无机填料改性聚硫密封胶的研究

研究了纳米碳酸钙、轻质碳酸钙、重质碳酸钙、滑石粉、绢云母和TiO<,2>等6种无机填料对聚硫密封胶(PSS)的力学性能、玻璃化转变温度(Tg)和耐溶剂性能的影响.研究表明,纳米碳酸钙和钛白粉具有较好的补强效果,在添加量为80份时,PSS的断裂伸长率和拉伸强度分别为430%、2.63MPa和369%、2.62MPa.填充...     

Field emission from multi-walled carbon nanotubes with various fillers

Pastes for field emission test were prepared by 3-roll milling of multi-walled carbon nanotubes (MWNTs) and UV-sensitive binder solution. The effects of four filler additives, namely two types of indium tin oxide (ITO) powder, glass frit and Ag on the field emission properties of the screen-printed paste were investigated and compared to those without filler using a diode-type configuration. The paste formulation was shown to be adequate for fine patterning using a UV-lithography technique. MWNT pastes containing any type of filler showed better emission properties than the paste without filler, thereby confirming the importance of the filler. The MWNT paste with 1 wt.% glass frit showed the best results with the lowest turn-on field of 1.75 V/μm at 1 μA/cm², highest emission current density of 78 μA/cm² at 5 V/μm, and β-factor of 17,000 approximately, which are satisfactory for practical application.     

Wear behavior of light-cured resin composites with bimodal silica nanostructures as fillers

To enhance wear behavior of resin composites, bimodal silica nanostructures including silica nanoparticles and silica nanoclusters were prepared and proposed as fillers. The silica nanoclusters, a combination of individually dispersed silica nanoparticles and their agglomerations, with size distribution of 0.07–2.70 μm, were fabricated by the coupling reaction between amino and epoxy functionalized silica nanoparticles, which were obtained by the surface modification of silica nanoparticles (~ 70 nm) using 3-aminopropyl triethoxysilane (APTES) and 3-glycidoxypropyl trimethoxysilane (GPS) as coupling agents, respectively. Silica nanoparticles and nanoclusters were then silanized with 3-methacryloxypropyl trimethoxysilane (γ-MPS) to prepare composites by mixing with bisphenol A glycerolate dimethacrylate (Bis-GMA) and tri (ethylene glycol) dimethacrylate (TEGDMA). Experimental composites with various filler compositions were prepared and their wear behaviors were assessed in this work. The results suggested that composites with increasing addition of silica nanoparticles in co-fillers possessed lower wear volume and smoother worn surface. Particularly, the composite 53:17 with the optimum weight ratio of silica nanoparticles and silica nanoclusters presented the excellent wear behavior with respect to that of the commercial Esthet-X, although the smallest wear volume was achieved by Z350 XT. The introduction of bimodal silica nanostructures as fillers might provide a new sight for the design of resin composites with significantly improved wear resistance.     

The properties of epoxy resin coated silica fillers composites

Epoxy resin coated silica fillers composites with high percentage of filler loading, such as 80 to 95 vol.% are able to be produced by a mechanical mixing technique. The advantages of high filler loading of theses materials are noted from the thermal and flexural modulus. Apparently, the materials exhibit low coefficient of thermal expansion (CTE) at as low as or below 10 ppm/°C and high flexural modulus of above 20 GPa. In general, these promising characteristics fulfill the requirement to be used as substrate materials in electronic packaging applications.     

SiO2-聚合物杂化微球改性聚丙烯的非等温结晶动力学

将原位乳液聚合制得的SiO₂-聚合物杂化微球与聚丙烯熔融共混制备了SiO₂/聚丙烯(SiO₂/PP)复合材料, 利用差示扫描量热法(DSC)研究了SiO₂/PP复合材料的非等温结晶动力学行为。结果表明, SiO₂-聚合物杂化微球具有明显的异相成核效应, 提高了PP的结晶温度和结晶速率, 同时降低了PP的结晶度, 提高了PP的结晶活化能。运用Mo法处理纯PP和SiO₂/PP复合材料的非等温结晶动力学, 结果显示SiO₂-聚合物杂化粒子降低了聚丙烯在单位结晶时间内达到一定结晶度时所需的降温速率。     

The mechanical properties of rubber compounds containing soft fillers

Rubber compounds are traditionally reinforced with carbon black or silica fillers of minute particle size. Prior studies in which much larger recycled rubber scrap has been incorporated, indicate that only low levels can be tolerated before significant deterioration in performance is noted. Failure can be superficially linked to macroscopic flaws as is commonly observed in both thermoplastics and elastomers. In this study a detailed examination of soft elastomeric fillers in a polybutadiene matrix is described. In particular the effect of filler hardness and interfacial bonding is stressed. An estimation of the interfacial adhesion is made from peel tests.     

SiO2-聚合物杂化微球改性聚丙烯的非等温结晶动力学

将原位乳液聚合制得的SiO2-聚合物杂化微球与聚丙烯熔融共混制备了SiO2/聚丙烯(SiO2/PP)复合材料,利用差示扫描量热法(DSC)研究了SiO2/PP复合材料的非等温结晶动力学行为.结果表明,SiO2-聚合物杂化微球具有明显的异相成核效应,提高了PP的结晶温度和结晶速率,同时降低了PP的结晶度,提高了PP的结晶活化能.运用Mo法处理纯PP和SiO2/PP复合材料的非等温结晶动力学,结果显示SiO2-聚合物杂化粒子降低了聚丙烯在单位结晶时间内达到一定结晶度时所需的降温速率.     

功能性填料改性聚合物材料的摩擦学研究进展

聚合物材料因其质轻、价廉、耐腐蚀以及优异的自润滑特性而广泛应用于工程机械润滑领域中。加入功能性减摩和增强填料复合改性聚合物树脂可以克服本征型高分子材料的一些固有缺陷,得到低摩擦因数、高耐磨性、高承载力以及耐高温等优异特性的摩擦学复合材料。本文综述了功能性填料如碳基材料、过渡金属硫化物、微胶囊、软金属、陶瓷纳米颗粒、矿物盐以及自润滑高分子对复合材料的减摩抗磨效果及机理。同时,力学性能是保证聚合物材料服役性能和使役寿命的关键参数,也会对材料的摩擦学性能带来显著影响。本文还重点论述了纳米颗粒和纤维等填料对复合材料的增强和增韧机理。最后,展望了功能性填料对力学性能与摩擦学性能的协效作用,以及计算机模拟在复合材料摩擦学中应用的发展趋势。     

The mechanical properties of rubber compounds containing soft fillers

A detailed examination of failure of properties of polybutadiene containing soft elastomeric fillers has previously been described [1]. Here the effect of filler modulus and filler-matrix adhesion on tear strength is measured. Tear behaviour depends upon the level of interfacial adhesion; when high, tear strength increases with increasing filler hardness, but if interfacial adhesion is low, incorporation of fillers may result in low tear strengths. An estimate of the edge flaw size is made from the tear strength and strain energy densities at break. It was found that compounds with low interfacial adhesion generally had edge flaw sizes of the same order as the maximum filler particle size. A correlation between tear strength and tear surface morphology is made.     

Thermal and mechanical behaviour of flexible polyurethane foams modified with graphite and phosphorous fillers

Flexible polyurethane foams (FPF) are polymer materials that have high flammability. Fyrol PNX (FPNX) and expandable graphite (EG), have been used to modify the properties of these materials. The aim of this study was to assess the possibility of improving the thermal stability and flame retardancy of FPF by the addition of FPNX and EG fillers. The prepared foams were characterised by their apparent density, hardness, flexibility, irreversible strain and linear flammability, as well as thermogravimetric analysis (TGA), dynamic mechanical analysis, Fourier transform infrared spectroscopy (FT-IR) and pyrolysis combustion flow calorimetry (PCFC) measurements. The apparent density, hardness, flexibility and irreversible strain results showed that the addition of graphite and phosphorous fillers to the FPF makes slight changes to the mechanical properties, which remain within the acceptable norms. It was also observed that reducing the amount of Fyrol PNX and replacing it with the same amount of EG allowed similar values of linear flammability to be obtained with a simultaneous increase in thermal stability, as shown in the TGA study and the PCFC test. Moreover, it was found that the modification of flexible polyurethane foam by the addition of a mixture of FPNX and EG fillers allows the best properties of this type of materials to be obtained. This result indicates that this type of modification could be an effective way to improve the thermal stability of FPF.     

Effects of various fillers on the sliding wear of polymer composites

Short fibre reinforced polymer composites are nowadays used in numerous tribological applications. In spite of this fact, new developments are still under way to explore other fields of application for these materials and to tailor their properties for more extreme loading conditions. The references given at the end of this review describe some of these developments. In the present overview further approaches in designing polymeric composites in order to operate under low friction and low wear against steel counterparts are described. A particular emphasis is focused on special filler (including nanoparticle) reinforced thermoplastics and thermosets. Especially, the influence of particle size and filler contents on the wear performance is summarised. In some of the cases, an integration of traditional fillers with inorganic nanoparticles is introduced and presents an optimal effect. Furthermore, some new steps towards the development of functionally graded tribo-materials are illustrated.     

Preparation of high silica microporous zeolite SSZ-13 using solid waste silica fume as silica source

Silica fume (SF) is a kind of solid waste that produced in the process of industrial silicon smelting. The disposal of SF for environmental problem is of great urgency. Here, a facile and novel one-step approach of high silica microporous materials SSZ-13 (SF-SSZ-13) were hydrothermally synthesized using silica fume (SF) as silica source. This method requires significantly shorter reaction times (48?h) compared to conventional SSZ-13. The as-synthesized SF-SSZ-13 exhibited high purity structure, popcorn-like morphology, and a large BET surface area of 545.74?m²?g^?1. Additionally, on the basis of controlled growth under different hydrothermal times, the formation mechanism of the SF-SSZ-13 outlined for further extension to other materials. The results on time- and energy-efficient of SF-based preparation of SSZ-13 pave the way for the reducing the cost of production of raw materials and decreasing environment load of solid waste, and also extend the application of silica fume.     

Influence of silica fillers on the ageing by gamma radiation of EDPM nanocomposites

This study evidences that the presence of silica fillers as well as their surface treatment influences the impact of gamma irradiation on the mechanical properties of the filled materials. It influences it both chemically, by a modification of the kinetics of the degradation reactions, and physically, through the complex modification of the filler–filler and filler–matrix interactions involved in the mechanical properties of the filler network.     

Mechanical properties and rheology of polyalkenoate cements using various low-cost fillers

Low-cost polyalkenoate cements analogous to dental cements, i.e., cements based on polymers of acrylic acid crosslinked via bridging metal cations, were developed with a goal of producing a more flexible alternative to Portland cement. Economic constraints necessitated the replacement of the acid-degradable glass normally used in dental cements; the purpose of the glass is to provide both a source of polyvalent cations for crosslinking and solid filler for a composite material. The dual functionality of the powdered glass was accomplished via the use of manganese tetraoxide as the filler and aluminum chloride as the cation source for the ionic crosslinks. Unlike dental cements that have a gel-like consistency before setting, low viscosity cements were produced by using acrylic acid monomer rather than low-molecular weight poly(acrylic acid). Mechanical and rheological properties were used to monitor cement characteristics. Because of the large number of formulation variables, a design of experiments (DOE) approach was used. DOE helped narrow the search for formulations that would result in hardened cements and find the optimal set of ingredients that led to cements with the best properties given the economic constraints on the ingredients. Rheology was adjusted to match that of Portland cement by altering the filler volume fraction, which was very effective since the rheology depended strongly on that variable. The most pertinent independent variables for the mechanical properties were the curing time and monomer/cation ratio in the ranges tested; however, the monomer/water ratio was fixed at the minimum level possible and not increased because of economic considerations. The best materials produced in terms of mechanical properties resulted when acrylic acid monomer was partially replaced by N,N′-methylenebisacrylamide; this substitution resulted in a stronger and tougher cement. An erratum to this article can be found at     

Effect of fillers on natural rubber/high styrene rubber blends with nano silica: Morphology and wear

The blends of high styrene rubber (HSR) and natural rubber (NR) with nano silica were prepared using a blending technique in presence of different types of carbon black. The effect of filler on morphological and wear characteristics was studied. ISAF (Intermediate Super Abrasion Furnace) type of carbon black have showed a significant effect on optimum cure time, cure rate index and mechanical properties by reacting at the interface between HSR and NR matrix. All the samples show only one melting peak on the DSC curve; this is attributed to the same backbone structure of the matrix and the carbon black reinforcement. The samples containing 30 wt.% of HSR with ISAF type of carbon black has shown maximum heat buildup, lower swelling and lower compression set value. Blends containing ISAF type of carbon black with 30 wt.% of HSR showed high abrasion resistant properties against Du-Pont abrader, DIN abrader and different mining rock surfaces and also is found to be the toughest rubber against all types of rock. Coal is main abrader against the rubber under this study.     

Preparation and properties of exfoliated graphite modified with iron compounds

Using the anodic oxidation of graphite in Fe(NO₃)3-HNO₃ mixed electrolytes, followed by heat treatment, we obtained exfoliated graphite modified with iron oxides. All of the samples obtained were characterized by X-ray diffraction, M?ssbauer spectroscopy, and scanning electron microscopy. The results demonstrate that the proposed approach allows one to produce exfoliated graphite containing up to 14% Fe in the form of oxides and hydroxides, whose composition depends on the exfoliation temperature.     

Modelling the effects of various contents of fillers on the relaxation rate of elastomers

This paper describes numerical investigations conducted on filled rubbers. Some experimental data on stress relaxation tests carried out on various filled elastomers evidenced that increasing the content of rigid particles such as fillers or changes in the crystallization index, result in higher values of the stress relaxation rate. This result seems to indicate that higher rigid particle contents promote macroscopic viscoelastic strain. To better understand this effect, finite element analyses were carried out on axi-symmetric unit cells as well as unit cell for numerical homogenization with periodic computations.