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Morphological changes in Polyvinyl Butyral (PVB) electrospun nanofibres can be acquired by preparation of PVB spinning solution in different solvents. Accordingly, three solvents, including ethyl alcohol, n-butanol and isopropanol, with diverse physical properties (e.g. boiling point, density, dipole moment and dielectric constant) were used to prepare PolyVinyl Butyral (PVB) spinning solution. The PVB polymer was used in two ranges of molecular weight. Scanning Electron Microscopy (SEM) was employed to determine the morphological aspects. Results demonstrated a very high increase in the nanofibre diameter, with decreasing dipole moment and increasing boiling point and density of solvents. The smallest nanofibre diameter and bead structure was revealed for the PVB solution prepared by n-butanol. With regard to morphological aspects, isopropnol was selected as the most suitable solvent for a range of PVB molecular weightsKeywords: Electrospinning, Polyvinylbutiral, Nanofibre, Isopropanol, Butanol, Ethanol
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بزرگترین منبع صنعتی پلی وینیل الکل، پلی وینیل استات است. سایر منابع تنها برای کارهای پژوهشی و ویژه موجوداند. باتوجه به منابع عظیم نفت و گاز و دسترس پذیری خوراک اولیه تولید این پلیمر در داخل کشور (مونومر وینیل استات تولیدی پتروشیمی اراک)، پتانسیل مناسبی برای تولید پلی وینیل استات و پلی وینیل الکل و مواد حاصل از این محصولات (مانند پلی وینیل بوتیرال و...) درکشور وجود دارد. ارزیابی های فنی و اقتصادی تولید این پلیمر پرمصرف وارداتی، با آمارهای ارائه شده توسط وزارت های صنعت، معدن و تجارت و نفت، تولید صنعتی آن را در صدر اولویت های سرمایه گذاری قرارداده است. پلی وینیل الکل با توجه به درجه آبکافت و جرم مولکولی های مختلف دارای درجه های متفاوتی است که با تغییر شرایط فراورش در طول تولید می توان به آنها دست یافت. این مقاله تلاشی برای بررسی جایگاه پلی وینیل الکل در صنعت و اقتصاد است.
کلید واژگان: پلی وینیل الکل, ارزیابی فنی, ارزیابی اقتصادی, روش تولید, درجه آبکافتPolymerization, Volume:3 Issue: 3, 2013, PP 14 -24The main source of polyvinyl alcohol is polyvinyl acetate. Other sources and methods for polyvinyl alcohol synthesis are intended for research and specific purposes. Considering the significant sources of oil and gas in Iran and the availability of raw material for PVOH (vinyl acetate monomer by Arak Petrochemical Company) and polyvinyl acetate there is a good potential for production of polyvinyl butyral and related polymers. The economical and technical studies by Ministries of Industry, Oil and Commerce have brought the industrial production of PVOH in the first priority of investment activities. This polymer can be produced at different degrees of hydrolysis and molecular weight by variations in processing condition. Different grades of polyvinyl alcohol have found various applications in industry.Keywords: polyvinyl alcohol, technical investigation, economic investigation, method of production, degree of hydrolysis -
در این تحقیق اثر پاراتولوئن سولفونیک اسید (P T S A) و پلی وینیل بوتیرال رزین (P V B) بر خواص بین لایه یی، حرارتی و سایش درپانویس{a b l a t i o n} کامپوزیت های کربن/فنولیک مورد بررسی قرار گرفته است. چهار دسته نمونه برای آزمایش فداشونگی حرارتی توسط مشعل پلاسما آماده شده است. برای مقایسه ی استحکام برشی بین لایه یی نمونه های کامپوزیتی، از آزمایش برش تیر کوتاه استفاده شده است. نتایج نشان می دهد که افزودن 20 درصد بوتیرال رزین به زمینه باعث کاهش 15 درصدی نرخ سایش خطی کامپوزیت های کربن/فنولیک نسبت به سایر نمونه ها می شود. همچنین استفاده از پاراتولوئن سولفونیک اسید در پخت نمونه ها، نرخ سایش وزنی کامپوزیت های کربن/فنولیک را 35 درصد کاهش می دهد. بیشتر بودن شاخص عایق بودن نمونه های حاوی بوتیرال رزین باعث شده است که این کامپوزیت ها بهترین محافظ حرارتی در میان کامپوزیت های مورد بررسی معرفی شوند. با توجه به نتایج حاصل از آزمایش برش تیر کوتاه، استحکام برشی بین لایه یی کامپوزیت های حاوی پلی وینیل بوتیرال رزین 12 درصد بیشتر از سایر نمونه هاست.
کلید واژگان: کامپوزیت های کربن فنولیک, سایش, استحکامبرشی بین لایه یی, مشعل پلاسماDuring atmospheric re-entry, a ballistic or space vehicle is subjected to severe aerodynamic heating and its successful return through the Earth's atmosphere depends largely on the provision that is made for reducing aerodynamic heat transfer to its structure. For this purpose, an ablative heat shield is normally used, which undergoes physical, chemical, and mostly endothermal transformations. These transformations produce new liquid or gas phases, which are subsequently injected into the environment.The interfacial, thermal and ablation properties of carbon fiber/phenolic resin composites are evaluated in this study. Different materials, such as plain carbon fabrics, as reinforcement, resole type phenolic (IL800, Resitan Co.) as matrix, p-toluene sulfonic acid (PTSA) and polyvinyl Butyral resin (PVB) as additive, have been used in the synthesis of the composites. Four groups of samples were fabricated to be investigated by a plasma torch. In order to explore the interlaminar shear strength of the composites, short-beam shear tests were conducted. Short-beam shear tests indicate that the interlaminar shear strength of the C/P/PVB composite is 17% greater than that of the other samples. Observations show that 20% PVB has an important effect on proper adhesion between carbon fibers and the resole matrix of C/P composites, and on achieving improved interlaminar characteristics. The ablation test results reveal that composites with 20% polyvinyl butyral resin (C/P/PVB) have the highest ablation resistance, and the erosion rate (mm/s) of these specimens are 20% lower than other specimens. Additionally, the high insulation index of the C/P/PVB samples indicates that these composites are the best ablative materials in the present study. But, results show that the mass reduction percentage of C/P/PTSA/PVB samples is around 28% lower than C/P/PVB samples. According to Table 3, addition of PVB to C/P composites caused 70% improvement in the thermal conductivity of C/P/PVB composites. Regarding samples with 4-7 wt% PTSA, against our expectations, these samples, because of their porous structure, did not have appropriate ablative performance.Keywords: Carbon phenolic composites, ablation, interlaminar shear strength, plasma torch -
Polyvinyl butyral (PVB) was synthesized by condensation reaction of polyvinyl alcohol (PVA) with butanal in aqueous medium containing an effective emulsifier and an inorganic acid as catalyst. The product was characterized by, IR, TG and DTG techniques. Percentage of vinyl alcohol groups in the PVB was determined by a chemical method according to a standard method. Some clear and soft film samples containing the PVB and some high boiling point plasticizers were made by hot press. For this purpose plasticizers such as bis(2-ethylhexyl)phthalate (DOP) and bis(2-ethylhexyl) terephthalate (DOTP) were purchased and the triethylene glycol bis(2-ethylhexanoate) (TEGB) was synthesized. The film samples containing 30 percent mixture of triethylene glycol bis(2-ethylhexanoate) and bis (2-ethylhexyl)phthalate with ratio 65/35 showed some improved mechanical and optical properties.Keywords: polyvinyl butyral, polyvinyl alcohol, safety glass, Mechanical Properties, clarity
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This research is aimed to undertake a comparative study on stability and thermal degradation kinetics of un-irradiated and high energy protons irradiated polyvinyl butyral (PVB) based on weight loss analysis and non-isothermal approaches. The weight loss by the un-irradiated PVB upon heating was found to be in two stages but due to high energy protons accelerated exposure following by chemical etching, this weight loss transition proceeds in a major one stage with increases in the highest rate of weight loss temperature. In addition, the samples were analyzed using the FT-IR spectroscopy technique to illustrate the stability of irradiated-chemical etched PVB, and also elucidate the mechanism of degradation. The effect of irradiation on the surface of PVB films was investigated by scanning electron microscope (SEM) after and before irradiation. The kinetic triplet and other related thermal kinetic parameters of un-irradiated and irradiated-chemical etched PVB films are presented and compared together. The results showed that due to high energy protons irradiation exposure following by chemical etching, the thermal stability of the PVB film is significantly increased.
Keywords: FT, IR, Polyvinyl butyral, Proton irradiation, TGA, Thermal Degradation -
In this work, polypyrrole/ZnO nanocomposite PPy/ZnO NC was produced through synthesis of polypyrrole polymer in the presence of ZnO nanoparticles. The corrosion behavior of polyvinyl butyral coatings without and with different weight percentages of nanocomposite on the surface of 7075 Al alloy was investigated in 3.5 NaCl solution at different times of immersion using electrochemical impedance spectroscopy EIS and electrochemical noise EN techniques. The coating with 0.025 PPy/ZnO NC revealed the highest corrosion resistance. In order to analysis of EN data, wavelet transform was used to obtain the standard deviation of partial signal SDPS plots. The good agreement between the EIS and EN results indicates that the EN technique, as well as the EIS method, can be used successfully for the corrosion evaluation of coatings.Keywords: Nanocomposite, Polyvinyl butyral, Electrochemical Impedance Spectroscopy, Electrochemical Noise, Wavelet Analysis
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In the present work, four polymeric nanocomposite PNC coatings were prepared with different concentrations of yttrium aluminum garnet nanoparticles YAG-NPs in polyvinyl butyral PVB matrix. The corrosion protection of the PNC coatings applied on the carbon steel surface was investigated in 1.0 M HCl solution by electrochemical impedance spectroscopy EIS. The YAG-NPs were synthesized by pulse electrochemical method. The formation of YAG-NPs was confirmed through XRD and SEM analysis. The EIS data obtained from the coated samples both without and with YAG-NPs samples were fitted with an equivalent circuit containing two time constants. The protection efficiency values of the PNC coatings were calculated from EIS data. The PNC coating containing 0.025 wt YAG-NPs as the efficient coating showed the best corrosion protection in HCl solution for immersion times up to 28 days.Keywords: YAG Nanoparticles, Polyvinyl Butyral, Protection Efficiency, Electrochemical Impedance Spectroscopy (EIS)
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In this work, a series of polypropylene/polyvinyl butyral (PP/PVB) blends were prepared by melt-blending process, at PVB loadings 3 wt%, 10 wt%, and 30 wt%. The effects of PVB on crystallization behavior of PP were investigated by differential scanning calorimetry (DSC), and polarized optical microscopy (POM). The isothermal crystallization kinetics were analyzed by Avrami equations. It was found that the addition of PVB strikingly reduced the overall crystallization rate of PP. The POM results further indicated that the crystallization rate of PP/PVB was significantly reduced by reducing the nucleation density of PP with the addition of PVB. The fractured surface morphology of PP/PVB blends was characterized by scanning electron microscopy (SEM), and the results showed that the PVB was uniformly dispersed in the PP matrix as small spherical particles, with a good dispersion and dimensional stability.Keywords: PP, PVB blend, isothermal crystallization, nucleation density, morphology
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Herein, polyvinyl butyral (PVB) films were synthesized using casting method and added to the PVB solution to make composites of PVB-nanoparticles were made via mixing 0.001 wt/wt % each time of each of the following metal nanoparticles (CuO, Cr2O3, NiO, TiO2 and Co3O4(NPs)) with PVB solution at room temperature. The PVB-NP composites as films were irradiated with UV light for prolonged period which demonstrated spectral, and weight-loss changes. Those changes were much more significant than that of the blank PVB films undergo under identical conditions. Incorporating surface morphology examination of the composites were conducted using scanning electron microscopy (SEM), energy x-ray dispersive (EDX) spectroscopy and atomic force microscope. Overall, findings revealed that PVB-(CuO, Cr2O3, NiO, TiO2 and Co3O4) NP composites showed a higher weight loss in compared to the PVB blank suggestive of higher photodegradation of the PVB-NP composites compared to the neat PVB film. A proposed photodegradation mechanism will be discussed.Keywords: UV exposure, poly(vinyl butyral), Nanoparticles, FESEM, irradiation
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پلیمرها در طیف وسیعی از صنایع کاربرد دارند. در این پژوهش، به بررسی رفتار مکانیکی پلیمرهای مورد استفاده در صنایع شیشه سازی پرداخته شده است. پلیمرهای مورد بررسی شامل پلی یورتان ترموپلاستیک (TPU)، پلی وینیل بوتیرال (PVB) و سنتری گلس (SG) بودند. این پلیمرها در نرخ کرنش های مختلف از s-1 001/0 تا 25/0 تحت آزمایش های کشش و فشار قرار گرفتند. همچنین، خواص دینامیکی مکانیکی پلیمرها با استفاده از آزمون آنالیز دینامیکی مکانیکی در فرکانس ثابت انجام شد. نتایج آزمون کشش نشان داد که رفتار مکانیکی پلی یورتان به نرخ کرنش وابسته نبوده ولی SG به شدت به نرخ کرنش حساس بوده است. همچنین، با افزایش نرخ کرنش، تنش شکست SG به شدت کاهش یافت. نتایج آزمون فشار نشان داد که TPU تنش بیشتری را می تواند تحمل کند. دمای شیشه ای شدن TPU نسبت به پلیمرهای دیگر پایین تر بود. در مجموع می توان نتیجه گرفت که در میان پلیمرهای مورد بررسی در این پژوهش، TPU رفتار مکانیکی بهتری داشته است.
کلید واژگان: پلیمر, نرخ کرنش, آزمون دینامیکی مکانیکی, بارگذاری شبه استاتیکی., میان لایهPolymers are used in a wide range of industries. In this research, the mechanical behavior of polymers used in the glass industry has been studied. The investigated polymers included thermoplastic polyurethane (TPU), polyvinyl butyral (PVB) and sentry glas (SG). These polymers were subjected to tension and compression tests at different strain rates from 0.001 to 0.25 s-1. Also, the mechanical dynamic properties of the polymers were extracted using the mechanical dynamic analysis test at a constant frequency. The tensile test results showed that the mechanical behavior of polyurethane is not dependent on strain rate, but SG is highly sensitive to strain rate. Also, with increasing strain rate, the fracture stress of SG decreased drastically. The pressure test results showed that TPU can withstand more stress. The glass transition temperature of TPU was lower than the other two polymers. Overall, it can be concluded that among the polymers studied in this research, TPU had better mechanical behavior.
Keywords: Polymer, strain rate, mechanical dynamic analysis, quasi-static loading, interlayer
نکته:
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علمی763
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معتبرحذف فیلتر
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