Search results

This study aims to synthesize two different benzoxazines (Bz) monomers using bio-based and petroleum-based primary amines, respectively, and they have been compared to study their thermal and mechanical performances.

A bio-based bisphenol, Divanillin (DiVa), was formed by reacting two moles of vanillin with one mole of ethylenediamine (EDA) which was then reacted firstly with paraformaldehyde and EDA to form the benzoxazine DiVa-EDA-Bz, and secondly with paraformaldehyde and furfuryl amine (FFA) to form the benzoxazine DiVa-FFA-Bz. The molecular structure and thermal properties of the benzoxazines were characterized by fourier transform infrared spectroscopy and nuclear magnetic resonance (1H,13C) spectroscopies, differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA), respectively. The benzoxazines were further coated on mild steel panels to evaluate their mechanical properties and chemical resistance.

The DSC results of DiVa-FFA-Bz showed two exothermic peaks related to crosslinking compared to the one in DiVa-EDA-Bz. The DiVa-FFA-Bz also showed a higher heat of polymerization than DiVa-EDA-Bz. The TGA results showed that DiVa-FFA-Bz exhibited higher thermal stability with a residual char of 54.10% than 43.24% for DiVa-EDA-Bz. The chemical resistance test results showed that DiVa-FFA-Bz showed better chemical resistance and mechanical properties due to its higher crosslinking density.

This study shows the use of bio-based materials, vanillin and FFA, for synthesizing a benzoxazine resin and its application at high temperatures.

This study aims to synthesize Prussian blue {Fe^III₄[Fe^II(CN)₆]₃} pigment by reacting ferric chloride with different ferrocyanides through the same procedure. The influence of the ferrocyanide used on resulting pigment properties is studied.

Prussian blue is commonly synthesized by direct or indirect methods, through iron salt and ferrocyanide/ferricyanide reactions. In this study, the direct, single-step process was pursued by dropwise addition of the ferrocyanide into ferric chloride (both as aqueous solutions). Two batches – (K-PB) and (Na-PB) – were prepared by using potassium ferrocyanide and sodium ferrocyanide, respectively. The development of pigment was confirmed by an identification test and characterized by spectroscopic techniques. Pigment properties were determined, and light fastness was observed for acrylic emulsion films incorporating dispersed pigment.

The two pigments differed mainly in elemental detection owing to the dissimilar ferrocyanide being used; IR spectroscopy where only (Na-PB) showed peaks indicating water molecules; and bleeding tendency where (K-PB) was water soluble whereas (Na-PB) was not. The pigment exhibited remarkable blue colour and good bleeding resistance in several solvents and showed no fading in 24 h of light exposure though oil absorption values were high.

This article is a comparative study of Prussian blue pigment properties obtained using different ferrocyanides. The dissimilarity in the extent of water solubility will influence potential applications as a colourant in paints and inks. K-PB would be advantageous in aqueous formulations to confer a blue colour without any dispersing aid but unfavourable in systems where other coats are water-based due to their bleeding tendency.

The purpose of this paper is to show the effect of the corporate governance (CG) on firms’ performance in the United Arab Emirates (UAE). The governance mechanisms employed in this study are board size, board independence and audit committee’s (AC) characteristics. The examined AC characteristics are: AC member’s independence, number of financial experts in the committee, ratio of meetings held during the year, and the incentives received by the AC members.

This paper uses all the public listed corporations in the UAE financial markets. The secondary data for four years are used starting from 2010 where the mandatory corporate governance code had been mandated.

Board independence has been found to negatively affect firms’ performance. AC meetings and financial experts’ ratio did not affect firm’s performance, while AC incentives and AC independence negatively affected firms’ performance.

This study is supposed to fill the gap of the lack in CG studies based on fast growing economy which is UAE. Besides, this research investigates the AC’s characters’ effect on firms’ performance which was rarely covered in literature.

The purpose of this paper is to investigate selected corporate governance attributes and financial reporting lag and their impact on financial performance of listed firms in Ghana.

The study uses 90 firm-year data for the period 2012–2014 for firms listed on the GSE. Each annual report was individually examined and coded to obtain the financial reporting lag. Descriptive analysis was performed to provide the background statistics of the variables examined. This was followed by regression analysis, which forms the main data analysis.

The descriptive statistics indicate that over the three years, the mean value of timeliness of financial reporting (ARL) is 86 days (SD 21 days), minimum is 55 days and maximum is 173 days. The regression analysis results indicate that financial reporting lag has a negative statistically significant relationship with firm performance. This negative sign indicates that when financial performances of companies are high (good news), companies have the tendency to disclose this situation early to the public.

Firms that are not timely in the financial reporting practices will find it difficult to attract capital as the delay will affect their reputation.

This study is one of the few to measure financial reporting lag and its impact on firm financial performance in Sub-Saharan Africa.