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Article
The effect of inorganic pigment on the tensile properties of polycarbonate irradiated with UV – light
تأثير الصبغات غير العضوية على خصائص الشد للبولي كاربونيت المشعع بالاشعة فوق البنفسجية

Author: Z.R.AL-Shammary زينب رحيم الشمري
Journal: Iraqi Journal of Physics المجلة العراقية للفيزياء ISSN: 20704003 Year: 2011 Volume: 9 Issue: 16 Pages: 52-56
Publisher: Baghdad University جامعة بغداد

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Abstract

The effect of UV-light on the tensile properties of pure PC has been studied. It was shown that irradiation of PC undergo a drop in the tensile properties of 30 hour of exposure. The results of irradiated samples shows that the addition of ZnO and TiO2 with different percentages (0.5, 1, 1.5 %) will reduce the Young modulus and ultimate stress of PC/ZnO ,PC/ TiO2 composites.

تم في هذا البحث دراسة خصائص الشد للبولي كاربونيت المشعع بالاشعة فوق البنفسجية . لوحظ من خلال البحث ان خصائص الشد تتناقص عند تشعيع البولي كاربونيت بزمن تشعيع قدره 30 ساعة. تبين النتائج بانه عند اضافة ثاني اوكسيد التيتانيوم واوكسيد الزنك وبنسب مختلفة ((0.5,1 and 1.5% الى البولي كاربونيت وتشعيع النماذج فان قيم معامل يونك وقيمة الشد القصوى سوف تتناقص .


Article
The effect of denture cleaners on Tensile Strength and Indentation hardness of denture base materials Raghdaa

Author: Karim Jassim B D S, MSc, PhD * د. كريم جاسم
Journal: MUSTANSIRIA DENTAL JOURNAL مجلة المستنصرية لطب الاسنان ISSN: 18138500 Year: 2006 Volume: 3 Issue: 2 Pages: 202-206
Publisher: Al-Mustansyriah University الجامعة المستنصرية

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Abstract

Background: Denture cleaner solutions are used extensively for the cleaning ofprosthesis both plastic and metallic component .The chemical composition of cleanersolution are virtually important in defining their adverse effect on properties of acrylicpart of prosthesisAims of the study The present study carried out to study the effect of somecleaning solution on tensile strength and indentation hardness of both types of acrylicresin (hot and cold cured) and compare the effect on different types of denturematerials.Materials and methods: Specimens of hot and cold cured acrylic resin wereprepared according to ADA specification for both indentation hardness and tensilestrength test. The specimen were immersed in distilled water for seven days then wereleft in containers containing one of the following denture cleaners, Staradent 1%H202,5%HCL& vinegar solution. Each container contained five specimens of either heatcure or cold cure with one type of denture cleaners and they were left for seven days.Specimens were then tested for indentation hardness and tensile strength test.Results: The results showed that Vinegar solution has an deleterious effect ontensile strength and indentation surface hardness of hot cured acrylic resin ascompared with control while for cold cure all specimens affected by all cleaningsolutions.


Article
Numerical Study of Stress Concentration in a Tensioned Plate
دراسة عددية لتمركز الإجهاد في صفيحة مشدودة

Author: Dr.Riyah N.Kiter , Ahmed N.Uwayed, Arz Yahya Rzayyig
Journal: Tikrit Journal of Engineering Sciences مجلة تكريت للعلوم الهندسية ISSN: 1813162X 23127589 Year: 2012 Volume: 19 Issue: 4 Pages: 1-13
Publisher: Tikrit University جامعة تكريت

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Abstract

A numerical study using (FEM) has been carried out to investigate the effect of some parameters on the stress concentration factor in a plate, having different types of cutout and subjected to uniaxial tension. These parameters include the location of cutout, orientation of cutout with respect to the axis of loading, radius of bluntness of cutout and the thickness of the plate. Maximum values of stress concentration factor (SCF) were found in cases of: 1. the cutout is in the center of the plate, 2. the angle of a corner of cutout is bisected by an axis perpendicular to the loading axis, 3. the corners of cutout are sharp (zero radius), and 4.the plate is very thin.

أجريت دراسة عددية بأستخدام طريقة العناصر المحددة لغرض البحث في تأثير بعض العوامل على معامل تمركز الأجهاد في صفيحة تحتوي على قطوعات مختلفة و معرضة لشد محوري احادي. تضمنت هذه العوامل موقع القطع ، أتجاه القطع بالنسبة لمحور التحميل ، نصف قطر حافة القطع و سمك الصفيحة. أظهرت الدراسة ان معامل تمركز الأجهاد يبلغ ذروته في الحالات التالية : عندما يكون القطع في مركز الصفيحة. عندما تكون زاوية حافة القطع منصفة بمحور عمودي عاى محور التحميل. عندما تكون حافات القطع حادة (نصف قطر يساوي صفر) و أخيراً. عندما تكون الصفيحة رقيقة جداً.


Article
Evaluation of transverse and tensile bond strength of repaired nylon denture base material by heat, cold and visible light cure acrylic resin

Authors: Firas A.F. --- Ghazwan A.A. --- Ali A.M.
Journal: Journal of baghdad college of dentistry مجلة كلية طب الاسنان بغداد ISSN: 16800087 Year: 2013 Volume: 25 Issue: special issue 1 Pages: 1-5
Publisher: Baghdad University جامعة بغداد

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Abstract

Background: Denture fracture is one of the most common problems encountered by the patients andprosthodontists. The objective of present study was to evaluate the transverse strength of nylon denture base resinrepaired by using conventional heat polymerized, autopolymerized and visible light cure {VLC} resins, surfacetreatment that used for repair and adjustment of insufficient nylon denture bases and in case of addition of artificialteeth. As these corrective procedures are common chair side procedures in dental clinic.Materials and methods: One hundred twenty nylon specimens were prepared by using metal patterns withdimension of (65x10x2.5 mm) length, width, and thickness respectively for transverse strength test while for tensilebond strength a dumbbell-shaped with measurement (65x12.5x25mm) length, width, and thickness respectively wereflasked with stone. The nylon specimens were molded by reflasked with dental stone that used as an index for thesespecimens in the repair procedure and repaired with 45 degree bevel joint by using metal holding device. The twoparts of nylon specimen to be repaired were realigned in its repair index and adhere with special adhesive materialto stabilize the combination during repair procedure. The dough of heat and cold cure resin was packed into thejoint and then cured. The specimen repaired with cold cure resin was placed in the Ivomat containing water at(40°C) and pressure (30IB/inch²) for 15 minutes. The specimen repaired with {VLC} was placed in the light cure unit for4 minutes following manufacturer’s instruction. The fractured nylon specimens were divided according to the type ofrepaired materials into (40) specimens received heat cure acrylic and the (40) specimens received cold cure acrylicand the other 40 specimens received {VLCR}. Each 40 specimens were subdivided according to the type of surfacetreatment received into 20 specimens were treated with coarse stone bur (control), 20 specimens were treated withcombination of coarse stone bur and monomer of the heat cure acrylic. After that the specimens were subjected totransverse {Tr} and tensile bond {TB} strength tests. For each test 10 specimens.Results and conclusions: This study showed that specimens treated with combination of coarse stone bur andmonomer of the acrylic (heat, cold or VL cure) had the highest transverse and tensile strength values, followed bythe specimens treated with coarse stone bur. The results showed that the specimens repaired with heat cure acrylichad transverse and tensile strength values higher than the specimens repaired with cold and VL cure acrylic whencompared between subgroups of heat, cold and VL cure acrylic that received the same treatments


Article
Effect of Filler Type on some Physical and Mechanical Proparties of Carbon Fibers / Polyester Composites
تأثیر نوع الاضافه على بعض الخواص الفیزیائیه والمیكانیكیه من الیاف كاربون ومتراكبات البولي استر

Authors: Osama Sultan Muhammed --- Abbas Khammas Hussein --- Ruaa Haitham Abdel-Rahim
Journal: Engineering and Technology Journal مجلة الهندسة والتكنولوجيا ISSN: 16816900 24120758 Year: 2013 Volume: 31 Issue: 15 Part (A) Engineering Pages: 2905-2924
Publisher: University of Technology الجامعة التكنولوجية

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Abstract

In the present study, traditional and hybrid composites were prepared by Hand lay-upmolding and investigated. The composites constituents were unsaturated polyester resinas the matrix, 3% and 6% volume fractions of carbon fibers as reinforcement and 3% ofAl2O3, Al, Cement and local Gypsum (calcium sulfate anhydrate CaSO4) as fillerparticles. The investigated physical properties were density, porosity while themechanical properties were tensile properties, bending modulus of elasticity. Theexperimental results showed that increased volume fraction of carbon fibers to (6%) ledto increase in physical properties (density, porosity. As for the mechanical properties,carbon fiber composites and (3% carbon fibers/Al2O3)-contained hybrid composites gavethe higher tensile and fracture strength, carbon fiber then gypsum composites gave thehigher bending modulus.


Article
Evaluation the Effect of Different Methods of Disinfection on Tensile Strength and Bond Strength of Soft Denture Lining Ma-terials

Author: Lamia T Rejab
Journal: Al-Rafidain Dental Journal مجلة الرافدين لطب الأسنان ISSN: 18121217 Year: 2013 Volume: 13 Issue: 1 Pages: 58-65
Publisher: Mosul University جامعة الموصل

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Abstract

Aims: Aim of the study to evaluate the effect of two different disinfection methods for two periods of time on tensile strength and bond strength of soft denture lining materials (Vertex and Molloplast-B). Materials and methods : The effect of two disinfection methods ,first chemical disinfection method (which include artificial saliva , saturated salt and vinegar solution), and second microwave method on two physical properties the tensile and bond strength of soft denture lining materials for two periods of times (14 and 30 days) was evaluated, two hundred samples were prepared, one hundred samples to each property test . ANOVA and Duncan's multiple range test were performed to determine the signifi-cant difference among the tested groups at p ≤ 0.05% . Results: The result showed that the highest val-ue of tensile and bond strength of Vertex after 14 and 30 days were achieved with the microwave group, while for Molloplast -B highest value achieved with the control distilled water group. The low-est value was achieved after immersion in vinegar group for both soft lining material. A significant difference between the two soft lining materials among all disinfection methods at p≤ 0.05.Conclusions : The results appeared that the chemical disinfection and microwave disinfection methods have a significant effect on the tensile strength and bond strength of both vertex and Mol-loplast –B soft ling materials for two periods of time. Microwave disinfection has less effect than the chemical disinfection on the properties. The effect of disinfection increase significantly with increas-ing period of time .


Article
The Effect of PVP Addition on the Mechanical Properties Of [84%LLDPE: 15 %(( 100- X) %PP: X%PVP):1%Basalt Particle] Polymer Blend Composites.
دراسة تأثير أضافة (PVP) على الخواص الميكانيكيه للخليط البوليمري المتراكب: [84%LLDPE:15%((100-X)%PP:X%PVP):1%basalt particle]

Authors: Teeb A. Mohammed --- Akram R. Jabur --- Sihama E. salih
Journal: Engineering and Technology Journal مجلة الهندسة والتكنولوجيا ISSN: 16816900 24120758 Year: 2014 Volume: 32 Issue: 3 Part (A) Engineering Pages: 573-585
Publisher: University of Technology الجامعة التكنولوجية

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Abstract

Polymer blends composites were prepared according to the formula [84%LLDPE:15%((100-X)%PP:X%PVP):1%B.P] with weight ratios selected for X values (0,4,8,12,16 %), as strips by double screw extruder and use press process the strips to prepare the samples according ASTM specification, the mechanical properties were studied for all theprepared samples which are (tensile, flexural, compression, impact, hardness, and creep tests). The results are as following:- results showed increment of mechanical properties as PVP ratio increases except elongation, furthermore the results recorded highest values of fracture strength, young modulus, compressive strength, flexural strength, maximum shear stress, flexural modulus and creep modulus at PVP 8% wt. which are (31.32MPa, 0.14GPa, 27.4MPa,24MPa, 0.6MPa, 1.08GPa and 0.558GPa) respectively.While the highest values of fracture toughness and hardness recorded at 12% wt. (1.4696Pa√m), and at 4% wt. (56.5) respectively.

حضرت المتراكبات ذات أساس الخليط البوليمري الثلاثي, وفق الصيغة [84%LLDPE:15%((100-X)%PP:X%PVP):1%B.P] وبنسب وزنية مختارة لقيم x 16,12 ,8 ,4 ,0) %). وقد تم تحضيرها بشكل شرائط حضرت بعملية البثق بواسطة باثقة ثنائية اللولب واستخدمت عملية كبس الاشرطة لتحضير العينات وفق المواصفة القياسية (ASTM) , درست الفحوصات الميكانيكية للعينات المحضرة والمتمثلة ( فحص الشد والانحناء والانضغاط والصدمة والصلادة والزحف) أظهرت النتائج زيادة في الخصائص الميكانيكية مع زيادة نسبة PVP باستثناء المطيلية وعلاوة على ذلك سجلت النتائج أعلى قيم لمقاومة الشد, معامل الرونة, مقاومة الانضغاط ومقاوة الانحناء واعلى أجهاد قص ومعامل مرونة الانحناء ومعامل الزحف عند نسبة (8% wt) PVPوهي على الترتيب (31.32MPa , 0.14GPa , 0.6MPa , 27.4MPa , ( 0.558GPa , 1.08Gpaفي حين سجلت أعلى قيم لمتانة الصدمة وقيم الصلادة عند نسبةPVP 12% wt.)) (1.696 Pa√m) و 4%wt ((56.5 على الترتيب .


Article
Modeling of Arc Metal Welding Process of Low Carbon Steel (304)
نمذجة طريقة لحام القوس المعدني للفولاذ المنخفض الكاربون نوع (304)

Author: Majid Hameed Abdul Majeed
Journal: Engineering and Technology Journal مجلة الهندسة والتكنولوجيا ISSN: 16816900 24120758 Year: 2014 Volume: 32 Issue: 3 Part (A) Engineering Pages: 643-652
Publisher: University of Technology الجامعة التكنولوجية

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Abstract

This work includes an investigation of the effect and optimization of welding parameters on the tensile strength in the arc metal welding process. The experimental studies were conducted under varying welding currents, wire diameters, and heat input. The settings of welding parameters were determined by using the Taguchi experimental design method. The level of importance of the welding parameters on the tensile strength is determined by using analysis of variance (ANOVA). The optimum welding parameter combination was obtained by using the analysis of signal-to-noise (S/N) ratio. The tensile strength model was formulated based on Analysis of Variance (ANOVA) using Minitab® statistical package. The experimental results confirmed the validity of the used Taguchi method for enhancing the welding performance and optimizing the welding parameters in the arc metal welding process.

يتضمن هذا البحث دراسة تاثير عوامل لحام القوس المعدني على مقاومة الشد للفولاذ (304) بالاضافة الى ايجاد العوامل المثلى , وتم اجراء الدراسات التجريبية تحت تاثير التغير في قيم تيار اللحام , قطر السلك , بالاضافة الى الدخل الحراري. اما اعداد معاملات اللحام فقد تم تحديدها وفقا لطريقة تاكوجي(اي تصميم التجارب وفقا لطريقة تاكوجي). اما مستوى تاثير هذه المعاملات فقد تم تحديده وفقا لتحليل التباينANOVA . كما تم الحصول على عوامل اللحام المثلى باستخدام تحليل نسبة الاشارة/الضوضاء S/N, اما الموديل الرياضي لمقاومة الشد فقد تم نمذجتة وفقا لتحليل التباين باستخدام الحزمة الاحصائية لبرنامج MINITAB, واظهرت النتائج التجريبية صحة استخدام طريقة تاكوجي لرفع اداء اللحام وتحديد العوامل المثلى لطريقة لحام القوس المعدني للفولاذ نوع304.


Article
Experimental Investigation and Mathematical Modeling of Tensile Properties of Unsaturated Polyester Reinforced by Woven Glass Fibers
التقصي العملي والنمذجه الرياضيه لخصائص الشد للبولي استر الغير مشبع المقوى بالياف الزجاج الحصيرية

Authors: Jawad Kadhim Oleiwi --- Emad Saadi Al- Hassani --- Alaa Abd Mohammed
Journal: Engineering and Technology Journal مجلة الهندسة والتكنولوجيا ISSN: 16816900 24120758 Year: 2014 Volume: 32 Issue: 3 Part (A) Engineering Pages: 653-666
Publisher: University of Technology الجامعة التكنولوجية

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Abstract

This research studied the tensile properties of glass fiber reinforced unsaturated polyester with different fiber volume fraction Vf, and angle of fibers for coarse and fine woven fibers reinforcement. The composite specimens were prepared by hand lay-up technique and cutting according to (ASTM D – 638) for tensile test to obtain modulus of elasticity, ultimate tensile strength and elongation percentage of the composite specimens. Mathematical models were done by using statistical analysis which shows the tensile properties of the composite specimens as a function of volume fraction and fiber angle.The results show that the maximum value of the modulus of elasticity was (11.5 GPA) and the maximum value of ultimate tensile strength was (240 MPa) which happed at (11% VF) for fine woven fibers and for (0º/90º) fibers angle, and vice versa for percentage elongation was (2.5%).

في هذا البحث تم دراسة خواص الشد للبولي استر غير مشبع مقوى بالياف الزجاج عند تغير كل من الكسر الحجمي وزاوية الليف لنوعين من التقوية الحصيرة الخشنه والناعمه. حضرت العينات المركبة بالطريقة اليدوية وقطعت وفق المواصفه (ASTM D – 638) لفحص الشد للحصول على معامل المرونة واقصى أجهاد شد والاستطالة النسبية لهذه العينات. تم عمل نماذج رياضية باستخدام التحليل الأحصائي الذي يبين خواص الشد كدالة لكسر الحجمي وزاوية الليف. بينت النتائج بان اقصى قيمة لمعامل المرونة كانت(11.5 GPa) واقصى اجهاد شد كان(240 MPa) يحصلان عند الكسر حجمي (11%) عند التقوية بالحصيرة الناعمة ولزاوية ليف (0º/90º) والعكس بالعكس للاستطاله النسبية حيث كانت 2.5%) ).


Article
Retentive forces, tensile strength and deflection fatigue of Acetal thermoplastic clasp material in comparison with cobalt-chromium alloy

Authors: Samar S. Alwan سمر علوان --- Intisar J. Ismail انتصار جميل اسماعيل
Journal: Journal of baghdad college of dentistry مجلة كلية طب الاسنان بغداد ISSN: 16800087 Year: 2014 Volume: 26 Issue: 1 Pages: 59-66
Publisher: Baghdad University جامعة بغداد

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Abstract

Background: Nowadays there is an increasing of the emphasis on aesthetic, dentist have been concerned about providing aesthetics and functional removable partial dentures to their patients and this was make the mission more difficult because of the goal now is achieving optimal aesthetic of the denture - while maintaining retentive, stable, and conservative to the health of supporting tooth and supporting tissue. The traditional use of metal clasp like cobalt-chromium, gold, stainless-steel and titanium hampers esthetics because of its obvious display conflicts with patient’s prosthetic confidentiality. Acetal resin (poly oxy methylene) may be used as alternative denture clasp material. This material was promoted primarily on the basis of its superior esthetic.Material and method: In this study, Acetal resin of Flexite and co-cr alloy of Wirocast companies were used. Four metal models of two premolars and two molars were surveyed to have 0.25mm and 0.5mm undercut depth for each one of the materials. eighty clasps were prepared and tested by testing machine to measure the load required to dislodge Acetal and co-cr clasps of 2mm. thickness (for premolar and molar). Tensile test were utilized for both Acetal resin and co-cr. tensile values will be used in special formula to calculate the amount of deflection.Results: The results of this study revealed that Acetal resin clasp of molar with 0.5mm undercut depth have the higher retentive force, and premolar with 0.25 mm undercut depth have the lowest retentive force as compared to co-cr. Also Acetal had lower values of the tensile strength as compared to co-cr alloy but it had higher deflection value than co-cr and it can withstand higher deflections than those of co-cr before having permanent deformation or fractureConclusions: Acetal resin can be used with limitation as an alternative to co-cr alloy clasps in removable partial dentures.

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