Polyurethane Catalysis by Tertiary Amines

Kim

J of Applied Polymer Sci

et al. 2008

An attempt was made to synthesize polyurethane (PU)/organoclay nanocomposite foams with high thermal insulation properties. The organoclay was modified by polymeric 4,4 0 -diphenylmethane diisocyanate (PMDI) with a silane coupling agent. The structure of the organoclay-modified PMDI with the silane coupling agent was determined by Fourier transform infrared spectroscopy and nuclear magnetic resonance. Transmission electron micrographs and wide-angle X-ray diffraction patterns showed that the interlayer distance increased for the PU/organoclay nanocomposites with the addition of the silane coupling agent. It was expected that the distance between the organoclay layers would increase and that the organoclay would be dispersed on a nanoscale in the PU matrix because of the organic/inorganic hybrid bond formation between the organoclay and silane coupling agent.Compressive and flexural strengths of the PU/silane coupling agent/organoclay nanocomposite foams were similar to those of the PU/organoclay nanocomposite foams. However, the thermal conductivity appreciably decreased from 0.0250 to 0.0230 W/m h 8C in the PU/silane coupling agent/organoclay nanocomposite foams. Scanning electron micrographs showed that the cell size of the PU/silane coupling agent/clay nanocomposite foams also decreased. On the basis of these results, it is suggested that the smaller cell size and lower thermal conductivity of the PU/silane coupling agent/organoclay nanocomposite foams were mainly due to enhanced exfoliation of the organoclay layers by the silane coupling reaction.

Section: Introductionmentioning

confidence: 99%

Effects of a silane coupling agent on the exfoliation of organoclay layers in polyurethane/organoclay nanocomposite foams?

Kim

J of Applied Polymer Sci

et al. 2008

“…As it is well known that the reaction between isocyanates and alcohols, such as polyol, follows second-order kinetics, catalyst amines play an important role in the PU reaction 75 ) . When the numbers of amino groups in a molecule increases, catalytic activities tend to increase 76 ) . Therefore, while uses for tetraamines and triamines have increased, the possibility of occupational exposure to di and monoamines has decreased, which could result in little additional field exposure data for low molecular weight amine compounds in the PU industry.…”

Section: Discussionmentioning

confidence: 99%

Amines as occupational hazards for visual disturbance

Jang

2016

INDUSTRIAL HEALTH

Various amines, such as triethylamine and N,N-dimethylethylamine, have been reported to cause glaucopsia in workers employed in epoxy, foundry, and polyurethane foam industries. This symptom has been related to corneal edema and vesicular collection of fluid within the corneal subepithelial cells. Exposure to amine vapors for 30 min to several hours leads to blurring of vision, a blue-grey appearance of objects, and halos around lights, that are probably reversible. Concentration-effect relationships have been established. The visual disturbance is considered a nuisance, as it could cause onsite accidents, impair work efficiency, and create difficulties in driving back home. Occupational exposure limits have been established for some amines, but there is shortage of criteria. Volatility factors, such as vapor pressure, should be considered in industrial settings to prevent human ocular risks, while trying to reduce levels of hazardous amines in the atmosphere.

J of Applied Polymer Sci

“…However, studies on the EMI SE of PUF/conductive filler composites are rare. Therefore, it is worthwhile to study the EMI SE of PUF with conductive fillers such as MWCNTs, carbon fiber, and graphite since studies on PUF have been focused mostly on its thermal insulating properties so far . A low concentration of well‐dispersed nanoparticles in the polyurethane matrix may produce a copious number of bubbles by reducing the activation energy required for nucleation.…”

Section: Introductionmentioning

confidence: 99%

Electrical conductivity andEMIshielding effectiveness of polyurethane foam–conductive filler composites

Kim

Lee

Jang

et al. 2016

The morphological, electrical, and thermal properties of polyurethane foam (PUF)/single conductive filler composites and PUF/hybrid conductive filler composites were investigated. For the PUF/single conductive filler composites, the PUF/nickel‐coated carbon fiber (NCCF) composite showed higher electrical conductivity and electromagnetic interference shielding effectiveness (EMI SE) than did the PUF/multiwall carbon nanotube (MWCNT) and PUF/graphite composites; therefore, NCCF is the most effective filler among those tested in this study. For the PUF/hybrid conductive fillers PUF/NCCF (3.0 php)/MWCNT (3.0 php) composites, the values of electrical conductivity and EMI SE were determined to be 0.171 S/cm and 24.7 dB (decibel), respectively, which were the highest among the fillers investigated in this study. NCCF and MWCNT were the most effective primary and secondary fillers, and they had a synergistic effect on the electrical conductivity and EMI SE of the PUF/NCCF/MWCNT composites. From the results of thermal conductivity and cell size of the PUF/conductive filler composites, it is suggested that a reduction in cell size lowers the thermal conductivity of the PUF/conductive filler composites. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44373.