A master’s student, Hussein M. S. Jaafar, defended his thesis “Development of Hybrid Polymer Blend Composite Used in Dentures Fabrication” on Wednesday, January 15^th, at the conference room (C), Department of Materials Engineering, University of Technology. The Committee members included:

The dissertation was scientifically evaluated by Ass. Prof. Dr. Ahmed F. Ali, Babylon University, College of Materials Engineering, and linguistically by Ass. Prof. Mayada R. Issa, University of Technology, English Language Center.

The discussion was conducted in a scientific atmosphere and a master's degree with grade of pass was awarded to the student after the completion of all the corrections that have been decided by the examiners.

Abstract

      The aim of this study is to develop the properties of PMMA prepared by heat treatment through the manufacturing of bio composites materials that, consist of a polymer blends (PMMA: X% NR or SR where x=2% or 3%) as matrix materials reinforced by two types of natural nanoparticles (  pomegranate peels powder (PPP) and clove powder (CP))  used individually with selected weight percentages (0.0, 0.1, 0.3, 0.5, 0.7%) in PMMA composites.  

      Based on the results of mechanical properties for bio composites samples, one sample was selected as an optimal sample of nanocomposites samples (PMMA: 2%NR: 0.7%PPP)), that was used to prepare hybrid composites specimens, which was reinforced at 0.75% weight ratio of nylon fibers in the form of (mono-filament and multifilament fiber). All samples were fabricated by utilizing (Hand Lay-Up) technique.

       The biological activity test was done on composites samples to make sure from the biological effect for both of natural particles (PPP and CP) and nylon fibers. AFM inspection was done in order to measure the average size of natural particles and average diameter of nylon fibers. In addition to studying the analysis of FTIR spectra and structure morphology by SEM for the prepared composites.

       The experimental part of this study include performing many mechanical tests which involve: tensile strength, compression strength, flexural strength, flexural strain, hardness, impact strength, fracture toughness, wear resistance and surface roughness. In addition to the physical properties that involve: thermal conductivity, density, water absorption and contact angle for all the prepared specimens. The results showed that using various kinds of natural nanofillers as reinforcing materials had a considerable effect on the characteristic of base dentures which were prepared. As well as observed that the values of most properties increased with increasing content ratios of both types pomegranate peels powder and clove powders in bio composite specimens. On the other hand, the values of surface roughness, contact angle, wear rates and density values ​​of all prepared samples decreased with adding of natural nano-filler materials. Also, the results have shown that the values of all mechanical for bio composite reinforced with pomegranate peels powder higher than that reinforced with clove powder and reached to the maximum values at 0.7% of the percentages weight of pomegranate peel powder. Moreover, the properties of hybrid bio composite increased when reinforced with multifilament nylon fiber, that have the higher values as compared with that reinforced by mono-filament fiber. furthermore, from  the analysis of infrared spectra it was observed that is no shifting in peaks of characteristic frequencies of bio nanocomposites, relative to those spectra of polymer blend and neat PMMA, this indicates the occurrence of physical bonds and the absence from any chemical reactions or cross linking that may occur as a result of the mixing process. Moreover, the morphological analysis results indicated a good interfacial adhesion between all constituents of composite materials, especially those reinforced by PPP nanoparticle. to put it another way, this indicated to a perfect compatibility between the constituents of polymer blend and the natural nanoparticles (PPP or CP) and nylon fiber, which led to enhance the mechanical properties.

A master’s student, Heba M. Abdelkader, defended her thesis “Synthesis of Bio-Medical Materials Using Electroless Deposition Technique” on Tuesday, January 14^th, at the conference room (C), Department of Materials Engineering, University of Technology. The Committee members included:

The dissertation was scientifically evaluated by Ass. Prof. Dr. Mazhir T. Mohamed, University of Diyala, College of Engineering, Materials Engineering Department, and linguistically by Ass. Prof. Dr. Samir A. Ameen, Mechanical Engineering Department, University of Technology.

The discussion was conducted in a scientific atmosphere and a master's degree with grade of pass was awarded to the student after the completion of all the corrections that have been decided by the examiners.

Abstract

In this work, the Ni-based nanocomposite coatingmetal matrix)                       nanocomposite coating) by electroless deposition technique on a stainless steel (316L) substrate was prepared, where this coating technique is representing an alternative technique to obtain coatings on various substrates. However, the effect of the bath composition on the phase structure, microhardness and corrosion rate is very important, therefore the present work will compare the effects of incorporation of (Al2O3, ZrO2 and MWCNTs) at different concentrations (1.25% wt, 2.25% wt and 4.25% wt) g/L to pure nickel path coating and preparation of the (Ni–Al2O3, Ni–ZrO2 and Ni– MWCNTs) nanocomposites coatings on the phase microstructure,  the mechanical property (microhardness), chemical properties (corrosion rate and ion release) and structural analysis (XRD, SEM and EDS) were studied for the all types of nanocomposite coatings specimens. The results of microhardness tests showed a significant improvement in the hardness property of (Ni-Al2O3), (Ni-MWCNTs), and (Ni- ZrO2) nanocomposites coatings were prepared by electroless deposition technique at the concentration (4.25%wt) were (Hv 521.6, Hv 495.3, and Hv 397.4) , respectively. Where nanocmoposite coating above recorded the highest values compared with that for base coating of pure nickel (395.2Hv). The corrosion rate of the coated specimen (Ni-Al2O) nanocomposites coating was improved with excellent at of different concentrations of alumina nanoparticles by the electroless deposition technique at the concentrations. (4.25 and 1.25 g / l) which the corrosion rate (81.9 mpy and 94.4 mpy), respectively. It is lower than the corrosion rate of the Ni- pure coated sample (254.8 mpy) The corrosion rate of the coated specimen (Ni–MWCNT) nanocomposites coating was enhanced at concentration (4.25%wt and 1.25%wt) and the corrosion rate results (117.5 mpy and 152mpy) respectively. For (Ni- ZrO2) nanocomposites coating at concentrations (4.25%wt and 1.25%wt), the corrosion rate of coating was improved (143mpy and 190 mpy),respectively. Regarding the results of the ions release for the substrate coated by electroless (Ni-Al2O3, ZrO2) nanocomposites coating, the results of the coating analysis of elements (Ni, Fe, Al, and Zr) for the added concentrations (1.25% wt, 2.25% wt, and 4.25% wt). Showed the presence of ions release in the immersion tests for ( 3 and 7 ) days in Ranger’s solution was found within the permissible limit according to the quantity of nickel with the amount of iron allowed to exist within the human body.  Concerning the ions release for different embedded concentrations (1.25%wt, 2.25%wtand 4.25%wt) for MWCNTs, it was observed that the carbon ions release in the immersion tests for (3 and 7) days in Ranger’s solution increased with increasing concentration of MWCNTs and with the increase of immersion time. These amounts of carbon ions release cause toxicity inside the body.

A master’s student, Wahad I. Medhat, defended her thesis “Binary Titanium Alloys as Dental Implant Materials” on Saturday, January 12^th, at the conference room (C), Department of Materials Engineering, University of Technology. The Committee members included:

The dissertation was scientifically evaluated by Ass. Prof. Dr. Nawal M. Dawood, Babylon University, College of Materials Engineering, and linguistically by Lecturer Yassin M. Taher, University of Technology, English Language Center.

The discussion was conducted in a scientific atmosphere and a master's degree with grade of pass was awarded to the student after the completion of all the corrections that have been decided by the examiners.

Abstract

The element Titanium utilized in dentistry from the past and prescription in implantation. Through those years, not just the pure Ti as well as composites, for example, double and tertiary Ti alloys were utilized. This element and its alloys utilized in different medicinal uses, like, abutment, prostheses, and orthodontic wires. Hip balls can make from titanium, and attachments (being joint substitution) can remain inside the human body for more than 20 years. Thus, because of their high biocompatibility, good mechanical properties, and high corrosion resistance. Cp-Ti, (Ti –(10,20,30) %Ag ), (Ti – (10,20,30) % ZrO2 ) alloys are prepared in this work by powder metallurgy technique .The examinations performed are (X-ray diffraction), scanning electrons microstructure, energy dispersive X-ray spectroscopy, corrosion rate for specimens treated by the (Ringers solution) fluid and hardness. The X-ray diffraction, SEM and microstructure results show that (CP-Ti) samples consist of only pure Ti(α)phase , While the alloys of (Ti-Ag) and (Ti-ZrO2) samples consist of one phase (α- phase) until reaching the (30%wt) of Ag and ZrO2 there would be an intermetallic compound of (Ti2Ag) with titanium –silver alloys and (TiZr)3O intermetallic compound with titanium-zirconia alloys, that with the presence of (α- phase). In the hardness test, there is no significant effect for the (Ti2Ag)  intermetallic compound on improving the hardness of the samples and this is attributed to its low percent and the major effect of porosity on the hardness which declined it's effect.     The corrosion results showed a good corrosion resistance increases with increasing the silver content as the corrosion rate would be the best at (30%Ag) content with(0.091 mpy) at sintering temperature of 700 C̊. And with a sintering temperature of 900 C̊, the best result was with (30%Ag) with (0.059) mpy. In the Ti-ZrO2 alloys, the best result was with the zirconia content of (30%ZrO2) when cooled in air with (1.347) mpy at sintering temperature of 700 C̊, this results obtained in Ringer’s solution.

A master’s student, Tiba Y. Jassem, defended her thesis “Preparation and Characterization of a Polymeric Scaffold Used for Skin Substitution” on Thursday, January 9^th, at the conference room (C), Department of Materials Engineering, University of Technology. The Committee members included:

The dissertation was scientifically evaluated by Prof. Dr. Khaled M. Owaid, Al-Mustansiriyah University, College of Engineering, Department of Materials Engineering, and linguistically by Mayada R. Issa, University of Technology, English Language Center.

The discussion was conducted in a scientific atmosphere and a master's degree with grade of pass was awarded to the student after the completion of all the corrections that have been decided by the examiners.

Abstract

Burns and skin necrosis is considered one of the major problems faced in the medical field and a lot of researches are focusing on developing tissues as substitutes for damaged skin using many fabrication methods. Electrospinning is one of the most important fabrication methods used for scaffold preparation, by providing fibrous structure which enhances cell adhesion through the high surface area to volume ratio. Besides, the porous structure with open porosity will allow the cells to penetrate to form a 3-D tissue. In this study, the mechanical properties (tensile strength), wettability, cytotoxicity% and Rat Embryonic Fibroblast REF cells proliferation of electrospun pure polyurethane PU scaffold in a concentration of 10% w/v were improved by blending polyurethane with chitosan. This natural material will enhance the cell adhesion since it is a hydrophilic material. Blending polyurethane with chitosan highly increased the tensile strength of the prepared scaffolds. The first specimen with ratio [1:6] [chitosan:PU] revealed medium increase in the modulus of elasticity but with non-uniform fibrous structure. Increasing the ratio of polyurethane to chitosan in other specimens [1:10] and [1:20] [chitosan:PU], highly increased the modulus of elasticity of pure polyurethane from 1.518 Mpa to 12.99 and 12.81 Mpa respectively with more uniform fibrous structure.

Moreover, the wettability of the electrospun fibrous structures is highly related with the average fiber diameter, it is decreased with decreasing fiber diameter since it becomes hydrophobic. Adding chitosan to PU will increase the wettability% because of the primary amine NH2 and OH functional groups. The best wettability% noticed in [1:6] and [1:20] blend scaffolds.

Cytotoxicity % decreased with adding chitosan to PU especially in [1:10] and [1:20] blend scaffolds, because adding natural material (chitosan) with the synthetic material will enhance the biocompatibility and increase the number of viable cells. Best REF cells proliferation was also notices in [1:10] and [1:20]

blend scaffolds