Polycarbonate blocks

Today about 75% of the market is held by General Electric and Bayer with their products Lexan and Makrolon respectively. Other manufacturers are ANIC (Italy), Taijin Chemical Co., Mitsubishi Edogawa and Idemitsu Kasei in Japan and, since 1985, Dow (USA) and Policarbonatos do Brasil (Brazil). Whilst this market is dominated by bis-phenol A polycarbonates, recent important developments include alloys with other thermoplastics, polyester carbonates and silicone-polycarbonate block copolymers. 

There has also been active interest in blends of PBT with other polymers. These include blends with PMMA and polyether-ester rubbers and blends with a silicone/polycarbonate block copolymer. 

Figure 2. Oxygen index of silicone/bisphenol-A polycarbonate block polymers of varying silicone block content.

P.D. Phelps, E.P Boden, G.C. Davis, D.R. Joyce, and J.F. Hoover, Silicone-polycarbonate block copolymers and polycarbonate blends having reduced haze, and method for making, US Patent 5530083, assigned to General Electric Company (Schenectady, NY), June 25,1996. 

The modulus and yield kinetic parameters of the block polymer B can be related to those of the homopolymer in terms of a microcomposite model in which the silicone domains are assumed capable of bearing no shear load. Following Nielsen (10) we successfully applied the Halpin-Tsai equations to calculate the ratio of moduli for the two materials. This ratio of 2 is the same as the ratio of the apparent activation volumes. Our interpretation is that the silicone microdomains introduce shear stress concentrations on the micro scale that cause the polycarbonate block continuum to yield at a macroscopic stress that is half as large as that for the homopolymer. The fact that the activation energies are the same however indicates that aside from this geometric effect the rubber domains have little influence on the yield mechanism. 

In addition to the D units [Me2Si(Oo.s)2 ] and bisphenol A (BPA) carbonate units [21 ], the nature of the polymer synthesis (85) gives rise to single BPA units [22] isolated between two silicone blocks. The Si NMR spectrum of a sample polymer with average silicone block length hpDMs = 10 is shown in Fig. 17. Peaks A and A correspond to silicon atoms adjacent to polycarbonate blocks. The peak B corresponds to the second siloxane units in the silicone block and the rest of the... 

Hoover, J. Sybert, P.D. Compositions of Silox-ane Polycarbonate Block Copolymers and High Heat Polycarbonates US Patent 5,455,310, October 3, 1995. 

Ward et al. (31) TFC membranes made of silicone/ polycarbonate block copolymers extremely high permeation rate of -2 1 8.6x10 at a low 8 1... 

Numbers In the Figure correspond to those In Table II. PolyDMS/Polyvlnylphenol (72/28) cross-linked polydlmethylslloxane, (16) PolyDMS/PolyC(60/40) polydlmethylslloxane/polycarbonate block copolymers. (9 )... 

Chem. Descrip. Thermoplastic silicone-polycarbonate block copolymer dissolved in trichloroethane solvent... 

Silicone-polycarbonate block copolymer. See Silicone-polycarbonate copolymer... 

Synonyms Silicone-polycarbonate block copolymer Ciassification Thermoplastic... 

Silicone robber Silicone-polycarbonate block copolymer Silicone-nitrite copolymer Natural robber SBR... 

Poly(isobutene)/polycarbonate blocks are produced by conversion of poly (bisphenol-A carbonate) that contains isocyanate groups and dihydroxytelechelics of poly (isobutene). 

Fig. 5 Top and isometric views of the 9-electrode array. The 200-tim diameter wires are embedded in a polycarbonate block...

Goldberg EP (1963) Elastomeric polycarbonate block copolymers. J Polym Sci C Polym Symp 4 707-730... 

Jiang et al. [38] describe the synthesis of polystyrene-polycarbonate block copolymers. These were used to compatibilize blends of poly(ethylene terephthalate) (PET) and polyp-phenylene oxide (PPO) (which is miscible with polystyrene. Section 5.4). The dispersed phase sizes were significantly reduced. 

Okushita H and Muramutsu T (2001) Heat-resistant flexible polyamide-polycarbonate block elastomers, EP Patent 1253165, to Ube Ind., Chem 137 326423. 

The thermal degradation of 5a-c was followed by dynamic TGA and showed a two-stage decomposition. The polycarbonate block decomposed at 280 T, while the PO block decomposed at 350 °C (Tables 2 and 3). Since the decomposition points of the blocks were resolvable, this provided a measure of copolymer composition... 

Recently, Mench and Wang [19] used specially built segmented flow fields with serpentine flow channels for both the anode and cathode sides, where the individual segments were separately controlled by a multichannel potentiostat/galvanostat. The segmented flow fields were fabricated by embedding gold-plated stainless steel ribs in a polycarbonate block. The... 

Similar results with respect to the initiation step were obtained with dibutyl magnesium [13], aluminum trialcoholates [14], dibutyltin dimethoxide [14], diethyl zinc [14], tin octoate and rare-earth metal compounds as initiators [15-22]. With these initiators, a coordination-insertion mechanism is active which, for some of the initiators, has been studied in detail [30, 31]. A special initiator with an aluminum alcoholate group is that of tetraphenylporphyrin aluminum this has an alkoxy group as the third ligand (RO—Al—TPP) at the aluminum, and is known as the Inoue catalyst [32]. This initiator is active for various monomers, and is therefore used for the preparation of block copolymers with one or two polycarbonate blocks. Initiation occurs by the nucleophiUc addition of RO—Al—TPP to the carbonyl group of the carbonate. 

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