Browsing by Author "Jabbar, Abdul"

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    Characterization and antibacterial property of Kapok fibers treated with chitosan/AgCl-TiO2 colloid
    (TAYLOR & FRANCIS LTD, 2-4 PARK SQUARE, MILTON PARK, ABINGDON OR14 4RN, OXON, ENGLAND, 2019-01-02) Hai, Abdul Moqeet; Ahmed, Mehboob; Afzal, Ali; Jabbar, Abdul; Faheem, Sajid
    The aim of this research is to investigate the antibacterial activity of Kapok fibers modified with AgCl/TiO2 and Chitosan colloid. A very simple, single-step (pad-dry-cure) method was used for the application of AgCl/TiO2 and Chitosan colloid on kapok fibers, the chemicals used are easily available. Different blend ratios of chitosan and AgCl/TiO2 colloid were applied to the bleached kapok fibers and antibacterial properties were assayed against gram positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria. The treated kapok fibers were characterized by Fourier Transform Infrared Spectroscopy (FTIR), X-ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). It was observed that the bacterial growth was significantly reduced in the samples which had a higher concentration of chitosan and AgCl/TiO2 colloid. However, a significant reduction in bacterial growth with the use of this colloid was observed.
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    Charakterizace mechanického a termomechanického chování udržitelných kompozitních materiálů na bázi juty
    (Technická Univerzita v Liberci, 2013-02-04) Jabbar, Abdul;
    V posledních letech je zájem soustřeďován na kompozity z přírodních polymerních vláken díky jejich ekonomickým benefitům, vlivu na životní prostředí a nízké spotřebě energie při jejich výrobě. Materiáloví inženýři se soustředí na využití výplní z celulózových vláken pro polymerní kompozity. Během mechanického zpracování textilních vláken vzniká odpad, který slouží jako levný zdroj suroviny pro přípravu těchto celulózových vláken/ kompozitních výplní. Hlavní nevýhodou přírodních vláken jako výztuže do kompozitu je nízká adheze mezi vláknem a polymerní matricí. Proto je nutné modifikovat jejich povrch. Tato práce se zabývá vlivem přídavku tuhých mikroskopických fibril celulózy a nanocelulózy extrahovaných z odpadu juty a jejich depozicí na jutovou tkaninu. Dále se zabývá metodami její aplikace a testováním mechanických vlastností i z hlediska dynamických zkoušek kompozitních struktur na bázi juta a ekologicky šetrné epoxidové pryskyřice. Odpad z vláken juty byl použitý v obou případech jak pro výrobu jutových celulózových fibril včetně jejich fragmentování, tak i jako prekurzor pro čištění a extrahování nanocelulózy. Jutová tkanina byla zpracována novými technikami jako je CO2 pulzní infračervený laser, ozón, enzymy a plazma. Tři různé kategorie vrstvených kompozitních materiálů byly připraveny metodou ručního vrstvení a kompresní technikou s použitím stejné ekologické epoxidové matrice. První kompozit obsahoval 1, 5 a 10 hmotnostních % mikro fragmentů jutových vláken (PJF) použitých jako plnivo spolu s alkalicky ošetřenou jutovou tkaninou. Druhý typ byl tvořen jutovou tkaninou povrstvenou nanocelulózou v koncentracích 3, 5 a 10 hmotnostních %. Třetí typ byl vytvořen z povrchově upravené jutové tkaniny. Povrchová topologie upravených jutových vláken, jutových a celulózových nanofibril (CNF), drcených jutových fibril (PJF), nanocelulózou potažené jutové tkaniny a zlomy v povrchu kompozitu byly charakterizovány pomocí rastrovací elektronové mikroskopie (SEM). Krystalinita jutových vláken po různém chemickém ošetření byla měřena pomocí rentgenové difrakce (XRD). Nově povrchově upravené jutové tkaniny, alkalicky ošetřené jutové tkaniny a chemicky předupravená odpadní jutová vlákna byla charakterizována pomocí spektroskopie FTIR. Mechanické vlastnosti kompozitů byly stanoveny podle doporučených mezinárodních norem. Tečení a dynamické mechanické zkoušky byly prováděny v režimu tříbodového ohybu pomocí dynamického mechanického analyzátoru (DMA). Tři modely tečení materiálu, tj. Burgerův model, model Findleyho zákona a jednoduchý dvouparametrový mocninový model byly použity k modelování tečení materiálu (creep) v této studii. Princip časově teplotní superpozice (TTSP) byl použit k predikci dlouhodobého tečení. Výsledky ukázaly zlepšení modulu v tahu, ohybových vlastností, doby do únavy materiálu a odolnosti v lomu, s výjimkou poklesu pevnosti v tahu u nanocelulózou potažené jutové tkaniny/ekologického epoxidového kompozitu ve srovnání s kompozitem s nepotaženou jutou. Inkorporace PJF a nových povrchových úprav výrazně zvyšuje odolnost proti tečení kompozitů. Burgerův model byl dobře použitelný k modelování tečení v krátkodobém horizontu, zatímco Findleyho model byl uspokojivý při předvídání chování dlouhodobého tečení. DMA ukázala, že u všech tří kategorií kompozitů došlo ke zvýšení paměťového modulu a ke snížení výšky tangentových píků.
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    Determining the light transmission of woven fabrics through different measurement methods and its correlation with air permeability
    (Technická Univerzita v Liberci, 2014-01-01) Haleem, Noman; Ibrahim, Sayed M.; Hussain, Tanveer; Jabbar, Abdul; Malik, Mumtaz Hassan; Malik, Zulfiqar Ali
    The study aims to present a relationship between air permeability of woven fabrics and their light transmission properties. Polyester / cotton (48:52) blended woven fabrics were utilized in the study. Air permeability is measured using the standard test method already established while the light transmission through the fabric is measured by means of two different methods. One method is based on measurement of light transmitted from a back lit fabric by means of a light sensor. The second method is based on image processing techniques which require a digital back lit image of fabric and an algorithm is applied to measure the amount of light transmitted through it. Results from both methods are compared and correlated with the air permeability and porosity of woven fabrics. Analysis shows that the results from former method have a stronger and more significant relationship with air permeability of woven fabrics comparatively. © 2014, Association Nonwoven Fabrics Industry. All rights reserved.
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    Effect of surface modification and knife penetration angle on the Quasi-Static Knife Penetration Resistance of para-aramid fabrics
    (2019-04-03) Javaid, Muhammad Usman; Militky, Jiri; Wiener, Jakub; Jabbar, Abdul; Salacova, Jana; Umair, Muhammad
    The focus of this paper is to describe the effect of change in surface friction of single layer para-aramid (TwaronA (R)) square woven fabric and change in knife penetration angle on its Quasi-Static Knife Penetration Resistance (QSKPR). The surface friction of fabric was changed by depositing SiO2 on its surface by using water glass as a precursor. Six different knife penetration angles (0 degrees, 22.5 degrees, 45 degrees, 67.5 degrees, 90 degrees and 135 degrees) were selected. Untreated and treated fabric samples were compared for change in QSKPR. It was observed that the deposition of SiO2 on the surface of TwaronA (R) fabric increased the surface friction which resulted in the increase in QSKPR. The response of fabric against QSKPR changed from partial yarn cutting to individual yarn cutting in fewer steps and load was distributed to a larger area due to decrease in yarn slippage. The change in penetration angle changed the distance, knife cutting edge travelled to cut each next yarn(s) and when this distance increased, the QSKPR was reduced. The post-penetration image analysis of damaged fibres showed that the load distribution among warp and weft yarns was complementary and change in penetration angles changed the distribution of stabbing load among the warp and weft yarns. When yarns with higher tensile strength and less slippage were loaded, the fabric showed highest resistance to penetration. A QSKPR prediction model was also proposed at the end.
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    Empirical modeling of sound absorption properties of natural nonwoven fabric (Antiaris toxicaria barkcloth)
    (2017-01-04) Rwawiire, Samson; Tomková, Blanka; Militký, Jiří; Hes, Luboš; Kale, Bandu Madhukar; Jabbar, Abdul
    The desire to mitigate climate change due to greenhouse gas emissions has led to the exploration of plant fibers as alternative materials for various industrial applications acoustics inclusive. In this investigation, sound absorption properties of barkcloth, a nonwoven fabric from Antiaris toxicaria were characterized. Theoretical empirical sound absorption models based on Delany and Bazley such as Miki, Wu and Allard – Champoux were utilized to validate the experimental data. The empirical models were in agreement with experimental data; Incorporation of an air-gap between the fabric layers had a positive influence on the overall sound absorption behavior of barkcloth fabrics rendering the fabric a good sound absorption material. © 2016 Trans Tech Publications, Switzerland.
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    Inclusion of recycled PPTA fibre in development of cut-resistant gloves
    (Technická Univerzita v Liberci, 2015-01-01) Awais, Muhammad; Tausif, Muhammad; Ahmad, Faheem; Jabbar, Abdul; Ahmad, Sheraz
    PPTA is a high-performance fibre with premium mechanical and heat-resistant properties. This study focused on developing cut-resistant gloves from recycled PPTA fibre. The cut resistance of knitted glove, from virgin and recycled PPTA fibre yarn with/without steel core, was evaluated to determine the performance of the glove. The fibre and yarn parameters were studied to understand the underlying factors which aided in premium cut-resistant properties of gloves manufactured from recycled fibres - higher than that of gloves manufactured from virgin PPTA fibres.
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    Investigation of Mechanical and Thermomechanical Properties of Nanocellulose Coated Jute/Green Epoxy Composites
    (2018-01-01) Jabbar, Abdul; Militký, Jiří; Ali, Azam; Javed, Muhammad Usman
    The present study was aimed to investigate the effect of nanocellulose coating on the mechanical and thermomechanical properties of jute/green epoxy composites. Cellulose was purified from waste jute fibers, converted to nanocellulose by acid hydrolysis and subsequently 3, 5 and 10 wt% of nanocellulose suspensions were coated over woven jute reinforcement. The composites were prepared by hand layup and compression molding technique. The surface topologies of treated jute fibers, jute cellulose nanofibrils (CNF), nanocellulose coated jute fabrics and fractured surfaces of composites were characterized by scanning electron microscopy (SEM). The prepared composites were evaluated for tensile, flexural, fatigue, fracture toughness and dynamic mechanical properties. The results revealed the improvement in tensile modulus, flexural strength, flexural modulus, fatigue life and fracture toughness of composites with the increase in concentration of nanocellulose coating over jute reinforcement except the decrease in tensile strength. Dynamic mechanical analysis (DMA) results also showed the increase in storage modulus and reduction in tangent delta peak height of nanocellulose coated jute composites.
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    Nanocellulose coated woven jute/green epoxy composites: Characterization of mechanical and dynamic mechanical behavior
    (Elsevier Ltd, 2017-01-01) Jabbar, Abdul; Militký, Jiří; Wiener, Jakub; Kale, Bandu Madhukar; Ali, Usman; Rwawiire, Samson
    This paper presents the preparation and characterization of nanocellulose coated woven jute/green epoxy composites. Waste jute fibers were used as precursor to purify and extract nanocellulose by chemical treatments. The prepared suspensions with 3, 5 and 10 wt% of nanocellulose were coated over jute fabric followed by preparation of composites by compression molding technique. The surface morphologies of treated jute fibers, jute cellulose nanofibrils (CNF), nanocellulose coated jute fabrics and fractured surfaces of composites were characterized by scanning electron microscopy (SEM). The crystallinity of jute fibers after different chemical treatments was measured by X-ray diffraction (XRD). The effect of nanocellulose coating over jute reinforcement on the tensile, flexural, fracture toughness and dynamic mechanical properties of prepared composites has been investigated. Fracture toughness was measured using single end notched bend (SENB) specimens and dynamic mechanical test was performed in three point bending mode. The results revealed the improvement in tensile modulus, flexural properties and fracture toughness except the decrease in tensile strength of nanocellulose coated woven jute/green epoxy composites as compared to uncoated jute composite. Dynamic mechanical analysis (DMA) results also showed the increase in storage modulus and reduction in tangent delta peak height of nanocellulose coated jute composites. © 2016 Elsevier Ltd
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    Short-term creep of barkcloth reinforced laminar epoxy composites
    (2017-01-04) Rwawiire, Samson; Tomková, Blanka; Wiener, Jakub; Militký, Jiří; Kasedde, Allan; Kale, Bandu Madhukar; Jabbar, Abdul
    There is a global surge in the application of natural fiber reinforced polymer composites in various industries. Polymer reinforced composites are faced with dimensional instability during their service life, the reason being that the realistic environment of application has got frequency and temperature variables. Therefore, in order to pinpoint the dimensional stability of the composites, creep tests are usually carried out. In this investigation, for the first time, alkali, enzyme, and plasma treated barkcloth reinforced epoxy laminar composites were investigated using dynamic mechanical analysis for the creep behavior between the temperature range of 30 °C–100 °C. The results show that creep is affected by the layering pattern of the laminar composites whereas alkali treatment leads to a higher creep resistance of the composites. © 2016 Elsevier Ltd
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    Study of dynamic compressive behaviour of aramid and ultrahigh molecular weight polyethylene composites using Split Hopkinson Pressure Bar
    (Textile Composite Materials Research Group, Faculty of Engineering and Technology, National Textile University, Faisalabad, Pakistan; Department of Material Engineering, Technical University of Liberec, Liberec, Czech Republic; Uludag University Vocational, School of Technical Sciences, Gorukle, Bursa, Turkey, 2017-02-15) Shaker, Khubab; Jabbar, Abdul; Karahan, Mehmet; Karahan, Nevin; Nawab, Yasir
    In this paper, high strain rate compression properties of aramid and ultrahigh molecular weight polyethylene composites in the out-of-plane direction are tested at room temperature on a Split Hopkinson Pressure Bar apparatus. Tests were conducted on composites reinforced with woven or Uni-Directional (UD) fabrics made from aramid or ultrahigh molecular weight polyethylene as well as on composites reinforced with hybrid reinforcement. The strain rate is varied in the tests by changing the projectile shooting pressure. Four different pressures 2, 4, 6 and 8 bar were selected to change the strain rate. Stress-strain and energy absorption behaviour of eight type of samples were noted. Hybrid samples showed better performance in the energy absorption compared with other samples. © SAGE Publications.