Search results

The purpose of this paper is to obtain high-solids-content and low-viscosity starch adhesive, and improve bonding strength of the pure starch adhesive.

Maize starch was treated by hydrochloric acid solution with different concentrations, and acid-thinned starch adhesive was prepared. Polyisocyanate as a crosslinking agent was added to improve water resistance of the pure starch adhesive.

The physical and chemical properties of the acid-thinned starch adhesive were characterised. Acid hydrolysis did not change structure of starch granules, but increased its crystallinity. After acid modification, starch granules became less smooth and some fragments appeared. Acid treatment had little influence on thermal stability of starch, when acid hydrolysis was not strong. High concentration of HCl solution led to starch granules being destroyed, resulting in decrease in bonding strength. The optimal HCl concentration was 0.5 mol/L. Polyisocyanate addition was beneficial to improve the bonding strength of the acid-thinned starch adhesive.

Acid hydrolysis changed the properties of the starch adhesive.

Acid hydrolysis decreased viscosity of the starch adhesive and improved its solids content, which had a positive effect on the application of the starch adhesive.

It was helpful to develop an environment-friendly, natural polymer-based wood adhesive.

The properties of acid-thinned starch and acid-thinned starch adhesive were studied.

The purpose of the study was to prepare melamine-urea-formaldehyde (MUF) resin that would be resistant to boiling water and high temperature and exhibit low formaldehyde emission.

The authors prepared MUF resin with different F/(M + U) and changed the amount of melamine added, through the analysis of MUF resin properties to get the best reaction parameters, and used different amino acid cure systems including NH₄Cl cured the resin.

Resin’s heat resistance and water resistance are mainly determined by the amount of melamine added, and formaldehyde emission of the plywood can be changed by adjusting F/(M + U). The peak temperature of the curing agent-cured resin increases as compared with the self-curing resin. Stronger the acidity of curing agent, faster the viscosity increased in probation period and lower the bonding strength and heat resistance of the resin.

Melamine improves the heat resistance and water resistance of the resin. When the amount of melamine is more than a certain value, water resistance of the resin decreased.

MUF resin that is resistant to boiling water and exhibits low formaldehyde emission can be used in high temperature, high humidity and strict formaldehyde emission environment and can also be combined with other materials.

It was helpful to reduce the effect of formaldehyde emission on people’s health and environmental pollution and is also beneficial for the expansion of the application range of aldehyde resin.

The originality is twofold: the influence of the acid strength of curing agent on the bonding strength of the resin adhesive and the method for preparing high performance MUF resin by following the traditional process.

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.

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.

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.

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.

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.

The mechanisms of the deblocking reaction of the polyurethane with blocking agent were investigated in detail relatively using thermogravimetric analysis (TGA), Fourier transform infrared spectrometry (FTIR) and X-ray photoelectron spectroscopy (XPS). This kind of method for polyurethane as the application of wood adhesives can provide the conditions of application and the main theoretical basis.

The blocking rate and latex particle size distribution were determined using the titrimetric analysis and the laser particle analysis, respectively. TGA, FTIR, XPS and differential scanning calorimetry were used to investigate the deblocking temperature and time of the blocked isocyanate in detail.

The results indicated that the blocking rate was approximately 97 per cent and the average particle size was 360 nm. The results of laser particle analysis have confirmed that the dispersivity of the blocked polyurethane emulsion was good. XPS results showed that the amount of –O = C-N-benzyl groups increased with an increasing deblocking temperature and subsequently reached equilibrium. In summary, the blocked isocyanate was deblocked at temperatures ranging from 50 to 90°C.

An important approach in future wood adhesive work would be to gain access to man-made board application data.

The paper provided some useful information about deblocking mechanisms of blocked polyurethane that would be helpful to guide applied practical applications as wood adhesive.

To promote China’s wood processing technology progress and solve the problem of shortage of the natural quality of wood is of important practical significance.

The paper is the first to use the XPS characterisation method to characterise deblocking polyurethane solution.

The occurrences of natural hazards in Southeast Asia have become not only more frequent but their severity has also intensified. More than 200,000 persons perished from the 2004 tsunami resulting from the 9.1 magnitude earthquake in coastal Sumatra, Indonesia, which was the third strongest since 1900. A record-breaking typhoon internationally named Haiyan (locally known as Yolanda) ravaged Central Philippines in 2013. Failure of the communities, as well as the countries, to cope with the hazards has led to disasters that have compelled them to seek external assistance, especially internationally. In the 2004 and 2013 disasters referred to, one specific form of assistance was the conduct of art therapy especially for children. This chapter surveys the literature and examines why and how art therapy has been used in disasters in the region, and which areas either need further exploration or research.

Coral aggregate seawater concrete (CASC) is a new type of lightweight aggregate concrete that is becoming widely used in reef engineering. To investigate the corrosion behavior of different kinds of rebar in CASC exposed to simulated seawater for 0-270 d, the electrochemical techniques, including linear polarization resistance (LPR) technique and the electrochemical impedance spectroscopy (EIS), were used in the present work.

The electrochemical techniques, including LPR technique and the EIS, were used in the present work.

Based on the time-varying law of linear polarization curves, self-corrosion potential (E_corr), polarization resistance (R_p), corrosion current density (I_corr), corrosion rate (i), and the characteristics of EIS diagrams for different types of rebar in CASC, it can be found that the anti-corrosion property of them can be ranked as epoxy resin coated steel > 2205 duplex stainless steel (2205S) > 316 L stainless steel (316 L) > organic coated steel > ordinary steel. Additionally, the linear regression equation between R_p and charge transfer resistance (R_ct) was established. Finally, the EIS corrosion standard of rebar was established from the LPR corrosion standard, which provides a direct standard for the EIS technique to determine the condition of rebar in CASC.

The linear regression equation between polarization resistance and charge transfer resistance was established. And the EIS corrosion standard of rebar was established from the LPR corrosion standard, which provides a direct standard for the EIS technique to determine the condition of rebar in CASC.

The purpose of this paper is to develop a preliminary model of instructional leadership in the Chinese educational context and explore the ways in which Chinese school principals locate their instructional-leadership practices in response to traditional expectations and the requirements of recent reforms.

In-depth interviews were conducted with 22 selected primary school principals in Shenzhen and Guangzhou. A qualitative analysis was conducted to categorize the major leadership practices enacted by these principals.

An initial model of instructional leadership in China with six major dimensions is constructed. The paper also illustrates and elaborates on three dimensions with the greatest context-specific meanings for Chinese principals.

The paper explores the ways in which Chinese principals enact their instructional leadership in a context in which “the west wind meets the east wind”; that is, when they are required to accommodate both imported reform initiatives and traditional expectations. The paper contributes to the sparse existing research on principals’ instructional leadership in non-western cultural and social contexts.

The purpose of this paper is to introduce error ellipse into the bootstrap method to improve the reliability of small samples and the credibility of the S-N curve.

Based on the bootstrap method and the reliability of the original samples, two error ellipse models are proposed. The error ellipse model reasonably predicts that the discrete law of expanded virtual samples obeys two-dimensional normal distribution.

By comparing parameters obtained by the bootstrap method, improved bootstrap method (normal distribution) and error ellipse methods, it is found that the error ellipse method achieves the expansion of sampling range and shortens the confidence interval, which improves the accuracy of the estimation of parameters with small samples. Through case analysis, it is proved that the tangent error ellipse method is feasible, and the series of S-N curves is reasonable by the tangent error ellipse method.

The error ellipse methods can lay a technical foundation for life prediction of products and have a progressive significance for the quality evaluation of products.

This paper aims to investigate how different types of idiosyncratic deals (i-deals) in the hospitality industry enhance occupational well-being (OWB) through organization-based self-esteem (OBSE).

In 2019, 679 questionnaires were distributed to middle- and high-level managerial staff who had worked in high-end hotels in China for at least 1 year, and 642 valid responses were collected. The survey data were analyzed using structural equation modeling. Follow-up interviews were conducted with 20 hotel managers to verify and lend additional support to the survey findings.

Both task i-deals and career and incentives i-deals positively affected OBSE and OWB, whereas flexibility i-deals negatively affected OBSE. OBSE positively affected OWB, thereby mediating the relationships between the three types of i-deals and OWB.

This study is groundbreaking in its exploration of how various i-deals contribute to OWB through OBSE among middle- and high-level managerial staff. The findings provide initial evidence of the links between i deals, OBSE and OWB and demonstrate how i-deals can address the practical problem of the shortage and loss of competent operational and administrative talent in the hospitality industry.

Massive increases in international trade and investment extend industries beyond national borders, so states and enterprises have become the two critical players in the boundary of industries. The purpose of this paper is to provide a new conceptual framework to analyze the role of states and enterprises in enhancing the industrial international competitiveness (IIC).

Being a research‐based paper, the topic is approached by theoretical analysis and conceptual development. The paper reviews IIC literature and argues for a rational study ICC in the context of global value chain. Next, the paper puts forward a two‐dimensional governance model and five typical governance systems of the industries of developing countries. Examples of typical governance system are given based the practice of Chinese industries, such as appeal, rare earths, automotive, etc.

This paper constructs an industrial two‐dimensional governance model of the developing countries in the context of global value chain based on the interaction between industry governance and market governance, and also presents five typical governance systems – free to market, public governance, industrial governance, joint governance and network governance. Different governance system reflects different roles of states and enterprises played in the global value chains and result in different IIC in the end.

The limitation is based primarily on methodology. The two‐dimensional governance model provides target‐oriented guidance for foresting international competitiveness of different types of industries. Future studies should include more in‐depth case studies on different governance system.

The paper presents a framework of the industrial two‐dimensional governance model, which emphasizes the important role of both states and enterprise in the IIC in the context of global value chain.