Abstract: Al2O3 dispersion strengthened copper composite (Al2O3p/Cu composite) was produced by internal oxidation. The hardness and electrical conductivity of the produced Al2O3p/Cu composite (0.60 wt.% Al2O3) subjected to high temperature annealing treatments after different cold work deformations have been investigated; the microstructures of the composite have also been analyzed by TEM. Results show that the microstructure of the composite is characterized by an uniform distribution of nano-Al2O3 particles in Cu-matrix; the composite can maintain more than 91% hardness retention after 1h, 1000°C annealing treatment; the recrystallization of the Cu-matrix can be largely retarded and only partially happened even annealing for 1h at 1050°C, following cold deformation of 84%.
Abstract: Adding nano-particles with high refractive index can greatly improve the optical
properties of the PMMA-based composites, which were developed as the new-type rear projection screen. In this paper, the influence on the optical properties, such as gain and view angle, by the content of additive TiO2 nano-particle was studied. Curves of optical properties versus content of nano-particle were obtained and the rational factors were found. Finally the reasons were discussed from the nanostructure point of view and the scattering principle.
Abstract: A novel exfoliated polyurethane (PU)/clay Interpenetrating Polymer Networks (IPNs) nanocomposite has been synthesized with polyurethane and organoclay. MTPAC is used as swelling agent to treat Na-montmorillonite for forming organoclay. The results indicate that there is very good compatibility between organoclay and PU. Nanoscale silicate dispersion was analyzed by XRD. The mechanical properties of the nanocomposites have been measured by tensile testing machine. The nanocomposites show obviously improved physical and mechanical properties when compared with the pure polymer. Additionally, PU /MTPAC- clay shows lower water absorption properties than pure PU do. In addition, the reinforcing and intercalating mechanism of silicate layers in polyurethane matrix are discussed.
Abstract: Stearic acid coated nanometer CaCO3 was encapsulated by polystyrene (PS) network via emulsion polymerization, where a polyfunctional monomer trimethyol propane trimethacrylate (TMPTMA) or divinyl benzene (DVB) was used as crosslinker. The feed modes of monomer and initiator are investigated. Batch mode is shown to be more convenient than semi-continuous mode in view of network perfection. With the amount of crosslinkers increased from 1 wt% to 7 wt%, the
percentage of unextractable PS is high (not lower than 95%) for all samples in the system of TMPTMA, while this value decreases sharply from 74% to 3% in the system of DVB. The yield in the system of DVB is higher than that of TMPTMA. With increased amount of CaCO3, encapsulation ratio can be varied from 5.2 to 2.6, while the yield and unextractable PS decrease. FT-IR spectra of the products after extraction indicate tight encapsulation between PS and CaCO3, and TEM photographs of composite particles give direct evidence of encapsulation.
Abstract: This study considers a method for producing SWNTs reinforced lightweight
metal-matrix composites. In this research, fluorination has been applied to achieve
considerable improvement in the dispersion of purified single-walled carbon nanotubes. It has been demonstrated that surface fluorination is a possible approach to entrap catalytic nucleation centers along the walls of SWNTs. The results show that nickel could be successfully plated onto the activated surfaces of fluorinated SWNTs (F-SWNTs) through electroless plating which is an effective way for producing nanotube/metal systems. It was observed that high surface coverage of Pd-Sn catalytic nuclei is needed to form high quality coatings. A two-step approach was used and the coating mechanism is described in this paper.
Abstract: Resin matrixes for aeronautic advanced composites based on thermoplastic PEK-C
(modified polyetherketone) and blending epoxies of DGEBA (diglycidyl ether of bisphenol A) and TGMDA (tetraglycidyl methylenedianiline) are analyzed by DMTA in this paper. The effects of blending ratios and high-temperature post-curing processes on DMTA properties are investigated. The results show that epoxies exhibit different curing features with the existence of high viscous thermoplastic, by contrarily the neat epoxies systems cure according to a random copolymerization
rule. The primary peak of tangent delta of DMTA mainly attributes to segment motions of thermoplastic in a blend and the secondary peak mainly for those of the DGEBA cured networks. The higher the ratio of TGMDA to DGEBA is the more obviously the separation degree of tangent delta peaks adopt. Increasing the amount of TGMDA is helpful for separating of phases in the blends. High temperature post-curing promotes separating of phases. In a blend the continuous
phase mainly consists of a mass of thermoplastic and some TGMDA, DGEBA mainly collects in dispersed phases.
Abstract: A radar absorbing structure composite (RAS) which contains circuit analogue structure (CAS) made from conductive foil was studied in this paper. The results show that CAS acting as a reflection screen can cause the interference of incident EM wave with reflection EM wave. So, through rational composite material design and preparation, the radar absorbing structure composite with CAS can exhibit good radar absorbing property. The results also show that in the composites with gradually changed impedance, when other design parameters are not changed but
only increase the size of CAS, the electromagnetic parameter and the thickness of the medium laminate, the maximum absorbing peak of the reflectivity will move to the direction of the lower frequency. The above research results show that the introduction of CAS into the radar absorbing structure composites can improve the wave-absorbing properties. Therefore the radar absorbing structure composite with CAS is a promising radar absorbing structure composite form.
Abstract: A super-absorbent polymer (SAP) is synthesized with polystyrene foam (PSF) and sodium acrylate through inverse emulsion polymerization. The influence of experiment conditions such as solvent of PS, composition of comonomers, initiator and cross-linking agent on the absorption capacity of the resins are discussed. The maximum water absorption rate of the prepared SAP is about 1600g/g.
Abstract: Tetra-needle like ZnO whisker modified NR-SBR-BR and PPS composites were
prepared. The outcome of the investigation indicated that T-ZnO had an instinct effect on reinforcing polymer material isotropically. Further analysis showed that experiment results of T-ZnO/PPS composite gave much higher strength than that of the theoretical calculation from classical rule of mixing, and the explanations were put forward. The experimental tests on wear behavior of the composites of T-ZnO/NR-SBR-BR were carried out and got the conclusion that T-ZnO had a good effect of improving the wear resistance. The worn surfaces of the composites of
T-ZnO/NR-SBR-BR appeared an instinct character of fractal, and the values of both the fractal dimension and the abrasion loss decreased synchronously as the increasing of T-ZnO loading in the composites.