• Proceedings of the KIEE Conference
• /
• 2000.11c
• /
• pp.458-460
• /
• 2000

We attempted to fabricate polyurethane derivatives (PU-CN, PU-DCM) LB films by using LB method. Also, we investigated the monolayer behavior at the air-water interface by surface pressure-area ($\pi$-A) isotherms. And, the surface morphologies and the physicochemical properties of LB films were investigated by atomic force microscopy (AFM) and UV-vis spectroscopy, respectively. Also, the electrical properties of polyurethane derivatives LB films were investigated by using the conductivity, the dielectric constant and activation energy. In the surface morphologies, physicochemical, electrical properties of polyurethane derivatives LB films, the properties is different as to the Polyurethane derivatives, it is considered that this phenomena could be described by the difference of lumophore pendant which was adhered at PU main chain.

• Applied Chemistry for Engineering
• /
• v.4 no.3
• /
• pp.616-626
• /
• 1993

Polyurethane(PU) have an excellent flexibility and toughness so that it has been widely used as an elastomer. PMMA was blended with PU to improve the impact property. Five types of PU, having different molecular weight and different polyol types, were prepared and blended with PMMA in order to investigate the effect of molecular weight and polyol type of PU on property of PU-PMMA blend. Tensile strength of PU-PMMA blend was determined by Inston. Differential Scanning Calorymetry(DSC) and Scanning. Elctron Microscopy(SEM) were used to observe morphology change and glass transition temperature changes of PU-PMMA blends. Transparency of PU-PMMA blends was determined by haze meter. But, owing to intrinsic incompatability of PU-PMMA, Low impact strength of PMMA wasn't improved through PU-PMMA blend. therefore, polyurethane dimethacrylate(PUD), having similiar chemical structure to PU and two vinyl group at both ends, was prepared and reacted with methyl methacrylate(MMA) to form crosslinked copolymer Mechanical property of this crosslinked polymer, such as impact strength and transparency, was investigated by Instron, Izod type (Cantilever beam) impact tester and haze meter. Results of these measurements showed that crosslinked copolymer of PUD-MMA was better impact resistance than PMMA and maintained similar transparency to PMMA.

• Polymer(Korea)
• /
• v.25 no.1
• /
• pp.41-48
• /
• 2001

Polyurethane(PU) microgels were synthesized from poly(caprolactone) diol(PCD) and/or poly(ethylene glycol)(PEG), diisocyanate and 1,2,6-hexane triol by solution polymerization method. A critical gelation concentration of the PU microgels with, mole ratios of PCD/PEG were the important factors influencing the formation and property microgel or macrogels. The physical and thermal properties of the PU microgels prepared with depending upon the structure of diisocyanate, mole ratio of PCD/PEG, and molecular weight of PEG were investigated. It was found that PU microgels were distributed by polydisperse, spherical small particles below 300nm and showed the properties of low viscosity.

• International Journal of Industrial Entomology and Biomaterials
• /
• v.5 no.2
• /
• pp.163-170
• /
• 2002

In this paper, silk fibroin (SF)/polyurethane (PU) blend films were fabricated to develop a new biomaterial for biomedical applications. These blend films were prepared using formic acid as a cosolvent, and structural characteristics and properties of blend films were investigated. FTIR results suggested that there was no specific interaction between SF and PU, implying molecular immiscibility in SF/PU blend films. Furthermore, it was revealed by XRD method that the crystalline region of blend components was not perturbed by counterpart polymers. The degree of phase separation of SF/PU blend films was diminished by increasing PU content in blend. Especially, the blend with 70% content of PU showed no evidence of macro-phase separation in SEM observation. However, SF/PU blend (70/30) was revealed to be phase-separated in a lower dimension confirmed by DMTA measurement. TGA result showed that thermal decomposition temperature of blend film was slightly decreased compared to those of SF and PU polymer itself, Though mechanical properties of SF/PU blend films were not good enough due to the solvent, blood compatibility of PU can be enhanced markedly by mixing with SF for SF/PU blend film.

• Elastomers and Composites
• /
• v.58 no.3
• /
• pp.121-127
• /
• 2023

The effect of diisocyanate type on the decomposition temperature of polyurethane (PU) hydrolysis was investigated in a subcritical water medium up to 250℃. PU samples were prepared using different types of diisocyanate: two aromatic diisocyanates (4,4'-methylene diphenyl diisocyanate (MDI) and methyl phenylene diisocyanate (TDI)), one unbranched aliphatic diisocyanate (hexamethylene diisocyanate (HDI)), and two cyclic aliphatic diisocyanates (4,4'-methylene dicyclohexyl diisocyanate (H₁₂MDI) and isophorone diisocyanate (IPDI)). The pressure had no effect on hydrolysis in the range of 70-250 bar. The decomposition temperature of the PU samples increased in the following order: TDI-PU (199℃) < H₁₂MDI ≈ IPDI ≈ HDI (218-220℃) < MDI-PU (237℃). This order of increase in temperature is related to the electron-donating ability of the group to connected to the nitrogen of the urethane unit. When the temperature of the (PU + water) mixture reached the specific decomposition temperature, the PU samples hydrolyzed completely within 5 min into primary amine and 1,4-butanediol. The hydrolysis products from MDI-PU and H₁₂MDI-PU were separated into a liquid phase rich in (BD + water) and a solid low phase rich in amine, whereas the products from TDI-, IPDI-, and HDI-PU existed in a single aqueous phase.

• The Transactions of the Korean Institute of Electrical Engineers C
• /
• v.50 no.8
• /
• pp.371-375
• /
• 2001

We attempted to fabricate polyurethane derivatives (PU-CN, PU-DCM) LB films by using LB method. Also, we investigated the monolayer behavior at the air-water interface by surface pressure-area (${\pi}$-A) isotherms. The surface morphologies and the physicochemical properties of LB films were investigated by atomic force microscopy(AFM) and UV-vis spectroscopy, respectively. And, the electrical properties of polyurethane derivatives LB films were investigated by using the conductivity and the dielectric constant. In the surface morphologies, physicochemical and electrical properties of polyurethane derivatives LB films, the properties is different as to the polyurethane derivatives, it is considered that this phenomena could be described by the difference of lumophore pendant which was adhered at PU main chain.

• Elastomers and Composites
• /
• v.31 no.2
• /
• pp.104-110
• /
• 1996

The polyurethane was synthesized by the reaction of polycaprolactone diol(Mw 2000), 4,4'-diphenylmethane diisocyanate and 1,4-butanediol as the chain extender. Also, the modified polyurethane polymers based on liquid polybutadiene as a part of soft segment and dimethylolpropionic acid as a chain extender, giving polyurethane with various polarity, were synthesized. The thermal, mechanical, adhesion properties and water contact angles of the polyurethanes were examined. From the result of the water contact angle, the polarity of the acid modified PU containing 6% acid content was unchanged but mechanical and adhesion properties were improved. The water contact angles on polybutadiene modified PU films were increased with increasing polybutadiene content. The mechanical properties of the polybutadiene modified PU were higher than that of acid modified PU. However, the mechanical properties were reduced as polybutadiene content increased. The result is presumably due to phase separation between hard segment and soft segment. The peel strength of the polyurethane introduced with 5wt% polybutadiene was improved about 150% than that of unmodified PU. The same as the mechanical properties, the more polybutadiene was introduced, the lower peel strength was obtained.

• Proceedings of the Korean Fiber Society Conference
• /
• 2001.10a
• /
• pp.348-350
• /
• 2001

Polyurethane(PU)은 내마모성, 내약품성, 내용제성이 좋으며 내노화성과 산소에 대한 안정성이 뛰어난 고분자로서 spandex를 비롯하여 코팅, 고무, 도료, 플라스틱, 복합재료 등의 여러 분야에서 이용되어지며 PU를 전기방사 하여 얻은 부직포는 wound dressing, anti-bacteria mask, 인조 피혁, stent 등에 이용할 수 있을 것으로 기대된다. (중략)

• Fire Science and Engineering
• /
• v.20 no.4 s.64
• /
• pp.110-115
• /
• 2006

Polyurethane(PU) was mixtured by the treatment with flame retardants such as Tri(chloroisopropyl) phosphate(TCPP), Triethyl phosphate(TEP) and Trimethyl phosphate(TMP) at about $90^{\circ}C$. Rigid polyurethane foam was produced using the mixured products as flame retardants. The mechanical property and flammability of rigid polyurethane was investigated. The mixtured polyurethane shows reduced flammability over virgin polyurethane. Mechanical strength of mixtured polyurethane also shows as high as that of virgin polyurethane. In order to evaluate flame retardant properties of the mixtured polyurethane foams, heat release rate(HRR) of the foam was measured by cone calorimeter. Scanning electron micrograph of mixtured PU shows uniform cell morphology as virgin PU.

• Proceedings of the Membrane Society of Korea Conference
• /
• 2003.07a
• /
• pp.87-89
• /
• 2003

Thermoplastic polyurethane(PU)-based blend membranes were prepared by the solvent evaporation process. The gas sorption, diffusion, and permeation properties of PU-based blend membranes have been studied. The morphology of PU-based blend membranes was investigated by SEM. The result showed that phase separation occurred with increasing blend ratio. $CO_2$ permeation behaviors of blend membranes were affect by blend composition. Thermoplastic polyurethane(PU)-based membranes showed high $CO_2$ permeation and $CO_2$/$N_2$ selectivity of the blend membrane was improved with increasing the blend ratio.