Search results

The purpose of this paper is to synthesize chitosan, N-octyl chitosan (NOCh) and carboxymethyl chitosan (CMCh) derivative from prawn shell wastes and identify their applications as modifiers on cellulosic fibres, jute and cotton, to develop quality textile fibres.

Chitosan was obtained by deacetylation of chitin. NOCh was obtained by reductive amination of chitosan. Water-soluble CMCh was prepared by reacting chitosan with monochloroacetic acid in aqueous alkaline media at ambient conditions. Chitosan, NOCh and CMCh were applied on cellulosic fibres, and structure and physico-chemical characteristics of chitosan derivatives and modified fibres were investigated and analysed.

The molecular weight, degree of deacetylation and ash content of prepared chitosan were 1,39,958 Da, 85 and 2.33 per cent, respectively. The moisture content, water holding capacity and total nitrogen content were above 10, 450 and 6.5 per cent, respectively. Average degree of substitution of CMCh was 0.82 as determined by titrimetric analysis. Fourier transform infrared spectroscopy (FTIR) spectra showed characteristic peaks of carbonyl group at 1,659 cm⁻¹, –NH2 at 1,600 cm⁻¹, symmetric stretching of C-H in the methyl group at 1,520 cm⁻¹ and carboxylic group at 1,737 cm⁻¹. Thermograms showed moderate thermal stability in treated fibres compared to untreated fibres. Surface morphology of the modified fibres exhibited smoother surface due to the absorption of chitosan, NOCh and CMCh.

Modification of jute and cotton by sorption of NOCh and CMCh introduced new functional groups on the fibre surface with chemical bonding, which was confirmed by FTIR. Surface morphology of the fibres was carried out by scanning electron microscopy. As the modified fibres also showed good dyeability and colour fastness as well as other properties, the chitosan derivatives as a textile modifier would be helpful to avoid synthetic petroleum-based chemical modifiers as well as to manage the environmental pollution from prawn shell waste and other toxic chemicals.

Colorfastness properties of dyed degummed and dyed stannic chloride weighted silk fiber were studied as a function of exposure to sunlight in air, washing with soap solution and spotting with alkalis.

Improved multi-voltine variety of degummed silk fibers was weighted with the treatment of stannic chloride at the varying pH level. Maximum weighting of silk fiber was achieved at the optimum SnCl₄ concentration, pH of the solution, time and temperature. The degummed (un-weighted) and weighted silk fibers were then dyed with Direct Blue 1 and Direct Red 28 dyes at the optimized dying conditions.

The role of base (Na₂CO₃) on dyeing of weighted silk fiber with Direct Red 28 was found very influential. The loss in tenacity of degummed silk fiber was higher than that of SnCl₄ weighted silk fiber when they were exposed to sunlight in air.

The colorfastness of weighted dyed silk was comparatively higher than that of un-weighted dyed silk.

This study aims to explore the use of knitted rag by synthesizing different grades of carboxymethyl cellulose (CMC) by applying multiple-step carboxymethylation techniques.

CMC was synthesized from knitted rag, a cellulosic waste of textile and garment industries, in aqueous ethanolic sodium hydroxide and subsequently mono-chloroacetic acid reaction medium. Low-substituted to high-substituted products were obtained from single-step to seven-step carboxymethylation of cellulose. In this way, it was possible to produce low-cost and different grades of substituted carboxymethylated cellulose. The synthesized CMC was characterized, and their physical properties were investigated. The structure of CMC and grafted CMC were investigated by Fourier transform infrared spectroscopy.

Solubility, CMC content, degree of substitution and molecular weight of CMC were increased gradually with the increase in the number of reaction steps, although fourth step attained the optimum. The cellulosic waste of knitted rag can easily be used to produce value-added products such as CMC and other cellulose derivatives, and that will ultimately reduce the pollution problems from this waste.

Grafting of prepared CMC film with methyl methacrylate monomer increased their strength, although decreased rigidity and moisture content because the incorporation of hydrophobic methyl methacrylate monomer was observed.

The conventional textile dyeing process requires various operational characteristics, and determining the most reliable factor in dyeing performance has always been a challenge for the textile industry. Thus, the present paper aimed to evaluate the process sensitivity of C. I. Reactive Blue 194 dyeing of cotton fabric using a statistical technique.

An L₂₇ orthogonal array-based Taguchi's methodology was used with six parameters and three levels of each parameter. The signal-to-noise (S/N) ratio and analysis of variance were studied using total fixation efficiency (T%) as the response of the process sensitivity.

Results showed that dyebath pH was the most influential factor on the process and total fixation efficiency (p-value = 0.00 and contribution percentage 45.03%), followed by dye-fixing temperature, dye mass, electrolyte concentration, dye-fixing time and material to liquor ratio.

Overall this study provides a foundation for the determination of dyeing process sensitivity that will be useful in textile industries toward further development.

The modification of jute fiber with acetic (aliphatic) and phthalic (aromatic) anhydrides has revealed pronounced improvement of the inherent drawbacks (such as breaking strength, thermal stability, color fastness, etc.) of jute fiber. Between the acetic anhydride (AA) and phthalic anhydride (PA) modified fibers, the latter have shown better improvement of the described properties. Modification of jute with anhydrides is carried out in an aqueous medium (solid-liquid system) with potassium persulfate as the initiator under the catalytic influence of ferrous sulfate (FeSO4). At an optimized reaction condition, the percent weight gain and efficiency of the modifying agents are 12.94% and 14.38% for AA respectively and 15.18% and 18.98% for PA respectively. The FT-IR spectra confirm the modification reaction and the TGA shows an improvement in the thermal properties. The mechanical properties are investigated with a tensile tester. Upon prolonged exposure of the modified fibers to sunlight, the color fastness of the modified and unmodified fibers is measured with a grey scale.

The study focused on improving stiffness and premature failure, the weaknesses of the other retrofitting techniques and the retrofitted beam. A detailed study regarding the section properties and effective length of the angles was also carried out in this study.

In this article, a comprehensive study was carried out using a finite element method to investigate the behavior and performance of steel angles as a retrofitting technique subjected to flexure. A model was developed in ABAQUS and validated with the available experimental works. The model was then applied to examine the beams retrofitted with the steel angles.

From the investigation, the strengthening technique successfully enhanced the flexural capacity and stiffness of the beam. The stiffness of the retrofitted beam achieved more than 2.5 times of the controlled beam. The thickness and flange width of the angles improved both the load capacity and stiffness whereas, web width, having same flange width, improved the stiffness only. This study also illustrates that a premature failure can be minimized by maintaining L/S (length to span) ratio between 0.7 and 1.0 along with the welding to provide the connections between the angles and stirrups.

The developed model and the findings can be used for designing the retrofitting technique for the damaged as well as beams to be increased their capacity.

The research focused on the implication of a new technique of retrofitting, steel angles to improve the stiffness of beam, which is one of the major drawbacks of traditional techniques. Moreover, the research aimed to improve premature failure by bonding the retrofitting materials with the stirrups of the mother beam through welding.

The purpose of this investigation is to determine the nature of the flow field, temperature distribution and heat and mass transfer in a triangular solar collector enclosure with a corrugated bottom wall in the unsteady condition numerically.

Non-linear governing partial differential equations (i.e. mass, momentum, energy and concentration equations) are transformed into a system of integral equations by applying the Galerkin weighted residual method. The integration involved in each of these terms is performed using Gauss’ quadrature method. The resulting non-linear algebraic equations are modified by the imposition of boundary conditions. Finally, Newton’s method is used to modify non-linear equations into the linear algebraic equations.

Both the buoyancy ratio and thermal Rayleigh number play an important role in controlling the mode of heat transfer and mass transfer.

Calculations are performed for various thermal Rayleigh numbers, buoyancy ratios and time periods. For each specific condition, streamline contours, isotherm contours and iso-concentration contours are obtained, and the variation in the overall Nusselt and Sherwood numbers is identified for different parameter combinations.

The purpose of this paper is to explore the approaches used by researchers in examining the influences of external factors towards voluntary disclosure in emerging countries.

The data collected in this study were collected through a review of empirical literature based on 35 articles published between 1998 and 2013. The sample articles on the link between external factors and the level of voluntary disclosure were located by searching keywords in the most relevant social science research databases such as Business Source Premier, Emerald full text, JSTOR, Science Direct, Scopus, and Social Science Research Network.

The result reveals that research in voluntary disclosure practices by companies in emerging countries remains low. The majority of studies employed content analysis to examine the extent of voluntary disclosure practices. Results from studies show that greater regulatory enforcement in the region and increase in stakeholders’ comprehension about their rights and choices with regards to business activities can influence the majority of the companies to provide voluntary disclosure. The literature revealed that social responsibility and environmental information are the popular categories of voluntary disclosure while risk and human capital/intellectual capital are the least popular categories.

The paper is limited to a review of 35 articles.

The study provides avenues for policy makers and regulators to carry out reforms on voluntary disclosure practices.

The findings may provide insights to capital market regulators when conducting effective regulation and supervision of information transparency in listed companies.

Since limited studies exist that examine voluntary disclosure in emerging countries, little is known about the implications of external factors such as a country’s policy, regulations, stakeholders, and business environment on voluntary disclosure practices. This paper contributes to filling this gap by a review of articles of empirical research on voluntary disclosure in emerging countries.

This research paper attempts to empirically examine the relationship between the performance of the banking industry and foreign direct investment (FDI), thereby helping the readers contemplate one of the least explored areas of the existing literature associated with the idiosyncratic characteristics of FDI resulting from its interaction with the efficient banking performance of the host country. The study has focused on the economy of Bangladesh because of its significant amount of FDI inflows from the rest of the world and its adoption of many liberalization policies, especially in the banking sector and in the areas of international business and trade.

The study, to produce unbiased estimates, employed the autoregressive distributed lag (ARDL) model for analyzing the time series data collected from reliable sources.

The key outcomes of the study reveal that the sound performance of the banking industry appears to be counterproductive for FDI inflows, which is a bit unconventional insight. In the context of Bangladesh, trade openness, inflation rate and infrastructural development seem to be the dominant factors behind the rising inflows of FDI. Market size appears to be an insignificant determinant of FDI inflows.

This is a unique study because of its focus on the unexplored area in the literature.

This paper presents recently published resources on library instruction and information literacy. It provides an introductory overview and a selected annotated bibliography of publications covering various library types, study populations and research contexts. The selected bibliography is useful to efficiently keep up with trends in library instruction for busy practitioners, library science students and those wishing to learn about information literacy in other contexts.

This article annotates 424 English-language periodical articles, monographs, dissertations, theses and reports on library instruction and information literacy published in 2021. The sources were selected from the EBSCO platform for Library, Information Science, and Technology Abstracts (LISTA), Education Resources Information Center (ERIC), Scopus, ProQuest Dissertations and Theses, and WorldCat, published in 2021 that included the terms “information literacy,” “library instruction,” or “information fluency” in the title, abstract or keywords. The sources were organized in Zotero. Annotations summarize the source, focusing on the findings or implications. Each source was categorized into one of seven pre-determined categories: K-12 Education, Children and Adolescents; Academic and Professional Programs; Everyday Life, Community, and the Workplace; Libraries and Health Information Literacy; Multiple Library Types; and Other Information Literacy Research and Theory.

The paper provides a brief description of 424 sources and highlights sources that contain unique or significant scholarly contributions.

The information may be used by librarians, researchers and anyone interested as a quick and comprehensive reference to literature on library instruction and information literacy within 2021.