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Poly , projection

Mihtary interest in the development of fuel and thermal resistant elastomers for low temperature service created a need for fluorinated elastomers. In the early 1950s, the M. W. Kellogg Co. in a joint project with the U.S. Army Quartermaster Corps, and 3M in a joint project with the U.S. Air Force, developed two commercial fluorocarbon elastomers. The copolymers of vinyUdene fluoride, CF2=CH2, and chlorotrifluoroethylene, CF2=CFC1, became available from Kellogg in 1955 under the trademark of Kel-F (1-3) (see Fluorine compounds, ORGANic-POLYcm.OROTRiFLUOROETHYLENE Poly(vinylidene) fluoride). In 1956, 3M introduced a polymer based on poly(l,l-dihydroperfluorobutyl acrylate) trademarked 3M Brand Fluorombber 1F4 (4). The poor balance of acid, steam, and heat resistance of the latter elastomer limited its commercial use. [Pg.508]

An analogous case, of identical chain conformations as well as of similar unit cell dimensions, have been described for the two crystalline forms of poly-p-phenylene terephtalamide [33-36] (better known with the trade name of Kevlar). The projections along the c axis of the packing of the chains proposed for the two forms [36] has been sketched in Fig. 8, corresponding to the localization of the chain axes in (0,0, z) and (1/2,1/2, z) for the more common polymorph, in (0, 0, z) and (1/2,0, z) for the other polymorph. [Pg.194]

A second project [10] was based on the production of Pd nanocluster inside poly-methacrylic acid (8%mol)-A,iV-di-methylacrylamide (88 % mol)-A, A -methylenebisacrylamide (4% mol). ISEC (Inverse Size Exclusion Chromatography) analysis of the resin in water in terms of cylindrical pores [7]... [Pg.414]

Figure 8.37. Equatorial streak analysis of a poly(ether ester) during straining as a function of elongation, . (a) Intensity projected on the cross-sectional plane (b) 2D CLD computed from the projected intensity... [Pg.182]

The precipitated silica (J. Crosfield Sons) was heated in vacuo at 120° for 24h. before use. Two grades of surface areas 186 and 227 m g l (BET,N2), were used during this project. Random copolymers, poly(methyl methacrylates) and polystyrene PS I were prepared by radical polymerization block polymers and the other polystyrenes were made by anionic polymerization with either sodium naphthalene or sodium a methylstyrene tetramer as initiator. The polymer compositions and molecular weights are given in Table I. [Pg.298]

The orthogonal projection of the epitaxial poly(DMDA) could not be indexed using the unit cell data for the bulk polymerized crystal (8). However, poly(DMDA) cannot usually be polymerized to completion or to high crystallinity in the bulk due to cross-linking. The use of an epitaxial substrate may have controlled the polymerization process that led to oriented single crystals. [Pg.232]

Scheme 1.1 Typical steric defects in a (mainly) isotactic poly-l-alkene chain (adapted Fisher projections) for (a) chain-end-stereocontrol (b) enantiomorphic site stereocontrol. Scheme 1.1 Typical steric defects in a (mainly) isotactic poly-l-alkene chain (adapted Fisher projections) for (a) chain-end-stereocontrol (b) enantiomorphic site stereocontrol.
CEL dye. A CEL solution was obtained by dissolving poly(N-vinylpyrrolidone) (PVP) (7 g) and Dl (5.8 g) in 50 wt% aqueous acetic acid. (87.2 g). The CEL layer was spin-coated onto a photoresist, RI-7000P (Hitachi Chemical Co.), and baked at 80T for 20 minutes. Exposure was performed with an in-house i-line reduction projection aligner. The resist was developed in a 2. 38 wt% tetramethylammonium hydroxide aqueous solution. The film thickness was measured with an Alpha-step 200 (Tencor)... [Pg.320]

Figure 1.14 Three-dimensional projection of dendrimer core-shell architecture for G = 4.5 poly(amidomine) (PAMAM) dendrimer with principal architectural components (I) core, (II) interior and (III) surface... Figure 1.14 Three-dimensional projection of dendrimer core-shell architecture for G = 4.5 poly(amidomine) (PAMAM) dendrimer with principal architectural components (I) core, (II) interior and (III) surface...
Encouraged by the experimental finding (Itoh, 1967 Wasserman et al., 1967) that the dicarbene [15 m = 2] ( = [3]) had a ground quintet state, i.e. all four spins were ferromagnetically coupled, Iwamura and Itoh have been engaged in a project directed towards the construction of the higher series of poly(carbenes) [15], [23] and [24] (Iwamura et al., 1985 Teki et al., 1983, 1985, 1986). [Pg.210]

Fig. 3. A plot of the observed rate constant versus a for the hydrolysis of 3-nitro-4-acetoxy-benzene sulfonate in the presence of (1) 0.016 Af 4-methylpyridine (control) and (2) poly(4-vinyl-pyridine) with 0.01 M pyridine units. Line (3) is a calculated line projected from the pH dependence of the hydrolysis of a neutral substrate, dinitrophenyl acetate. From Letsinger and Savereide (55). Fig. 3. A plot of the observed rate constant versus a for the hydrolysis of 3-nitro-4-acetoxy-benzene sulfonate in the presence of (1) 0.016 Af 4-methylpyridine (control) and (2) poly(4-vinyl-pyridine) with 0.01 M pyridine units. Line (3) is a calculated line projected from the pH dependence of the hydrolysis of a neutral substrate, dinitrophenyl acetate. From Letsinger and Savereide (55).
When [W(CN)s] " was coimmobilized with BOD and poly(L-lysine) on carbon felt sheet of 1-mm thickness on an RDE, a current density of 17 mA/ cm was observed at 0.4 V and 4000 rpm in oxygen-saturated phosphate buffer, pH 7. The authors partially attribute the high current density to convective penetration of the oxygen-saturated solution within the porous carbon paper electrode. This assertion is justified by calculation of an effective electrode area based on the Levich equation that exceeds the projected area of the experimental electrode by 70%. ° This conclusion likely applies to any... [Pg.640]

Fig. 2. End projection of atactic poly(vinyl fluoride) [poly(l-fluoroethane-l,2-diyl)] chains in the crystalline state. Broken circles show fluorine atoms with 50% probability [16]. Fig. 2. End projection of atactic poly(vinyl fluoride) [poly(l-fluoroethane-l,2-diyl)] chains in the crystalline state. Broken circles show fluorine atoms with 50% probability [16].
There are three principal stereochemical types of poly(l-alkene)s, illustrated in Scheme 8.38 for polypropylene. In isotactic polypropylene 80 (i-PP) all methyl substituents have the same relative orientation (m). The scheme shows the stereochemistry with the usual Fischer projection underneath. In syndiotactic PP (81, s-PP) every second CHMe unit has the opposite stereochemistry to the first, while in atactic PP (82, a-PP) the orientation of the methyl substituents is random. In some polymers there is partial order, i. e. only every second monomer orientation is random (83, hemi-isotactic PP). [Pg.345]


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Poly , projection conformation

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