Polymeric materials/polymers elastomeric

Polymeric Materials. The single-ply membranes are made from a wide variety of polymers. The following is a brief description of those polymers and their characteristics. There are three thermosetting-type elastomeric membranes as of this writing (1996) neoprene, CSPE, and EPDM. Neoprene is still used where oil resistance is needed. For instance, Hydrotech uses neoprene flashings, the base of which is hot-set in rubberized asphalt (see Elastot rs, synthetic-polychloroprene). 

Only very few studies with alternative materials and fabrication methods have been published. Ekstrom et al. [35] demonstrated the feasibility of structuring inexpensive polymeric materials by means of a microfabricated master for the production of microchannel systems. The structured polymer film was mechanically clamped between two glass plates to form a closed channel system. Recently, a similar route for the fabrication of microchannel chips that relies on casting of an elastomeric polymer material against a microfabricated master has been presented by Effenhauser et al. [36] (see Sect. 3.4). 

The successful co-polymerization of ethylene with styrene is another polymeric material conquest of homogeneous catalysis. At low styrene incorporation, the co-polymer is substantially a functionalized crystalline polyethylene. Increasing the styrene content results in a decrease of crystallinity while elastomeric properties arise, 3 up to about 80 mol% styrene for higher styrene contents, the co-polymer becomes a glassy amorphous material. A comprehensive review on the properties of ethylene/styrene co-polymers is available.624... 

Equation 11.21 shows another example, where 1-methylcyclobutene polymerizes to form polyisoprene primarily with cis stereochemistry about the C=C. The properties of this polymer are quite similar to those of natural rubber, which is also ct s-polyisoprene.52 In this case, Katz used a discrete metal-carbene complex to catalyze the polymerization. One reason why there has been general interest in ROMP is because cycloalkenes often polymerize to give materials with elastomeric (rubber-like) properties. 

A number of different polymers have been used in the production of microchip electrophoretic devices. One class of polymers is thermoplastics, which melt above a certain temperature but are hard at room temperature. Materials from this class that have been used in the formation of microchip devices include polymethylmethacrylate, polycarbonate, polyethylene, polystyrene, and a number of others. An excellent review on the fabrication and use of polymeric materials in microchips was presented by Becker and Gartner. The second class of materials is elastomeric polymers, the most widely used of which is poly(dimethylsiloxane) (PDMS). Use of this material was covered in a review by McDonald et al. ... 

Catalytic polymerizations of 1,3-butadiene into essentially 1,4 elastomeric polymers are by now pretty well-mastered processes. It is the purpose of this paper to demonstrate the still very vivid interest in that time-honored backbone, within the frame of a much broader trend developing now in the field of polymeric materials. 

In the case of polymer-based materials, composites are often preferred because the mechanical properties of the pure polymer phase are inadequate for the proposed application [4]. To overcome this problan, polymeric materials are reinforced in some way, typically by incorporating a substantial amount of rigid filler. For some polymers, the problem may be that they lack the toughness required for a particular application, and for these materials, elastomeric fillers are used. These fillers have the effect of increasing toughness and the concomitant effect of reducing brittleness. However, this approach is not used for restorative dental materials. 

The impact strength of the polymeric materials is directly related to the overall toughness of the material. Toughness is defined as the ability of the polymer to absorb applied energy. The incorporation of elastomeric phase, such... 

Although most of the everyday, high-tonnage polymers in present use are insulators, this book is devoted to an important class of recently developed polymers that conduct. Many polymeric materials can be formed into thin, mechanically strong films, and it is obviously desirable to confer the additional property of electrical conductivity on polymers that already benefit from being flexible and compact. Consequently, much ingenuity has been displayed over the past decade or more in developing plastic and elastomeric materials which conduct ions and/or electrons [1-5]. 

The impact modifiers or toughening agents described above are all hnear polymers or segments. More recently, there has been some interest in the use of Core-Shell tougheners. These materials consist of a glassy shell grafted by seeded emulsion polymerization onto an elastomeric core. 

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