• Journal of Ocean Engineering and Technology
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• v.36 no.4
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• pp.217-231
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• 2022

Reinforced polyurethane foam (R-PUF), a material for liquefied natural gas cargo containment systems, is expected to have different mechanical properties depending on its stacking position of foaming as the glass fiber reinforcement of R-PUF sinks inside R-PUF under the influence of gravity. In addition, since R-PUF is not a homogeneous material, it is also expected that the coordinate direction within this material has a great correlation with the mechanical properties. So, this study was conducted to confirm this correlation with the one between the mechanical properties and the stacking position. In particular, in this study, R-PUF of 3 different densities (130, 170, and 210 kg/m³) was used, and tensile, compression, and shear tests of this material were performed under 5 temperatures. As a result of the tests, it was confirmed that the strength and modulus of elasticity of the material increased as the temperature decreased. Specifically, the strength and modulus of elasticity in the Z direction, which was the lamination direction, tended to be lower than those in the other directions. Finally, the strength and elastic modulus of different specimens of the material found at the bottom of their lamination compared to the specimens with these properties found at positions other than their lamination bottom were evaluated. Further analysis confirmed that as the temperature decreased, hardening of R-PUF occurred, indicating that the strength and modulus of elasticity increased. On the other hand, as the density of R-PUF increased, a sharp increase in strength and elastic modulus of R-PUF was observed.

• Journal of the Korean Institute of Gas
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• v.16 no.6
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• pp.123-127
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• 2012

In order to establish the cause of the deformation of polyurethane foam, compression set was measured according to the aging temperature and time. FT-IR, TGA, DSC and DMA were used for investigating the cause of deformation of aged PUF. The results of FT-IR and TGA reveals that no structure change occurred during deformation of PUF. Resilience of aged PUF was reduced by the increase of reduction ratio in storage modulus over the glass transition temperature of hard segment.

• Applied Chemistry for Engineering
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• v.24 no.2
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• pp.208-213
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• 2013

In this study, the effect of phosphorus flame retardants on the flame retardancy of the flexible polyurethane foam (PUF) was investigated. Tetramethylene bis(orthophosphorylurea) [TBPU] and phosphinyl alkylphosphate ester [CR-530], resorcinol bis diphenylphosphate [RDP], triethyl phosphate [TEP] were used as flame retardants. The results of thermogravimetric analysis (TGA) indicate that TBPU added PUF produces more charred residues than the other flame retardant added PUF. It was found that TBPU added PUF exhibits low mean heat release rate (HRR), peak HRR, effective heat of combusion (EHC), mass loss rate (MLR), CO yield and $CO_2$ compared to those other flame retardants.

• Journal of the Korean Institute of Gas
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• v.14 no.3
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• pp.21-25
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• 2010

An objective of this study is to develop a polyurethane foam(PUF) maintaining its mechanical strength at room temperature as well as at extremely low temperature. The effect of temperature on the physical properties of PUF with the increase in polyol functionality was investigated. At room and cryogenic temperature, compressive strengths of the PUFs increased up to 70% and 30% with an increase in polyol functionality, respectively. At room temperature tensile strength of PUFs tends to increase as functionality of polyol increases, however, the strength at $-190^{\circ}C$ shows different tendency. Compressive strength of PUF is higher in cryogenic temperature than in room temperature. However, as the number of polyol functionality become more than 4, tensile strength of PUF is lower in cryogenic temperature than in room temperature.

• Journal of the Korean Institute of Gas
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• v.7 no.1 s.18
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• pp.28-32
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• 2003

In order to apply the properties of fiber reinforced plastic(FRP) to support panel of polyurethane foam in LNG storage tank, we estimated the mechanical properties, degree of vapour barrier, chemical stability and thermal conductivity changes as ageing. According to the results, the mechanical strength (i.g. compressive strength, bending strength, tensile strength and shear strength) are more than 30 times higher than those of plywood. The FRP-polyurethane foam(PUF) composites have lower thermal conductivity changes as ageing than plywood-PUF composites. FRP-PUF sandwich composite for LNG storage tank with these remarkable properties are compared the abilities of these structures with those of the conventional structures(plywood-PUF sandwich composite). Finally, we can obtain the effects such as superior mechanical properties and fuel saving through improved ability of vapor barrier.

• Elastomers and Composites
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• v.50 no.1
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• pp.13-17
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• 2015

A study of the effects of MWCNT as a nucleating agent on the formation reactions of the rigid polyurethane foams (RPUFs) was carried out. Sample PUFs, formulated with grease-type master batch of MWCNT/surfactant, were fabricated by free-rising method. Temperature changes with time during foaming process were measured using a digital thermometer. RPUF foaming process was observed to undergo 2-step processes with temperature inflection around 60 sec after the start of reaction, and then reached slowly the max. temperature. While the max. temperature of neat PUF was measured as ca. $120^{\circ}C$, that of the samples with MWCNT were as higher value as ca. $130^{\circ}C$, and, even the time to reach that temperature was reduced by about 15 sec. Average cell size of PUF samples decreased from 185.1 for the neat PUF to $162.9{\mu}m$ for the sample of 0.01 phr of MWCNT. As the result, it was considered that MWCNT in RPUF foaming process could play a roll both as a nucleating agent and as a catalyst.

• Polymer(Korea)
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• v.26 no.2
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• pp.185-192
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• 2002

Rigid polyurethane foams (PUFs) were prepared from polymeric 4.4'-diphenyl-methane diisocyanate (PMDI), polyether polyol, 1,4-butane diol, silicone surfactant, and distilled water. The density of the PUF was decreased from 173.7 to 41.7 kg/㎥ with an increase in distilled water from 0.5 to 3.0 php (parts per hundred polyol by weight), respectively, at the 0 php butane diol. The cell size of the PUF increased from 115 to 258 $mu extrm{m}$ with an increase in the amount of distilled water from 0.5 to 3.0 php, respectively, at the 10 php butane diol. It was found that the compressive strength of the PUF increased with the content of distilled water, at the same density. Out of the study for the surfactant effect on the properties of the PUF, it was observed that the cell site of the PUF decreased from 360 to 146 $mu extrm{m}$ with an increase in the amount of the surfactant from 0 to 0.33 php, respectively, but the tell size did not change significantly when the amount of the surfactant exceeded 0.33 php.

• Journal of Environmental Health Sciences
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• v.42 no.2
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• pp.102-111
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• 2016

Objectives: This study was conducted to evaluate the use of polyurethane foam disk passive air samplers (PUF PAS) for better measurement of atmospheric polychlorinared dibenzo-p-dioxins/furans (PCDD/Fs) concentrations compared to PUF PAS combined with high volume air samplers (HVS). Methods: Air samples were collected by a low volume air sampler (LVS) and PUF PAS. A total of two pairs were continuously collected for six months, but the PUF was replaced every two months. Results: A good correlation was shown ($R^2=0.8595$, p<0.0001) between atmospheric PCDD/Fs concentration measured by the LVS and PUF PAS. The average air sampling rate ($1.5m^3/day-sampler$) of all PCDD/Fs congeners showed a middle of the means which were measured using a HVS by other researchers in different cities. In addition, the air sampling rates of the LVS for each congener made less difference than did those of the HVS. Conclusion: It was found that measurements using the LVS were less influenced by atmospheric peak PCDD/Fs concentrations. However, trace POPs such as PCDD/Fs may involve relatively large analytical errors in measurement, and as a result the air sampling rate of the respective PCDD/Fs isomer is also likely to involve errors. The method of using a regression straight line between the concentrations obtained from the LVS and those from the PUF PAS was judged higher than the method using the air sampling rate, since the former compensated for the experimental errors in the process of evaluation of atmospheric PCDD/F concentrations using the PUF PAS.

• Journal of the Korean Institute of Gas
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• v.16 no.6
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• pp.115-122
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• 2012

Polyurethane foams were synthesized with different contents and kinds of catalysts to know change of properties under various NCO index. UTM(universal testing machine), DSC(differential scanning calorimetry), SEM(scanning electron microscope) and FT-IR(Fourier transform spectroscopy) were used for studying the PUF's physical properties change. Compressive strength of PUF increased with increasing contents of catalyst. Glass transition temperature(Tg) and compressive strength of PUF using PC-8 and 33LV catalyst, increased with increasing NCO index at the aging. According to the results of Infrared spectral analysis, reduction of NCO peak was found in gelling catalyst, because unreacted NCO reacted with polyurethane. Although Tg and compressive strength of PUF using TMR-2, unchanged with increasing NCO index at the aging, because trimerization of isocyanate.

• Journal of the Korean Institute of Gas
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• v.17 no.5
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• pp.75-80
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• 2013

In this study, the effect of phosphorus flame retardants on the flame retardancy of the rigid polyurethane foam(PUF) was studied. Tetramethylene bis(orthophos-phorylurea)[TBPU] and Tris(2-chloroethyl) phosphate[TCEP], Tris(2-chloropropyl)phosphate [TCPP], Triethyl phosphate[TEP] were used as flame retardant. It was found that TBPU added PUF exhibits low mean heat release rate(HRR), peak HRR, effective heat of combusion(EHC), mass loss rate (MLR), CO yield and $CO_2$ compared other flame retardants.