Papers by Author: Su Ran Liao

Abstract: The kinetics of the reaction is essential for the synthesis of polyurethane. In this study, the reaction kinetics and polymerization conditions in two-step process of isophorone diisocyante (IPDI) and polypropylene glycol (PPG) with organo-tin mixed catalyst were investigated by chemical titration. The results showed that the reaction obeyed the second-order equation of step-growth polymerization, the rate constants of IPDI and PPG reaction at 50, 60 and 70°C were 0.0161, 0.0373 and 0.0806 kg•mol-1•min-1，respectively. The activation energy obtained from the result was 74.25 kJ•mol-1. The polyurethane with number molecular weight 38721 was synthesized and was characterized by Fourier transform infrared (FTIR).

Abstract: The study of polyurethanes are of continuing interest due to their excellent physical properties. In this study, the reaction kinetics and polymerization conditions in two-step process of toluene diisocyante (TDI) and polypropylene glycol (PPG) with organo-tin mixed catalyst were investigated by di-n-butylamine back-titration. It was showed that the reaction obeyed the second-order equation of step-growth polymerization, the rate constants of TDI and PPG reaction at 50, 60 and 70°C were 0.0922, 0.3373 and 0.5828 kg•mol-1•min-1，respectively. The activation energy obtained from the result was 71.63 kJ•mol-1. The number average molecular weight (Mn) and molecular-weight distribution (Mw/Mn) of the polyurethane were 45175 and 1.53, respectively, and the content of hydrogen bonding in the N-H group from Fourier transform infrared spectrum (FTIR) was 80.75%, which manifested that the large amount of N-H were present in hydrogen bonding.

Abstract: Effect of substrate conditions, including material type, thickness and radius of substrate, on residual thermal stresses of plasma spraying Sm₂Zr₂O₇ TBCs was analyzed though finite element method in this paper. The radial and shear stresses of Sm₂Zr₂O₇ decrease with increasing of distance from the center to edge along radius of specimen, and they decrease abruptly at the edge of the specimen, while the axial residal stress increase abruptly at the edge of substrate. All residual stresses increase with increasing of thermal expansion coefficient of substrate. The thickness of substrate has slight effect on the radial residual stress, and axial residual stress and shear stress are almost uneffected by thickness of substrate. The optimum thickness of substrate is 10mm. Radius of substrate have no effect on radial stress when it is greater than 28mm, and radius of substrate has no effect on axial stress and shear stress of Sm₂Zr₂O₇ TBCs.

Abstract: Y2Ce2O7 ceramic material was prepared by solid reaction at 1600°C for 10h. The phase composition, microstructure and thermal conductivity of this material were investigated. XRD results reveals that single phase Y2Ce2O7 with fluorite structure was synthesized. Microstructure of Y2Ce2O7 was dense and no other unreacted oxides or interphase existed in the interfaces between grains. Because of phonon scattering by oxygen vacancies and difference in atomic mass between substitutional atoms and host atoms, thermal conductivty of Y2Ce2O7 is lower than that of 8YSZ, which implies that this ceramic can be used as novel candidate materials for thermal barrier coatings in the future.

Abstract: This paper reviews the theory of thermal conduction of ceramic materials with the aim to reduce further the thermal conductivity of plasma sprayed thermal barrier coatings. Methods of reducing thermal conductivity of plasma sprayed thermal barrier coatings including seeking for alternative ceramic materials to 8YSZ, addition of some dopants, preparing nanostructured coating and double-ceramic-layer coating are advised. It is indicated that the combination of colouring plus nanostructured and double-ceramic-layer coating of new ceramic candidate materials of lower thermal conductivity should be an very important research direction in future.

Abstract: The waterborne polyurethane (WPU) was synthesized from isophorone diisocyanate (IPDI), polypropylene glycol (PPG), dimethylolpropionic acid (DMPA) and 1,4-butanediol (BDO) under acetone reflux. The cast films obtained from it were characterized by Fourier transform infrared (FTIR), nuclear magnetic resonance (¹H NMR) and differential scanning calorimetry (DSC). The curve of DSC presented a bimodal profile. It showed that the waterborne polyurethane resin degraded obviously at about 305°C and 381°C, which was an endothermic course. The scanning electron microscopy (SEM) micrographs revealed that hexanitrohexaazaisowurtzitane (HNIW) was coated with waterborne polyurethane by means of water volatilization. The impact sensitivity experimental results indicated that the characteristic height H₅₀ of HNIW coated with waterborne polyurethane increased from 25.1cm to 34.2cm. That is, the waterborne polyurethane can decrease the impact sensitivity of HNIW.