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91.
Gisèle Lecomte-Nana Amina Mokrani Nicolas Tessier-Doyen Kévin Boussois Hervé Goure-Doubi 《Ceramics International》2013,39(8):9047-9053
The present work aimed to investigate the processing of textural clay based materials using tape casting together with freezing. Two model raw materials were used, namely: BIP kaolin from France and ABM montmorillonite from Mediterranean region. The mixtures of both clays were studied, whereby, the amount of montmorillonite was 0, 5, 10, 20 or 50 mass%. After tape casting, the as-obtained green bands were frozen into liquid nitrogen, lyophilized and then fired at 1050 °C or 1200 °C.The amount of montmorillonite appeared as a critical parameter that controls the cohesion of the dry products. For montmorillonite content ≥20 mass%, the products exhibited multiple cracks after lyophilisation. With lower montmorillonite content, the cohesion of the dry products was satisfactorily and a macroscopic cross-linked surface texturation was observed. After calcination at 1050 °C or 1200 °C, the texturation appeared well defined. Moreover, calcination at 1200 °C increased the densification of products and the occurrence of a glassy phase was noted.The combination of both tape casting and freezing (freeze tape casting) is a promising way to develop various clay-based and composites materials exhibiting unique microstructure organization and characteristics with potential application in the field sustainable and environmentally friendly filtration, adsorption or catalysis. 相似文献
92.
Novel pH sensitive alginate–protein–clay composite beads were investigated for the in vitro oral delivery of the model protein, bovine serum albumin (BSA). X-ray diffraction (XRD) results revealed that BSA enter between layers of montmorillonite (MMT) by expanding interlayer distance and finally an exfoliated structure forms in the alginate hydrogel. MMT incorporation increases protein entrapment efficiency to 78%, compared to 40% of conventional alginate beads. The release ratio of BSA from composite beads is 9–13% depending on MMT contents after around a 2 h stay in gastric fluid. More importantly, no BSA release is detected until 60–90 min after the first contact time of beads with gastric solution. The presence of clay in alginate beads prevents burst release in higher pH of intestine by slowing release rate of BSA to 45–55% within around 9 h, resulting in a potential matrix for intestinal release of protein drugs. 相似文献
93.
Freezing–thawing is used as a new method to disperse montmorillonite (MMT) in dialdehyde carboxymethyl cellulose (DCMC) crosslinked gelatin-based films. The effects of freezing–thawing on the structure and properties of gelatin-DCMC-MMT films were investigated. The data of XRD indicate that freezing–thawing plays an important role in dispersing MMT into gelatin matrix and reducing the nanoparticles aggregation. The optical properties studies show that gelatin-DCMC-MMT films are very transparent and have excellent barrier properties against UV light. Freezing–thawing process decreases the transparency of films at visible region due to the better dispersion of MMT. The resulting films exhibit similar total soluble matter (TSM) values. However, the films prepared by freezing–thawing method have higher moisture content (MC), may be resulting from the more void volume obtained during the freezing–thawing process. The water vapor permeability (WVP) measurements show that the addition of MMT decreases the WVP of the films. Moreover, the freezing–thawing method can further decrease the WVP of the films. In addition, the films prepared by freezing–thawing are observed with better mechanical properties and thermal stability. The results suggest that the freezing–thawing method is beneficial to dispersing MMT into the gelatin matrix and raising the properties of DCMC crosslinked gelatin-MMT films. 相似文献
94.
Ying Xia Xi-gao Jian Jian-feng Li Xin-hong Wang Yan-yan Xu 《Polymer-Plastics Technology and Engineering》2013,52(3):227-232
The synergistic effects of organic montmorillonite (OMMT) and intumescent flame retardant (IFR) based on the ammonium polyphosphate (APP) and pentaerythritol (PER) on flame retardant enhancement of acrylonitrile-butadiene-styrene copolymer (ABS) were investigated by using the limiting oxygen index (LOI), the UL-94 (vertical flame) test, thermogravimetric analysis (TGA), x-ray diffractometry (XRD) and scanning electron microscopy (SEM). The LOI data and vertical flame tests show that OMMT has a synergistic flame retardant effect with IFR and the LOI value of ABS/OMMT/IFR (96/4/20) reaches 28.7%. The TGA data demonstrate that the incorporation of OMMT and IFR is very effective in enhancing the thermal stability of ABS/OMMT/IFR system at high temperature (T > 500°C). The results of XRD show that the composite of ABS/OMMT is a kind of intercalated nanocomposite and the gallery height of ABS/OMMT nanocomposite is 3.5 nm. The microstructures observed by SEM demonstrate that a suitable amount of OMMT with IFR can promote formation of compact intumescent charred layers in ABS blends. 相似文献
95.
Ayça Bal Tülin Banu İyim Saadet Özgümüş 《Polymer-Plastics Technology and Engineering》2013,52(10):990-995
Waterborne acrylic emulsion was obtained by using methyl methacrylate, ethyl and butyl acrylate monomers. Emulsions containing nanoparticles were prepared by blending the stable dispersions containing SiO2 or MMT nanoparticles. The films were prepared from emulsions and coating tests were applied. The physical properties of prepared emulsions are better than the commercial emulsions. The addition of the nanoparticles especially SiO2 have positive effect on the resistance to environmental conditions of emulsions. Waterborne acrylic emulsions containing nanoparticles prepared in this study can be used in the manufacturing of the semi-lustrous emulsion type nano paint with low cost, high performance and environmentally friendly. 相似文献
96.
Intumescent flame-retardant (IFR) high-density polyethylene, poly[ethylene-co-(vinyl acetate)], and organically-modified clay nanocomposites consisting of ammonium polyphosphate (APP) and other charring agents, as well as the nanocomposites pentaerythritol (PER), polyamide-6 (PA), and PA/OMT were investigated. Their thermal and flammability properties have been characterized by thermogravimetric analyses, cone calorimetry, a limiting oxygen index, and the UL-94 test. Results show that the PER-contained sample exhibits different thermal and flammability behaviors from the samples containing polymer charring agents. The difference is postulated to be responsible for the formation of various intumescent structures and their changes in response to heightened temperatures. 相似文献
97.
98.
聚丙烯/蒙脱土纳米复合材料的制备与性能 总被引:67,自引:5,他引:62
用烷基季铵盐对钠基蒙脱土进行有机化处理,使其成为有机蒙脱土。X射线衍射(XRD)表明有机阳离子已同钠离子发生离子交换作用,导致层间距扩大。用熔融插层法制备聚丙烯/蒙脱土纳米复合材料,测试了力学性能。通过XRD、DSC等手段研究了其结构与结晶行为,并与聚丙烯进行了对比。实验表明,通过熔融插层可使聚丙烯插层于蒙脱土片层之中,且所得聚合物的冲击强度有所提高。 相似文献
99.
100.
A novel composite polymer electrolyte membrane composed of a PVA polymer host and montmorillonite (MMT) ceramic fillers (2–20 wt.%), was prepared by a solution casting method. The characteristic properties of the PVA/MMT composite polymer membrane were investigated using thermal gravimetric analysis (TGA), differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), scanning electron microscopy (SEM), and micro-Raman spectroscopy, and the AC impedance method. The PVA/MMT composite polymer membrane showed good thermal and mechanical properties and high ionic conductivity. The highest ionic conductivity of the PVA/10 wt.%MMT composite polymer membrane was 0.0368 S cm−1 at 30 °C. The methanol permeability (P) values were 3–4 × 10−6 cm2 s−1, which was lower than that of Nafion 117 membrane of 5.8 × 10−6 cm2 s−1. It was revealed that the addition of MMT fillers into the PVA matrix could markedly improve the electrochemical properties of the PVA/MMT composite membranes; which can be accomplished by a simple blend method. The maximum peak power density of the DMFC with the PtRu anode based on Ti-mesh in a 2 M H2SO4 + 2 M CH3OH solution was 6.77 mW cm−2 at ambient pressure and temperature. As a result, the PVA/MMT composite polymer appears to be a good candidate for the DMFC applications. 相似文献