دانلود رایگان ترجمه مقاله ویژگی اسپکتروسکوپی واکنش کراس لینک هیدروژل پلی وینیل الکل – وایلی ۱۹۹۹
دانلود رایگان مقاله انگلیسی بررسی اسپکتروسکوپی واکنش کراس لینک هیدروژل پلی وینیل الکل و پلی اکریلیک اسید به همراه ترجمه فارسی
عنوان فارسی مقاله: | هیدروژل های پلی(وینیل الکل) / پلی ( اکریلیک اسید): بررسی اسپکتروسکوپی FT-IR واکنش کراس لینک و کار در نقطه گذار |
عنوان انگلیسی مقاله: | Poly(vinyl alcohol)/poly(acrylic acid) hydrogels: FT-IR spectroscopic characterization of crosslinking reaction and work at transition point |
رشته های مرتبط: | شیمی، شیمی کاربردی، شیمی آلی، شیمی پلیمر، مهندسی پلیمر، پلیمریزاسیون |
فرمت مقالات رایگان | مقالات انگلیسی و ترجمه های فارسی رایگان با فرمت PDF میباشند |
کیفیت ترجمه | کیفیت ترجمه این مقاله پایین میباشد |
توضیحات | ترجمه به صورت کمی خلاصه انجام شده است |
نشریه | وایلی – WILEY |
کد محصول | F93 |
مقاله انگلیسی رایگان |
دانلود رایگان مقاله انگلیسی |
ترجمه فارسی رایگان |
دانلود رایگان ترجمه مقاله |
جستجوی ترجمه مقالات | جستجوی ترجمه مقالات |
بخشی از ترجمه فارسی: واکنش کراس لینک پلی اکریلیک خالص و ترکیب آن با پلی وینیل الکل توسط طیف سنج FT-IR مطالعه شد. پی برده شد که ر ترکیبات، تشکیل انیدرید برای پلی اکریلیک اسید، یک واکنش کراس لینک غالب تحت گرمایش است. با این حال، تشکیل استر بین پلی وینیل الکل و پلی اکریلیک اسید به دلیل ارتعاشات استری و ارتعاشات قابل تشخیص است. درجه آماس و ضریب کشسانی یانگ ترکیب کراس لینک در آب مقطر بستگی به زمان و دمای تیمار حرارتی دارد. در وابستگی مقدار اسیدیته عامل آماس، ترکیب یا متورم شده و یا این که آب خود را از دست می دهد.انرژی کار در فرایند آماس یا از دست دهی آب ناشی از تغییر مقدار اسیدیته ترکیبات می باشد که در این مطالعه اندازه گیری شد. مقادیر در یک دامنه قابل قبول فنی بودند. |
بخشی از مقاله انگلیسی: The crosslinking reaction of pure poly(acrylic acid) and its blend with poly(vinyl alcohol) was studied by FT-IR spectroscopy. It is demonstrated that also in blends the anhydride formation characteristic for pure poly(acrylic acid) is the predominant crosslinking reaction upon heating. But the ester formation between poly(vinyl alcohol) and poly(acrylic acid) is detectable due to the ester C2O vibrations and C1O1C vibrations, respectively. The degree of swelling and the Young’s modulus of the crosslinked blend in deionized water depend on the time and temperature of the heat treatment. In dependence of the pH-value of the swelling agent the blends swell or shrink. The working energy at the shrinking or swelling process induced by a change of the pH-value of differently treated blends was measured. The values are in a range of technical interests and comparable with other microactuators. 1. Introduction Polyelectrolytes change their conformation with the degree of dissociation which is a function of such quantities as pH-value, polarity of the solvent, ionic strength and temperature. Thus, the change of conformation in swollen crosslinked polymers results in a dependence of the degree of swelling on the physical properties of the swelling agent. Hence the chemical energy can be converted reversibly into mechanical energy in such gels. The idea to use polymer gels as a muscle-like actuator originates from the work of Kuhn et al. on polyelectrolyte gels [1, 2]. Developments arising from the original idea can be followed in a more recent review [3]. One of the simplest pH-sensitive hydrogels can be prepared by crosslinking a blend of poly(vinyl alcohol) (PVA) and poly(acrylic acid) (PAA). There are several ways for the preparation of a network. It is possible to prepare a three-dimensional network by repetitive freezing and thawing cycles of PVA water solutions [4, 5]. It is demonstrated by 13C NMR spectroscopy that the junction points are formed by hydrogen bonds [6]. Applying the same cycles to a water solution of PVA and PAA leads to porous gels where the equilibrium degree of swelling depends on the pH-value of the swelling agent. It is assumed that an entanglement network with a high concentration of PVA and PAA chains in the physical junction points is formed [7]. Treatment of the hydrogel with 1 N HCl results in a chemical crosslinking via esterification. The gels are shape resistant and insoluble in boiling water but they are very soft due to their porous nature and not suitable for an application as actuators. pH-sensitive networks of PVA and PAA can also be formed by crosslinking polymerization of acrylic acid in the presence of PVA followed by crosslinking of the PVA [8]. These interpenetrating networks (IPN) are pH and temperature sensitive depending on their molecular structure [9]. Simply heating PVA and PAA and placing the system into water leads also to a crosslinked hydrogel. It is assumed that a crosslinking of the completely miscible blend system occurs via esterification [10]. According to Zhang et al. the miscibility of the blend system PVA/PAA is caused by strong hydrogen bonds between the COOHand OH-groups and that during the annealing procedure a polyester is formed [11]. The mechanical properties and the capability to carry out mechanical work is of fundamental importance for the application of thermally crosslinked PVA/PAA blends. The aim of this study is to understand quantitatively the chemical reactions occurring during the thermal treatment of PVA/PAA blends. FT-IR spectroscopy is applied as a suitable tool for these studies. The degree of swelling and the mechanical properties are studied as a function of the annealing time and annealing temperature of the PVA/ PAA blends. The volume related capability of work (working energy) during the change of the pH-value of the swelling agent of hydrogels with a different degree of crosslinking is measured as a function of the mechanical stress and compared to different microactuators |
ممنون از سایت بسیار عالیتون . لطفا از مقاله های شیمی فیزیک هم امکانش باشه روی سایتتون قرار دهید ممنون .