Effects of enzymatic treatments on the mechanical properties of corn husk fibers

Corn husk fibers were extracted by water retting, alkalization, and enzymatic processes at different concentration and duration levels. The effects of extraction process parameters on the mechanical and thermal properties and chemical characteristics of corn husk fibers were investigated. Chemical structures of the fibers were studied by IR measurements. The finest and the stiffest fibers were produced by water retting followed by an enzymatic treatment. The highest breaking strength and breaking tenacity were obtained by water-retted fibers. While resulting in loss of breaking tenacity and elongation in water-retted fibers, enzymatic treatment resulted in increase in initial moduli and breaking tenacity of alkalized fibers. No significant effect of enzymatic treatment duration was obtained on the mechanical properties of corn husk fibers. Alkalized fibers gave higher elongation and lower stiffness compared to water-retted ones. The IR spectra showed higher amount of lignin and hemicellulose in water-retted fibers compared to alkalized and enzyme-treated ones. Enzymatic treatment and alkalization enhanced the thermal durability of the fibers. The ranges for properties of the produced corn husk fibers can be summarized as a linear density 17.0-25.6 tex, initial modulus 150.9-401.8 cN/tex, breaking tenacity 6.8-21.7 cN/tex, and elongation 9.6-18.2%. © 2013 Copyright The Textile Institute

Biomedical applications of microbial cellulose nanocomposites

Microbial cellulose (MC) is a polysaccharide excreted extracellularly by certain bacteria. The species Gluconacetobacter xylinus (or Acetobacter xylinum as formerly known) is the most extensively studied cellulose-producing bacteria (Czaja et al., 2006). MC exhibits some unique features such as impressive mechanical strength, crystallinity (Blaker et al., 2010), water-holding capacity, purity, and in situ moldability, which are superior to those of plant cellulose (Klemm et al., 2001). MC presents an ultrafine nanofibril network (Wan et al., 2006). These characteristics render MC, which has been traditionally used in food industry and recently in the production of reinforced paper, valuable for biomedical applications (Shah et al., 2013). Its applications in artificial blood vessels, temporary skin substitutes, wound dressings (Shah et al., 2013), and scaffolds for tissue engineering of cartilage and bone have been reported. In vitro and in vivo studies have showed that MC is biocompatible. It has been studied as replacement in blood vessels in rats (Grande et al., 2009) and pigs (Bäckdahl et al., 2011). MC has the potential to be used in biodegradable nanocomposites. Different composites of MC have been studied. The component other than MC is determined based on the composite application, including vascular graft or bone regeneration and based on the properties required to be imparted to MC, such as biological activity or antimicrobicity (Shah et al., 2013). © 2016 by Taylor & Francis Group, LLC

Effect of chemical extraction parameters on corn husk fibres characteristics

Corn husk fibres have been extracted by alkalization process at different alkali concentrations and treatment durations. The effects of extraction process parameters on the physical properties, mechanical properties and thermal durability characteristics of corn husk fibres are investigated. Chemical structures of the fibres are studied by infrared spectroscopy measurements. The average length, linear density and moisture content of extracted fibres decrease with the increase in alkaline concentration and duration. Breaking force decreases with increased alkaline concentrations. Increasing treatment duration for all concentration levels increases the breaking force, tenacity and initial modulus up to a point and then decreases them with further increase in duration. The highest tensile performance could be obtained from 5-10 g/L NaOH treatment for 60-90 min. Alkalization under harsher conditions results in higher thermal durability up to 320°C with higher cellulose fraction, but lower durability above this temperature. The FTIR spectrum analysis proves higher cellulose but lower hemicellulose and lignin contents with harsher treatment conditions. The marginal effect of concentration decreases for higher concentrations which suggests that the available sites for chemical reaction are occupied at moderate concentrations

Multicomponent, semi-interpenetrating-polymer-network and interpenetrating-polymer-network hydrogels: Smart materials for biomedical applications

Multicomponent, semi-IPN, or IPN hydrogels are interesting materials which are composed of at least two different components and are able to respond to various stimuli, that is the change in certain properties of the medium such as temperature, pH, ion concentration, and so on. Based on this unique feature, these environmentally responsive materials may find use in biomedical applications in terms of changes in the properties of the medium in the human organism which occur naturally or induced by an outside source. Environmentally responsive hydrogels respond to changes in the physical, chemical, or biological properties of the medium by exhibiting a change in their size, shape, color, solubility, and so on. They can be fabricated from natural or synthetic components by a number of production methods including physical cross-linking and chemical cross-linking techniques as well as other novel fabrication methods such as cross-linking with genetically engineered protein domains. Environmentally responsive hydrogels have found in various subfields of the biomedical research area including drug delivery, biosensors, tissue engineering, actuators, and so on. Whereas hydrogels are promising materials, there are some drawbacks which should be overcome before these materials can be used clinically. To address the major concerns, the response rates should be increased while maintaining the necessary mechanical performance. Biodegradability and biocompatibility are other development fields. Environmentally responsive hydrogels with the desired properties can be prepared by use of the right components, production methods and forming the right polymer architecture

Design of acoustic textiles: Environmental challenges and opportunities for future direction

Textiles have begun to find use in acoustical applications for the past few decades. In order to consolidate the position of textiles as noise control materials, their performance characteristics should be further enhanced to a level comparable to conventional acoustic materials, the most common ones of which are glass fibre mats and polyurethane foams. The same recent history has also witnessed substantial growth in public concern related to environmental effects of industrial progress. As much as this situation imposes a burden on textile producers, it also opens a new battlefield against acoustic materials, where textiles can prevail. Conventional acoustic materials, mineral wool or polyurethane foam among others are under line of fire due to their adverse effects on the ecosystem as well as on human health. This situation can offer business advantage to textile producers, provided that the damage inflicted on the environment throughout the whole life cycle of the textile product is minimized and the functional properties are improved. This can be realized by implementing a sound design stage based on functional and environmental requirements related to acoustic textiles

Effect of finishing on performance characteristics of woven and warp-knitted terry fabrics

The influence of some finishing processes has been studied on the performance characteristics of woven and warp-knitted terry fabrics with open-end pile warp. Terry fabrics of similar structural parameters have been produced by weaving or warp knitting and then subjected to finishing processes which are commonly applied by the textile industry. Samples are extracted at different stages of the finishing processes. Water absorption behavior, structural parameters, and mechanical properties are evaluated and the results are compared by statistical analysis of the obtained data. It is observed that compared to greige terry fabrics, the finishing treatment increases basis weight and dimensional stability due to shrinkage occurred with relaxation, water absorption rate due to the removal of size and other hydrophobic substances, and elongation ratio because of the elimination of size film during pretreatment processing. Woven terry fabrics give higher strength values and warp-knitted terry fabrics show higher elongation. © 2015, National Institute of Science Communication and Information Resources (NISCAIR). All rights reserved

Effect of xylanase enzyme on mechanical properties of fibres extracted from undried and dried corn husks

60-64Fibres have been extracted from corn husks in undried and dried forms by an alkalization treatment followed by enzymatic process at different concentrations of xylanase enzyme. The effects of drying process and xylanase enzyme concentration on the mechanical and textile properties of corn husk fibres have been investigated. The linear density of extracted fibres decreases with the increase in enzyme concentration and drying. Increasing enzyme concentration increases the breaking tenacity and initial modulus up to a point and then decreases them with any further increase in concentration. Fibres obtained from dried husks show dull colour as compared to those obtained from undried husks. No negative effect of drying process is observed on the performance of corn husk fibres. The highest tensile performance and fineness values are obtained from fibres of dried husks, treated with 0.4% Pentopan® mono BG enzyme, with a breaking tenacity of 9.44 cN/tex, initial modulus value of 282 cN/tex, and a fineness of 21.6 tex

Effect of xylanase enzyme on mechanical properties of fibres extracted from undried and dried corn husks

Fibres have been extracted from corn husks in undried and dried forms by an alkalization treatment followed by enzymatic process at different concentrations of xylanase enzyme. The effects of drying process and xylanase enzyme concentration on the mechanical and textile properties of corn husk fibres have been investigated. The linear density of extracted fibres decreases with the increase in enzyme concentration and drying. Increasing enzyme concentration increases the breaking tenacity and initial modulus up to a point and then decreases them with any further increase in concentration. Fibres obtained from dried husks show dull colour as compared to those obtained from undried husks. No negative effect of drying process is observed on the performance of corn husk fibres. The highest tensile performance and fineness values are obtained from fibres of dried husks, treated with 0.4% Pentopan® mono BG enzyme, with a breaking tenacity of 9.44 cN/tex, initial modulus value of 282 cN/tex, and a fineness of 21.6 tex

Comparative advantage of textiles and clothing: Evidence for Bangladesh, China, Germany and Turkey

In this study, the comparative advantage of four countries in the world: Bangladesh, China, Germany and Turkey is analyzed with respect to the US and the EU-15 textiles and clothing markets by employing Balassa's revealed comparative advantage (RCA) index for the period 2000-2010. This country selection was made because all these countries rank in the top ten textile and clothing exporters in the world and they represent economies from four different income levels. The results have revealed that Bangladesh, China and Turkey have a strong comparative advantage in both the textile and clothing markets of the world, the US and the EU-15, while Germany has no significant comparative advantage in any of these markets. The findings show that the Bangladesh clothing industry has a substantially higher comparative advantage in all three markets compared to the other countries. It has also been found that Turkish textiles show the strongest comparative advantage in all three markets, whereas the comparative advantage of Chinese textiles indicates a slightly increasing trend in all aforementioned markets

Assessment of trends in the comparative advantage and competitiveness of the Turkish textile and clothing industry in the enlarged EU market

In this paper, Turkey's comparative advantage and competitiveness in the textile and clothing industries are analysed by using Balassa's revealed comparative advantage index and Vollrath's indices of competitive advantage for the period of 1988-2008 in the enlarged EU market. The results revealed that Turkey has overall a strong comparative advantage and competitiveness in textile and clothing in the EU market. All competitiveness indices for the years 2005-2008 showed an increasing trend for the textile industry and a decreasing trend for clothing. The decrease in the competitiveness of clothing was observed more intensively in the enlarged EU market compared to that of the EU12. These findings can be thus interpreted: the Turkish textile industry responded well to the elimination of quotas, while the clothing sector has been more vulnerable to the inclusion of low-cost labour countries in the market since 2005