Download or read book Catalytic Hydrogenation of Natural Rubber written by D. R. Burfield and published by . This book was released on 1985 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book A Study of Non catalytic Hydrogenation of Natural Rubber written by Jareerat Samran and published by . This book was released on 2005 with total page 288 pages. Available in PDF, EPUB and Kindle. Book excerpt: Hydrogenation is one of the most efficient methods to alter and improve the physical properties of unsaturated polymers and to produce a new material. The aim of this research is to transform partially the unsaturated part of natural rubber (NR) into saturated moiety in order to improve its thermal and oxidative properties and to widen its area of applications. In this study, non-catalytic hydrogenation process was applied by using diimide generated in situ from two types of hydrogenating agent i.e. thermal decomposition of p-tolueriesulfonylhydrazide (TSH) and oxidation of hydrazine (N2H4) by hydrogen peroxide (H2O2). The chemical structure of the hydrogenated rubbers was analyzed by vibrational and resonance spectroscopies i.e. FTIR, Raman, 1H- and 13C-NMR. First, the hydrogenation of NR and its modified form as epoxidized NR (ENR) was performed by using TSH in xylene solution at 135°C. The molar ratio of [TSH]:[C=C] equal to 2 was used for hydrogenation of NR and four different types of ENR i.e.ENR-10, ENR-22, ENR-30 and ENR-40, containing 10, 22, 30 and 40% mole of epoxide content, respectively. The quantitative measurements on fraction of saturated units determined by Raman, 1H-NMR in liquid state and 13C-NMR in solid state gave similar results which indicated that percent hydrogenation increased with increasing reaction time and about 80-89 % hydrogenation was obtained at 8h. While in the case of ENRs, the percent hydrogenation is approximately 93-98%. Cis-trans isomerization was also observed by 1H-NMR in liquid state and 13C_NMR both in liquid and solid state. Sorne side reaction occurred i.e. chain degradation of both NR and ENRs which might be due to a relatively high temperature process. In the case of hydrogenation of ENRs, formation of furan structure and fixation of p-toluenesulfinic acid (TSOH) by-product were detected by FTIR. For hydrogenation using (N2H4) and (H2O2), NR in the original form of latex was used. Various parameters affecting the hydrogenation reaction were investigated i.e. reaction time and temperature, amount of reactants, and dry rubber content. The hydrogenation progress could be monitored by means of NMR in liquid state as function of reaction condition. The results indicated that the best result was obtained when equimolar ratio of (N2H4) and (H2O2) was used. With addition of varying hydrazine and hydrogen peroxide contents, the best condition of diimide reduction is achieved when their content is 1.5 times the amount C=C of the rubber. Molecular characteristics in the NR, ENR-l 0 and the hydrogenated rubbers were investigated by Raman and 13C-NMR in solid state techniques. The relative variation force constant as analyzed by Raman spectroscopy tends to increase with the hydrogenation level. It might be suggested that the higher stiffness of the rubber chains upon hydrogenation is correlated to the increased relative variation force constants. In cross-polarization (CP) experiment of HNR and HENR, it was found that the rate of cross polarization of methyl carbon in HENR-30(8) is highest with respect to methyl carbon in HNR(8) and HENR-IO(8). It is clear that the methyl carbon of HENR-30(8) has the least mobility due to more furan units and chemical fixation of TSOH on the rubber chains. Thermal properties studied by a differential scanning calorimetry revealed thermal improvement after hydrogenation, both in solution and in aqueous systems. Comparison of the thermal stability using thermogravimetric analyzer, under air and nitrogen atmosphere, showed the decomposition temperature of HNR in air is lower than that in nitrogen atmosphere. The thermal stability of ENR was also enhanced after hydrogenation. Rheological properties of HNR samples measured using RPA rheometer exhibited the storage and loss moduli of HNR97 sample with the highest value compared to HNR38 and HNR69 samples. For instance, the fully hydrogenated NR has a significant increment in the loss and storage moduli of the samples. By using Raman mapping technique, it revealed that the hydrogenation of NR is a random process at the micron level.
Download or read book Studies on the Hydrogenation of Natural Rubber Using Nickel 2 ethylhexanoate as Catalyst written by Nadaraja Subramaniam and published by . This book was released on 1995 with total page 350 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Catalytic Hydrogenation of Rubber written by Harry Elmer Albert and published by . This book was released on 1939 with total page 126 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Chemistry Manufacture and Applications of Natural Rubber written by Shinzo Kohjiya and published by Elsevier. This book was released on 2014-02-17 with total page 543 pages. Available in PDF, EPUB and Kindle. Book excerpt: The growing demand for more sustainable materials has led to increased research on the properties of natural rubber. Chemistry, Manufacture and Applications of Natural Rubber summarizes this research and its significance for the industrial applications of natural rubber. Chapters in part one explore the properties and processing of natural rubber, including the biosynthesis of natural rubber in different rubber-producing species, chemical modification of natural rubber for improved performance, and the effect of strain-induced crystallization on the physical properties of natural rubber. Further chapters highlight hydrophobic and hydrophilic silica-filled cross-linked natural rubber and computer simulation of network formation in natural rubber. Part two focusses on applications of natural rubber, including eco-friendly bio-composites using natural rubber matrices and reinforcements, soft bio-composites from natural rubber and marine products, natural rubber for the tire industry, the application of epoxidized natural rubber in pressure sensitive adhesives (PSAs), and the use of natural rubber for vibration isolation and earthquake protection of structures. Finally, chapters in part three consider environmental and safety issues associated with natural rubber, including improving the sustainable development of natural rubber, the recycling of natural and synthetic isoprene rubbers and of sulfur cross-linked natural rubber, and recent research on natural rubber latex allergy. Chemistry, Manufacture and Applications of Natural Rubber is a comprehensive resource for academics, chemists, chemical engineers, mechanical engineers, and other professionals in the rubber industry, as well as those industries, including automotive, civil, and medical engineering, using natural rubber products. An updated review with systematic and comprehensive coverage of natural rubbers Covers a broad range of topics, including the chemistry, processing, sustainability, and applications of natural rubbers Coverage of the best international research, including key experts from Asia, the United States, South America, and Europe
Download or read book Synthesis and Characterization of Ni and Pd Nanoparticles in Natural Rubber Latex and Their Catalytic Activity for Hydrogenation of Latex written by Nurul Ain Ramli and published by . This book was released on 2013 with total page 129 pages. Available in PDF, EPUB and Kindle. Book excerpt: Natural rubber latex (NRL) is widely used as raw materials for rubber based products. The use of nLatex based polymer is constrained by its degradation in the environment due to the presence of carbon-carbon double bonds in their polymer backbone. Modifications of NRL via catalytic hydrogenation overcome this limitation. This research investigated the synthesis of Ni and Pd nanoparticles (NPs) in latex and determined the catalytic performances of both nanoparticles for the hydrogenation of latex. The effects of synthesis method, pH, sonication time and concentration of latex and metal ions precursor towards the formation of metal nanoparticles (Me-NPs) were studied. Transmission electron microscopy (TEM) was employed to study the morphology and particle size distribution of the NPs. The interactions between NPs with latex were studied using Fourier transform infrared (FTIR) spectroscopy. The catalytic hydrogenations of NRL by asprepared NPs were studied under different reaction conditions in order to investigate the effect of these variables towards the extent of hydrogenation. These include the effect of catalyst amount, nanoparticles size and solvent types. The structure, morphology and degree of hydrogenation of the hydrogenated NRL were determined by FTIR, scanning electron microscopy (SEM), field emission scanning electron microscopy (FESEM) and 1H nuclear magnetic resonance (NMR) spectroscopy respectively. Latex was found to be able to stabilize Ni and Pd NPs. Preparation involving the combination of ultrasonication and microwave irradiation upon the addition of NaBH4 into latex and metal ion mixture resulted in the most well dispersed NPs. The particle size of the NPs decreases as pH, sonication time, and stabilizer concentration increases. However, the particle size increases with the increase of metal ions precursor's concentration. It was found that 10 ml of 0.003 M metal ions precursor concentration with 30 ml of stabilizer at pH 11.50 exposed to 15 minutes of sonication is an optimum condition to synthesize Ni-NRL and Pd-NRL. Under this preparation condition, the mean size of Ni-NRL was 10.8±0.3 nm while that for Pd-NRL was 30.6±2.9 nm. Hydrogenation of NRL using as-prepared NPs showed that the degree of hydrogenation increases with catalyst amount. The extent of hydrogenation is dependent on the particles sizes of the Ni-NRL but weakly dependent on and Pd-NRL NPs. Under similar reaction condition, Pd-NRL caused higher conversion than that of Ni-NRL. Monochlorobenzene was observed to be a suitable solvent for the hydrogenation reaction. Aqueous phase catalytic hydrogenations of NRL by the Ni-NRL and Pd-NRL were also investigated and found to cause 30% conversion compared to 70% for that in monochlorobenzene. Quadrupling the amount of nanocatalyst used to 2.4 x 10-5 mole led to 90% conversion of latex. Hence in this research it was found that not only the nanoparticles of Ni and Pd could be formed and stabilized in natural rubber latex but they could catalyze the hydrogenation reaction of the latex. It was also found that the nanoparticles could also facilitate the hydrogenation reaction in aqueous medium at moderate condition indicating the possibility of green catalysis for hydrogenation of latex.
Download or read book Thermoplastic Vulcanizates Based on Hydrogenated Natural Rubber Polypropylene Blends written by Korn Taksapattanakul and published by . This book was released on 2016 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The non-catalytic hydrogenation of natural rubber latex (NRL) was carried out by using diimide generated in situ from the reaction between hydrazine (N2H4) and hydrogen peroxide (H2O2). The effects of mole ratios of [C=C]:[N2H4]:[H2O2], reaction conditions, solvent types, solvent volumes and reaction scale-up on the hydrogenation levels were investigated. Nuclear magnetic resonance (NMR), Fourier transform infrared (FTIR), and Raman spectroscopic techniques were employed to investigate the chemical structure of the hydrogenated natural rubber (HNRs) and to quantify the hydrogenationlevels. It was found that variations in moles of N2H4 and H2O2 in the range of 1.0-2.0 moles resulted in degrees of hydrogenation in the range of 10-18%. Little improvement in hydrogenation levels of HNRs was obtained when NRL particles were swollen in solvents by which toluene yielded better results than hexane. The increase in toluenevolume resulted in the increase in hydrogenation levels up to 42 %. TEM micrographs revealed that swelling mainly occurred at the surface of NRL particles, implying that hydrogenation reaction confined largely at the surface of NRL particles. After removal of toluene, particle size and particle size distribution of partially hydrogenated NRL remained unchanged. To further improve degrees of hydrogenation, the reaction volume was extended and 65% hydrogenation levels were obtained. Therefore, 14%HNR, 33%HNR, and 65%HNR were successfully prepared under suitable reaction conditions. However, crosslinking and cis-trans isomerization were side-reactions occurring during hydrogenation. Gel and trans contents increased with increasing hydrogenation levels, leading to the increase in hardness of HNRs. Mooney viscosities of HNRs increased with increasing degrees of hydrogenation due to the increased gel contents. Mooney torquerelaxation of NR and HNRs were similar. Thermogravimetric analysis revealed that vi HNRs had greater thermal stability than NR and thermal stability increased with increasing degrees of hydrogenation. HNR vulcanizates were much better resistant to ozone and UV than cured NR. Sulfur-vulcanized rubbers had greater ozone resistance than peroxide-cure rubbers due to less amounts of carbon-carbon double bonds present in rubbers. In addition, modulus at low strain and tensile strength of sulfur-cured rubbers were higher than those of peroxide-cured rubbers, but lower elongation due to higher crosslink densities. Also, modulus at low strain and tensile strength increased with increasing hydrogenation levels of HNRs, in contrast to strain at break. Thermoplastic vulcanizates (TPVs) from blends of HNR and Polypropylene (PP) were prepared via dynamic vulcanization using peroxide and sulfur as curing agents. The effects of blend ratios on mechanical properties of TPVs were investigated. Tensile strength increased with increasing PP portions, but breaking strain decreased. Morphology of TPVs was characterized with Raman mapping and scanning electron microscope (SEM). The phase sizes of crosslinked rubber obtained from both techniques were correlated well.
Download or read book Hydrogenated Skim Natural Rubber Prepared by Diimide Reduction and Its Vulcanizates written by and published by . This book was released on 2008 with total page 196 pages. Available in PDF, EPUB and Kindle. Book excerpt: Hydrogenation is an important method of chemical modification, which improves the physical, chemical and thermal properties of diene based polymers. Skim natural rubber latex (SNRL) produced as a by-product from the production of concentrated natural rubber latex, could be hydrogenated to a strictly alternating ethylene-propylene copolymer (EPDM) by diimide reduction, using hydrazine and hydrogen peroxide with copper sulfate as catalyst. The hydrogenated products were characterized by FTIR and NMR spectroscopy. The effect of various reaction parameters on the hydrogenation level, were investigated. Low temperature, long reaction time, high amount of hydrazine and lesser amount of hydrogen peroxide and copper sulfate were required to optimize the hydrogenation reaction of SNRL. Copper acetate was a highly active catalyst for the reaction. The kinetic result indicated that the diimide hydrogenation of SNRL exhibited a first order behavior with respect to the C=C concentration. The activation energy of catalytic and non-catalytic diimide hydrogenation of SNRL was 9.5 and 21.1 kJ/mol, respectively. The thermogravimetric analysis indicated that the thermal stability of hydrogenated skim natural rubber (HSNR) was higher than their parent polymer. From TEM micrograph of hydrogenated SNRL particles, non-hydrogenated rubber core and hydrogenated rubber layer were observed according to the layer model. The particle size and particle size distribution of hydrogenated SNRL were not changed during hydrogenation. In addition, the mechanical properties and ozone resistance of vulcanized HSNR blends were also investigated. The increase in HSNR content in the blends could retard the ozonolysis resulting in the surface cracking.
Download or read book Handbook of Natural Polymers Volume 2 written by M.S. Sreekala and published by Elsevier. This book was released on 2024-06-28 with total page 590 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Handbook of Natural Polymers, Volume Two: Functionalization, Surface Modification, and Properties covers modifications, functionalization, analysis and properties of polymers from natural sources. The book begins by introducing the current state-of-the-art, challenges and opportunities in natural polymers. This is followed by detailed coverage of methods for chemical, physical and surface modifications, and functionalization of natural polymers, including nanocellulose composites, gluten, chitin, alginate, pectin, keratin, shellac, wool, hemicellulose, lignin, natural rubber, albumin, collagen, gelatin, zein, soya protein, silk fibroin, gutta percha and gum. The final chapters explain several other key aspects, such as microscopical and spectroscopical analysis, mechanical, thermal, and more. The book aims to offer potential avenues for the preparation, modification, and implementation of advanced natural polymer-based materials with the desired properties for specific applications. Provides systematic coverage of the latest methods for functionalization, surface modification, and properties' analysis of natural polymers Includes an extensive range of natural polymer sources, including established biopolymers and emerging materials Explores modifications and properties of natural polymers and their related composites, blends, IPNs, gels and nanoparticles
Download or read book Advances in Organometallic Chemistry written by Pedro J. Perez and published by Academic Press. This book was released on 2015-10-07 with total page 135 pages. Available in PDF, EPUB and Kindle. Book excerpt: Advances in Organometallic Chemistry contains authoritative reviews on the field of organometallic chemistry, covering topics in organometallic synthesis, reactions, mechanisms, homogeneous catalysis, and more. The book will benefit a wide range of researchers involved in organometallic chemistry, including synthetic protocols, mechanistic studies, and practical applications. Contains contributions from leading authorities in the field of organometallic chemistry Covers topics in organometallic synthesis, reactions, mechanisms, homogeneous catalysis, and more. Informs and updates readers on all the latest developments in the field Carefully edited to provide easy-to-read material
Download or read book Direct Catalytic Hydrogenation of Unsaturated Diene based Polymers in Latex Form written by Zhenli Wei and published by . This book was released on 2006 with total page 125 pages. Available in PDF, EPUB and Kindle. Book excerpt: The direct catalytic hydrogenation of nitrile butadiene rubber (NBR) in latex form was studied as a model system for the development of a new latex hydrogenation process for the modification of unsaturated diene-based polymers. NBR is a synthetic rubber of copolymerized acrylonitrile and butadiene produced in latex form by emulsion polymerization. The catalytic hydrogenation of NBR is an important post-polymerization process resulting in a more stable and tougher derivative, hydrogenated NBR (HNBR), which has been widely used in the automotive and oil drilling industry. The present commercial process involves a number of cumbersome steps to obtain solid NBR from the latex and subsequent dissolution of the solid NBR in a large amount of organic solvent followed by solvent recovery after coagulation of the hydrogenated NBR. Since NBR is produced in latex form, it is very desirable to directly hydrogenate NBR in the latex form which will significantly simplify the hydrogenation process and facilitate subsequent applications. As an economical and environmentally benign alternative to the commercial processes based on the hydrogenation of NBR in organic solution, this direct latex hydrogenation process is of special interest to industry. The objective of this project is to develop an efficient catalytic system in order to realize the direct catalytic hydrogenation of NBR in latex form.
Download or read book Catalytic Hydrogenation of Nitrile Butadiene Rubber Using Ir COD PCy3 py PF6 Catalyst written by Jianzhong Hu and published by . This book was released on 2003 with total page 230 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Elastomers written by Nevin Çankaya and published by BoD – Books on Demand. This book was released on 2017-08-30 with total page 266 pages. Available in PDF, EPUB and Kindle. Book excerpt: Summary-Book Contents: Your purpose of reading this book is to concentrate on recent developments on elastomers. The articles collected in this book are contributions by invited researchers with a long-standing experience in different research areas. I hope that the material presented here is understandable to a broad audience, not only scientists but also people with many different disciplines. The book contains eleven chapters in two sections: (1) "Mechanical Properties of Elastomers" and (2) "Elastomers for Natural and Medical Applications." The book provides detailed and current reviews in these different areas written by experts in their respective fields. This book will be useful for polymer workers and other scientists alike and will contribute to the training of current and future researchers, academics, PhD students, and other scientists.
Download or read book Catalytic Hydrogenation of Polymers written by Mark David Gehlsen and published by . This book was released on 1993 with total page 536 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Natural Rubber Materials written by Sabu Thomas and published by Royal Society of Chemistry. This book was released on 2014 with total page 635 pages. Available in PDF, EPUB and Kindle. Book excerpt: A comprehensive two volume set covering the synthesis, characterization and applications of natural rubber based blends, interpenetrating polymer networks, composites and nanocomposites.
Download or read book Catalytic Hydrogenation of Nitrile Rubber in High Concentration Solution written by Ting Li and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Chemical modification is an important way to improve the properties of existing polymers, and one of the important examples is the hydrogenation of nitrile butadiene rubber (NBR) in organic solvent by homogeneous catalysis in order to extend its application. This process has been industrialized for many years to provide high performance elastomers (HNBR) for the automotive industry, especially those used to produce components in engine compartments. In the current commercial process, a batch reactor is employed for the hydrogenation step, which is labor intensive and not suitable for large volume of production. Thus, novel hydrogenation devices such as a continuous process are being developed in our research group to overcome these drawbacks. In order to make the process more practical for industrial application, high concentration polymer solutions should be targeted for the continuous hydrogenation. However, many problems are encountered due to the viscosity of the high concentration polymer solution, which increases tremendously as the reaction goes on, resulting in severe mass transfer and heat transfer problems. So, hydrogenation kinetics in high concentration NBR solution, as well as the rheological properties of this viscous solution are very essential and fundamental for the design of novel hydrogenation processes and reactor scale up. In the present work, hydrogenation of NBR in high concentration solution was carried out in a batch reactor. A commercial rhodium catalyst, Wilkinson's catalyst, was used with triphenylphosphine as the co-catalyst and chlorobenzene as the solvent. The reactor was modified and a PID controller was tuned to fit this strong exothermic reaction. It was observed that when NBR solution is in a high concentration the kinetic behavior was greatly affected by mass transfer processes, especially the gas-liquid mass transfer. Reactor internals were designed and various agitators were investigated to improve the mechanical mixing. Experimental results show that the turbine-anchor combined agitator could provide superior mixing for this viscous reaction system. The kinetic behavior of NBR hydrogenation under low catalyst concentration was also studied. It was observed that the hydrogenation degree of the polymer could not reach 95% if less than 0.1%wt catalyst (based on polymer mass) was used, deviating from the behavior under a normal catalyst concentration. The viscosity of the NBR-MCB solutions was measured in a rotational rheometer that has a cylinder sensor under both room conditions and reaction conditions. Parameters that might affect the viscosity of the solutions were studied, especially the hydrogenation degree of polymer. Rheological properties of NBR-MEK solutions, as well as NBR melts were also studied for relevant information. It is concluded that the hydrogenation kinetics deviates from that reported by Parent et al. [6] when polymer is in high concentration and/or catalyst is in low concentration; and that the reaction solution (HNBR/NBR-MCB solution) deviates from Newtonian behavior when polymer concentration and hydrogenation degree are high.
Download or read book Chemistry Manufacture and Applications of Natural Rubber written by Shinzo Kohjiya and published by Woodhead Publishing. This book was released on 2021-03-24 with total page 508 pages. Available in PDF, EPUB and Kindle. Book excerpt: Chemistry, Manufacture and Applications of Natural Rubber, Second Edition presents the latest advances in the processing, properties and advanced applications of natural rubber (NR), drawing on state-of-the-art research in the field. Chapters cover manufacturing, processing and properties of natural rubber, describing biosynthesis, vulcanization for improved performance, strain-induced crystallization, self-reinforcement, rheology and mechanochemistry for processing, computer simulation of properties, scattering techniques and stabilizing agents. Applications covered include natural rubber, carbon allotropes, eco-friendly soft bio-composites using NR matrices and marine products, the use of NR for high functionality such as shape memory, NR for the tire industry, and natural rubber latex with advanced applications. This is an essential resource for academic researchers, scientists and (post)graduate students in rubber science, polymer science, materials science and engineering, and chemistry. In industry, this book enables professionals, R&D, and producers across the natural rubber, tire, rubber and elastomer industries, as well as across industries looking to use natural rubber products, to understand and utilize natural rubber for cutting-edge applications. Explains the latest manufacture and processing techniques for natural rubber (NR) with enhanced properties Explores novel applications of natural rubber across a range of industries, including current and potential uses Discusses resources and utilization, and considers sustainable future development of natural rubber
