Browsing by Author "Onukwuli, Dominic Okechukwu"

Now showing 1 - 6 of 6
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    Effect of chemical agents on morphology, tensile properties and water diffusion behaviour of hibiscus sabdariffa fibers
    (2016) Azeez, Taofik Oladimeji; Onukwuli, Dominic Okechukwu
    Effective utilization of Hibiscus sabdariffa fibers in composites applications as a reinforcing fibers in polymer matrix have been a major concern due to its poor mechanical and hydrophilic properties. It will be of benefits to environmental and technological advancement, if its properties are properly handled. In this study, the morphological, tensile and water absorption characteristics of H. sabdariffa fibers was aimed to be investigated. H. sabdariffa fibers was modified using sodium hydroxides, sodium lauryl sulphate and ethylene diamine tetraacetic acid. The morphology using scanning electron microscopy, tensile properties (strength, modulus, elongation and energy at break), water absorption and water diffusion behaviours were studied. Chemical modifications improved fiber surface and roughness, tensile strength and modulus, elongation and energy at break with reduced water absorption of H. sabdariffa fibers. The water diffusion behaviour is less - Fickian controlled by water penetration rate. Hence improved the hydrophobic nature of H. sabdariffa fibers
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    Effect of chemically modified cissus populnea fibers on mechanical, microstructural and physical properties of cissus populnea/high density polyethylene composites
    (Federal University of Technology,Owerri, 2017-03-31) Azeez, Taofik Oladimeji; Onukwuli, Dominic Okechukwu
    The effect of chemically modified Cissus populnea (C. populnea) fiber using sodium hydroxide (NaOH) and sodium lauryl sulphate (SLS) on mechanical, morphological and physical (density and water absorption behaviour) properties of C. populnea fiber/recycled HDPE composites was aimed to be investigated. The composites of unmodified and modified C. populnea fiber/HDPE were prepared using injection molding machine. The mechanical properties (tensile strength and modulus, flexural strength and modulus, hardness and impact strength), interfacial shear stress, density, water absorption behaviour and microstructural properties using scanning electron microscope (SEM) and fourier transform infrared (FTIR) spectroscope were characterized. The results shows that C. populnea fiber increased the mechanical properties of HDPE matrix with reduced impact strength of the composites. The NaOH and SLS treatments, respectively, improved the mechanical properties of C. populnea fiber/HDPE composites, although NaOH treated C. populnea fiber reduced the tensile modulus. The change in morphology and functional group, respectively, due to the modification was observed in SEM and FTIR. The density and water absorption of the composites, respectively, reduced when SLS modified C. populnea fiber was used compared to untreated C. populnea fiber/HDPE composites. The SLS treated C. populnea fiber prove to be superior for reinforcement, stiffness and light weight material.
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    Effect of filler weight fraction on the mechanical properties of Bambara Groundnut (Okpa) husk Polyethylene composite
    (2013-07-18) Azeez, Taofik Oladimeji; Olaitan, Samuel Abiodun; Atuanya, Clement Uche; Onukwuli, Dominic Okechukwu; Akagu, Christian Chukwudi; Menkiti Mathew, Chukwudi
    The increased biomass level of bambara groundnut husk (BGH) in the environment through dumping as a refuge due to high consumption rate of bambara groundnut products has been an environmental concerned. The effect of mechanical properties of the recycled polyethylene (RPE) and recycled polyethylene with 20 percent virgin polyethylene (MPE) was investigated. The weight fractions of the BGH filler loading for this experiment were 10, 20, 25, 30 and 35 percent and processed for the reinforcement of RPE and MPE injection moulding machine to examine the mechanical properties on the composites. The tensile strength and modulus, flexural strength and modulus, and hardness of the composites increase fraction of the filler up to 25 percent in the composites and impact strength of the composites decreases with increased filler weight fraction. The increased tensile strength signified that BGH filler may be used for the reinforcement of RPE and MPE. There is significant improvement on the mechanical properties of the MPE composite compared with RPE composite at p < 0.01 and p < 0.05
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    Effects of the chemical treatment of avocado pear wood filler on the properties of LDPE composites
    (Carl Hanser Verlag GmbH & Co. KG, 2019) Government, Rabboni Mike ; Ani, Kingsley Amechi; Azeez, Taofik Oladimeji; Onukwuli, Dominic Okechukwu
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    Improving the unsaturated polyester matrix through commingled with chemically treat cissus populnea fibers
    (U. P., 2017) Azeez, Taofik Oladimeji; Onukwuli, Dominic Okechukwu
    The extent of improvement of chemically treated Cissus populnea fiber on morphology, mechanical, adhesion, and water sorption behaviors in Cissus populnea fiber/UPE composites was aimed to be investigated. Fibers were treated with sodium hydroxide (NaOH) and sodium lauryl sulphate (SLS), respectively. The composites were prepared by hand laying techniques of treated and untreated fibers with unsaturated polyester matrix (UPE) using response surface methodology with central composites design of DoE software. The mechanical properties (tensile strength, tensile modulus, flexural strength, flexural modulus, hardness and impact strength) were optimized. The interfacial shear stress (IFSS) using fiber pull-out method, scanning electron microscopy (SEM), density, and water sorption behavior using power law with Fickian diffusion law were studied at optimum level. The optimization of mechanical properties as dependent with factors (weight fraction of the fiber and weight fraction of the matrix) using RSM with CCD technique was done to avoid waste of materials and confusion on properties of the composites. Treatment of Cissus populnea fiber with NaOH and SLS, respectively, improved the tensile and flexural properties of the composites. NaOH treatment gave the best tensile strength while best flexural properties was achieved with SLS treatment. SEM images revealed the morphological changes caused by NaOH and SLS, respectively, at optimal composites production to corroborate interfacial adhesive between Cissus populnea fiber and UPE matrix on composite properties. NaOH and SLS treatments, respectively, reduced the water saturation point with less Fickian behaviour and increased water diffusion coefficient of the composite.
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    Mercerized milletia sp fiber epoxy composites: Fiber loading, aspect ratio and mechanical properties
    (U. P., 2018-06) Uzondu, Francis Nnamuzie; Onukwuli, Dominic Okechukwu; Azeez, Taofik Oladimeji; Osoka, C. Emmanuel; Obibuenyi, John Ifeanyi
    The fiber loading capacity and poor adhesion between fibers and matrix remains an area of concern in fiber polymer composites. The fiber loading capacity and aspect ratio of mercerized milletia sp fiber on mechanical properties (tensile strength, tensile modulus, tensile toughness, elongation, flexural and impact strength) of Milletia sp fiber epoxy composites was investigated. Milletia sp fiber was extracted using water retting approach. The extracted fiber was mercerized at optimum treatment conditions of 5.84 wt% NaOH and 42.58mins. The epoxy composite samples were prepared using hand layup method for epoxy 103 and amine hardner in a ratio 2: 1 and commingled with untreated and treated fiber, respectively, at optimum treatment conditions. The fiber loading of 10 – 50 wt% and aspect ratio of 42.68 – 213.38 mm/mm were used. The mechanical properties of mercerized milletia sp fiber epoxy composite were determined and optimized using RSM of MATLAB statistical tool box. The tensile strength, tensile modulus, toughness, elongation, flexural strength and impact strength for epoxy resin was 44.2 MPa, 1.9716 GPa, 0.8177 MPa, 3.1%, 85.4 MPa and 360 Kj/m2, respectively. At optimum aspect ratio and fiber loading, the mercerized milletia sp fiber increased the tensile strength, tensile modulus, toughness, elongation, flexural strength and impact strength of the epoxy resin by 46.38, 77.75, 97.99, 18.81, 125.06 and 217.78%, respectively. Thus, mercerized Milletia sp fiber enhanced the mechanical properties of epoxy composites.