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Article
Effect of thermocycling on some mechanical properties of polyamide hypoallergenic denture base material (comparative study)

Authors: Azad M.R. Al-Muthaffer ازاد المظفر --- Shatha S. Al-Ameer شذى الامير
Journal: Journal of baghdad college of dentistry مجلة كلية طب الاسنان بغداد ISSN: 16800087 Year: 2012 Volume: 24 Issue: special issue 2 Pages: 25-30
Publisher: Baghdad University جامعة بغداد

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Abstract

Background: Hypoallergenic denture base material became recently the most attractive option due to their use asalternative to poly methyl methacrylate in hypersensitive patients. The study of the effects of thermocycling on themechanical properties is very important, as it is beneficial for clinical purposes.Materials and methods: One hundred and sixty specimens were prepared according to manufacturer's instructionsand they were divided into two groups: Valplast and Vertex as a control group (eighty specimens for each), twentyspecimens from each material were used to test each of property. They were either thermocycled or notthermocycled (n = 10).Results: There was significant difference between polyamide and conventional heat cured acrylic in the four testedproperties. Furthermore, thermocycling significantly decreased the flexural strength of both polyamide and the heatcured acrylic and it significantly increased the tensile strength and hardness of both tested materials. Thermocyclingdid not significantly affect the impact strength of both materials.Conclusions: Vertex showed higher values of flexural strength than Valplast, flexural strength of both materialsdecreased post-thermocycling. Although the flexural strength of valplast was relatively low, it demonstrated greaterimpact strength than Vertex, impact strength of both tested materials was not affected by thermocycling. The tensilestrength of Vertex was more than Valplast, for both materials tensile strength increased after thermocycling. Thehardness of Vertex was higher than that of Valplast, both materials' hardness increased after thermocycling


Article
The Effect of some Natural Products as a Denture Cleansers on some Physical Properties of Acrylic Denture Base Material

Author: Nadira A. Hatim نادرة عبد الرضا حاتم
Journal: Tikrit Journal for Dental Sciences مجلة تكريت لعلوم طب الاسنان ISSN: 20731213 Year: 2013 Volume: 2 Issue: 2 Pages: 129-136
Publisher: Tikrit University جامعة تكريت

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Abstract

The study aims to evaluate the effect of some commercially available natural products (soda+ vinegar, soda +thymol , saturated salt solution) in relation to the commercial denture cleansers (Protifex) ,on surface roughness and hardness dimensional accuracy of acrylic denture base materials. one hundred samples were prepared from heat activated acrylic resin denture base material, they are (1cm*1cm*2mm length, width and thickness respectively). After that, half of the samples for each group were immersed for ½ hr per day in the denture cleanser, the other half of the samples immersed for 8 hr per day in the denture cleanser through one month. The denture cleansers used are three solutions prepared freshly everyday for immersion of the samples. The surface roughness of the samples were tested by using Stylus profilometer(Talysurf 10, England), while the hardness of the samples were tested by using Rockwell hardness tester (Wolpert, Germany), the mean is taken for each group and evaluated by using one way analysis of variance test, Dunnet T-test to compare the groups. The results demonstrated that there were no significant differences in the surface roughness and hardness, but with significant difference between treats of length of acrylic resin denture base material and duration of immersion at (P=0.05). All the prepared natural solutions would be accepted in relation to effect on surface roughness , dimensional accuracy, and hardness of acrylic denture base material.


Article
Effect of phosphate ester addition on transverse strength and hardness of heat cured acrylic denture base material

Authors: Zahraa saad abed karkosh زهراء سعد --- Basima M.A. Hussien
Journal: Journal of baghdad college of dentistry مجلة كلية طب الاسنان بغداد ISSN: 16800087 Year: 2018 Volume: 30 Issue: 2 Pages: 5-9
Publisher: Baghdad University جامعة بغداد

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Abstract

Background: acrylic resin denture base consider a common denture base material for its acceptable cost, aesthetic and easy processing but still has disadvantages including easy of fracture and low impact strength.Material and method: The experimental group was prepared by addition of 15% phosphoric acid 2-hydroxyethyl methacrylate ester (PA2HEME) with polymethyl methacrylate monomer; the experimental groups was compared with the control one. The specimens were prepared according to ADA specification No. 12 with dimension 65 mm x 10 mm x2.5 mm (length x width x thickness respectively). The prepared specimens were tested by three-point flexural strength utilizing Instron Universal Testing Machine (WDW, Layree Technology Co.), Shore D hardness tester used to measure hardness test. Statistical analysis used student T- test, mean and standard deviation.Results: The result of PA2HEME group showed high significant reduction comparing to the control group for both transverse strength and hardness test.Conclusion: Mixing 15% of PA2HEME with 85% methyl methacrylate (MMA) can reduce the mechanical properties of new modified polymethyl methacrylate (PMMA) acrylic resin


Article
INVESTIGATION SOME MECHANICAL PROPERTIES OF SELF CURED PMMA RESIN REINFORCED BYDIFFERENT TYPES OF NANO PARTICLES
الأستقصاء من بعض الخصائص الميكانيكية لراتنج البولي مثيل ميثا أكريليت المقوى بانواع مختلفة من الدقائق النانوية

Author: Qahtan Adnan Hamad قحطان عدنان حمد
Journal: Iraqi journal of mechanical and material engineering المجلة العراقية للهندسة الميكانيكية وهندسة المواد ISSN: 20761819 Year: 2017 Volume: 17 Issue: 3 Pages: 585-598
Publisher: Babylon University جامعة بابل

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Abstract

In the present research, study the effect of adding two different types of reinforcing particles, which included: nano-alumina (nano-Al2O3) and nano-silica (nano-SiO2), that added with different volume fractions of (1%, 2% and 3%), on the some mechanical properties of composite prosthesis complete denture base materials by using self (cold) cure poly methyl methacrylate (PMMA) resin as new fluid resin matrix . In this research the composite prosthetic dentures specimens consist of from two groups were prepared by using casting methods, type (Hand Lay-Up) method according to the types of reinforced particles which includes: the first group consists of PMMA resin reinforced by nano-alumina particles, and the second group consists of PMMA resin reinforced by nano-silica particles. The mechanical tests were performed on these specimens include compression test, impact test, and hardness test . The result of this study showed the values of (compression strength and hardness) properties increased with increasing the volume fraction of both (nano-Al2O3 and nano-SiO2) particles in PMMA complete denture base materials. While, the values of (impact strength) property decreased . Also the addition of (nano-Al2O3) particles has a noticeable effect on the most properties of composite material for prosthetic denture base specimens more than the (nano-SiO2) particles, except the impact strength property .

في هذا البحث تم دراسة تاثير اضافة نوعين مختلفين من دقائق التقوية تضمنت دقائق الالومينا النانوية ودقائق السيليكا النانوية والتي تمت اضافتهما بكسور حجمية مختلفة هي (%1%,2%,3)، على بعض الخواص الميكانيكية لمواد قاعدة طقم الاسنان الأصطناعية الكاملة المتراكبة, وذلك باستخدام راتنج البولي مثيل ميثا اكريليت المعالج ذاتياً كمادة أساس على شكل راتنج سائل جديد . في هذا البحث حضرت عينات أطقام الاسنان الأصطناعية المتراكبة باستخدام طرق السباكة, باستخدام طريقة (الصب اليدوي) على شكل مجموعتين هي: المجموعة الاولى تضم راتنج البولي مثيل ميثا اكريليت مقواة بدقائق الاولومينا النانوية، والمجموعة الثانية تضم راتنج البولي مثيل ميثا اكريليت مقواة بدقائق السيليكا النانوية.تضمنت الاختبارات الميكانيكية التي تم اجرائها على هذه العينات فحوصات الانضغاط، الصدمة، والصلادة للعينات. وقد أظهرت نتائج هذه الدراسة بان قيم خواص (مقاومة الانضغاط والصلادة) ازدادت مع زيادة الكسر الحجمي لكلا من دقائق الالومينا النانوية ودقائق السيليكا النانوية. بينما قلت قيم خواص (مقاومة الصدمة) . كذلك ان دقائق الالومينا النانوية تمتلك تاثير اكبر من دقائق السيليكا النانوية على أغلب خواص المواد المتراكبة لعينات قاعدة طقم الاسنان الأصطناعية, ماعدا خاصية مقاومة الصدمة .


Article
Effects of Irradiation by UV- Acceleration on Mechanical Properties of Polymer Blends (Polyester: Starch)

Authors: Sihama I. Salih --- Qahtan A. Hamad --- Safaa N. Abdul Jabbar --- Najat H. Sabit
Journal: AL-NAHRAIN JOURNAL FOR ENGINEERING SCIENCES مجلة النهرين للعلوم الهندسية ISSN: 25219154 / eISSN 25219162 Year: 2018 Volume: 21 Issue: 1 Pages: 147-152
Publisher: Al-Nahrain University جامعة النهرين

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Abstract

This work covers mixing of unsaturated polyester (un- polyester) with starch powders as polymer blends and study the effects of irradiation by UV-acceleration on mechanical properties of its. The unsaturated polyester was mixing by starch powders at particle size less than (45 μm) at selected weight fraction of (0, 0.5, 1, 1.5, 2, 2.5 and 3%). These properties involve ultimate tensile strength, modulus of elasticity, elongation percentage, flexural modulus, flexural strength, fracture toughness, impact strength and hardness. The results illustrate decrease in the ultimate tensile strength at and elongation percentage, while increasing modulus of elasticity, with increasing the weight ratio of starch powder to 3 % weight fraction, whereas the maximum value of hardness and flexural, impact properties happened at 1 % weight fraction for types of polymer blends.


Article
Study the Effect of Welding on Tensile and Hardness Properties for Carbon- Steel by Using Arc Welding &Tig Welding
دراسة تاثير اللحام على خواص الشد والصلادة للفولاذ الكاربوني باستخدام طريقتي Arc Welding &Tig Welding

Authors: عباس خميس حسين --- محمد مهدي جبار --- سحر حسين احمد
Journal: Engineering and Technology Journal مجلة الهندسة والتكنولوجيا ISSN: 16816900 24120758 Year: 2010 Volume: 28 Issue: 23 Pages: 1171-1183
Publisher: University of Technology الجامعة التكنولوجية

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Abstract

Welding is one of important industrial processes, Therefore many techniques are development to get an efficient and low cost welding for different kind of materials. This research is compared between two technique procedures of welding , (Arc welding ) & (Tig welding )for a specimen from low carbon steel, The mechanical tests like tensile and hardness are measured and taking a microstructure pictures ,We found that for the max strength in (Arc welding) is greater than unwelded specimen by (22.5%) , and for (Tig welding) it is smallerby (7.5%),The high value of hardness in (Arc welding) is (200 HV) and high value in (Tig welding) is (255 HV) .

يعتبر اللحام واحد من أهم العمليات الصناعية لذلك تم تطوير العديد من الطرق لغرض الحصول على لحام كفؤ وواطئ الكلفة ولأنواع مختلفة من المعادن .في هذا البحث تم المقارنة (Arc Welding ) بين طريقتين من أنواع اللحام هي طريقة القوس الكهربائي الاعتيادية باستخدام معدن من (Tig Welding ) وطريقة اللحام بالقوس الكهربائي باستخدام غاز حماية الفولاذ الواطئ الكربون, تم إجراء الاختبارات الميكانيكية كاختبار الشد وقياس الصلادة واخذ صور للبنى المجهرية للعينات الملحومة ومقارنتها بعينة من نفس المعدن غير ملحومة, ووجد أن بلغ ( 22.5 %) اكبر منها لغير الملحومة, أما (Arc) إجهاد الشد الأقصى للعينة الملحومة نوع فيكون اقل بنسبة ( 7.5 %) , أما القيمة العليا للصلادة فكانت( 255 (Tig) للعينة الملحومة بطريقة . (Arc) 200 ) في طريقة HV) بينما بلغت (Tig) بطريقة ( HV

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