Network Formation in PP/Layered Silicate Nanocomposites: Modeling and Analysis of Rheological Properties

PP/organophilic montmorillonite composites were prepared from PP homopolymer, maleinated polypropylene and a clay organophilized with octadecyl amine. Various approaches were used to analyze the rheological properties of the composites. Cole-Cole plots proved to be useful, since they detect the network very sensitively. The frequency dependence of the real part of complex viscosity was described with a series of Maxwel bodies coupled parallel to each other. The relaxation time of the melt changed in the range of 0.0005 and 200 sec. Under certain conditions long relaxation times appear in the spectrum, which indicate the formation of new structural units, probably a silicate network. A certain number of silicate layers are needed to create a house-of-cards structure. A threshold concentration of MAPP exists for network formation, which depends on silicate content.     

Formation and Detection of Clay Network Structure in Poly(propylene)/Layered Silicate Nanocomposites

Summary: The study of the structure and the rheological properties of poly(propylene) (PP)/montmorillonite (MMT)/maleinated PP (MAPP) composites strongly suggests that a silicate network may form under certain conditions. Network formation could not be proven unambiguously with the usual techniques, i.e., with TEM and by plotting the frequency dependence of viscoelastic properties. Cole‐Cole plots detect the network very sensitively. A certain number of silicate layers are needed to create a house‐of‐cards structure. A threshold concentration of MAPP exists in the investigated system, which depends on the silicate content.

Cole‐Cole representation of the viscoelastic properties of PP/OMMT/MAPP nanocomposites.     

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。     

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。     

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.     

Polypropylene-Clay Nanocomposites: Comparison of Different Layered Silicates

In former studies of the preparation of polypropylene(PP)-clay nanocomposites, different types of layered silicates were used. However, the obtained results were not comparable due to different preparation conditions and types of silicates. The aim of this work was the investigation of the influence of different layered silicates on the properties of the resulting nanocomposites. FT-IR-spectra, SAXS, TEM micrographs, elemental analysis, mechanical properties and surface tension measurements were used for the comparison of the four different layered silicates under investigation.     

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.     

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。     

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。     

Preparation and Flame Retardancy Properties of Novel PA12 and PE/Layered Titanoniobates Nanocomposites

Summary: We report herein a study performed on a layered titanoniobate KTiNbO₅ modified by octadecylamine to evaluate the fire retardancy properties of this novel hybrid nanofiller dispersed in PA12 and LLDPE, by polymer melt intercalation. The nanocomposites have been characterized using Electron Microscopy techniques to evaluate the degree of exfoliation and the morphologies. Thermogravimetric analyses and cone calorimeter tests have been carried out to assess the fire retardant performances.     

动态硫化EPDM／PP共混体系中PP相的结晶度及晶体结构的研究

研究了动态硫化ＥＰＤＭ／ＰＰ共混物中ＰＰ相的结晶度及晶体结构,同时讨论了制备工艺条件以共混物中ＰＰ相的结晶度和晶体结构的影响。结果表明：在动态硫化ＥＰＤＭ／ＰＰ共混物中,硫化的ＥＰＤＭ的分子键没有穿入ＰＰ的晶区,ＰＰ的结晶度随ＥＰＤＭ含量的增加而下降。提高共混温度,加入软化剂或碳黑均使共混物中ＰＰ的结晶度降低,共混时间１５ｍｉｎ时,共混物中ＰＰ相的结晶度最低,但ＰＰ的晶格不受制备工艺条件的影响。     

Quantitative Characterization of Clay Dispersion in Polymer-Clay Nanocomposites

Summary: A novel methodology has been developed to describe the microstructure of polymer-clay nanocomposites quantitatively. It builds on the image analyses of transmission electron microscopy and optical microscopy micrographs, and two parameters, degree of dispersion and mean interparticle distance per unit volume of clay, are proposed to characterize the level of clay dispersion. It provides insights into the ‘real’ clay dispersion using a combination of both microscopical and macroscopical aspects.     

Synthesis of Chain-End Functionalized PP and Applications in Exfoliated PP/Clay Nanocomposites

This paper summarizes our research to the preparation of chain-end functionalized isotactic polypropylene (i-PP) having a terminal functional group, such as an OH and an NH₂. The chemistry involves metallocene-mediated propylene polymerization using the rac-Me₂Si[2-Me-4-Ph(Ind)]₂ZrCl₂/MAO complex in the presence of styrene derivatives (St-f) and hydrogen, which serve as the chain transfer agents. The molecular weight of the resulting i-PP polymers with terminal OH or NH₂ groups (i.e., PP-t-OH and PP-t-NH₂) are inversely proportional to the molar ratio of [St-f]/[propylene]. Despite the extremely low concentration of functional groups, the high molecular weight NH₃⁺-terminated PP (PP-t-NH₃⁺) exhibits a distinctive advantage over other functional PP polymers containing side chain functional groups or long functional blocks. The terminal hydrophilic NH₃⁺ cation, with good mobility and reactivity, effectively ion-exchanges the cations (Li⁺, Na⁺, etc.) located between the clay interlayers, and anchors the PP chain to the clay surfaces. On the other hand, the remaining rest of the unperturbed, end-tethered, high molecular weight PP tail exfoliates the clay layers. This exfoliated structure is maintained even after further mixing of the PP-bearing platelets with pure, neat PP polymers.     

Effect of the Organoclay Structure on Morphology and Rheological Response of PBT Nanocomposites

In this paper the effect of different organoclays on the structure and the rheological properties of poly(butyleneterephtalate)–clay nanocomposites produced by melt compounding was investigated. The study was carried out using as nanometric fillers four commercial montmorillonites, treated with different organic modifiers and having similar interlayer spacing and organo-modifier concentration. Each organoclay was melt compounded with PBT (at 3%, 6% and 9% by weight of clay) using a twin screw extruder. Using the same processing conditions, hybrid samples containing the unmodified silicate were also prepared for comparison purposes. All the obtained nanocomposite samples were submitted to physico-chemical (XRD, TEM and FT-IR), and rheological measurements in order to evidence the role of polymer-clay affinity on the morphology and on the viscoelastic response of the materials. The results have pointed out that, with the used processing conditions, all nanocomposites exhibit a mixed intercalated/exfoliated structure; nevertheless, the clay dispersion homogeneity and the exfoliation level reached in the samples are higher for Nanofil 919 and Dellite 43B fillers, the organic modifiers of which may favorably interact with PBT matrix.     

聚苯胺/膨润土纳米复合材料的合成与表征

通过嵌入手段设计与合成同时具有某些无机和有机物双重性能的新型材料－无机／有机纳米复合材料,是科学家们关注的课题[1].Inoue等人[2]采用蒙脱土吸附苯胺单体然后电氧化的方法制备了聚苯胺／蒙脱土（Pan／Mont）复合材料,由于Mont片体的表面吸附了苯胺,所合成的为聚合物包覆的复合材料,这样在一定的程度上影响了材料的各向异性．本文采用离子交换,洗涤除去吸附在粘土颗粒表面的单体,成功地合成了非包覆的聚苯胺／膨润土壤（Ben）层状纳米复合材料,并用FTIR等方法对材料进行了表征．该材料兼有粘土的离子交换性能和聚苯胺的良好…     

层状硼酸铍H2BeB4O8的合成与结构

在硼酸介质中合成了一种新的具有层状结构的多硼酸铍H₂BeB₄O₈,并利用多晶X射线衍射方法确定了晶体结构。H₂BeB₄O₈的空间群为P2₁/n,晶胞参数a=17.7564(2)?,b=4.2948(1)?,c=7.1532(1)?,β=96.8797(9)°。H₂BeB₄O₈的层状结构由双三元环[BeB₄O₁₁]构成,层之间通过垂直于层平面的羟基所形成的氢键连接成三维结构。     

Zn/Al层状双氢氧化物-聚氯乙烯纳米复合物的制备与性能

用共沉淀法制备油酸钾改性的Zn2+、Al 3+层状双氢氧化物(Zn/Al-LDH),以环己酮为溶剂,用溶液插层法制备了Zn/Al层状双氢氧化物-聚氯乙烯(PVC)纳米复合物。采用傅里叶红外(FT-IR)、X-射线衍射(XRD)、透射电镜(TEM)对复合材料的结构及形貌进行了表征,并用热分析仪、万能试验机和紫外分光光度计研究了复合物的热稳定性能、拉伸性能和紫外吸收性能。结果表明:Zn/Al-LDH纳米片层无序分散在PVC基体中;Zn/Al-LDH对PVC低温时的骨干脱氯化氢有促进作用;与PVC膜相比,复合膜的分解温度降低,高温碳化温度升高,复合膜的拉伸强度及断裂伸长率得到提高,在300~380nm具有一定的紫外吸收性能。     

PP/尼龙66/聚碳酸酯/ABS共混高聚物的SEM样品制作

讨论了PP／尼龙66／聚碳酸酯／ABS共混高聚物的扫描电子显微镜样品制作中存在的问题,通过实验,探讨了出该材料最佳的样品制作条件。