Shu Hua Qi

Insulating and Thermally Conductive Composite Filled with Boron Nitride Particles

A new kind of thermally conductive composites reinforced by glass fibers with boron nitride (BN) as thermally conductive filler was prepared in heat press molding. Thermal conductivity of the composites was found to increase with increasing in filler content. But impact strength and flexural strength reach the top point, 385.05KJ/m2 and 912.6481MPa, with content of 50wt% and 20wt% respectively. The thermal conductivity of 0.8385 W/mK was obtained at 50wt% filler content. Experimental dates show that mixed matrix of epoxy (EP) and polyimide (PI) displays high thermal stability and can improve thermal stability compared to pure epoxy obviously at 50wt% PI content. Additionally, the obtained composites possess high surface resistivity and volume resistivity, which are suitable for substrate materials.

Preparation and characterization of thermoplastic acrylate pressure-sensitive adhesive/nickel/multiwalled carbon nanotubes

In this work, a novel polymer magnetic composite based on thermoplastic acrylate pressure-sensitive adhesive (acrylate PSA) filled with the nickel plating multiwall carbon nanotubes (Ni/MWNTs) were prepared using Ni/MWNTs obtained by electroless plating method. Then their morphology and properties were characterized by transmission electron microscope, scanning electron microscope (SEM), X-ray diffraction (XRD), vibrating sample magnetometer (VSM) and so on. Both SEM and XRD indicate that a large number of nickel particles are homogenously coated on the surface of MWNTs. SEM reveals that the Ni/MWNTs are homogeneously dispersed in thermoplastic acrylate PSA. The VSM show that the saturation magnetization (M s) of the Ni/MWNTs is 92.0 emu/g and the increase in the Ni/MWNTs content could enhance the M s of the thermoplastic acrylate PSA/Ni/MWNTs composites and decrease their coercivity (H c). When the content of Ni/MWNTs is 10.0 wt%, the magnetic and mechanical properties of the thermoplastic acrylate PSA/Ni/MWNTs composites are optimum.

Preparation and Characterization of Nickel Plating Graphite Nanosheet Filled Conductive Adhesive

In this paper, nickel plating graphite nanosheet (Ni plating GN) was developed by electroless plating method using graphite nanosheet (GN). The Ni and P content on the surface of GN is 34.08wt% and 2.99wt% according to the elementary analysis. The electrically conductive adhesives (ECAs) comprised acrylate pressure -sensitive adhesive (acrylate PSA) and Ni plating GN was studied. TEM result showed that Ni plating GN is homogeneously dispersed in the acrylate PSA. The electrical conductivity of the ECAs increases to 3.14×10-4 S/cm and the 180° peel strength and shear strength remains at a high level (180° peel strength about 0.58 MPa and shear strength about 0.48 MPa) when the content of Ni plating GN is 20 wt%.

Synthesis and Electromagnetic Properties of Polyaniline Nanofibers Using Polyglycol as ‘Soft’ Template in the Aqueous Ethanol

In this paper Polyglycol (PG) was used as ‘soft’ template to induce the polymerization of aniline in aqueous ethanol and hence control both the nucleation and growth of polyaniline (PANI) nanofibers. The products were characterized by Transmission electro microscope (TEM) and X-ray diffraction (XRD) techniques. TEM photos showed that the diameter of PANI nanofibers synthesized in pure water is 100nm while that of PANI nanofibers synthesized in aqueous ethanol is 50nm. It revealed that the volume fraction of ethanol showed really important effect on the morphological parameters of the PANI nanofibers. The X-ray diffraction patterns of the PANI nanofibers showed high crystallinity. Moreover, the resulting PANI nanofibers exhibited an unusual electromagnetic loss at the microwave frequency (f = 8.2~12.4 GHz) . Compared with 1.79, the highest electrical loss, tanδe, of the microparticles PANI at 8.47 GHz and 0.72, the highest magnetic loss, tanδm at 10.93 GHz, it was noted that the highest electrical loss, tanδe, of PANI nanofibers reached 3.26 at 10.4 GHz, and the highest magnetic loss, tanδm, was 2.85 at 9.35 GHz. It might arise from order arrangement of polaron as charge carrier caused by nanofibers morphology and can be used for the potential application as microwave absorbing materials.

Study on Glass Fiber Reinforced EP/PSF Insulating and Thermally Conductive Composite Filled with BN Particles

Polysulfone modified epoxy resin was chosen as the matrix of composite materials. The epoxy/glass fiber/boron nitride composite materials were prepared by heat press molding. The effect of different size and content of BN on the thermal, mechanical, electrical properties and thermal stability of the composite was investigated. The results showed that thermal conductivity and thermal stability of the composite increased with the content of the BN particles, the thermal conductivity of the composite reached 0.672W/m·K when filled with 1μm BN at 20 wt.%. Impact strength and flexure strength of the composite increased initially and then decreased with the increasing content of BN. The electrical insulating property of the composite remained with the content of 20 wt.% BN.

Preparation and Characterization of Purified Multi-Walled Carbon Nanotubes Filled Conductive Adhesive

In this paper, purified multi-walled carbon nanotubes (MWNTs) were obtained by acid treatment and oxidation treatment using the crude MWNTs, then purified MWNTs were filled into acrylate pressure-sensitive adhesive (PSA) to produce electrically conductive adhesives (ECAs). XRD and TEM results showed that the impurities were greatly eliminated after purification treatment. The electrical conductivity of the ECAs increased gradually as the content of the purified MWNTs increased. When the content of the purified MWNTs is 4.0vol%, the properties of ECAs are optimum.

Preparation and Magnetic Properties of Ce-Doped Strontium Ferrite Films

We have found that La substitutions can improve the magnetic properties of the strontium ferrite films without reducing the saturation magnetization. In this work, SrCexFe12-xO19 nanocrystalline films (x=0, 0.2…0.8) with high coercivity were synthesized and deposited on SiO2 substrate by sol-gel method and sintering at 900 OC for 2h. The films were characterized by various experimental techniques including X-ray diffraction analysis (XRD), Field Emission Scanning Electron Microscope (FESEM), Vibrating Sample Magnetometry (VSM) and vector network analyzer. The results show that with the increasing content of cerium the coercivity of the films improves greatly and reach the maximum 6678.78 Oe at x=0.2, which is larger than La-doped strontium ferrite films, however the saturation magnetization decreases a lot. In the frequency range of 11.5-12 GHz the electromagnetic properties of the Ce-doped strontium ferrite films are better than La-doped at x=0.2.

Preparation and Thermal Properties of Novolac Resin/Graphite Nanosheet Composites

In this study, a high thermal conductivity novolac resin /graphite nanosheet composite have been prepared via in situ polymerization at the presence of sonicated expanded graphite. Graphite nanosheets prepared via powering the expanded graphite had a thickness ranging 10~100 nm and a diameter range 5~10μm and were excellent nanofiller for the fabrication of polymer/graphite nanocomposite. Scanning election microscopy was used to characterize the structure and dispersion of the graphite nanosheets and the composites. The results showed that the structure of the nanosheets played an important role in forming thermal conducting network in the novolac resin matrix.

Conductive and Mechanical Properties of Graphite Nanoplatelets/PVC Nanocomposites Prepared by Melt Blending

Graphite nanoplatelets (Nano-Gs) were prepared by treating the expanded graphite with sonication in aqueous alcohol solution, and then the Nano-Gs/ PVC nanocomposites were fabricated by way of melt blending. The structure of Nano-Gs was characterized by FTIR and SEM, the conductive and mechanical properties of the Nano-Gs/ PVC nanocomposites were also studied. Results show that with a small amount of functional groups distributing on the surface, Nano-Gs have a thickness ranging 30-100nm and a diameter ranging 3-20μm, and disperse randomly in PVC resin matrix. The Nano-Gs/ PVC nanocomposites exhibit low volume resistivity of 104Ω•cm when the mass fraction of Nano-Gs goes beyond 10%, and the percolation threshold of the nanocomposites is as low as 6wt%. Furthermore, with the increase of the filled Nano-Gs, both the tensile strength and notched impact strength of the nanocomposites increase first and then decrease, and achieve the maximal value simultaneously with the addition of 1 wt% Nano-Gs, which increase by 8% and 29% respectively compared with the pristine PVC.