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Article
Publication date: 8 August 2018

Sainan Zhang and Xiankai Jiang

The purpose of this paper is to synthesize and characterize a series of two-component aromatic waterborne polyurethane (2K-WPU) which is composed of non-ionic and anionic…

241

Abstract

Purpose

The purpose of this paper is to synthesize and characterize a series of two-component aromatic waterborne polyurethane (2K-WPU) which is composed of non-ionic and anionic polyisocyanate aqueous dispersion and polyurethane polyol aqueous dispersion.

Design/methodology/approach

The polyisocyanate aqueous dispersion was synthesized through non-ionic and anionic hydrophilic modification procedures. The values of the hydrogen bonding index (HBI) and molecule structures of WPU were obtained by Fourier transform infrared (FTIR). The thermal, mechanical and water resistance properties of 2K-WPU films were investigated.

Findings

The appearance of non-ionic polyisocyanate aqueous dispersion and anionic polyisocyanate aqueous dispersion was colorless translucent pan blue and yellow opaque emulsions, respectively. FTIR not only showed that 2K-WPU was obtained from the polymerization of polyisocyanate component and polyhydroxy component by polymerization but also showed that the content of hydrogen bondings of anionic 2K-WPU (WPU 2) was higher than non-ionic 2K-WPU (WPU 1). The glass-transition temperature (Tg), storage modulus and water resistance of WPU 2 were higher than WPU1, whereas the thermal stability of WPU1 was better than WPU 2.

Practical implications

The investigation established a method to prepare a series of 2K-WPU which was composed of non-ionic or anionic polyisocyanate aqueous dispersion and polyurethane polyol aqueous dispersion. The prepared 2K-WPU film could be applied as substrate resin material in the field of waterborne coating.

Originality/value

The paper established a method to synthesize a series of 2K-WPU. The effect of HBI value and the molecule structure of soft segment on the thermal stability, mechanical and water resistance properties of 2K-WPU films were studied.

Details

Pigment & Resin Technology, vol. 47 no. 4
Type: Research Article
ISSN: 0369-9420

Keywords

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Article
Publication date: 13 August 2018

Jizhi Zhang and Xiankai Jiang

The purpose of this paper is to synthesize and characterize a series of alicyclic two-component waterborne polyurethane (2K-WPU) which is composed of non-ionic polyisocyanate…

260

Abstract

Purpose

The purpose of this paper is to synthesize and characterize a series of alicyclic two-component waterborne polyurethane (2K-WPU) which is composed of non-ionic polyisocyanate aqueous dispersion and hydroxyl aqueous dispersion.

Design/methodology/approach

The appearances of aqueous dispersions and 2K-WPU films were observed by photographs. The micromorphology of alicyclic polyisocyanate aqueous dispersion was examined by scanning electron microscopy (SEM). The molecule structures of WPU were studied by Fourier transform infrared (FTIR). The effect of NCO:OH molar ratio of two components and trimethylolpropane (TMP) content on the thermal stability, mechanical and water resistance properties of 2K-WPU films was studied.

Findings

It was found by SEM that alicyclic polyisocyanate particles in aqueous dispersion showed a kind of spherical particle appearance, in which hydrophobic polyisocyanate was encapsulated by hydrophilic ether linkages segment. FTIR showed that WPU was polymerized through mixture of polyisocyanate component and hydroxyl component and increasing NCO:OH molar ratio of two components from 1.1:1 to 1.5:1 had increased the content of urea, urethane and allophanate of 2K-WPU films. Increasing NCO:OH molar ratio had improved the mechanical and thermal properties of the 2K-WPU film, but the water resistance of the 2K-WPU film increased first and then weakened. Increasing TMP contents from 1 to 0.75 mol for 1:5 system had improved the mechanical, thermal and water resistance properties of the 2K-WPU film.

Practical implications

The investigation established a method to prepare alicyclic 2K-WPU which is composed of non-ionic polyisocyanate aqueous dispersion and hydroxyl aqueous dispersion. The prepared 2K-WPU film could be applied in the field of waterborne surface coating, e.g. textile, wood and synthetic leather surfaces (Hasan et al., 2017; Akindoyo et al., 2016).

Originality/value

The paper established a method to synthesize alicyclic two-component 2K-WPU. The effect of NCO:OH molar ratio and TMP content on the thermal stability, mechanical and water resistance properties of 2K-WPU films were studied.

Details

Pigment & Resin Technology, vol. 47 no. 4
Type: Research Article
ISSN: 0369-9420

Keywords

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Article
Publication date: 2 May 2017

Benfu Wang, Decai Ren, Qian Zhang, Xuduo Bai and Xiankai Jiang

This paper aims to investigate the electrochromic (EC) properties of poly(triphenylamine alkyl ether) and poly(triphenylamine aryl ether) in two different electrolyte solution to…

157

Abstract

Purpose

This paper aims to investigate the electrochromic (EC) properties of poly(triphenylamine alkyl ether) and poly(triphenylamine aryl ether) in two different electrolyte solution to study the resistive switching behaviour of acid-doped poly(triphenylamine alkyl ether).

Design/methodology_appach

By Buchwald–Hartwig coupling reaction, two novel poly[N-p-phenoxy-N-[4-[2-(2-methoxyethoxy)ethoxy]ethoxy]triphenylamineandpoly[N,N-bis(4-phenoxy)]triphenylamine were synthesized from 4-phenoxyaniline and two dibromo aromatic compounds, 1,2-bis[β,β′-(p-bromophenoxy)ethoxy]ethane and bis(4-bromophenyl) ether.

Findings

Poly(triphenylamine alkyl ether) displayed excellent EC characteristics, with a coloration change from a colourless neutral state to light blue and red oxidized states, while poly(triphenylamine aryl ether) showed coloration a change from a colourless neutral state to light blue oxidized state in tetrabutylammonium perchlorate electrolyte solution. Moreover, p-toluenesulfonic acid-doped poly(triphenylamine alkyl ether) exhibited a non-volatile bistable resistive switching behaviour with a high high-conductivity/low-conductivity ratio of up to 104, long retention time exceeding 2.5 × 103 s and the switching threshold voltage was also lower than −2V.

Research limitations/implications

In this paper, the non-volatile bistable resistive switching behaviour of acid-dopedpoly(triphenylamine alkyl ether) was in accordance with the molar ratio of 1:1. The effects of different molar ratios remained to be studied.

Practical implications

Poly(triphenylamine ether)s may find optoelectronic applications as new EC and resistive switching materials.

Originality/value

The effects of alkyl and aryl ether structures in the main chain on the EC and resistive switching behaviour of triphenylamine unit have not yet been reported.

Details

Pigment & Resin Technology, vol. 46 no. 3
Type: Research Article
ISSN: 0369-9420

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Article
Publication date: 8 November 2011

Yanhua Zhang, Jiyou Gu, Xiankai Jiang, Libin Zhu and Haiyan Tan

The purpose of this paper is to study the effective procedure for blocking and deblocking isocyanate by sodium bisulphite with special cosolvent and dropwise method.

737

Abstract

Purpose

The purpose of this paper is to study the effective procedure for blocking and deblocking isocyanate by sodium bisulphite with special cosolvent and dropwise method.

Design/methodology/approach

A number of analytical techniques, including Fourier transform infrared spectroscopy (FTIR), Differential scanning calorimetry (DSC) and Thermo gravimetric analyser (TGA) were employed to assess the reactions between isocyanates and sodium bisulphite, water, cosolvent, also the deblocking temperature of blocked isocyanates.

Findings

The blocked isocyanates reacted with sodium bisulphite, water and cosolvent via a special procedure. It was found that the − NCO functional groups of the isocyanates were completely blocked by sodium bisulphite and a new method for determining the lowest deblocking temperature of the blocked isocyanates was described. It was revealed that the deblocking temperature of blocked isocyanates by sodium bisulphite was lower than others.

Practical implications

The paper provides some useful information about the blocking and deblocking of isocyanate, which would be helpful for the preparation of blocking and deblocking isocyanate, and guiding the practical applications of blocked isocyanate.

Originality/value

The investigation found that the sodium bisulphite was a very efficient blocking agent for isocyanates at the room temperature via the special procedure developed. On the basis of emulsion polymerisation theory, polymer isocyanates were blocked by sodium bisulphite, which realised the new breakthrough effectively by means of controlled temperature, stirring speed and optimum dropwise speed in the whole reaction system. Meanwhile, the special cosolvent could improve the intermiscibility of isocyanate in sodium bisulphite aqueous solution, reduce the side reaction of isocyanate with water and accelerate reaction rate of isocyanate with sodium bisulphite. If no cosolvent was present, the blocked system would not be homogeneous.

Details

Pigment & Resin Technology, vol. 40 no. 6
Type: Research Article
ISSN: 0369-9420

Keywords

Available. Open Access. Open Access
Article
Publication date: 12 December 2022

Weicheng Guo, Chongjun Wu, Xiankai Meng, Chao Luo and Zhijian Lin

Molecular dynamics is an emerging simulation technique in the field of machining in recent years. Many researchers have tried to simulate different processing methods of various…

554

Abstract

Purpose

Molecular dynamics is an emerging simulation technique in the field of machining in recent years. Many researchers have tried to simulate different processing methods of various materials with the theory of molecular dynamics (MD), and some preliminary conclusions have been obtained. However, the application of MD simulation is more limited compared with traditional finite element model (FEM) simulation technique due to the complex modeling approach and long computation time. Therefore, more studies on the MD simulations are required to provide a reliable theoretical basis for the nanoscale interpretation of grinding process. This study investigates the crystal structures, dislocations, force, temperature and subsurface damage (SSD) in the grinding of iron-nickel alloy using MD analysis.

Design/methodology/approach

In this study the simulation model is established on the basis of the workpiece and single cubic boron nitride (CBN) grit with embedded atom method and Morse potentials describing the forces and energies between different atoms. The effects of grinding parameters on the material microstructure are studied based on the simulation results.

Findings

When CBN grit goes through one of the grains, the arrangement of atoms within the grain will be disordered, but other grains will not be easily deformed due to the protection of the grain boundaries. Higher grinding speed and larger cutting depth can cause greater impact of grit on the atoms, and more body-centered cubic (BCC) structures will be destroyed. The dislocations will appear in grain boundaries due to the rearrangement of atoms in grinding. The increase of grinding speed results in the more transformation from BCC to amorphous structures.

Originality/value

This study is aimed to study the grinding of Fe-Ni alloy (maraging steel) with single grit through MD simulation method, and to reveal the microstructure evolution within the affected range of SSD layer in the workpiece. The simulation model of polycrystalline structure of Fe-Ni maraging steel and grinding process of single CBN grit is constructed based on the Voronoi algorithm. The atomic accumulation, transformation of crystal structures, evolution of dislocations as well as the generation of SSD are discussed according to the simulation results.

Details

Journal of Intelligent Manufacturing and Special Equipment, vol. 4 no. 1
Type: Research Article
ISSN: 2633-6596

Keywords

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Article
Publication date: 29 November 2022

Liyao Huang and Weimin Zheng

This study aims to provide a comprehensive review of hotel demand forecasting to identify its key fundamentals and evolution and future research directions and trends to advance…

1315

Abstract

Purpose

This study aims to provide a comprehensive review of hotel demand forecasting to identify its key fundamentals and evolution and future research directions and trends to advance the field.

Design/methodology/approach

Articles on hotel demand modeling and forecasting were identified and rigorously selected using transparent inclusion and exclusion criteria. A final sample of 85 empirical studies was obtained for comprehensive analysis through content analysis.

Findings

Synthesis of the literature highlights that hotel forecasting based on historical demand data dominates the research, and reservation/cancellation data and combined data gradually attracted research attention in recent years. In terms of model evolution, time series and AI-based models are the most popular models for hotel demand forecasting. Review results show that numerous studies focused on hybrid models and AI-based models.

Originality/value

To the best of the authors’ knowledge, this study is the first systematic review of the literature on hotel demand forecasting from the perspective of data source and methodological development and indicates future research directions.

目的

本研究旨在对酒店需求预测进行全面回顾, 以确定其关键基础和演变以及未来的研究方向和趋势, 以推动该领域的发展。

设计/方法/方法

使用严格和透明的纳入和排除的标准对酒店需求建模和预测的文章进行识别和选择。通过内容分析, 最终有 85个实证研究作为综合分析的样本。

研究结果

综合文献发现, 基于历史需求数据的酒店预测在研究中占主导地位, 近年来预订/取消数据和组合数据逐渐引起研究关注。在模型演化方面, 时间序列和基于人工智能的模型是最受欢迎的酒店需求预测模型。审查结果表明, 许多研究都集中在混合模型和基于 AI 的模型上。

原创性/价值

本研究是第一次从数据源和方法发展的角度对酒店需求预测文献进行系统回顾, 并指出未来的研究方向。

Propósito

Este estudio tiene como objetivo proporcionar una revisión amplia de la previsión sobre la demanda hotelera a la hora de identificar sus fundamentos clave, la evolución y las direcciones y tendencias de investigación futuras para avanzar en el campo de estudio.

Diseño/metodología/enfoque

Se identificaron y seleccionaron de forma rigurosa artículos sobre modelado y previsión de la demanda hotelera utilizando criterios transparentes de inclusión y exclusión. Se obtuvo una muestra final de 85 estudios empíricos para su análisis integral a través del análisis de contenido.

Hallazgos

La síntesis de la literatura destaca que la previsión hotelera basada en datos históricos de demanda ha dominado la investigación, y los datos de reserva/cancelación, así como los datos combinados han atraído gradualmente en los últimos años la atención de la investigación. En términos de evolución del modelo, las series temporales y los modelos basados en IA son los modelos más populares para la previsión de la demanda hotelera. Los resultados de la revisión muestran que numerosos estudios se han centrado en modelos híbridos y basados en IA.

Originalidad/valor

Este estudio es la primera revisión sistemática de la literatura sobre la previsión de la demanda hotelera desde la perspectiva de la fuente de datos y el desarrollo metodológico e indica futuras líneas de investigación.

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