Advanced Materials Research Vols. 79-82

Abstract: In this paper, the effects of electrospun polysulfone/ CNTs hybrid nanofibers on mechanical properties of epoxy resin were investigated. The CNTs functionalized with the mixture of H2SO4 and HNO3 were characterized through Fourier transform infra-red spectroscopy (FTIR), and the morphorgy of functional CNTs was observed by transmission electron microscopy (TEM). The PSF/CNTs solutions with 1 wt %, 5 wt %, 10 wt % CNTs content were electrospun to fabricate hybrid nanofibers. The morphologies of PSF/CNTs nanofibers were observed by scanning electron microscopy (SEM) and TEM. Experimental results showed that the diameters of the nanofibers were reduced with increasing CNTs contents, and the CNTs were embedded dispersally into the nanofibers. The 2 wt % PSF/CNTs hybrid nanofibers toughened and reinforced epoxy with different CNTs contents were prepared, and compared the mechanical and thermal properties to those of PSF nanofibers toughened epoxy and pure resin matrix. The tensile strength of toughened and reinforced epoxy were higher than those of epoxy resin toughened with the same content of PSF nanofibers. Dynamic mechanical thermal analysis (DMTA) showed the glass transition temperature (Tg) of PSF/CNTs nanofibers toughened and reinforced epoxy increased by 10°C compared to that of epoxy matrix. SEM observations of toughened and reinforced epoxy showed that PSF spheres resulting from the inhomogeneous phase separation were aligned in random orientation and CNTs at different sites were dispersed in epoxy matrix or PSF spheres.

Abstract: Ni-P-CB nanocomposite coatings were successfully deposited on the ABS plastic matrix by electroless plating. Scanning electronic microscopy (SEM) and X-ray diffraction (XRD) spectrometer were used to examine surface morphology and structure of the as-plated coating. Energy dispersive spectroscopy (EDS) is adopted to obtain the component analysis of the Ni-P-CB composite coating, and the infrared emissivity of coatings were investigated by IRE-I Infrared Emissometer. The SEM and XRD results indicated that the nanoparticles were dispersed homogeneously in Ni-P coating. The result of EDS shows that the CB content in coatings increases with the increasing of CB concentration lower than 4g/L in the solution, and Infrared emissivity study at wavelength of 8–14 μm of nanocomposite and its components showed that the composite possessed lower emissivity value than those of pure ABS plastic and Carbon black, and high conduction had great effect on emissivity of nanocomposites. Thereby, the nanocomposite coatings can be extended in application as a novel low infrared emissivity material.value.

Abstract: Carbon/TiO2 composites were prepared via the reaction under Autogenic Pressure at Elevated Temperature (RAPET) using alkoxides as precursor, and then porous TiO2 hollow spheres were derived after removing the carbon ingredient by calcination at 600°C. The influence of surfactant additives, including the addition ratio and the nature of the surfactants, on the morphology and the structures of the Carbon/TiO2 composites and the derived TiO2 were also studied with scanning electron microscopy (SEM), X-ray diffraction (XRD), UV-Vis diffuse reflectance spectrophotoscopy (DRS) and nitrogen adsorption-desorption measurements. The results revealed that the morphology of the products turned to spherical and then fusiform and the structures turned from hollow to solid with the increasing of surfactant additive. The BET surface area of the hollow TiO2 was modified from 12m2/g to 57m2/g after calcinations. The XRD investigation indicates that the phases of the TiO2 in both the carbon/TiO2 composites and the derived TiO2 hollow spheres are anatase.

Abstract: This paper describered a simple and versatile method to prepare carbon nanotubes (CNTs)/magnetite nanocomposites (MNPs) by covalent interaction. The structure and morphology of CNTs/MNPs nanocomposites were characterized by FT-IR, XRD and TEM. The magnetic properties and electrical properties were measured by vibrating sample magnetometer (VSM) and LCR meter. The results showed that MNPs were effectively attached onto the surface of CNTs and CNTs/MNPs nanocomposites exhibited outstanding electrical and magnetic response. The saturation magnetization and electrical conductivity can reach ~ 40emu/g and 3.82×10-1S•cm-1, respectively. These one-dimensional electromagnetic nanostructures may find a wide range of applications in nanoelectronics, magnetic data storage, magnetically guided drug delivery and biosensors.

Abstract: The structure and the magnetic properties of 3.0 and 0.3 at.% Mn-containing ZnO-based DMSs, synthesized by a straightforward and experimentally simple nonaqueous route, have been investigated by various characterization techniques, including XRD, HRTEM, and EPR. The as-synthesized doped ZnO nanocrystals retain the wurtzite structure with a morphology in the form of flower-like shape. EPR spectra with g-factor values of 2.0023(3% at.%) and 2.0019(0.3 at.%), respectively, at room temperature were obtained, confirming that the Mn2+ is substitutionally incorporated into the ZnO nanocrystals.

Abstract: Water based resins have an important application in environmental benign coating to reduce the volatile organic compounds (VOC). This work describes the synthesis and characterization of an acrylic emulsion with core-shell structure by using pre-emulsion and seed emulsion polymerization technology for antifouling paints. The results indicate that when the ratio of soft and hard monomer is in the range of 1:1~2:1 and the amount of cross-linking agent is added, the comprehensive properties of acrylic emulsion are good. Although the coatings were found to develop a whitish aspect (blushing) due to water retrodiffusion, the films did not break and splint, further research are focused to increase their comprehensive properties for marine antifouling application.

Abstract: Composites of Sm doped TiO2 nanoparticles dispersed on carbon nanofibers (Sm-TiO2/CNFs) with different Sm contents were prepared by preoxidation, hydrolyzation and calcination of Sm-TiO2 precursor/PAN nanofibers. The characterizations of SEM, EDX, XPS and XRD showed that the CNFs surface was loaded by Sm-TiO2 nanoparticles with a uniform size of about 10nm, existing as anatase. It was concluded from XPS results that Ti element exist as Ti4+ and Sm doping increased the content of absorbed oxygen in composites. The effect of Sm doping on the photocatalytic activity of the Sm-TiO2/CNFs composite was investigated by the photocatalytic degradation of methyl orange aqueous solution under UV irradiation. It was found that Sm doping could improve the photocatalytic property of Sm-TiO2/CNFs effectively compared with the undoped specimen, and the photocatalytic activity of the Sm-TiO2/CNFs samples enhanced firstly and then reduced with Sm content increasing.

Abstract: In order to illustrate the role of alkali treatment of bamboo particles reinforced polyvinylchloride composites (BPPC), bamboo particles were treated by alkali aqueous solution with a serial concentration of 0.5%, 1%, 2%, 5% and 10%. Mechanical, thermal properties of alkali treated BPPC and micro-micrographs of the fracture surface were researched and compared with raw bamboo particles fabricated BPPC respectively. Results showed that tensile strength of BPPC increased before the solution reached the concentration of 5% and got a maximum value of 15.07MPa at the concentration of 5%. The curve decreased significantly as the concentration of solution went higher as to 10%. Modules of rupture got a highest value of 44.73MPa till reached the concentration of 2% and then decreased. Modules of elasticity increased in the whole before reached the concentration of 5% and the maximum value was 4362.48MPa which was 5 times more than the original bamboo particles. DSC curves illustrated that raw bamboo particles mixed with PVC showed a higher Tg which meant that raw fiber was not well compatible with PVC and BPPC treated with alkali solution performed a better compatibility. According to SEM observations, interface interaction of fiber-matrix that were modified of alkali solution upon bamboo particles appeared a better interlock action correlated to higher mechanical properties and better compatibility between fiber and matrix. Hence, the use of alkali treated bamboo particles as reinforcement was a feasible and competitive method of creating new materials.

Abstract: Coarse primary Mg2Si was usually found in Al-Mg-Si alloys. In this experiment, to refine the coarse primary Mg2Si size, ultrasound was used as a new process. Ultrasound was injected to the molten Al-Mg-Si melts directly and its effect was significant. Average size of primary Mg2Si was reduced from 70㎛ to 15㎛, morphology was also changed to polygonal from irregular shape. Moreover tensile strength was improved by 30%, from 112 to 148 after ultrasonic injection.

Abstract: The increasing proliferation and application of advanced polymer composites requires higher and broader performance resin matrices. Poly(oxypropylene) with –NH2 end-groups has been widely used to toughen epoxy resins, but the strength of resin matrix may be reduced due to the addition of flexible segments in the crosslinking network. Carbon nanotubes (CNTs) have been paid more and more attention in recent years because of their superior thermal and mechanical properties. In this paper, CNTs grafted with Jeffamines T403 were used to simultaneously improve the reinforcement and toughening of an epoxy resin. The untreated multi-walled carbon nanotubes (u-MWNTs) were functionalized with amine groups according to three steps: carboxylation, acylation, and amidation. The f-MWNTs were characterized by Fourier transform infra-red (FTIR) and X-ray photoelectron spectroscopy (XPS). The experimental results indicated that the T403 was grafted to the surface of MWCNTs. The mechanical and thermal properties of epoxy with f-MWNTs were investigated. The tensile and flexural strength increased by 7.77 % and 7.03 % after adding 0.5wt% f-MWCNTs without sacrificing the impact toughness. At the same time, dynamic mechanical thermal analysis (DMTA) showed that the glass transition temperature (Tg) of epoxy with f-MWNTs were increased. The fracture surface of epoxy with f-MWNTs was observed by scanning electron microscopy (SEM) to understand the dispersion of f-MWNTs in epoxy matrix and interfacial adhesion between f-MWNTs and epoxy matrix, which can be attributed to the strong interfacial bonding between f-MWNTs and epoxy resin.