Papers by Keyword: Isocyanate

Abstract: Metalloporphyrin-based nanostructures were fabricated on 3-aminopropylmethoxysilane-modified indium tin oxide (ITO) surface. UV-visible spectroscopy and cyclic voltammetry are used for investigating electronic absorption spectra and catalytic activity in oxygen reduction reactions as alternative cathode electrochemical catalysts for polymer electrolyte membrane fuel cells (PEMFCs). Using of 5,10,15,20-tetrakis-(4-amiophenyl)-porphyrin-Co (II) as a building block and 1,4-phenylene diisocyanate as a linker, the mixed toluene/chloroform solution-based layer-by-layer process can produce linear growth of 5,10,15,20-tetrakis-(4-amiophenyl)-porphyrin-Co (II) up to 30 layers through urea bonds. The vacuum thermal annealing process demonstrated the improvement of catalytic activity in oxygen reduction reaction.

Abstract: In this study, canola oil triglycerides have been successfully transformed into canola oil-based polyisocyanates via thiol-ene click reaction and Curtius rearrangement reaction sequently. The synthesis method is non-phosgene and green. The structure of these novel diisocyanates was confirmed through Fourier transform infrared spectroscopy (FT-IR) and proton nuclear magnetic resonance (NMR). The result shows that the goal product has been produce successfully.

Abstract: This article presents a comprehensive investigation in the acoustic characteristics of flame-retardant PET mesh composite fabric and PU foam with the various bulk density of foam and weight ratio of vermiculite. By using impedance tube, absorption coefficients and acoustic impedance of composite material which play an important roles in the estimation of the wave propagation passing through the specific material will be obtained. Results showed that foam with higher bulk density not only increased the material characteristics in the absorption but more importantly, cause the wider band for absorption. With the inclusion of vermiculites, the level of absorption of composite material will obviously increase, especially for the higher frequencies. Instead of 20wt% for vermiculites, the highest absorption coefficient can be found under the 15wt%. On the other hand, acoustic impedance of composite material presented in this article will slowly decrease with frequencies, and the influences of these two parameters are focused on the lower frequency range.

Abstract: As improvement of industry and society, some potential crisis happened in working and living environment is taken into account by human people. Meanwhile, different kinds of protective appliances develop rapidly, and composite boards with cushion and puncture-resistance property are required consequently. This study aims to develop a cushion/puncture-resistance PU foam protective composites. This paper used Polyol and Isocyanate to prepare porous PU foam composite via foaming and curing process. By changing foam density and addition amount, cushion and puncture-resistance property were tested and then evaluated to seek for PU foam composite with cushion and puncture-resistance property. Result shows that, when density was 80 kg/m³, PU foaming composite board had the optimum resilience rate of 44 %, lowest impact remaining load of 638 N and best puncture-resistance force of 138.3 N.

Abstract: The cotton fabrics was treated with the blending of organic fluorine water and oil repellent finishing agent and cross-linking agent. The contact angle to water was over 120°and that to oil was above 110°after the fabrics were washed 20 times, indicating that the water and oil repellent properties and durability of fabrics were excellent. And the technology was optimized as follows: the water and oil repellent finishing agent 50g/L, cross-linking agent 4g/L, curing temperature 150°C and curing time 200s.

Abstract: The urethane reaction kinetics of 1,2-propanediol and 1,3-butanediol with phenyl isocyanate are investigated in toluene. In-situ FT-IR is used to monitor the reaction to work out rate constant. The urethane reaction has been found to be a second order reaction and is largely accelerated with triethylamine as catalyst. Furthermore, the rate constants are different between initial stage and final stage when triethylamine is used as catalyst, which belongs to different hydroxyls in asymmetry diol. However, when there is no catalyst in the reaction system, the rate constant is the same. That is, there is no reactivity difference for hydroxyls in asymmetry diol. Moreover, 1,3-butanediol is more active than 1,2-propanediol when reacting with isocyanate.

Abstract: The urethane reaction kinetics of 1,2-propanediol with phenyl isocyanate are investigated in different solvents, such as xylene, toluene and dimethylformamide. In-situ FT-IR is used to monitor the reaction to work out rate constant. It showsthat the urethane reaction has been found to be a second order reaction, solvents largely affects reaction rates. The reaction is largely accelerated in polar solvents, following the order of dimethylformamide > toluene > xylene. Further more, when dimethylformamide is used as solvent, the rate constants are different between initial stage and final stage, which belongs to different hydroxyls in 1,2-propanediol. However, when toluene or xylene is used as solvent, the rate constant is the same. That is, there is no reactivity difference for hydroxyls in 1,2-propanediol.

Abstract: The poly(lactic acid) (PLA) was modified by 4,4'-diphenylmethane diisocyanate (MDI) successfully prepared to improve the stability of PLA. The MDI and the hydroxyl terminated PLA could form PLA modified by MDI (MDI-PLA) via addition reaction. The structure of MDI-PLA was confirmed by FTIR and its degradation properties were investigated. The results showed that the pH of the aqueous media and the ion strength together played an important role in the degradation behavior of the PLA and MDI-PLA. Both of the PLA and MDI-PLA had the highest degradation rate in 0.01 M NaOH. It offers the best stability to hydrolysis resistance by adding the 0.6 wt% of MDI to the PLA materials，and have a more stable of 15 times than unmodified PLA.

Abstract: The polymerization reaction kinetics of biodegradable polyurethane extended with soy protein isolate (SPI) with dibutyltin dilaurate (DBTDL) as the curing catalyst was studied by means of non-isothermal differential scanning calorimetry (DSC). Model-free methods, Kissinger method and Ozawa method, were applied for analyzing the DSC data. The Ea and lnA obtained from Kissinger method for catalyzed reaction between toluene diisocyanate (TDI) and Polyoxypropyleneglycol (PPG) are 60.80 kJ•mol-1 and 12.09, and for catalyzed reaction among TDI, PPG, and SPI they were 65.91 kJ•mol-1and 14.04. Similarly the Ea obtained from Ozawa method for catalyzed reaction between TDI and PPG and catalyzed reaction among TDI, PPG, and SPI were 63.49 kJ•mol-1 and 64.78 kJ•mol-1, respectively. The results showed that, the incorporation of a small amount of SPI into polyurethane did not affect the reaction kinetic strongly, but increases the reaction activation energy Ea and lnA.

Abstract: This paper aims at making a study on the bonding properties of birch with API adhesive. A non-formaldehyde adhesive to improve the bonding strength and water resistance of the emulsion was investigated. The adhesive was a composite system that was formulated from polyvinyl acetate (PVAc) emulsion, PVA, isocyanate and some other additives. In this study the effect of isocyanate at room temperature on the curing behavior of PVAc was investigated. A XPS technique has been established to analyze structure of crosslinking in bonding interface. The experimental results indicated that the occurrence for chemical reaction between PVAc-based API adhesive and birch wood.