• Elastomers and Composites
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• v.39 no.4
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• pp.274-280
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• 2004

Sorage modulus(G'), Impact and rebounding properties of polyurethane(PU), phylon(PH) and injection phylon(IP) foams were studied. The storage modulus of PU foam was dramatically increased with decreasing temperature. But the storage modulus(G') of IP and PH foams were not affected by temperature. The Impact force of PU foams was increased with decreasing temperature. But in the cases of IP and PH foams, the impact forces were not changed with temperature below $20^{\circ}C$. Impact farces of IP and PH foams were increased with the temperature above $20^{\circ}C$, but that of PU foam was not changed. Rebounding resilience of PU foam was lower than those of IP and PH foams from $-20^{\circ}C$ to $40^{\circ}C$.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 2010.04a
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• pp.79-83
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• 2010

포소화약제는 다양한 설비(이동식, 고정자동식), 대형의 유류화재 적합, 대량 연속적 생산가능 약제의 특수성 및 장기보관이 가능한 특징이 있어 이에 대한 개발 및 연구가 꾸준히 진행되고 있다. 그러나 포소화약제는 주변의 온도 및 환경에 따라 발포력의 변화가 큰 특징이 있어 실제 겨울철 소방 활동시에는 사용을 자제하고 있다. 따라서 본 연구에서는 사용온도에 따른 발포력 변화를 측정하며, 최적 발포율 도출을 위한 온도에 따른 적정 혼합율을 산정한다. 실험은 한국 소방산업기술원의 "포소화약제의 형식승인 및 검정기술기준(KOFEIS 0103)"에서 제시하고 있는 표준 발포기를 이용 측정하며, $5{\sim}30^{\circ}C$ 온도에서 혼합률에 따른 발포력 변화를 측정하였다.

• Polymer(Korea)
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• v.37 no.6
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• pp.685-693
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• 2013

The foams of a poly(lactic acid) modified by the reactive compounding were produced with the batch foaming technique using supercritical $CO_2(scCO_2)$. Experiments were performed at $105{\sim}135^{\circ}C$ and 12~24 MPa. The blowing ratio and foam structure were significantly affected by changing the temperature and pressure conditions in the foaming process. The blowing ratio first increased with increasing foaming temperature and saturation pressure, reached a maximum and then decreased with a further increase in the foaming temperature and saturation pressure. Decreasing the rate of depressurization permitted a longer period of cell growth and therefore larger microcellular structures were obtained.

• Composites Research
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• v.18 no.3
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• pp.47-52
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• 2005

Pultrusion process of phenolic foam composite is investigated. Phenolic foam composites provide heat and flame resistance with less weight. When made into foam, a variety of properties can be obtained with different bubble size and number density. In this study, effect of process variables on the foaming characteristics of phenolic resin composites during pultrusion process has been studied experimentally. The process variables considered are the heating temperature and the pulling speed as well as the mass fraction of blowing agent. Experiments were performed using a laboratory scale pultrusion apparatus. Optimal process condition was found by observing the micro-morphology.

• Elastomers and Composites
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• v.41 no.3
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• pp.147-156
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• 2006

To investigate the influence of the foaming temperature and carbon black content on the cure behaviors and foaming characteristics of the foams. natural rubber (NR) was foamed at five temperature zones (145, 150, 155, 160 and $165^{\circ}C$) and different feeding ratios of the carbon black. A decreasing trend of the scorch time, $t_{s2}$ and cure time, $t_{90}$ was observed upon increasing foaming temperature and carbon black content. The optimal temperature for vulcanization and foaming of NRs in this study was considered to be $165^{\circ}C$ where density of the loomed NRs is lower than those at other four temperature regions. The rule rate index of the NRs foamed at $145^{\circ}C$ is smaller than those at 150, 155, 160 and $165^{\circ}C$. The results of the expansion ratio and micrographs of the foamed NRs were founded to support the density characteristics. The thickness of each of the struts formed inside the rubber matrix decreases with increasing the foaming temperature, while it increases with increasing the carbon black content.

• Polymer(Korea)
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• v.24 no.4
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• pp.538-544
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• 2000

The characteristics of cell growth and foamed cell structures of PP were investigated by a continuous foaming process. The operating parameters were the contents of blowing agent and nucleating agent, nucleating agent contents, die temperatures and die dimensions. The foaming cells grew without collapse at less than 14.5 wt% of blowing agent, isopentane. But the cells were collapsed when the blowing agent content was more than 14.5 wt%. The foam density dramatically decreased when a very small amount of the nucleating agent, 1 wt%, was added. After the nucleating agent was added, the cell's weight plummeted to one-seventh of its previous weight. Stable foam cell structures were formed at the die temperature of 17$0^{\circ}C$. However, the effects of the pressure drop rate on the cell morphology were not serious.

• Journal of the Korean Applied Science and Technology
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• v.16 no.2
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• pp.179-185
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• 1999

The effect of blowing agents and inner temperature on the machanical properties of the flexible polyurethane foams were investigated. In the study used that chemical blowing agents is $H_2O$ and support blowing agents. CFC-11, HCFC-114b, dichloromethane, n-penthane, iso-pentane, cyclopentane. The flexible polyurethane foams were foamed by the density of $0.015{\pm}0.002g/cm^3$ and $0.024{\pm}0.002g/cm^3$ which were used in mechanical properties measurements. Inner temperature was measure as long as the preparation of the flexible polyurethane foams of each blowing agents. The density, tensile strength, elongation, tear strength, compression strength and compression set were measured after 48 hours hardening. The result of the study was optimized dichloromethane and cyclopentane at the support blowing agents.

• Polymer(Korea)
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• v.24 no.4
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• pp.529-537
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• 2000

The effects of the gel content on the cell structures of PP sheets by using an electron-curing system were investigated. Three extruded PP sheets crosslinked by three different doses were used for the batch foaming process with the supercritical state $CO_2$. Experiments were also performed in order to study the effects of the gel content, saturation pressure and temperature on cell structures. Then foaming conditions, such as temperature and duration of time, were changed. The amount of gas absorbed into PP samples was not affected by gel contents and the operating condition of saturation pressure, which was higher than 2000 psi. The foam cells of PP with a low gel content grew irregularly at a higher foaming temperature and for a longer duration of foaming time. However, PP samples with high gel content showed even cell structures and narrow tell size distributions under the severe conditions of high foaming temperatures and long duration of foaming time.

• Proceedings of the KAIS Fall Conference
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• 2005.05a
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• pp.309-311
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• 2005

본 연구에서는 폐유리를 별도의 전처리 과정 없이 최적조건에서 발포된 발포유리의 pH, 밀도, 열전도율, 압축강도 그리고 흡음율을 측정하였다. 최적조건에서의 온도변화에 따른 물성특성을 측정한 결과, 온도가 높아짐에 따라 밀도는 감소하였는데 이는 융용상 형성이 증가하고 표면에 형성된 응용상의 발포된 기체를 내부에 포집하여 큰 기공을 형성하여 밀도가 감소하는 것으로 사료된다. 또한 온도가 높아짐에 따라 pore size가 커지고, 압축강도가 감소하는 경향을 보인다.

• Polymer(Korea)
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• v.27 no.4
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• pp.340-348
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• 2003

A previous stud-pull test was modified to measure the bond strength of polyurethane foam to carbon steel substrate. This test was appropriate in that the specimen foamed on Zn phosphated steel (0.95 kN) was broken at higher load than that of smooth galvanizing treated steel (0.38 kN). Among the samples foamed on the substrate atvarious preheating temperatures, the polyurethane foam to the steel held over 60$^{\circ}C$ exhibited very high bond strength. The samples were exposed at water vapor absorption, and, then, their bond strengths were measured. The adhesion was significantly reduced in the samples foamed on the steel at temperatures below 40$^{\circ}C$ and above 70$^{\circ}C$. For the polyurethane foams formulated with two blowing gases, the adhesion was higher by 0.03 kN in the samples with HCFC-l4lb than that with HFC-245fa. When the these samples were exposed at water vapor soaking, the reduction of the bond strength for the HFC-245fa blown sample was negligible due to smaller area fraction of void area filled with gas at interfacial area. Consequently, it was found that adhesion of polyurethane foam to metal substrate was determined by variation of microstructural features with substrate preheating, surface treatment type of blowing agent.