• Elastomers and Composites
• /
• v.39 no.3
• /
• pp.234-243
• /
• 2004

The elastomeric and conductive polyurethane (PU) films were prepared by poly(propylene glycol) (PPG), toluene 2,4-diisocyanate, 3-methylthiophene (3-MT) at various preparation conditions, such as the reaction time, the $FeCl_3$ concentration, the weight ratio of the 3-MT to PU and the reaction temperature for the diffusion-oxidative reaction. The conductive poly (3-methylthiophene) (PMT) layers via the diffusion-oxidative reaction of 3-MT and ferric chloride were formed by immersing the film in organic solution of $FeCl_3$/ethyl acetate. The preparation conditions greatly affected the electrical conductivity of the 3-MT/PU composite. The effects of the reaction time and temperature on morphology and surface free energy were investigated by scanning electron microscopy (SEM) analysis and contact angle measurement, respectively. The conductivity of the composite was as high as 42 S/cm.

• Elastomers and Composites
• /
• v.38 no.1
• /
• pp.81-87
• /
• 2003

In this work, $Fe_3O_4$ (magnetite), conductive filler was prepared from $FeCl_2{\cdot}4H_2O,\;(CH_2)_6N_4$ (hexamethylene tetramine), and $NaNO_2$, followed by mixing with crystallizable chloroprene rubber(CR). The influence of conductive filler content on the properties of the conductive composite was studied and temperature dependence of the electrical conductivity (${\sigma}$) was also investigated. It is found that the percolation threshold concept holds true for the conductive particle-filled composite where ${\sigma}$ indicates a nearly sharp increase when the fraction of magnetite in the mixture exceeds 27%. The temperature dependence of ${\sigma}$ is thermally activated blelow or at the $P_c$. Magnetite acts as reinforcement and conductive filler for CR rubber. Moreover, it is shown that the composite with magnetite of 50 phr gives the most significant mechanical properties for tensile strength and elongation at break, which is due to the formation of optimum physical interlock and crosslinking. The results of 100%, 200%, and 300% moduli suggest that the moduli are related with reinforcement effect of magnetite and viscosity of the blend.

• Elastomers and Composites
• /
• v.43 no.3
• /
• pp.147-156
• /
• 2008

In this work, epoxy/carboxyl-terminated butadiene acrylonitirile (EP/CTBN) composites were prepared by employing a reinforcing filler, silica treated with silane coupling agent in different ratio by dry and wet method. Their curing characteristics, surface free energy, interface morphologies and mechanical properties such as tensile strength and impact resistance were carefully investigated. Differential scanning calorimetry(DSC) results showed that curing temperature was lowered with the increase of silane coupling agent because of the increase of relative curing agent cotent by filling the pores of silica. Wet method was proved to be more effective for lowering curing temperature of EP/CTBN composite. In general, surface free energy and impact resistance were increased with the increase of silane coupling agent in this work. Tensile strength, however, was observed to be decreased at 4 wt% of silane coupling agent. It was found that the dry method was proved to be preferable for pretreatment of silica with coupling agent.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2014.02a
• /
• pp.165-165
• /
• 2014

In this study, we demonstrated that the soft lithographic patterning processing of chemical vapor deposition (CVD) graphene and rGO sheets as large scale, low cost, high quality and simplicity for future industrial applications. Recently, a previous study has reported that single layer graphene grown via CVD was patterned and transferred to a target surface by controlling the surface energy of the polydimethylsiloxane (PDMS) stamp [1]. Using this approach, the surface of a relief-patterned elastomeric stamp was functionalized with hydrophilic dimethylsulfoxide (DMSO) molecules to enhance the surface energy of the stamp and to remove the graphene-based layer from the initial substrate and transfer it to a target surface [2]. Further, we developed a soft lithographic patterning process via surface energy modification for advanced graphene-based flexible devices such as transistors or simple and efficient chemical sensor consisting of reduced graphene oxide (rGO) and a metallic nanoparticle composite. A flexible graphene-based device on a biocompatible silk fibroin substrate, which is attachable to an arbitrary target surface, was also successfully fabricated.

• Composites Research
• /
• v.36 no.5
• /
• pp.355-360
• /
• 2023

Epoxy-based carbon fibers reinforced plastic (CFRP) exhibit limitations in their suitability for industrial applications due to high brittleness characteristics. To address this challenge, extensive investigations are underway to enhance their toughness properties. This research focuses on evaluating the toughening mechanisms achieved by Polyamide 6 particles(p-PA6) and Carboxyl-Terminated Butadiene-Acrylonitrile (CTBN) elastomer, with a specific emphasis on utilizing minimal additive quantities. The study explores the impact of varying concentrations of p-PA6 and CTBN additives, namely 0.5, 1, 2.5, and 5 phr, through comprehensive Mode I fracture toughness and tensile strength analyses. The inclusion of p-PA6 demonstrated improvements in toughness when introduced at a relatively low content of 1phr. This improvement manifested as a sustained fracture behavior, contributing to enhanced toughness, while simultaneously maintaining the material's tensile strength. Furthermore, the investigation revealed that the incorporation of p-PA6 affected in particle aggregation, thus influencing the overall toughening mechanism. Incorporation of CTBN, an elastomeric modifier, exhibited a pronounced increase in fracture toughness at higher concentrations of 2.5 phr and beyond. However, this increase in toughness was accompanied by a reduction in tensile strength, resulting in fracture behavior similar to conventional CFRP exhibiting brittleness. The synergy between pPA6, CTBN and CFRP appeared to marginally enhance tensile strength under specific content conditions. As a result of this study, optimized conditions for the application of the p-PA6, CTBN toughening technology have been identified and established.

• Composites Research
• /
• v.35 no.3
• /
• pp.127-133
• /
• 2022

Polypropylene (PP) has been received great attention as a next-generation high-voltage power cable insulation material that can replace cross-linked polyethylene (XLPE). However, the PP cannot be used alone as an insulation material because of its high elastic modulus and vulnerability to impact, and thus is mainly utilized as a form of a copolymer with rubber phases included in the polymerization step. In this paper, a soft PP-based blend was prepared through melt-mixing of impact PP, polyolefin elastomer, and propylene-ethylene random copolymer. The elastic modulus and impact strength of the blend could properly be decreased or increased, respectively, by introducing elastomeric phases. Furthermore, the blends showed a high storage modulus even at a temperature of 100℃ or higher at which the XLPE loses its mechanical properties. In addition, the blend was found to be effective in suppressing the space charge compared to the pristine PP as well as XLPE.