cyclic olefin copolymer properties

The initial radical anion of styrene converts to a dianion (or equivalently disodio-) species, which rapidly added styrene to form a "two – ended living polymer." In addition, a weak nucleophile (Nu:) can also added to reduce the concentration of active species even further, thus keeping the polymer "living". [1][2] This can be accomplished in a variety of ways. It is mandatory to procure user consent prior to running these cookies on your website. Dissertations from 2017. Index of Refraction Index of refraction, n, is an optical property that describes how light propagates through a material.It is defined as. [7], Today, living polymerizations are used widely in the production of many types of polymers or plastics. The synthetic techniques used range from ROMP to generic anionic or cationic living polymerizations. The chelate initiators have a high potential for living polymerizations because the ancillary ligands can be designed to discourage or inhibit chain termination pathways. Twenty years later, living polymerization was demonstrated by Szwarc through the anionic polymerization of styrene in THF using sodium naphthalene as an initiator.[9][6][10]. Found inside – Page 3-33Gas separation properties in cyclic olefin copolymer membrane studied by positron annihilation, sorption, and gas permeation. J. Membr. Sci. 274(12): 192–99. Huang, Shu Hsien, Chien Chieh Hu, Kueir Rarn Lee, Der Jang Liaw and Juin Yih ... [19], The first strategy involves a reversible trapping mechanism in which the propagating radical undergoes an activation/deactivation (i.e. small initiator to monomer ratio) the Mn is not easily to controlled, for some monomers, since self-condensation between monomers occurred more frequently due to the low propagating species concentration. *Dry air or nitrogen required for operation below 20 °C. If you continue browsing the site, you agree to the use of cookies on this website. Expatica is the international community’s online home away from home. Found inside – Page 2424.8.2.4 Cyclic Olefin Copolymer Cyclic olefin copolymer (COC) materials are widely used in optical devices inasmuch as they have very stable optical properties and display low fluorescence. They also have low moisture uptake (<0.01%), ... used. where c is the speed of light in a vacuum, and v is the speed of light through the material. Found inside – Page 233... monomer-titania nanocomposites. e-Polymers 14(4):267–275 Kasgoz A, Akın D, Ayten AI, Durmus A (2014) Effect of different types of carbon fillers on mechanical and rheological properties of cyclic olefin copolymer (COC) composites. [4], Metallocene initiators are considered as a type of Ziegler-Natta initiators due to the use of the two-component system consisting of a transition metal and a group I-III metal co-initiator (for example methylalumoxane (MAO) or other alkyl aluminum compounds). Found inside – Page 105excellent electrical properties and improved thermal resistance over polyethylene and polypropylene. Cyclo olefin copolymers offer an excellent mix of optical and mechanical properties compared to other optically clear plastics. SVKM’S NMIMS, Mumbai This issue has been up for debate the view points of different researchers can be found in a special issue of the Journal of Polymer Science titled Living or Controlled ?. 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This can lead to a high ability to tune the properties of the polymer to a desired application (electrical/ionic conduction, etc.)[4][18]. Starting in the 1970s several new methods were discovered which allowed the development of living polymerization using free radical chemistry. Fast and complete initiation of the monomer. TEMPO used in Nitroxide Mediated Radical Polymerization) or an organometallic species. Found inside – Page 66... norbornene yields the so-called cyclic olefin copolymers (COC), characterized by low degree of crystallinity, high glass transition temperature, low moisture uptake, and excellent optical properties. In addition to copolymerization ... Found inside – Page 123Among these new cyclic olefin copolymers, made accessible from metallocenes [22, 28, 38–93], ... These properties make them suitable for optical applications such as coatings for high-capacity CDs and DVDs, for lenses, medical equipment ... There are two general strategies employed in CRP to suppress chain breaking reactions and promote fast initiation relative to propagation. With in-depth features, Expatica brings the international community closer together. Of these three types, block and gradient copolymers are commonly synthesized through living polymerizations, due to the ease of control living polymerization provides.

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