Lamin polymerization

The racemic form is as effective as the (+) enantiomer for disrupting mating. This technique for population suppression has been evaluated in experiments to compare the effects of formulation, dose rate and population density on its efficacy. In light infestations, gypsy moth mating is effectively suppressed. Microcapsules, laminated polymeric "flakes" and hollow fibers were compared as controlled-release formulations. 

Traps. The racemic form of the pheromone has been used for a long time In survey traps placed throughout the United States. The (+) enantiomer Is now available In sufficient quantity to provide a bait for many thousands of traps. Only one-half a milligram Is needed In each trap throughout a season because dlsparlure Is formulated In a long-lasting, controlled-release device, usually a Hereon laminated polymeric dispenser. 

R Bodmeier. O Paeralakul. Drug relea.se from laminated polymeric lilms prepared from aqueous latexes. J. Pharm. Sci. 79 32-.36. 1990. 

Zhao, K., Harel, A., Stuurman, N., Guedalia, D., and Gruenbaum, Y. (1996). Binding of matrix attachment regions to nuclear lamin is mediated by the tod domain and depends on the lamin polymerization state. FEBS Lett. 380,161-164. 

To appear in the pellet fraction after centrifugation, lamin must be assembled into relatively large aggregates (Lin and Fisher, 1990). Hence, the apparently abrupt transition in lamin behavior seen by microcentrifugation when mitotic/ meiotic lamin is mixed with interphase lamin at a ratio of 1 8 versus 1 4 (Fig. 3) does not, in our estimation, reflect an abrupt change in lamin polymerization. Rather, it reflects an operational peculiarity of the centrifugation assay. Centrifugation is nevertheless useful in that it is easily and rapidly performed. 

A specialized form of the monolithic device consists of several adhered or laminated polymeric layers, which has the active ingredient impregnated in a central layer (active agent reservoir layer) between two outer plastic layers. The inner layer... 

Formed commercially by the polymerization of S, NajCOj and PhX in a sealed container at 275--370 C, substituted derivatives are known but not fully evaluated. Used as high-temperature adhesives, for laminates and in coatings. 

This polymerization is carried out in the two stages indicated above precisely because of the insolubility and infusibility of the final product. The first-stage polyamide, structure [IX], is prepared in polar solvents and at relatively low temperatures, say, 70°C or less. The intermediate is then introduced to the intended application-for example, a coating or lamination-then the second-stage cyclization is carried out at temperatures in the range 150-300°C. Note the formation of five-membered rings in the formation of the polyimide, structure [X], and also that the proportion of acid to amine groups is 2 1 for reaction (5.II). 

High performance composites may be laminates wherein veils of carbon fiber ate treated with an epoxy resin, stacked up to the desired final product thickness, and then laminated together under heat and pressure (see Composite materials Carbon and graphite fibers). Simply mixing together carbon or glass fibers and polymeric resins to form a reinforced plastic leads to a composite material, but this is not a laminate if not constmcted from discrete phes. 

Other reinforcements that may be used in the substrate layers of decorative laminates and throughout the stmcture of industrial laminates are woven fabrics of glass or canvas and nonwoven fabrics of various polymeric monofilaments such as polyester, nylon, or carbon fibers. Woven and nonwoven fabrics tend to be much stronger than paper and have much more uniform strength throughout the x—y plane. They greatly enhance properties of laminates such as impact and tear strength. 

During the press operation, which is actually a form of compression mol ding, the resin-treated laminate pHes are heated under pressure and the resins cured. The initial heating phases cause the resin to melt and flow into voids in the reinforcing ply and bond the individual pHes together. The appHed heat simultaneously causes the resin to polymerize and eventually to cross-link or gel. Therefore, resin viscosity reaches a minimum during the press cycle. This is the point at which the curing process becomes dominant over the melt flow process. Dynamic mechanical and dielectric analyses (11) are excellent tools for study of this behavior. 

In the paste coating method, a PVC paste, which contains emulsion-polymerized PVC and additives, is appHed onto a substrate and heated to gelation before fusion to produce a coating layer. This method is employed for products with a thin layer, ie, of 0.007—0.05 mm thickness. For foamed vinyl-coated fabrics, a substrate is laminated onto a transfer paper on which a PVC paste containing a foam-blowing agent has been appHed and geUed. After removal of the transfer paper, the paste is blown. 

Laminated MMCs. There are three types of laminated MMCs (/) metallic matrix-containing fibers oriented at different angles in different layers, similar to that of polymeric laminates (2) two or more different metallic sheets bonded to each other and (3) laminated metal/discontinuously reinforced MMC. 

Fleece-Back Sheet. A fleece-back sheet is a nonreinforced polymeric membrane that has had a nonwoven mat made of polyester, weighing 101.7—203.4 g/m, laminated to the back of the sheet. The prime use of the fleece-back sheet is in the fully adhered roofing systems. The fleece provides the chemical separator, which eliminates the need for an adhesive that is compatible with the specific membrane or a compatible substrate. 

Butyl and Halobutyl Rubber. Butyl mbber is made by the polymerization of isobutylene a small amount of isoprene is added to provide sites for curing. It is designated HR because of these monomers. Halogenation of butyl mbber with bromine or chlorine increases the reaction rate for vulcanization and laminates or blends of halobutyl are feasible for production of mbber goods. It is estimated that of the - 100 million kg of butyl (UR) and halobutyl (HIIR) mbber in North America, over 90% is used in tire apphcations. The halogenated polymer is used in the innerliner of tubeless tires. Butyl mbber is used to make innertubes and curing bladders. The two major suppHers of butyl and halobutyl polymers in North America are Exxon and Bayer (see ELASTOLffiRS,SYNTHETIC-BUTYLrubber). 

A continuing trend has been to polymeric retainers. Laminated phenoHc cages have often been used for high speeds at temperatures up to 130°C. Heat stabili2ed nylon-6,6 has come iato broad use ia small ball beariags, both with and without glass reinforcement (39). Polyimide and PTFE are used up to 250°C. 

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