壳聚糖基层状硅酸盐纳米复合材料

壳聚糖基层状硅酸盐纳米复合材料是采用简单的溶液插层法,将壳聚糖及其衍生物插层进入层状硅酸盐的纳米层间而获得的有机无机纳米杂化材料。该材料偶合了壳聚糖及其衍生物和层状硅酸盐的协同优势,为壳聚糖的研发应用开辟了新方向和新途径。本文在对壳聚糖和层状硅酸盐的特性及应用进行简单介绍的基础上,重点综述了壳聚糖基层状硅酸盐纳米复合材料的制备方法、插层机理及应用现状,并提出了目前存在的主要问题。     

聚合物/层状硅酸盐插层纳米复合材料的研究

简述了聚合物 /层状硅酸盐插层纳米复合材料方面的研究进展。阐述了层状硅酸盐的结构与性质以及纳米复合材料形成过程的热力学原理。重点介绍了尼龙、聚丙烯等聚合物的层状硅酸盐插层纳米复合材料的现状和技术发展趋势     

有机染料-层状硅酸盐光活性纳米复合材料*

有机-无机纳米复合材料,尤其是有机客体插层入无机层状固体自组装形成的纳米复合材料,因其独特的微观结构与性能,在超分子构筑纳米材料领域中具有特殊地位。本文主要介绍了光致变色与光致发光光功能性有机染料插层层状硅酸盐纳米复合材料的研究进展,着重讨论了螺吡喃、偶氮、二芳基乙烯、芘、香豆素等染料在二维纳米片层间独特的光学行为、有序排列形态、构筑的多层功能性薄膜及其在光功能性材料开发方面的应用前景。     

聚合物／层状硅酸盐纳米复合材料研究进展

聚合物／层状硅酸盐（ＰＬＳ）纳米复合材料是近１０年迅速发展起来的研究交叉科学。由于聚合物纳米复合材料具有常规聚合物复合材料所没有的结构、形态以及较常规聚合物复合材料更优异的物理力学性能、耐热性和气体液体阻隔性能等,因而显示出重要的科学意义和应用前景。本文综述了聚合物／层状硅酸盐纳米复合材料的制备,结构表征和物理力学性能,对制务过程进行了热力学和动力学分析,最后对其应用前景进行了展望。     

聚氨酯基层状硅酸盐纳米复合物研究进展

具有优良综合性能的聚合物基层状硅酸盐纳米复合物是当前材料科学研究的重要方向。本文介绍了以聚氨酯材料为基质的聚合物基层状硅酸盐纳米复合物的制备技术、表征手段、物理化学性能以及结构形态,对该复合材料的工业开发前景、国内外研究现状以及发展趋势进行了分析。     

聚合物/层状硅酸盐纳米复合材料的性能

取合物／层状硅酸盐纳米复合材料是近十年发展起来的一类新型材料，即使硅酸盐纳米填料的含量很低，一般在5％（wt）以下，就使该类材料具有许多优良的性能，如杨氏模量，储能模量，热稳定性，气体阻隔性及阻燃性等均有较大的提高。本文综述了该类材料的性能。     

Toughening of Epoxy Nanocomposites: Nano and Hybrid Effects

In this paper, we review recent progress made in the field of epoxy-based binary and ternary nanocomposites containing three-, two-, and one-dimensional (i.e., 3D-, 2D-, and 1D) nano-size fillers with a special focus on their fracture behaviors. Despite investigations conducted so far to evaluate the crack-resistance of epoxy nanocomposites and attempts made to clarify the controlling toughening mechanisms of these materials, some questions remain unsolved. It is shown that silica nanoparticles can be as effective as rubber particles in improving the fracture toughness/energy; but incorporation of carbon nanotubes (CNTs) or clay platelets in epoxy matrices delays crack growth only modestly. The “nano” effects of silica (<25 vol.%) and rubber (>10 wt.%) nanoparticles in toughening epoxy resin are confirmed by comparison with silica and rubber micro-particles of the same loading. There is clear evidence of both synergistic and additive toughening effects in the silica/rubber/epoxy ternary nanocomposites. In addition, positive hybrid toughening effect has been observed in the nano-rubber/CNT/epoxy composites; however, a negative hybrid effect is predominant in nano-clay/nano-rubber/epoxy ternary nano-composites. Future research directions for epoxy-based nanocomposites towards multi-functional applications are discussed.     

聚合物/层状硅酸盐纳米复合材料的环境稳定性

过去的十多年里，聚合物／层状硅酸盐纳米复合材料在制备、结构与性能方面的研究取得了长足的进步。一些聚合物基的纳米复合材料已实现工业生产，在汽车、家电和包装等领域得到应用。环境稳定性是聚合物材料应用的一个重要方面。本文从材料的耐候性、耐热性和阻燃性能的角度出发，评述了近年来聚合物／层状硅酸盐纳米复合材料在紫外光降解、热降解和燃烧性能方面的研究进展，以期对纳米复合材料的基础研究及应用开发有所裨益。     

Structure Development in Flexible Polyurethane Foam-Layered Silicate Nanocomposites

Summary: Polyurethane foam nanocomposites were formed via in-situ copolymerisations, in which polyether polyol/water-montmorillonite mixtures were reacted with toluene diisocyanate. The unmodified Na⁺- montmorillonite (MMT) was swollen in polyol/water using an ultrasound technique resulting in intercalated layers with increased basal spacings of 2.3 ± 0.1 nm. Measurements of quasi-adiabatic temperature rise showed higher reaction rates as MMT loading increased from 0 to 10 wt.-%. Forced-adiabatic FTIR spectroscopy was used to determine the kinetics of both the copolymerisation and of the microphase separation between poly(ether-urethane) soft segments and polyurea hard segments. The apparent microphase-separation transition time decreased from 70 ± 3 to 42 ± 2 s upon addition of ≤10 wt.-% MMT, but at reaction times >100 s there was significant retardation of the development of hydrogen bonding in the urea groups of the hard-segment phase.     

可降解聚合物/层状硅酸盐纳米复合材料的研究进展

作为一类性能优良的环保功能材料，生物降解性聚合物/层状硅酸盐（BPLS）纳米复合材料正日益引起人们的关注。本文综述了BPLS纳米复合材料的制备途径、结构表征方法及其性能特点，同时对其应用前景作了展望。     

Hydrothermal Synthesis of Magnesium Silicate Montmorillonite for Polymer-Clay Nanocomposites

Conditions of hydrothermal synthesis of magnesium silicate montmorillonite Mg₃Si₄O₁₀(OH)₂·nH₂O with a particle size of 50–100 nm are optimized, including the temperature, initial chemicals, reaction medium, and run duration.__________Translated from Zhurnal Prikladnoi Khimii, Vol. 78, No. 1, 2005, pp. 28–35Original Russian Text Copyright © 2005 by Golubeva, Korytkova, Gusarov.     

TPEV/Layered Silicate Nanocomposites with Dynamic Vulcanizing Process

Thermoplastic Elastomer Vulcanizates (TPEV) prepared by dynamic vulcanizing process, is a material which has both the properties of a vulcanized rubber (elasticity) and thermoplastics (processibility). TPEV is cost effective for its good processibility and eco-friendly for its recyclability. TPEV/layered silicate nanocomposites can give a greater advantage of weight reduction which is a key issue in automotive industry because of fuel efficiency. Applying TPEV/layered silicate nanocomposites, the amount of reinforcement mineral filler can be reduced greatly compared to general TPEV which is reinforced by talc or kaolin clay. The mechanical strengths of TPEV/layered silicate nanocomposites using small amounts of MMT is similar to those of general TPEV using larger amounts of general filler. Various evaluations such as degree of crosslinking, degree of filler dispersion (XRD and TEM), surface hardness and tensile properties were carried out for the TPEV/layered silicate nanocomposites.     

Thermal Behaviour of Poly(propylene) Layered Silicate Nanocomposites

The thermal degradation behaviour of nanocomposites based upon poly(propylene)/organoclay, modified with protonated octadecyl amine (C18) in comparison to that of non‐exfoliated microcomposites based upon organoclay, modified with protonated butyl amine (C4), was studied by thermogravimetry. In the case of the nanocomposite, the temperature at which volatilisation occurs increases as compared of the microcomposite. Moreover, the thermal oxidation process of the polymer is strongly slowed down in the nanocomposite with high char yield both by a physical barrier effect, enhanced by ablative reassembling of the silicate, and by a chemical catalytic action due to the silicate and to the strongly acid sites created by thermal decomposition of the protonated amine silicate modifier.     

剥离型聚合物-层状硅酸盐纳米复合材料的线性粘弹性计算

在二元限制模型的基础上,计算了剥离型聚合物-层状硅酸盐纳米复合材料的线性粘弹性,提出了纳米复合材料在低频下的弹性增加主要是由吸附聚合物链长松弛模式引起的.     

有机硅建筑材料

概述了有机硅在建材工业中作为涂料、助剂、密封胶和防粘剂及防水剂的组成、种类、发展及其应用     

Interfacial Interactions and Properties of Polyethylene‐Layered Silicate Nanocomposites

Summary: Organically modified montmorillonites (OMs), carrying alkyl chains, phenyl groups, or a combination of both, were prepared and compounded with polyethylene. The oxygen permeability coefficients and tensile properties of the nanocomposites were correlated to the exfoliation of the OMs. Partial exfoliation was achieved, although no intercalation was observed. Aromatic moieties attached to the clay surface led to a stronger interaction between the OM layers and less exfoliation.

Transmission electron micrograph of a 2.8 vol.‐% dioctadecyldimethylammonium nanocomposite. The dark lines are cross sections of aluminosilicate layers.     

Polymer Layered Silicate/Carbon Nanotube Nanocomposites: Morphological and Rheological Properties

Morphological and rheological properties of new ternary nanocomposites based on ethylene vinyl acetate copolymers (EVA), commercial organo-modified clays (organoclays) and purified multi-walled carbon nanotubes (MWNTs), prepared via direct melt blending, have been evaluated. For sake of comparison, the corresponding binary compositions, i.e., EVA filled with either organoclays or MWNTs, have been investigated as well. While extensive exfoliation can be observed for binary EVA/clay nanocomposites, the addition of MWNTs appears to limit clay exfoliation. Rheological properties show that both clay and MWNTs increase the elastic modulus of the nanocomposites, reflecting the high degree of nanoparticle interconnectivity that can be found in these materials.     

Preparation and Properties of Layered Silicate Nanocomposites Based on Ethylene Vinyl Acetate Copolymers

(Nano)composites based on ethylene vinyl acetate copolymers (EVA) and montmorillonite modified by various alkylammonium cations were processed by mechanical kneading. Polymer intercalation and filler exfoliation were evidenced by X‐ray diffraction and transmission electron microscopy, respectively. Nanocomposites tensile properties showed that Young's modulus increases significantly even at very low content of the organo‐modified filler while preserving high ultimate elongation and tensile stress. The matrix thermal stability in air was increased by 40°C and, interestingly, the obtained nanocomposites present flame retardant properties.     

The Aspect Ratio and Gas Permeation in Polymer‐Layered Silicate Nanocomposites

Summary: Organophilized montmorillonite‐epoxy and ‐polyurethane nanocomposites, useful for packaging applications, were prepared and their oxygen permeability was measured. The composite morphology was mixed, exfoliated and intercalated, as shown by wide‐angle X‐ray diffraction (WAXRD) and transmission electron microscopy (TEM). The gas‐barrier performance of the polyurethane composites was better than that of the epoxy composites due to more exfoliation. The average aspect ratio of the montmorillonite platelets in the nanocomposites could be estimated from the reduction in permeability by a numerical finite element approach.

A computer model comprising 50 randomly distributed and oriented round platelets with an aspect ratio of 50 at 3 vol.‐% loading, periodic boundary conditions applied.     

Molecular Dynamics Simulation of the Fracture in Polymer‐Exfoliated Layered Silicate Nanocomposites

Summary: The MD technique was used to investigate the fracture behavior in fully exfoliated layered silicate (nanoplatelet)‐polymer nanocomposites. MD results reveal that the addition of the nanoplatelets can improve the fracture strength of polymers. The interactions between the surface of the nanoplatelets and the segments of the polymer, and the relaxation time of polymer chains have significant influences on the fracture strength of the polymer. For polymers with T_g below room temperature, such as polyurethane, or close to room temperature, such as nylon, the nanoplatelets are always working for the enhancement of the mechanical properties. However, for polymers with T_g above room temperature, such as epoxy and polystyrene, the addition of the nanoplatelets is not working well for toughening these polymers. If the nanoplatelets are to enhance the mechanical properties of these polymers, it is necessary to build up a stress relaxation interface between the polymer and the nanoplatelet in order to reduce the effect of the difference between the relaxation time of nanofillers and that of polymers.

Force per area versus distance curves as a function of the difference of the relaxation times of the nanoplatelets and polymer chains.