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Author: EZEIBEKWE STEPHEN UZODINMA

Title: Studies of Some Mechanical Properties of Watermelon Rind/Pawpaw Peel Reinforced Polyethlene Composites

Affiliation: Food Science Technology Department
School of Engineering and Engineering Technology
Federal University of Technology, Owerri Imo State

Date: June, 2016

ABSTRACT
Some mechanical properties of water melon rind and pawpaw peel reinforced Low
density  polyethylene  (LDPE)  and  Linear  Low  Density,  (LLDPE)  composites  have
been studied. Two sets of filler loaded LDPE and LLDPE composites were prepared   using the injection moulding techniques at a processing temperature of 1900C
Dispersing agent, silicon oil, was added to the composite as a plasticizer to improve
flow, processability and to reduce the brittleness of the product. A comprehensive
range of mechanical properties: tensile strength, (modulus of elasticity, elongation at
break, elongation at yield), impact energy test and hardness test were carried out.
Tensile properties of the composite showed an increase in tensile modulus, impact
energy test, hardness test, a decline, in elongation at yield and break with increasing
filler loading.  The tensile strength was enhanced with the incorporation of the two
fillers up to 20% filler loading and then decreased with further addition of filler. The
result  obtained  showed  that  pawpaw  peel  and  water  melon  rind  can  be  used  as
reinforcing fillers in thermoplastics and secondly, development of composites,
enhances their mechanical properties. 
 

Author: AYO, MARK DADA

Title: Physico-Mechanical Properties of Natural Rubber Filled with Treated Groundnut Shell Powder for Shoe Sole Production

Affiliation: POLYMER SCIENCE Department 

School of Engineering and Engineering Technology

Federal University of Technology, Owerri Imo State

 

Date: March, 2016

 

ABSTRACT

Physico-Mechanical properties of natural rubber filled with chemically modified groundnut shells were studied. Natural rubber composites were prepared using modified fillers at varying concentrations of sodium hydroxide (NaOH) Solution and acetylating solutions respectively. The processing conditions, mechanical properties and sorption characteristics of these composites were analyzed. The cure characteristics of the compounded rubber were determined using Mosanto Rheometer (model MDR - 2000). The maximum torque and crosslinking density increases with increase in concentration of the mercerizing and acetylating agent. The fibre reinforcing efficiency of the chemically treated composites were compared with that of the untreated composite. Composites containing chemically treated fillers were found to posses improved tensile properties(from 18.30 to 31.50MPa for acetylated composites and  18.30 -28.00MPa for mercerized fillers), hardness (48 to 65 IRHD for acetylated filler and 48 to 58 for mercerized fillers) and abrasion resistance (from 31.55 t0 42.50% for acetylated filler and 31.5 to 39.30 for mercerized filler). These properties increases with increase in mercerizing and acetylating agent up to 20% concentration and starts decreasing. At higher concentration, the fibre is destroyed hence reduction in properties. These results were in agreement with empirical analysis. The sorption properties of the composite also decrease with the concentration of the mercerizing and acetylating agent. The improved properties observed were as a result of the increase in affinity between the rubber matrix and the chemically treated groundnut shell fillers. From this research work, it is recommended that chemically treated groundnut shell powder, particularly at 20% concentration can be employed for articles such as shoe soles, footmats and hoses that require less stress during service life. 

Author: OLAWUNI, IJEOMA ADANMA

Title: A Comparative Study of Solar and Direct Sun Drying of Pre-Treated Green Plantain

Affiliation: Food Science Technology Department
School of Engineering and Engineering Technology
Federal University of Technology, Owerri Imo State

Date: April, 2016

ABSTRACT
A comparative study of solar and direct sun drying of pre-treated green plantain was conducted. A distributed – type natural circulation solar dryer fabricated from locally available materials and direct open sun drying were used to investigate the drying characteristics of green plantain slices between January and February, 2012. The fingers harvested weekly from the 9th to 13th week were washed, peeled and cut into slices (1cm thickness). Each batch of the sliced plantain fingers were pre-treated by soaking in citric acid, sodium metabisuphite and blanching prior to direct sun and solar drying. The untreated plantain flour served as control. The thermal properties which included starch gelatinization temperature and enthalpy were by Rapid Visco Amylograph and Differential Scanning Calorimetry. The shelf stability of the flour samples was also investigated over a period of 6 months by monitoring the microbial load. Assessment of the functional properties showed no significant differences in the oil absorption capacity, gelling point and bulk density of the flour samples irrespective of harvesting time and pre-treatment. However, there were significant differences in water absorption (p< 0.05) with the sodium metabisuphite treated sample having the highest value of 2.74ml/g. Higher pH values were recorded for flours treated with sodium metabisulphite and blanched with values ranging from 6.87 – 7.54. Also, in the swelling index (P<0.05) the 13th week blanched sample had the highest value of 3.76 ml/ml. The minimum temperature of the solar dryer during the drying period was 31.50C and maximum gave 45.6.00C. Relative humidity minimum was 32% and maximum was 81%. The moisture content for the dried flours ranged from 9.68 to 13.53% with the lowest value from flour treated with combined citric acid and blanching and the highest 13.53% coming from flour treated by blanching alone.  Total starch showed 75.42 to 82.72% and no significant difference existed in using direct sun drying or solar dryer. The variations of moisture ratio with time were used to test twelve different one-layer drying models. Reduced chi square and root mean square error (RMSE) were used in testing the consistency of all the models and coefficient of determination (r2) was used to determine the best fit of the drying model. The Verma experimental model was found to be superior in terms of fitting performance. The Verma model gave maximum r2 of 0.9989 and RMSE minimum of 0.0008. The pasting temperature varied from    66.9 0C to 84.30C with direct sun dried samples showing the lowest value. The gelatinization enthalpy (∆H) varied significantly with the solar dried having the highest value of 11.81 (J/g). The microbial load count showed no species of yeast in all the dried flour samples and the staphylococcus counts were quite low 1 x 104 to 1 x 105 cfu/g for the flour samples. The properties of unripe plantain slices whether by direct sun or solar drying indicated possible application in food formulations.  
Keywords: Green plantain, solar dryer, direct sun drying, functional, thermal, chemical properties, and microbial load.

Author: ANYIAM, CHIOMA KEZAIAH

Title:    Use of Modified Sweet Potato Starches as Corrosion Inhibitors of Selected Metals  

Affiliation: POLYMER SCIENCE Department 

School of Engineering and Engineering Technology

Federal University of Technology, Owerri Imo State

 

Date: July, 2016

 

ABSTRACT

Sweet potato starch was modified via extrusion, alkaline steeping and acid steeping to yield physically modified starch (PMS), alkaline treated sweet potato starch (ASS) and acid treated sweet potato starch (ATS). The unmodified and modified starches were characterized using the Fourier transform infrared spectroscopy and assessed for corrosion inhibition efficacy on mild steel and galvanised steel in 0.25 M H2SO4 and 1 M HCl using  gravimetric (weight loss) measurements and potentiodynamic polarization techniques. All the starch samples inhibited corrosion of the metals in the acidic media, with maximum efficiency ranging from 22.86 to 62.76 % for mild steel and 24.27 to 63.48 % for galvanised steel. Introduction of potassium iodide notably increased inhibition efficiency up to 85.59 %, 85.09 %, 83.64 %, 87.72 % for NS, PMS, ASS, and ATS respectively for mild steel and for galvanised steel 92.60 %, 95.62 %, 93.67 % and 93.94 % respectively for NS, PMS, ASS and ATS. Fourier transform infrared spectroscopy was used to analyse the scrapped metal after corrosion in presence and absence of the additives in the acidic media. Atomic force microscopy was used to analyse the surface morphology of the corroded metals in the presence and absence of the additives in the acidic media. The inhibitor adsorption characteristics were found to obey Langmuir isotherms. Temperature studies (30-60OC) investigated showed higher inhibition efficacy at lowest temperatures, thus suggesting physiosorption adsorption mechanism. These results were in agreement with the kinetic and activation energy parameters investigated. Potentiodynamic polarization measurements showed that NS, PMS, ASS and ATS are mixed-type inhibitors.

Author: ONYEDIKACHI ALOYSIUS OGUAGHAMBA

Title: Analysis of Buckling and Postbuckling Loads of Isotropic Thin Rectangular Plates.

Affiliation: Civil Engineering Department
School of Engineering and Engineering Technology
Federal University of Technology, Owerri Imo State

Date: November, 2015

ABSTRACT
This study investigated the analysis of buckling and postbuckling loads of isotropic thin rectangular plates. The study derived the governing differential equations defining the postbuckling behaviour of isotropic thin rectangular plates, known as von Karman’s equilibrium and compatibility large deflection equations; as well as the governing differential equation of plates’ buckling. In view of the complex nature of these equations, it is not possible to obtain their closed-form solutions. Hence, the study used the direct integration method to solve the governing differential equation of plates’ buckling and the von Karman’s compatibility large deflection equation of plates to obtain their deflections and stresses functions respectively for different support conditions. Then, the study applied these functions in the von Karman’s equilibrium large deflection equation to solve for the buckling and postbuckling loads of these plates using work principle technique. The displacement parameters, Wuv, stress coefficients, Wuv2 and load factors, Kcx for the various support conditions of plates were determined using the Johasen yield line theory, leading to the critical buckling and postbuckling loads and stresses of these plates. The study’s numerical analysis among other things revealed that thin rectangular plates possess postbuckling reserve of strength upon buckling. That is, they do not fail at mere critical buckling loads. Their postbuckling reserve of strength upon buckling loads are due to the transverse and longitudinal fibers of the plates which undergo stress redistribution with consequential tensile stress build up in the plates. Another finding of the study is that plates’ reduction in axial stiffness upon buckling is due to the in-plane load postbuckling bending stresses developed in the plates, in the cause of buckling. These bending stresses lower the axial stiffness of plates. Other revelation of the study is that plates would reach yield stress at different out of plane deflections, depending on their support conditions. SSSS, CCCC, CSCS, CSSS, CCSS, CCSC, SCFC and CCFC, plates reach yield stress at out of plane deflection coefficient of 4.1, 0.1, 1.4, 3.1, 1.8, 1.1, 3.0, and 2.80 of their plates’ thicknesses, h respectively. These group of thin rectangular plates could be adequately be designed for in – plane loads using their critical buckling and postbuckling loads and stresses. While SSFS, CSFS and SCFS plates possess yield stresses far below the yield stress of steel material (250MPa), even at 5.0h out of plane deflection. In the design of such plates, the deflections criteria should be implored as their yield stresses would result to inadmissible deflections. This study has made useful contribution towards solving the problem of dearth of literature on the analysis of buckling and postbuckling loads of isotropic thin rectangular plates, especially with regard to the use of direct integration method and work principle to solve these differential equations. Other novel feat of the study is the use of Johasen yield line theory to deduce the displacement parameters, Wuv, stress coefficients, Wuv2 and load factors, Kcx for the various support conditions of thin rectangular plates.