In this study, carbon nanotubes (CNTs) were introduced into carbon fiber (CF) wet-laid composites as functional nano-fillers to fabricate multi-functional composites with improved mechanical, electrical, and thermal properties. It was considered that the wet-laid process was most suitable in order to introduce filler into brittle and rigid carbon fiber substrates, and we established the conditions of the process that could impart dispersibility and bonding between the fibers. We introduced polyamide 6 (PA6) short fiber, which is the same polymeric material as the stacking film, into carbon fiber and CNT mixture to enhance the binding interactions between carbon fiber and CNTs. Various types of CNT-reinforced carbon fiber wet-laid composites with PA6 short fibers were prepared, and the morphology, mechanical and electrical properties of the composites were estimated. As CNT was added to the carbon fiber nonwoven, the electrical conductivity increased by 500% but the tensile strength decreased slightly. By introducing short fibers of the same material as the matrix between CNT–CF wet-laid nonwovens, it was possible to find optimum conditions to increase the electrical conductivity while maintaining mechanical properties.

The reportedly synergistic effects of carbon nanotubes (CNTs) and graphene hybrids have prompted strong demand for an efficient modifier to enhance their dispersion. Here, we investigated the ability of poly(acrylonitrile) (PAN) to overcome the van der Waals interaction of multi-walled CNTs (MWCNTs) and graphene by employing a simple wrapping process involving ultrasonication and subsequent centrifugation of PAN/MWCNT/graphene solutions. The physical wrapping of MWCNTs and graphene with PAN was investigated for various PAN concentrations, in an attempt to simplify and improve the polymer-wrapping process. Transmission electron microscopy analysis confirmed the wrapping of the MWCNTs and graphene with PAN layers. The interaction between the graphitic structure and the PAN molecules was examined using proton nuclear magnetic resonance, ultraviolet-visible spectroscopy, Fourier transform infrared spectroscopy, thermogravimetric analysis, and Raman spectroscopy. The obtained results revealed that the cyano groups of the PAN molecules facilitated adhesion of the PAN molecules to the MWCNTs and graphene for polymer wrapping. The resulting enhanced dispersion of MWCNTs and graphene was verified from zeta potential and shelf-life measurements.

In this paper, multi-junction clamp was used for junction strength evaluation under 20, 50 and 100 mm/min of strain rate at ambient condition. One~eight rib specimens were gripped in the clamps and each gage length was 50 mm, 100 mm and 150 mm, respectively. Warp knitted and woven type geogrids were used to compare the effects of multi-junction clamping on junction and tensile strength, respectively. The results indicate that junction strength decreased while the number of junctions increased. When the strain rate was increased, junction strength of woven type increased, but there was no effect of strain rate on warp knitted type. The newly designed clamp test for geogrid junction strength in this research is more accurate than the single-junction test, considering the scale effect of specimens.

New pressure sensitive adhesives (PSAs) for polarizer film were prepared by electron beam (e-beam) radiation to acrylic copolymers, and their adhesive properties were investigated. The acrylic copolymers were synthesized by free radical polymerization of n-butylacrylate (BA), 2-hydroxyethyl methacrylate (HEMA), and acrylic acid (AA). The acrylic copolymers were coated on PET release films to a thickness of 25 µm, laminated to polarizer films, and then radiated with e-beam at room temperature. Gel fractions of all the acrylic copolymers after e-beam radiation at 50 kGy were higher than 93%, and their crosslinking densities were increased with increasing the content of HEMA units. PSA prepared by e-beam radiation of acrylic copolymer synthesized with a feed ratio of BA/ HEMA/AA = 89.5/10/0.5 (w/w/w) at a dose of 50 kGy exhibited the best adhesion performances in terms of peel strength, creep resistance, durability and reliability, and light leakage. It is expected that the preparation method of PSAs via e-beam irradiation will improve the producibility and workability of polarizer film for liquid crystal display.Keywords: pressure sensitive adhesives, polarizer film, acrylic copolymers, electron beam radiation.

The purpose of this study was to investigate the radiation attenuation effect due to reflection and refraction that occurs when radiation passes through the composite material through simulation. The gamma-ray shielding ability of composites with different structures, such as layered composite, fibrous composite, and particle-added composites, was compared. For the layered composites, regardless of the thickness, the gamma-ray attenuation effect due to the structure of the layered composite could not be seen. The simulated attenuation coefficient was found to be different than the theoretical value, which increased with the content of inorganic materials. Assuming that the cesium ions absorbed on the nonwoven fabric are located in the center of the nonwoven fabric and the radioactive material absorbent is used in an appropriate amount, it is expected that more than 50% of gamma rays emitted from radioactive cesium can be shielded. If the nonwoven composites have such a shielding ability, it is expected that after adsorbing 137Cs, the intensity of gamma rays due to the adsorbed radioactive cesium can be partially attenuated, thereby contributing to radioactive waste treatment.