Polymer and modified chitosan-based nanocomposite: impending material for technical application

This article highlights research endeavors on various aspects of polymer/modified chitosan nanocomposite counting their fabrication, features, application, and future prospects. Chitosan is biocompatible/biodegradable polymer having exclusive physical and chemical properties in modified forms. Chitosan possess enormous structural prospects through functionalization with carbon nanotube, graphene, nanoclay, and metal nanoparticle. Modified chitosan own optimal moisture absorption, heat stability, chemical and flame resistance. Incorporation of nano-functionalized chitosan in matrices generate innovative efficacies of nanocomposite in sensors, dye removal, membrane technology, packaging, antimicrobial, and biomedical materials. Polymer/modified chitosan nanocomposite reveal superior characteristics such as strength, heat stability, electrical conductivity, photo-luminescent, antimicrobial, and biomedical features.     

Sponge-like chitosan-based nanostructured antibacterial material as a topical hemostat

In this study, chitosan/alginic acid/zinc oxide (CHI/AA/ZnO) nanostructured hydrogel sponges were fabricated by incorporating ZnO nanoparticles (<100 nm) into polymer matrix to develop a new potential biomaterial for hemorrhage control. For this purpose, the crosslinked CHI/AA/ZnO nanostructured sponges were synthesized by freeze-drying technique. Genipin was used as a crosslinker. The prepared chitosan-based sponges were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, and scanning electron microscopy—energy-dispersive spectroscopy analysis. The effects of ZnO content on the physicochemical characteristics of sponge-like nanostructured hydrogels were evaluated by swelling ratio in two different pH values. Physical immobilization of dexamethasone as a model drug in hydrogel matrix resulted sustained release of drug more than 3 days. Antibacterial activity of hydrogel sponges was assessed against Staphylococcus aureus. The cytotoxicity and hemostatic efficacy of crosslinked CHI/AA/ZnO sponge like-nanostructured hydrogels was evaluated in vitro and in vivo, respectively. The results of this study demonstrated that the prepared CHI/AA/ZnO nanostructured sponge had the potential to be an antibacterial topical hemostat. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47522.     

Development of porous permeable ceramic material and filtering element technology for candle-shaped filter equipment

Areduction in manufacture expenditure for a production unit, and also preparation of metals and alloys in pure and ultra-pure form may be achieved using newly created filtering elements made of porous permeable ceramic materials with a pore size controlled from “micro” to “nano”. Methodology is presented for creating filtering elements made of porous permeable ceramic based on a concentrate of disthene-sillimanite for candle-shaped filtering elements. Translated from Novye Ogneupory, No. 1, pp. 23 – 27, January 2009.     

陶瓷膜在水处理中的发展与应用

介绍了无机陶瓷膜的结构、原理及特性;综述了陶瓷分离膜技术的发展过程及其国内外发展现状;分类介绍了其在给水处理、海水淡化、废水处理等方面的应用研究及进展;最后讨论了陶瓷膜在水处理应用中存在的问题及发展趋势,指出其在水处理中具有良好的应用前景.     

料浆法陶瓷涂层用胶粘剂研究现状

综述了料浆法陶瓷涂层技术的特点及应用,重点介绍了料浆法陶瓷涂层用胶粘剂-无机胶粘剂中的硅酸盐类和磷酸盐类胶粘剂的性能和应用。     

Catalytic reactors based on porous ceramic membranes

This overview discusses some of the developments and outstanding opportunities in the field of catalytic reactors based on porous ceramic membranes, both inert and catalytic. This is an emerging area, where inputs from heterogeneous catalysis, material science and reactor engineering are playing the key roles. Rather than attempting a thorough review of the relevant literature, this work deals with some general concepts and then concentrates on a few selected examples that illustrate the application of membrane reactors.     

漫谈多孔陶瓷材料及其过滤技术

多孔陶瓷作为过滤元件组成的陶瓷过滤器,在各行业的分离,净化领域中已得到较全面的推广应用。陶瓷过滤器以其独特的功能特性,在各分离,净化领域中已成为一种不可替代产品。根据多孔陶瓷滤材技术的发展变迁,研究了多孔金属滤材与多孔陶瓷滤材的性能优势,阐述了多孔陶瓷滤材过滤元件的性能指标及过滤原理,介绍了多孔陶瓷及过滤器的应用市场,...     

蓄热及多孔陶瓷蓄热材料

介绍了蓄热材料的分类及特点并重点分析了蓄热储能多孔陶瓷材料的制备工艺,包括其孔隙,性能,材料的设计与选择等.     

Fabricating porous ceramic materials via phase separations in blends of cellulose acetate and ceramic nanoparticles

As applications of porous ceramic materials have gradually expanded, the novel technologies for the fabrication of porous ceramic materials with a delicate and controllable structure are still attractive. In this work, three types of porous monolithic ceramic materials, including Al₂O₃–SiO₂, TiO₂, and SiC, have been fabricated by thermally impacted and non-solvent-induced phase separations in blends of cellulose acetate and ceramic nanoparticles. These materials possessed three-dimensional interconnected porous structures with low densities, high porosities, and hierarchical pores ranging from 5 nm to 6 μm. The relationships between microstructures and phase separations were systematically investigated. Furthermore, electromagnetic shielding effectiveness of 20 dB from 5 to 18 GHz in porous SiC materials has been achieved, revealing that those materials have potential applications in the electromagnetic shielding. This work provides a powerful and general approach to fabricate porous monolithic ceramic materials with a wide range of various ceramic nanoparticles.     

Fabrication of ceramic membranes on porous ceramic supports by electrophoretic deposition

Abstract

Nanoporous alumina membrane and continuous zeolite L membrane were fabricated on the inner surface of microporous alumina tubes. In the former case, an electrophoretic deposition (EPD) technique was used for the deposition of bimodal alumina particles for the subsequent low temperature sintering. In the latter case, the EPD was used for the seeding process of zeolite L particles for the subsequent hydrothermal synthesis. A thin layer of polypyrrole was synthesised on the inside wall of the porous tubes by the chemical polymerisation of pyrrole to give the wall electric conduction for the EPD electrode. The thickness of the coating layers was controlled by altering the applied voltage and deposition time. The interfacial connection of the alumina or zeolite coated layer and the substrate was evaluated by SEM observations before and after the thermal treatment. The nanoporous structure of the alumina membrane was also characterised by a pore size analyser.     

多孔陶瓷膜制备技术研究进展

多孔陶瓷膜具有化学稳定性好、机械强度大、耐酸碱、耐高温等优点,在石油和化学工业等苛刻环境中有着广泛的应用,多孔陶瓷膜的制备技术是推动多孔陶瓷膜产业发展的核心部分。多孔陶瓷膜制备技术的核心和关键是以提高陶瓷膜整体性能为导向,通过对陶瓷膜微结构的调控,实现陶瓷膜制备技术的突破。针对近十年来陶瓷膜领域的研究,概述了当前陶瓷膜领域在制备具有高渗透性、高渗透选择性的陶瓷膜以及陶瓷膜低成本化方面的研究进展,并对未来陶瓷膜领域的发展趋势及瓶颈性问题进行了讨论。     

陶瓷过滤机在磷精矿脱水工艺中的应用

为了降低磷矿的物流成本,采用陶瓷过滤机对磷精矿浆进行脱水处理。介绍了陶瓷过滤机的结构及工作原理,以及在磷精矿脱水工艺应用中存在的问题及整改措施。通过在工艺与设备方面对陶瓷过滤系统进行整改,使得脱水后的磷精矿中w(H2O)达到12%,产能基本达到了设计要求。     

煤气化残渣基多孔陶瓷的制备研究

为拓展煤气化残渣综合利用途径,提高煤气化渣的附加值,以工业固体废弃物煤气化残渣为主要原料,采用模压成型工艺,在较低温度下烧结制备了煤气化残渣基多孔陶瓷,着重研究了不同烧结温度对多孔陶瓷的机械性能、物相结构、孔隙率以及N_2通量的影响。结果表明,多孔陶瓷烧结物相主要以莫来石相和石英相为主,反应烧结是主要的烧结过程机制。烧结温度为1 100℃时,煤气化残渣基多孔陶瓷性能最优,孔隙率为49.2%,平均孔径为5.96μm,0.01 MPa压力下平均N2通量达到2 452.6 m~3/(m~2·h),抗弯强度达到8.96 MPa。制备的煤气化残渣基多孔陶瓷具有高强度、高通量以及低成本的优异性能,有望用于高温气体过滤以及污水处理,解决煤气化残渣的环境污染问题。     

The preparation of SiC ceramic photosensitive slurry for rapid stereolithography

Stereolithography is one of the most widely used additive manufacturing techniques for preparing high precision and complex ceramic components. Due to the high optical absorbance and refractive index of SiC powder, the rapid stereolithography of SiC ceramics components has become a key challenge. Here, we innovatively use graded silica to improve the curing thickness, rheological and settling performance of the slurry. And we presented a preparation method of SiC ceramic slurry for stereolithography with high solid content, low viscosity, low sedimentation rate and high curing thickness. The printable precision of the slurry is more than 75 μm, the dynamic viscosity is less than 2 Pa·s, and the 24 h sedimentation height is less than 5%. This strategy demonstrates a tantalizing possibility and promising prospect to rapid stereolithography of large size SiC ceramic green body.     

Direct ink writing of porous cordierite honeycomb ceramic

Herein, we fabricated honeycomb ceramics with different porosities and pore shapes via the layer-by-layer deposition of cordierite (2MgO·2Al₂O₃·5SiO₂) particle ink, obtaining proper rheological properties using a direct-writing technology. No collapses as well as minimal cracking and bending were observed in the internal structure of the samples after calcination. We measured and compared the internal porosity and specific surface area of honeycomb ceramics with the same pore shape but different pore dimensions, as well as the same pore dimension but different pore shapes. The samples were both loaded with an γ-Al₂O₃ washcoat and Pd-based catalyst using the same method for the catalytic combustion of toluene. The different porosity and pore shape influenced the catalytic efficiency. This study may provide some useful guidelines for fabrication of honeycomb ceramics by direct writing technology, which could be used to remove volatile organic pollutants(VOCs).     

连续陶瓷纤维制备技术的研究进展

作为先进复合材料的增强剂,高性能陶瓷纤维日益引起材料研究人员的广泛关注,并导致了纤维制备技术的不断发展。与早期的物理成形技术和化学气相合成技术相比,先驱体转化法具有易于制备细径纤维、组成结构可调的优点,是目前研究与开发的重点,其中溶胶一凝胶法比较适合制备氧化物陶瓷纤维,而有机聚合物转化法则比较适合制备非氧化物陶瓷纤维。     

Analysis of spherical indentation of porous ceramic films

Spherical indentation of a porous brittle La_0.6Sr_0.4Co_0.2Fe_0.8O₃ ceramic film (porosity = 39.7%) on a stiffer elastic Ce_0.9Gd_0.1O_1.95 substrate is simulated by finite element modelling incorporating the Gurson model to account for densification. The simulated load-displacement curves, apparent elastic modulus E, indentation hardness H and densification profile are all in good agreement with experimental data for the film. The simulations show that E and H are not sensitive to film residual stress. However E is very sensitive to the indent depth-film thickness ratio f, although H is less so for f < 0.3. The simulated dependence of E and H on f are highly consistent with experimental data, supporting the extrapolation of E and H measured for 0.1 < f < 0.3, to zero depth for good estimates of the film-alone properties. The inclusion of densification in the simulation makes only a small difference to E, but has a large influence on H as a function of indentation depth.     

Spherical indentation of bilayer ceramic structures: Dense layer on porous substrate

Spherical indentation of thin 8YSZ ceramic layers on porous substrates (NiO/Ni-8YSZ) was studied. Indentation-induced elastic and plastic deformation and damage of the bilayer was experimentally analysed. FE simulations of the indentation process were carried out using the Gurson model to account for densification of the porous substrates. The simulated load-depth responses were in excellent agreement with the measured ones. The resulting stress distributions showed that the damage to the YSZ initiates in a tensile region near the interface due to bending during loading at a failure stress of ∼2 GPa, which is consistent with pores of ∼1 μm size seen in the YSZ. Delamination occurs on unloading due to the elastic recovery of YSZ being greater than that of the substrates at a de-bonding stress of 120 MPa. Residual compressive stress in the YSZ inhibits crack opening displacements normal to the layer plane which is beneficial for application of these structures in SOFCs.     

基于壳聚糖纳米粒子载药体系的制备与应用研究进展

壳聚糖纳米粒子载药体系因其天然无毒、生物相容性高、可生物降解等特点,在生物医学、化工和食品等领域有广阔的应用前景。本文对制备壳聚糖纳米粒子的离子交联法、聚电解质复合法、乳化交联法、喷雾干燥法和溶剂蒸发法等主要方法进行了综述,并阐述了其制备原理和优缺点。此外,本文结合国内外学者近期的研究工作,综述了壳聚糖纳米粒子载药体系在抗肿瘤药物和抑菌药物方面的应用研究进展,并对壳聚糖装载降糖药物、降脂药物、治疗骨质疏松药物和抗癫痫药物应用进行了简介。最后结合壳聚糖纳米载药体系在制备方法及应用中存在的实际问题,提出多学科研究相结合,开发壳聚糖纳米载药体系的智能控释、靶向递送功能和突破人体特殊生物屏障功能将是其近期的重点研究方向。