Papers by Author: Jia Hau Liu

Abstract: PU/hydrogel compounds prepared byγ-ray radiation technique were investigated in this study. We used nanosized clay solution or powder, Polyurethane (PU), thermosensitive N-isopropyl acrylamide (NIPAAm) and acrylic acid (AAc) as starting materials to prepare PU/hydrogel nanocomposite products. The dipping and weighing tests, Material Testing Machine (LLOYD) were utilized to analyze the physical and mechanical properties differentially. In addition, the drug release and wound closure experiments were also finished by Enzyme-link immunosorbent assay (ELISA) reader and five groups of treatment dressings. From the final results, We obtained that the PU/hydrogel composite incorporating FGF-2 as a wound dressing was able to effectively interact with the wound in a suitable moist healing environment. These composites make them more compatible with skin.

Abstract: Two processes, the floating catalyst chemical vapor deposition (CVD) process and the rapid heating and cooling (RHC) process, were adopted for synthesizing single walled carbon nanotubes (SWNTs) and multi-walled carbon nanotubes (MWNTs). Batch production of SWNTs and MWNTs with the diameters of 0.8~1.5 nm and 15~40 nm, respectively, were prepared using the floating catalytic chemical vapor deposition (CCVD) process. The production rate is 70±20 mg every 10 minutes. The as-synthesized carbon nanotubes (CNTs) were used for fabricating carbon nanotubes reinforced composites and field emitter for lighting. On the study of nano-composites, around 70% enhancement of tensile strength was detected when 1.5 wt% MWNTs in the form of network structure were introduced to the phenolic matrix. Comparisons on the mechanical properties of the composites reinforced with the network MWNTs and SWNTs were made. Microstructures of the MWNTs and SWNTs were studied by Field Emission Scanning Electron Microscope (FESEM) and High Resolution Transmission Electron Microscope (HRTEM). In the RHC process for fabricating the device for lighting, the carbon nanotube array was grown on a silicon substrate which was pre-coated with a catalyst thin film. The synthesis process was performed in a thermal CVD chamber equipped with a rapid heating apparatus. The as-synthesized CNT array was then transferred onto the substrate which was coated with silver paste. After heat treatment, field emission properties of the CNT-based cathode were tested, high current density of 35 mA/cm2 and low turn-on voltage of 0.65 V/μm were achieved in this work.

Abstract: Composites of phenolic resin reinforced by the multi-walled carbon nanotubes (MWCNTs) were fabricated and its mechanical properties were measured. The MWCNTs were synthesized by the floating catalyst method in a thermal chemical vapor deposition chamber. Benzene, hydrogen, ferrocene, and thiophene were used as carbon source, carrier gas, catalyst, and growth promoter, respectively. The nano-composites were made by the melt mixing and the resin infiltration methods. Tensile strength, Poisson’s ratio, and modulus were measured and the morphologies on the fracture surface were examined by the field emission scanning electron microscope (FESEM). The microstructure of the synthesized MWCNTs reinforced nano-composites was examined by FESEM. The influences of MWCNTs amounts on the mechanical properties of the nano-composites were discussed.

Abstract: Two different types of multi-walled carbon nanotube (MWNT), the dispersed and the network MWNTs, were used to reinforce the phenolic resin. The MWNTs/phenolic nanocomposites were tested by a dynamic mechanical analyzer (DMA) to characterize their dynamic mechanical properties. The results showed that increasing the MWNT content can increase the storage modulus, the loss modulus and the glassy transition temperature of the MWNTs/phenolic nanocomposites. A subambient loss transition is seen in the nanocomposites with network MWNTs which results in a better impact resistance property in the nanocomposites. The glassy transition temperature of the nanocomposites with network MWNTs is higher than that of nanocomposites with dispersed MWNTs. The MWNT additive in phenolic resin can be used to improve the dynamic mechanical properties of the MWNTs/phenolic nanocomposites. The tensile failure morphologies of MWNTs/phenolic nanocomposites were also examined using field emission scanning electron microscope (FESEM) to explain the difference between the two types of nanocomposites.