• Applied Chemistry for Engineering
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• v.31 no.1
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• pp.30-35
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• 2020

In this study, polyurethane-silica composite foams were synthesized to analyze thermal insulation characteristics and mechanical properties. In order to synthesize polyurethane-silica composite foams, polyester-silica composite polyols were first synthesized via a polymerization reaction with silica sol, dicarboxylic acid and glycol in monomer state. Physical properties of polyurethane-silica composite foams synthesized using the composite polyols were analyzed. From the thermal conductivity analysis, no significant differences among HPUF0, HPUF1, HPUF3 and HPUF5 were found. The compressive strength of polyurethane-silica composite foams increased as the silica content increased. The mechanical property of HPUF5 was also about 25% higher than that of HPUF0.

• Applied Chemistry for Engineering
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• v.16 no.1
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• pp.39-44
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• 2005

In this study, polyurethane-acryl emulsion resins were synthesized from HDI (hexamethylene diisocyanate), IPDI (isophorone diisocyanate), Polyol, 2-HEMA (2-hydroxy ethylmethacrylate), n-BA (n-butyl acrylate) and MMA (methylmethacrylate). The effects of polyol types on the properties of polyurethane-acryl emulsion resin, such as degree of strength and water resistance and on the manufacturing process were investigated. In addition, the results were compared with those of acrylic emulsion. The test results showed that polyester type polyol demonstrated stronger tensile strength and higher water resistance with time than did acrylic emulsion and polyether type polyol.

• Polymer(Korea)
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• v.29 no.2
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• pp.140-145
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• 2005

Effects of the polyol type and the hard segment content of thermoplastic polyurethane (TPU) on the crystallization of hard segments in TPUs were studied employing differential scanning calorimetry. Diols used for the preparation of TPUs were poly(tetramethylene ether glycol) (PTMEG), poly(propylene glycol) (PPG), polycaprolactone (PCL), poly(butylene adipate) (PBA) the molecular weights of which were 2000 and the hard segments contents of TPUs were $35\~44\;wt\%$. We found that crystallization of hard segments in TPUs were observed at higher temperatures and became faster with increasing hard segment contents of TPUs. The crystallization rate of TPU was also affected by the types of polyols used for the preparation of TPUs. It is postulated that lower miscibility of soft segments and hard segments results in higher crystallization rate and increase of cooling crystallization temperatures due to better hydrogen bending between hard segments in melts.

• Textile Coloration and Finishing
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• v.5 no.4
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• pp.60-66
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• 1993

Aqueous polyurethane(PU) anionomer dispersions were prepared from isophorone diisocyanate (IPDI), polytetramethylene adipate glycol(PTAd) and dimethylol propionic acid(DMPA) as potential anionic centers. The effects of polyol molecular weight(Mn) on the state of dispersion, thermal, mechanical, and viscoelastic properties and swelling of emulsion cast film were determined. With increasing Mn of PTAd, particle size of emulsion and soft segment T$_{g}$ decreased, and solvent swell, emulsion viscosity, and hard segment $T_{g}$ increased. Tensile strength showed minimum with PTAd 1000, and elongation at break generally increased with the Mn of PTAd. These results were possibly nterpreted in terms of soft segment-hard segment phase separation and crystallization of high molecular weight PTAd.

• Journal of the Korean Institute of Gas
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• v.5 no.4 s.16
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• pp.79-84
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• 2001

In this study, the effect of polyol structure(OH-value, functionality) on the reactivity, mechanical property and cell morphology of polyurethane foam and the possibility of replacing HFC-36smfc was examined by evaluating how each blowing agent(CFC-11, HCFC-l4lb, HFC-36smfc) affects the reactivity, mechanical property and cell morphology. Results of the experiment showed that as the functionality and OH-value of polyol increased, there was an increase in the temperature profile, reaction rate, density and compressive strength. However. as the functionality and OH-value increased. the ceil size became smaller The use of different kinds of blowing agents did not appear to have and significant influence on the temperature profile, reaction rate, density and compressive strength. The foam using HFC-365mfc produced more uniform cells compared to the foam using HCFC-l4lb.

• Journal of the Korean Institute of Gas
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• v.16 no.5
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• pp.66-75
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• 2012

Polyurethane foams were synthesized by substituting a portion of petroleum base polyether polyol with castor oil-derived polyol(COP). Contact angle tester and surface tensionmeter were used to examine the compatibility of petroleum base polyether polyol and COP. To investigate the optimum content of COP and surfactant, the content of COP has been changed from 0 wt% to 80 wt%. From the results of polyurethane foams synthesized by surfactant L-580K, DC-5950 and BF-2470, the best mechanical properties was observed when the content of COP was 30wt% and surfactant BF-2470.

• 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 Adhesion and Interface
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• v.3 no.2
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• pp.1-8
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• 2002

Polyurethane NCO prepolymers were synthesized with the polyols such as PTMG, GP and the isocyanate such as TDI at $40^{\circ}C$ for 8.5 minutes. As average molecular weights (${\bar{M_n}}$: 1000, 2000, 3000, 4000) of PTMG, and GP were decreased from 4000 to 1000, ratio of oil gelation increased from 298%, to 440%, for Bunker B. When oil and water were emulsified, the ratio of gelation was increased approximately two times. Ratio of gelation for emulsive Bunker B was increased from 402% to 910%, for PTMG1000 and increased from 440%, W 958% for GPI1000. Ratio of oil gelation for emulsive Bunk C which has higher viscosity than Bunker B was measured w 923% for PTMG1000 made with chain extender, i.e. EG, and measured to 1098% for GP1000. The gel made from GP which has three functional group showed soft and strong characteristic, as a result, it can be removed easily from oil spilled ocean.

• Elastomers and Composites
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• v.48 no.3
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• pp.190-194
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• 2013

In this study, sebacic acid made from castor oil was used as monomer with isophthalic acid and glycols for polyester polyol synthesis. Polyurethane adhesive was synthesized from the various polyester polyol. From the result of adhesion strength test, polyester polyol made from sebacic acid showed better adhesive force than that of adipic acid due to higher cohesive energy. Branched glycol containing methyl group represented better adhesion than linear glycol. In the chain extender, adhesion strength increased going from PG, EG, BD. From the measurement of TGA, BD showed the best heat stability, and followed by PG, EG. Glass transition temperature increased in the order PG, EG, BD by the result of DMA.

• Applied Chemistry for Engineering
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• v.16 no.1
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• pp.93-100
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• 2005

8 functionality photocurable polyester polyol modified hyperbranched methacrylates of two types were prepared from trimellitic anhydride, glycidyl methacrylate, and 4 functionality polyester polyol of two types. The physical properties of photocurable polyester polyol modified hyperbranched methacrylate were investigated. Thermal stability obtained by using TGA showed that HBMA-2 (hyperbranched methacrylate-2) was superior to the HBMA-1 (hyperbranched methacrylate-1). Hardness, abrasion resistance and tensile strength of HBMA-2 showed that were also superior to the HBMA-1. Value of yellow index of HBMA-2 showed the higher.