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.     

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.     

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.     

Thermal properties of polystyrene with fillers

The article describes the results of an experimental investigation of the thermal properties of type A emulsion polystyrene filled with glass fibers.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol.19, No. 2, pp. 332–334, August, 1970.     

Organically modified silica nanoparticles with covalently incorporated photosensitizer for photodynamic therapy of cancer

We report a novel nanoformulation of a photosensitizer (PS), for photodynamic therapy (PDT) of cancer, where the PS molecules are covalently incorporated into organically modified silica (ORMOSIL) nanoparticles. We found that the covalently incorporated PS molecules retained their spectroscopic and functional properties and could robustly generate cytotoxic singlet oxygen molecules upon photoirradiation. The synthesized nanoparticles are of ultralow size ( approximately 20 nm) and are highly monodispersed and stable in aqueous suspension. The advantage offered by this covalently linked nanofabrication is that the drug is not released during systemic circulation, which is often a problem with physical encapsulation. These nanoparticles are also avidly uptaken by tumor cells in vitro and demonstrate phototoxic action, thereby highlighting their potential in diagnosis and PDT of cancer.     

Photocatalytic properties of the SBA-15 mesoporous silica molecular sieve modified with titanium

We describe three methods of post-synthesis modification of the SBA-15 mesoporous molecular sieve with titanium: impregnation with Ti(OEt)₄ in an ethanolic solution, grafting with titanocene dichloride, and modification with colloidal titania. The products were characterized using X-ray diffraction (XRD) and N₂ adsorption as well as Fourier-transform infrared and ²⁹Si NMR spectroscopies. All three methods yield materials containing 1.4--4.7 wt.% titanium and with high surface areas. The absorbance at 960 cm⁻¹ in SBA-15 modified with colloidal titania and SBA-15 grafted with titanocene indicates the formation of Ti–O bonds. All products showed significant activity towards the degradation of p-chlorophenol. UV-vis absorption spectra of SBA-15 samples modified with titanium indicate that the variation in the photocatalytic activity is governed by isolated titanium sites.     

Comparison of antibacterial properties of commercial bone cements and fillers with a zinc-based glass polyalkenoate cement

Postoperative infection following invasive surgical procedures is a significant cause for concern, particularly in spinal reconstructive surgery. The objective of this study is to compare the antibacterial efficacy of a novel zinc-based glass polyalkenoate cement (Zn-GPC) based on 0.04SrO–0.12CaO–0.36ZnO–0.48SiO₂ glass, to a number of commercially available bone cements and fillers including Simplex P + Tobramycin (S_Tob), Spineplex (S_pine) and Novabone Putty (N_Put). The agar diffusion test was performed on each material against Escherichia coli, Staphlococcus epidermidis, Pseudomonas aeruginosa and Staphlococcus Aureus. S_Tob was found to produce large inhibition zones in each of the bacteria tested and was statistically significantly higher than any other material. The experimental Zn-GPC (B_TSC) was found to exhibit antibacterial properties in both E. coli and S. epidermidis. Neither S_pine nor N_Put showed any inhibitory effect in any of the bacteria tested. A study was also performed to determine the effect of antibiotic release from S_Tob and Zn-GPC (B_Tob) containing the antibiotic tobramycin (Tob). Antibacterial efficacy was found to increase with respect to maturation with B_Tob, whereas S_Tob was found to decrease significantly over the time period of 0–14 days. The final objective is to investigate any change in agar composition during the agar-diffusion test. Little change was observed for S_Tob as antibiotic release cannot be determined using EDX. There was, however, an increase in Zn levels when analysing B_TSC which suggests that Zn is playing a role in the antimicrobial nature of the Zn-GPC. No significant changes were observed for S_pine or N_Put.