توجه: محتویات این صفحه به صورت خودکار پردازش شده و مقاله‌های نویسندگانی با تشابه اسمی، همگی در بخش یکسان نمایش داده می‌شوند.
۱Thermal degradation process of a char forming phenolic matrix composite
اطلاعات انتشار: دهمین کنگره ملی مهندسی شیمی ایران، سال
تعداد صفحات: ۱۰
Thermo gravimetric analysis have been used to study the mechanisms involved in the thermal degradation process of polymer and composites. A process of thermal degradation for char forming of phenolic matrix composite is analytically investigated and evaluated experimentally.In this work the effect of air atmosphere on the thermal degradation of resol–type phenolic\asbestos composite during pyrolysis was investigated and compared with that of nitrogen atmosphere, using DSC, and TGA techniques. Reaction rate constant for thermolysis of chemical bonds, gas production, and char forming could be determined from parametric fits of the process of charring model to the thermo gravimetric data.As the results of this work activation energy, frequency factors and degree of thermal degradation in air and nitrogen were obtained.<\div>

۲Thermal conduction mechanism of the high performance layered silicate resol type phenolic resin nanocomposite
اطلاعات انتشار: یازدهمین کنگره ملی مهندسی شیمی ایران، سال
تعداد صفحات: ۱۰
An important requirement for the thermal design of the heat shield, which is subjected to extremely high heat loads during the atmospheric re–entry, is to have prior accurate information regarding the thermal properties of the materials utilized.
In this work we present the solution of the inverse problem of parameter estimation, used for the identification of the effective thermal diffusivity of resol type phenolic resin–asbestos cloth composite and its layered silicate nanocomposites. The experimental setup is an oxyacetylene torch according to ASTM E 285–80. Based on the results of this work the effective thermal diffusivity of resol type phenolic resin–asbestos cloth composite and kaolinite layered silicate nanocomposite (6 wt. % of clay) are approximately equal to 9.3*10–8 and 6.47*10–8 m2.s–1 , respectively<\div>

۳A curing kinetic model of montmorillonite layered silicate nanocomposite
نویسنده(ها): ،
اطلاعات انتشار: پنجمین کنگره بین المللی مهندسی شیمی، سال
تعداد صفحات: ۷
Recent advances in polymer layered silicate nanocomposites especially improved all of properties, encourages the examination of this unique class of evolving materials as potential industrial application and heat insulator. The resol type phenolic resin is widely used as a polymeric matrix in heat and electric resistance composite and nanocomposite. The effect of montmorillonite on the cure kinetics of resol type phenolic resin\organomontmorillonite (Org– MMT) nanocomposite is investigated by X–ray diffraction (XRD) and by a single–heating–rate DSC method. The XRD result indicates that an exfoliated nanocomposite was obtained. The experimental data obtained from DSC are explained by the phase boundary method. The addition of Org–MMT reduces the gelation time tg, and increases the rate of the curing reaction and the value of the kinetic constant k. the values of kinetic constant k rise as the cure temperature increases. The nanocomposite has a larger value of k and smaller value of n and E comparing with the phenolic resin system without Org–MMT.<\div>

۴Ablative performance of resol\ kaolinite nanocomposite
اطلاعات انتشار: پنجمین کنگره بین المللی مهندسی شیمی، سال
تعداد صفحات: ۱۰
Spacecraft heat shield use thermal protection system materials which ablate at high temperature for mass efficient rejection of aerothermal heat load. Recent advances in polymer layered silicate nanocomposites especially improved heat protection performance. Additionally, provided that the char remains intact, resistance to thermal and chemical ablation ultimately limits lifetime. Mass and energy balance equations have been solved in order to model the ablation of an ablative material. A method to determine and calculate some of the parameters in the ablative equation is proposed from the simultaneous thermal gravity and differential scanning calorimetry analysis techniques. Inverse analysis techniques have been used successfully for the estimation of thermal properties of ablating materials. The objective of this work is to model ablating and thermal degradation behaviour of a heat shield resol–type phenolic resin\asbestos cloth composite and its kaolinite layered silicate nanocomposite in oxyacetylene flame test according to ASTM–E–285–80. All of the theoretical results confirmed with experimental data.<\div>

۵Flammability of kaolinite layered silicate\ phenolic resin\ asbestos cloth nanocomposite
اطلاعات انتشار: پنجمین کنگره بین المللی مهندسی شیمی، سال
تعداد صفحات: ۱۰
Thermal degradation of composite and nanocomposite by various environmental effects such as temperature is very important factor in prediction of the durability of these materials in there applications. An evaluation of the relative performance advantage of the various heat insulation materials has been made based on thermal degradation mechanism and thermal stability. The objective of this work is to investigate the effect of montmorilonite nanocrystal on the thermal degradation of resol–type phenolic\asbestos\montmorilonite nanocomposite during pyrolysis using thermo gravimetric analysis and to compare the results with that of phenolic\asbestos composite. Thermal degradation and char forming mechanisms could be obtained from parametric fits of the process of thermo gravimetric model to its counterpart test data. Model predictions and experimental data show good agreement with each other. As the results of this work, activation energy, frequency factors and degree of thermal degradation are determined which enable to clarify the thermal degradation mechanism.<\div>

۶Effect of Clay Loading on Mechanical Properties of Highly Filled Nanocomposites
اطلاعات انتشار: کنفرانس بین المللی فرآورش پلیمرها، سال
تعداد صفحات: ۵
Composite materials reinforced on a molecular scale are a new class of materials in which an inorganic clay mineral is dispersed in an organic polymer on a nanometre scale. These new materials show dramatic improvements in mechanical and thermal properties. But only few attempts have been made so far to achieve highly filled nanocompositesIn this work, highly filled clay nanocomposites based on asbestos– phenolic system are prepared and characterized by XRD, 3 point bending test and SEM and optical microscopy.Results reveal decreasing of modulus and flexural strength and increasing in elongation at break, with adding montmorillonite. Reduction of strength was attributed to the formation of micro–voids in the system due to the rapid increase of viscosity during mixing. The results also show that nanocomposite samples with 50 and 60 phr clay have acceptable mechanical properties in compare of composite counterpart. These systems could be used in different applications such as thermal barrier.<\div>

۷The Effect of Clay on the Ablation Behavior of NBR\OMMT Nanocomposites
اطلاعات انتشار: کنفرانس بین المللی فرآورش پلیمرها، سال
تعداد صفحات: ۴
In special applications, elastomeric composite heat insulators are more attractive issues in compare to their similar non–elastomeric counterparts due to their excellent thermal stresses and large deformation bearing. A few works have been recently reported concerning ablative properties of elastomeric nanocomposites containing different fillers such as organically modified montmorillonite (OMMT). However, the effect of loading level of OMMT on the ablation behavior of elastomeric heat insulator has not been reported.In this work, the ablative properties of nitrile butadiene rubber nanocomposite with difference loading levels of OMMT were investigated. The back temperature of elastomeric nanocomposite heat shield with different thickness (2.5 and 5 mm) was measured using oxyacetylene flame test and the effect of clay on it was studied. Also, the ablation rates were calculated.The results showed that NBR\OMMT nanocomposite with higher loading level of clay (13.35 wt%) has lower ablation rates (about 7 times in mass loss and about 11 times in erosion rate) and lower magnitude of back temperature (about 513°C) than its composite counterpart. From the viewpoint of thermal shielding capability, elastomeric nanocomposites exhibit better ablation resistance.<\div>

۸The effect of shear strain amplitude and loading cycle on the horizontal characteristics of fiber reinforced nanocomposite elastomeric seismic isolators
اطلاعات انتشار: کنفرانس بین المللی فرآورش پلیمرها، سال
تعداد صفحات: ۴
Fiber–reinforced elastomeric isolators (FREIs) are a new generation of seismic isolation devices which steel plates are replaced by fibers. FREIs have a number of advantages over SREIs including; superior energy dissipation capability, potentially low manufacturing cost, light weight, and the possibility of being produced in long rectangular strips or large sheets and being modified to the required size locally [1]. The main purpose of this work was to investigate the effect of shear strain amplitude and loading cycles on the horizontal characteristics of fiber reinforced nanocomposite elastomeric isolators (FRNEIs) which were manufactured based on nanocomposite rubber compounds. The results of typical isolator horizontal test showed that by increasing the number of cycles of loading and shear strain, the values of effective horizontal stiffness and shear modulus of FRNEI decrease and the viscous damping increases. This stress softening is known as Mullins effect which occurs in the filled rubbers [2].<\div>

۹Toughening Mechanism of Polymer\ Layered Silicate Nanocomposites
اطلاعات انتشار: کنفرانس بین المللی فرآورش پلیمرها، سال
تعداد صفحات: ۴
Phenolic resin (PR) have been widely used as coating, adhesives, composites, etc. due to their excellent flame and chemical resistance, thermal stability and dimensional stability properties However their brittleness has significantly limited their widespread applications.In this work, highly filled clay nanocomposite systems based on asbestos– phenolic system are prepared and investigated by XRD, 3 point bending test, SEM and TOM microscopy.The results showed improvement of fracture toughness of highly filled nanocomposites by adding organoclay in nanocomposite.The toughening mechanism of highly filled nanocomposite is crack branching due to flake shape and strength of clay sheets.<\div>

۱۰Quantitation of the reinforcement effect of SiAlON nanoparticles on the tribological and corrosion resistance of epoxy coating
اطلاعات انتشار: کنفرانس بین المللی فرآورش پلیمرها، سال
تعداد صفحات: ۴
The effect of incorporating SiAlON nanoparticles loading level (0, 3, 5 wt.%) on abrasion resistance, and the corrosion resistance of epoxy–coated steel was investigated by electrochemical impedance spectroscopy (EIS). The electrochemical monitoring of the coated steel over 35 days of immersion in 3.5 wt.% NaCl solutions at room temperature suggested the beneficial role of SiAlON nanoparticles in significantly improving the corrosion resistance of the coated steel. nanocomposites containing 5 and 3 wt% of SiAlON nanoparticles improved wear resistance, 34% and 59%, respectively. Nanoparticles characterized by linier light scattering analysis(LLS). The SiAlON nanopowders size of deagglomerated product is mostly less than 100 nanometers. The epoxy resin chemical resistant coating grade based on bisphenol A was used with polyamine hardener as a curing agent<\div>

۱۱Improvement of Mechanical and Chemical Properties of Epoxy Coating forNatural Gas Pipeline by SiAlON Nanopowders
اطلاعات انتشار: هفتمین کنگره ملی مهندسی شیمی، سال
تعداد صفحات: ۶
The influence of SiAlON nanoparticles loading level (0, 3, 5, 7 wt%) on chemical and mechanical properties of internal nanocomposite coating based on Epoxy resin\ SiAlON were experimentally investigated. The nanocomposite coatings were characterized by fracture toughness, abrasion andimmersion tests, followed by scanning electron microscopy (SEM) of the surface cracks samples. Also nanoparticles characterized by Linier Light Scattering analysis (LLS). The epoxy resin used was a bisphenol A–type epoxide resin with polyamine hardener as a curing agent. Results indicatean enhancement in the epoxy nanocomposite mechanical and chemical properties due to the addition of small fraction of SiAlON nanoparticles. energy per unit area of crack surface ofnanocomposites with 3 wt% and 5 wt% of SiAlON nanopowders improves compared to neat resin.The nanocomposite containing 5 wt % of SiAlON nanoparticles exhibited the maximum GIC values which are 23% higher. Also nanocomposites with 3 and 5wt% of SiAlON nanopowder in Na2CO3 solution have chemical resistance higher than neat epoxy resin based on crack initiation andpropagation. All of samples in H2CO3 solution have chemical resistance because wasn’t shown any crack on samples surface. Also nanocomposites containing 5 and 3 wt% of SiAlON nanoparticles improved wear resistance, 34% and 59%, respectively.<\div>
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