Xiong Chuanxi

Microstructure and properties of fluoroelastomer/butadiene-acrylonitrile rubber interpenetrating polymer networks

Interpenetrating polymer networks (IPNs) based on fluoroelastomer/ butadiene-acrylonitrile rubber (FKM/NBR) by molten blending at a high temperature and chemical cross-linking of two components were prepared. The influence of the two networks component on the mechanical properties and thermostabilities was studied. The experimental results show that the mechanical properties of the IPNs are superior to those of the individual FKM and NBR networks due to forming the case of interpenetrating and intercross-linking between the two networks, the mechanical properties and thermal resistance exhibit higher values when 80/20 (w/w) FKM and NBR is blended and respectively cured simultaneously. The co-continuous morphology of the IPNs in the blends of 80/20 (w/w) FKM/NBR is found by transmission electron microscopy (TEM), the differential scanning calorimetry (DSC) determination shows that the blends of 80/20 (w/w) FKM/NBR have better compatibility, and the glass transition temperature of the elastomer is −21.5 °C.

Characterization of PZT/PVC composites added with carbon black

A new three-phase PZT/C/PVC composite comprising PZT (50vol%), nanocrystalline PVC (50 vol%) and a small volume fraction f of carbon black (C) was prepared by the hot-pressing technique. The dielectric property of the composite as a function of the frequency and the dielectric and piezoelectric properties as a function of the volume fraction f of C were studied. The measured dielectric property demonstrates that a percolation transition occurs in the three phase composites as in normal two-phase metal-insulator continuum media. The dielectric constant varies slightly with f at f<0.1 and increases rapidly when f is close to the percolation threshold at 1 kHz. The optimum properties were obtained for f=0.5 before the percolation threshold in the PZT/C/PVC (50/f/(50−f) vol%) composite with its d33(20 pC/N) being 50% higher than that of the PZT/PVC (50/ 50vol%), and its g33 (47.23×10−3 Vm/N) and Kμ(0.25) much higher than the earlier reported values XRD patterns and P-E hysteresis loops were used to interpret the experimental results.

Dielectric behavior of nano-PbTiO3/PVDF nanocomposites in-situ synthesized by the sol-gel method

BaTiO3/PVDF nanocomposites were prepared via in-situ growth of nanosized BaTiO3 particles in PVDF matrix by using the sol-gel method. The present elements of BaTiO3/PVDF nanocomposites were analyzed by an electron probe X-ray microanalyser. Nanosized BaTiO3 grown in the composite films was characterized by an X-ray diffractometer and a transmission electron microscope, and the dielectric properties of the composite films were measured. The distribution of BaTiO3 nanoparticles in-situ grown in the PVDF matrix was examined using a scanning electron microscope.

Preparation of polyacrylate-based conductive coatings and its PTC effect

Polyacrylate-based conductive coatings were prepared from polyacrylate emulsion as matrix and carbon black (CB) whose surface was treated with titanate coupling agent as conducting particles. One kind of organic crystal was added to study its effects on the electrical conductivity and PTC (positive temperature coefficient) effect of the conductive coatings. Experimental results show that the coatings containing only polyacrylate emulsion and CB exhibit an excellent electrical conductivity but bad PTC effect, and when organic crystal is added, PTC effect is characterized and can increase by 2 orders of magtitude. The critical transformation temperature of polyacrylate emulsion/CB PTC composites is decided by melting point of organic crystals.

Modification of nanocomposites by melting intercalation of polypropylene in montmorillonite

The polypropylene was modified by ultraviolet irradiation. The polypropylene-montmorillonite nanocomposites were prepared by direct melting intercalation of polypropylene powders. The structure of polypropylene, the polyproprlene irradiated, montmorillinote and polypropylene-montmorillonite composites were studied by XRD, IR and DSC. The results show that the PP molecules can are oxidized during ultraviolet irradiation, melt polypropylene can intercalate into montmorillonite layer. As a result, the layered distance (d001) of montmorillonite increases, and the melt absorption peak of polypropylene in layer is eliminated.

The dielectric properties and preparation method of BaTiO3/PVDF 0–3 composites

A series of 0–3 composites of the polyvinylidene fluoride (PVDF) and BaTiO3 was prepared. BaTiO3 was modified with titanate coupling agent. The dielectric properties and the interfacial interaction of composites by different preparation methods were examined and compared. The result shows that the relative dielectric constant ∈ of the composite prepared in solution has a maximum value at about 70% weight fraction of BaTiO3 and the dielectric loss tanδ increases rapidly when the fraction exceeds 70%. For the composite prepared in melt, the relative dielectric constant ε almost reaches a maximum value at about 60% weight fraction of BaTiO3 and the dielectric loss is comparatively lower. The dielectric properties of composites are improved by using a coupling agent.

Rheology in Processing of in Situ Composites of Polypropylene and Low Melting Poing Metals

The low melting point metallic tin powder or alloy of tin and lead was blended with polypropylene. A kind of in situ composite has been prepared. The variations of torque were studied when the composites were mixed in Haake torque rheogeniometer. By way of capillary extrusion, effects upon rheology of the in situ composites of the low melting point metals (LMPM) and coupling agent for their different variety and content, were investigated. From flow curves, the results indicate that in situ composites mixed with the LMPM are a kind of pseudoplastic fluid. If the LMPM were melted, the higher the content of the LMPM, the lower apparent viscosity of composites. Meanwhile, when the coupling agent is added into composites, the viscosity of composite will go up first and drop then. This shows that the LMPM have a promoter flow action on the polypropylene.