-reinforced unsaturated polyester composites modified with carbon nanotubes

To improve the interfacial properties in carbon fiber (CF)-reinforced unsaturated polyester (UP) composites, we directly introduced functionalized carbon nanotubes dispersed in the fiber sizing onto the fiber surface. For comparing the influence of polymer type on sizing effect, two different polymers (UP MR13006 and water-soluble epoxy (EP)) were used to prepare sizing agent. Morphology and surface energy of CFs were examined by scanning electron microscopy and dynamic contact angle analysis test. Tensile strength was investigated in accordance with ASTM standards. Mechanical properties of the composites were investigated by interlaminar shear strength (ILSS) and impact toughness. Test results indicate that TS, ILSS, and impact toughness were enhanced simultaneously. For UP matrix, the sizing agent containing UP has better reinforcing and toughening effect than the sizing agent containing water-soluble EP.     

Reactive and stimuli-responsive maleic anhydride containing macromers – multi-functional cross-linkers and building blocks for hydrogel fabrication

Macromers with functional groups that allow for chemical derivatization, polymerization reactions or impart specific physico-chemical properties are functional building blocks for polymeric systems used in different biomedical applications. With this motivation, a series of oligomeric macromers was synthesized by free radical polymerization of maleic anhydride (MA) with N-isopropylacrylamide (NiPAAm) and pentaerythritol diacrylate monostearate (PEDAS). This chemical design provides anhydride groups for effective reactivity of the macromers with amines and other nucleophiles, copolymerized NiPAAm for temperature responsiveness and lipophilic stearate domains for increased hydrogel stability. Macromers were synthesized with different MA co-monomer feeds and oligomeric molecules (Mn below 5000 Da) were obtained with MA contents between 7% and 27% as determined by titration. The fraction of chemically intact anhydrides was calculated to range from 75% to 80%. The ability of the macromers to cross-link di- or oligovalent amines as a function of MA content was investigated rheologically. It was also demonstrated that monovalent amines, e.g. aminofluorescein, could be grafted to the macromer chain utilizing only a fraction of the anhydride functionalities. The derivatized macromers could still participate in cross-linking reactions due to the remaining anhydrides. Temperature sensitivity was shown for aqueous solutions of macromers with fully dissociated anhydride groups. The solutions were additionally responsive to changes in calcium ion concentration and pH. Extracts from macromer cross-linked polyether hydrogels showed no toxicity on L929 fibroblasts.The macromers have perspective as biocompatible cross-linkers for hydrogel fabrication from various biomacromolecules with the opportunity to decorate the gels with monoamine molecules that alter the biological or physico-chemical properties.