• Korean Chemical Engineering Research
• /
• v.58 no.1
• /
• pp.44-51
• /
• 2020

The basic catalyst 1-benzyl-3-methyl-imidazolium hexafluoroantimonate (BMH) was synthesized and analyzed by FT-IR and ¹H-NMR. A crystalized biphenyl-based epoxy was synthesized by using tetramethyl biphenol (TMBP) and epichlorohdrine. In order to consider the curing tendency of the synthesized BMH, the mass ratio was changed to 0.5, 1.0, 2.0 wt.% under heated conditions and the curing tendency was analyzed by differential scanning calorimeter (DSC). As a result, the BMH catalyst showed a fast curing result in the stepwise heating pr℃ess of the biphenol-A epoxy and the cationic polymer. From these results, the BMH catalyst showed excellent thermal stability as a potential heat curing catalyst. In addition, we considered the application possibility of epoxy molding compound (EMC) which required a skeleton structure and a high heat resistance because the synthesized biphenyl epoxy had a characteristic of rapidly lowering viscosity at a constant temperature and a rigid skeleton structure of biphenol. As a result, it was confirmed that the TMBP-based epoxy developed in this study was composed of a crystalline structure, and a curing reaction was observed with a Novolac resin at a high temperature. In the presence of a catalyst, a curing reaction was observed around 150 ℃ and thus TMBP-based epoxy was successfully applied as a raw material of EMC.

• Korean Journal of Materials Research
• /
• v.2 no.4
• /
• pp.298-305
• /
• 1992

The carbonization behaviors of CFRP fabricated with 2D-woven fabric and matrix phenolic resin have been studied. The changes in dimension were observed in the temperature range of 365-37$0^{\circ}C$ in the thickness direction, 118-12$0^{\circ}C$ in the normal direction each other by TMA analysis. Observation with the optical microscope shows that the formed cracks and pores during the fabrication of CFRP were propagated with the increase of pyrolysis temperaure. New cracks and pores were formed in the pyrolysis temperature range of 400-50$0^{\circ}C$ In line with the formation and propagation of cracks, porosity was increased and density was decreased rapidly in the pyrolysis temperature range of from 40$0^{\circ}C$ to 70$0^{\circ}C$. Therefore heating rate in the carbonization process need to be controlled carefully by intervals.

• Polymer(Korea)
• /
• v.25 no.3
• /
• pp.435-440
• /
• 2001

The objective of this study was to examine the effect of oxidation inhibitor contents on the work of adhesion, fracture toughness, and impact strength of the unidirectional carbon-carbon composites (C/C composites). The molybdenum disilicide ($MoSi_2$) used as an oxidation inhibitor was impregnated with phenolic resins to improve the anti-oxidation properties of the composites in different concentrations of 4, 12 and 20 wt%. Based on Wilhelmy equation, the work of adhesion of C/C composites was calculated by contact angle methods. Fracture toughness and impact strength were pressured by three-point bending test for the critical intensity factor ($K_IC$) and Izod test method, respectively. As a result, the composites made with $MoSi_2$ resulted in an increasing of both fracture toughness and impact strength. Especially, the composites made with 12 wt% $MoSi_2$ content showed the highest value of London dispersive component, $W_A\;^L$, in work of adhesion, resulting from improving the interfacial adhesion force among fibers, filler, and matrix in this system.

• Journal of the Korean Wood Science and Technology
• /
• v.29 no.2
• /
• pp.109-117
• /
• 2001

This research was carried out to develop the Hanji(Korean paper) sludge wood particle composite utilizing the waste sludges occurring from the making process of Hanji(Korean paper). In the research, four mixing ratios of white or black sludge to wood particle(10:90, 20:80, 30:70, and 40:60), three types of the resin adhesives(PMDI, urea and phenol resin) and three levels of the densities(0.60, 0.75 and 0.90) were designed to investigate the physical properties of Hanji(Korean paper) sludge wood particle composite. The linear expansion of Hanji(Korean paper) sludge wood particle composite was not always increased, compared to control boards. For thickness swelling, PMDI-bonded composites had the lowest value, and thickness swelling of composite was generally decreased with the increase of Hanji sludge. The water absorption of white sludge wood particle composite had no tendency, hut that of black sludge wood particle composite was decreased with an increase of mixing ratio of Hanji sludge.

• Journal of the Korean Wood Science and Technology
• /
• v.29 no.2
• /
• pp.69-75
• /
• 2001

This study was carried out to investigate the properties of woodceramics made from thinned logs of Cryptomeria japonica. In order to find the effect of steam injection time on the woodceramics fabricated with boards, boards were made with the non-steamed treatment and steamed treatment 1, 5, 10 min. at $250^{\circ}C$. The percentage of weight loss was proportional to the increased density of board The reducing rate of length and thickness, however, decreased with increasing density of board. The rate of weight loss, length and thickness reduction in non-steamed board were slightly higher than those of steamed board. When the resin impregnation rate increased, the bending strength and compressive strength of woodceramics had a tendency to increase. The bending strength and compressive strength of woodceramics in non-steamed board was higher than those of steamed board. But there was little difference between dimensional and strength properties of woodceramics and steam injection time of board.

• Journal of the Korean Wood Science and Technology
• /
• v.42 no.6
• /
• pp.723-731
• /
• 2014

Nondestructive evaluation (NDE) technique method using a resonance frequency mode was carried out for ceramics made by different carbonizing temperatures (600, 800, 1000, $1200^{\circ}C$) after impregnating the phenol resin with Miscanthus sinensis var. purpurascen particle boards. Dynamic modulus of elasticity increased with increasing carbonizing temperature. There were a close relationship of dynamic modulus of elasticity and static bending modulus of elasticity to modulus of rupture (MOR). However, the result indicated that correlation coefficient was higher in dynamic modulus of elasticity to MOR than that in static modulus of elasticity to MOR. Therefore, the dynamic modulus of elasticity using resonance frequency by free vibration mode is more useful as a nondestructive evaluation method for predicting the MOR of ceramics made by different carbonizing temperature for Miscanthus sinensis var. purpurascens particle boards.

• Elastomers and Composites
• /
• v.48 no.3
• /
• pp.232-240
• /
• 2013

Microcapsules having healing agent were prepared in which 2,6-dimethylphenol (DMP) as a healing agent forms the core and melamine/formaldehyde resin forms the shell. Microcapsule-contained asphalts showed better mechanical properties than non-contained ones. And as the rest time passed the impact strength of microcapsule-contained asphalt was getting higher than that of asphalt without the microcapsule. As the rest time of 15 days passed, the original strength was restored. This tells that microcapsule-contained asphalt had the ability of self-healing. X-ray photos proved that DMP on asphalt fracture surface, which were burst out of the microcapsules when cracks occurred on asphalt, were polymerized to polyphenyleneoxide and this PPO covered the crack and healed the damage.

• Journal of Bio-Environment Control
• /
• v.2 no.1
• /
• pp.37-45
• /
• 1993

The purpose of this research was to develop ideal substrates for the production of good quality tomatoes in bag culture system and also to improve media with low or no environmental pollution by blending and mixing artificial substrate including peatmoss, perlite, vermiculite, granular rockwool, polyphenol resin foam, bark, and smoked rice hull. The highly efficient media proved by experiments were vermiculite, smoked rice hull, polyphenol resin foam, granular rockwool, and perlite, which showed good results in the early growth as well as the marketable yield of tomato in the bag culture. Tomato plants grown in the media mixed with peatmoss, vermiculite and granular rockwool at the ratio of 3 : 1 : 1(by volume) showed the highest marketable yield, and the next at the ratio of 2 : 1 : 1. The perlite-granular rockwool mixtures at the ratio of 2 : 3 and 1 : 4, and the peatmoss vermiculite mixtures at the ratio of 2 : 3 and 3 : 2, seemed to be promising media for bag culture.

• Korean Journal of Materials Research
• /
• v.3 no.3
• /
• pp.292-299
• /
• 1993

In this paper the effects of the length of carbon fiber on the wear properties of carboni carbon composites were investigated. Carbon/carbon composites were fabricated by the liquid impregnation method using the resol-type phenolic resin as a matrix precursor and PAN-based, non-surface treated carbon fiber as a reinforcement. The measured values of the friction coefficient of carbon/carbon composites against AlSl 304 stainless steel ranged from 0.2 to 0.3 under the operating condition used in this study. The effect of the length of carbon fiber on the friction coefficient of carbon/carbon composites were not found. But, it was realized that the wear rate of carbon/carbon composites tends to increase, as the length of carbon fiber increases.

• Korean Journal of Materials Research
• /
• v.4 no.7
• /
• pp.733-740
• /
• 1994

Oxidized-PAN fiber reinforced composite(OFRP), carbon fiber reinforced composite(CFRP), aramid fiber reinforced composite(AFRP), and glass fiber reinforced composite(GFRP) were fabricated with phenolic resin matrix by hot press molding. We tested the friction coefficient and wear rate varying with fiber weight fraction and observed the effect of fibers according to characteristics of individual reinforcement. When the amount of aramid fiber was 45wt%, average friction coefficient was maximum value of 0.353~0.383, where as, when the amount of pitch based carbon fiber was 45wt%, average friction coefficient was the lowest value of 0.164~0.190. The wear rate of AFRP and CFRP was low, but that of GFRP and OFRP increases drastically in the case of increasing of fiber weight fraction. Wear diagram of OFRP was unstable, but that of CFRP and AFRP was a bit stable. Through very unstable diagram of GFRP, we found that friction stability of GFRP was the lowest.