Zan Liu

High dielectric constant and low loss of polymeric dielectric composites filled by carbon nanotubes adhering BaTiO3 hybrid particles

We reported the preparation of carbon nanotubes adhering BaTiO3 nanoparticles (BT@CNTs) via chemical vapor deposition (CVD). Scanning electron microscopy, transmission electron microscope and Raman spectroscopy were carried out in order to confirm the successful adhesion. Dielectric properties of the PVDF-HFP composites filled by BT@CNTs were also studied. With the content of BT@CNTs increasing, the dielectric constant of composites remarkably increased, but the loss tangent gradually decreased. At 10 vol%, the dielectric constant of the PVDF-HFP/BT@CNTs composite was significantly increased to 27.7 at 50 Hz, which was 3 times and 65% higher than that of the pure PVDF-HFP and PVDF-HFP/BT composite, respectively. The loss tangent of the PVDF-HFP/BT@CNTs composite was lower even than that of pure PVDF-HFP. These attractive features of the PVDF-HFP/BT@CNTs composites suggested that the method proposed herein was a new approach to develop high performance composites, especially those with high dielectric constant and low dielectric loss.

Preparation of oleic diethanolamide-capped copper borate/graphene oxide nanocomposites and their tribological properties in base oil

Graphene oxide (GO) nanosheets were decorated with copper borate (CuB) nanoparticles via a liquid phase-based ultrasonic-assisted stripping method to afford CuB/GO nanocomposites. The as-prepared nanocomposites were characterized using FT-IR, XRD, Raman, UV-vis, TEM and AFM techniques, revealing CuB nanoparticles anchored on the surface of GO nanosheets. To inhibit the agglomeration and improve the dispersion stability of the nanocomposites in the base oil, the CuB/GO nanocomposites were modified with oleic diethanolamide (OD), to obtain oleic diethanolamide-capped copper borate/graphene oxide nanocomposites (OD-CuB/GO). The tribological properties of these nanocomposites, when used as an additive in base oils with different viscosities, were evaluated with a four-ball friction and wear tester. The results showed that when the OD-CuB/GO nanocomposites were added into the base oil at a mass fraction of up to 4.0%, the friction coefficient and wear scar diameter of the OD-CuB/GO-based oil were respectively about 43.6% and 49.3% lower than those of the base oil. This indicates that the OD-CuB/GO nanocomposites can significantly improve the tribological properties of the base oil and possess a good anti-wear ability and load-carrying capacity.

Study on adsorption of rhodamine B onto Beta zeolites by tuning SiO 2 /Al 2 O 3 ratio

The exploration of the relationship between zeolite composition and adsorption performance favored to facilitate its better application in removal of the hazardous substances from water. The adsorption capacity of rhodamine B (RB) onto Beta zeolite from aqueous solution was reported. The relationship between SiO2/Al2O3 ratio and adsorption capacity of Beta zeolite for RB was explored. The structure and physical properties of Beta zeolites with various SiO2/Al2O3 ratios were determined by XRD, FTIR, TEM, BET, UV-vis and so on characterizations. The adsorption behavior of rhodamine B onto Beta zeolite matched to Langmuir adsorption isotherm and more suitable description for the adsorption kinetics was a pseudo-second-order reaction model. The maximum adsorption capacity of the as-prepared Beta zeolite with SiO2/Al2O3 = 18.4 was up to 27.97mg/g.

Novel Preparation of Calcium Borate/Graphene Oxide Nanocomposites and Their Tribological Properties in Oil

The calcium borate/graphene oxide (CB/GO) nanocomposites have been successfully prepared by a liquid phase-based ultrasonic-assisted stripping method, which were subsequently explored as lubricant additive. The structure and morphology of the as-prepared nanocomposites were characterized by FT-IR, XRD, Raman, TEM, EDS and TGA, revealing that CB nanoparticles were uniformly loaded on GO surfaces. The nanocomposites were highly dispersed into the base oil by sand milling. The tribological properties of CB/GO nanocomposites as lubricating oil additive were investigated using a four-ball machine, and the wear scar surfaces were observed by the 3D Laser Scanning Microscope. The results indicated that CB/GO nanocomposites were of excellent antifriction, antiwear ability and load-carrying capacity.

High-performance PTFE nanocomposites based on halloysite nanotubes

Abstract Halloysite nanotubes (HNTs)/polytetrafluoroethylene (PTFE) nanocomposites were prepared by the cold compression moulding method. The effects of addition of HNTs (HNTs ‘filling’) on the performances of PTFE were explored using X-ray diffraction, Fourier Transform infrared spectroscopy, scanning electron microscopy and thermogravimetric analysis which showed that HNTs were well dispersed in the PTFE matrix by means of physical mixing at lower contents of 2-5 wt.%; the introduction of HNTs into PTFE could improve the heat stability of the PTFE. Furthermore, the mechanical and tribological performances of the nanocomposites were measured to examine the filling effect. The tensile strength of the HNTs/PTFE nanocomposites at 2-5 wt.% HNTs content increased by ∼3.5% while their wear rates decreased by 55-90% relative to pure PTFE, clear proof of the filling effect of HNTs with a high aspect ratio.

A study on synergistic reinforcing effect of halloysite nanotubes/diatomite mixture-filled polymer (PP and PA6) composites

ABSTRACT In this paper, the nanotubular halloysite nanotubes (HNTs)/disc-shaped diatomite mixture (HD) was used to study the synergistic reinforcing effect of the filler in polymer matrix (PP and PA6). The structure of the HNTs/diatomite mixture filler-filled polymer composites with different proportions of HNTs/diatomite was determined by XRD and SEM. The mechanical performance of the composites was extensively investigated. The results indicated that the HNTs/diatomite mixture filler with different shapes could significantly reinforce the mechanical performance of polymer regardless of whatever it was filled in — PP or PA6. The synergistic reinforcing effect of HNTs/diatomite mixture filler in polymer matrix was verified.

Preparation and tribological properties of oleic acid-decorated MoS2 nanosheets with good oil dispersion

Abstract In this paper, the self-made two-dimensional MoS2 nanosheets with five-layer thickness were attempted to be modified with oleic acid (OA) with a simple one-step route, denoted OA-MoS2. The OA-MoS2 nanosheets were confirmed by a series of characterizations. The results showed that OA molecules could chemically seal MoS2 nanosheets through C-S bonds, which significantly improved the dispersibility and stability of MoS2 nanosheets in base oil. The OA-MoS2 nanosheets possessed better dispersibility in base oil and could maintain the stability in oil up to 96 h. Furthermore, the tribological properties of OA-MoS2 nanosheets as an additive in base oil were completely studied through a ball-on-ball configuration four-ball testing machine. The experimental results showed that the average friction coefficient and average wear scar diameter of the 0.04 wt.% OA-MoS2-based oil were decreased by about 41.2% and 17.1% as compared to base oil, respectively. In addition, its extreme pressure performance increased by about 13.0%. These results indicated that OA-MoS2 nanosheets exhibited better antifriction, antiwear and extreme pressure abilities in oil due to the desirable solved dispersibility. Graphical Abstract

HNTs-Templated Preparation of Carbon Nanorods by Hydrothermal Nanocasting Method

A novel method to prepare carbon nanorods through hydrothermal nanocasting method was presented using halloysite nanotubes (HNTs) as the template and polyvinyl alcohol (PVA) as the carbon source. This method involved in three steps, i.e . nanocasting PVA in HNTs, carbonization and etching removal of template. A series of characterization, such as XRD, FT-IR, SEM, TEM, Raman, XPS, SAED and N 2 adsorption-desorption were used to detect the formation and structure of the as-prepared carbon nanorods (CNRs). The CNRs with a 1D rod-like structure were of high specific surface area (408 m 2 ·g -1 ) and possessed typical mesoporous characterization.

Preparation and Permeation Properties of NaA Zeolite Membrane by Vapor Phase Transformation Method

The NaA zeolite membranes with high permeance were synthesized by seeding and secondary growth both using vapor phase transformation method (VPT). The SEM image of seed layer on substrate indicated that the size of seeds was about 60nm. The XRD patterns showed that the formation of NaA zeolite membrane was after vapor phase transformation of 12h, and the pure NaA zeolite crystals formed on substrate. The SEM images showed that the NaA zeolite membrane consisted of compact polycrystalline crystals with an average size of ca. 2µm. The permeation results showed that the H2 permeance s of NaA membranes attained at the level of 10-6 mol/Pa·m2·s, and the maximum permselectivities of the H2/N2, H2/CO and H2/C3H8 were 4.15,4.78 and 10.1, respectively, which were higher than those of the corresponding Knudsen diffusion selectivities. However, the permeation of C3H8 suggested that there existed unwanted intercrystalline pores or defects in the membranes.

A Generalized Route to Synthesize Nanometer-Sized Metal Oxides by Using Frothing Method

The nanometer-sized oxides of transition metals including copper, nickel, zinc, titanium and zirconium with higher surface area were easily synthesized by using frothing method. It revealed that the method not only had a simple prepared process and low cost, but also exhibited a superiorly size-controlled ability.