Polycarbonate

About: Polycarbonate is a research topic. Over the lifetime, 14032 publications have been published within this topic receiving 141740 citations. The topic is also known as: PC & Polycarbonate, PC.

Method for making an aromatic polycarbonate

Abstract: This invention relates to an extrusion method preparing polycarbonates from a solution of an oligomeric polycarbonate. A mixture of bis(methyl salicyl)carbonate (BMSC), BPA and a transesterification catalyst are first equilibrated at moderate temperatures to provide a solution of polycarbonate oligomer in methyl salicylate. The solution is then fed to a devolatilizing extruder, where the polymerization reaction is completed and the methyl salicylate solvent is removed. The solution comprising the oligomeric polycarbonate can also be pre-heated under pressure to a temperature above the boiling point of methyl salicylate and subsequently fed to a devolatilizing extruder equipped for rapid flashing off the solvent. The method provides polycarbonate with greater efficiency than the corresponding process in which unreacted monomers are fed to the extruder. Additionally, the method of the invention does not require the isolation of a precursor polycarbonate comprising ester-substituted phenoxy terminal groups.

Molding material for optical recording medium

Abstract: PROBLEM TO BE SOLVED: To obtain the subject molding material having the moldability suitable for producing optical recording media such as a compact disk or a laser disk compatible with low birefringence properties by composing the molding material of a specific polycarbonate having an intrinsic viscosity within a specified range. SOLUTION: This molding material is composed of a polycarbonate having (A) a structural unit represented by formula I (R1 to R4 are each H, a 1-5C alkyl, a 6-12C aryl, a 2-5C alkenyl or the like) [e.g. 9,9-bis(4-hydroxy-3- methylphenyl)fluorene] and a structural unit represented by formula II so as to provide 10-90 mol% of the structural unit represented by formula I in the total structural units and further 0.3-0.5 dL/g intrinsic viscosity. The molding material is obtained by blowing phosgene into a compound represented by formula III and 4,4'-[1,3-phenylenebis(1-methylethylidene)] bisphenol in the presence of an aqueous solution of an alkali and an organic solvent, then adding a quaternary ammonium salt, initiating a polycondensation reaction and subsequently adding a monohydric phenol and further a tertiary amine polymerization catalyst and accelerating the polycondensation.

Morphological-studies of Polycarbonate-poly(butylene Terephthalate) Blends By Transmission Electron-microscopy

Abstract: The morphology of polycarbonate (PC)-poly(butylene terephthalate) (PBT) blends prepared by melt-processing in an extruder or a Brabender Plastograph was studied by Transmission Electron Microscopy. Transesterification during blending was avoided by the use of di-n-octadecyl phosphite, an efficient transesterification inhibitor. Ruthenium tetraoxide was used to selectively stain the PC fraction. Observation of ultrathin sections revealed the biphasic nature of the blends and the partial compatibility of the polymers in the molten state. The most striking consequence of this Is the presence, of PBT crystalline lamellae growing inside the PC-rich phase for samples annealed in the proper temperature range. A preliminary study of the morphology as a function of composition and thermal annealing was undertaken. The RuO4 staining technique was also applied to the commercial blend Xenoy CL 100 from General Electric, which was shown to contain an MBS impact modifier (a methylmethacrylate butadiene-styrene copolymer) exclusively located In the PC-rich phase.

UV-Stabilized polycarbonates

Abstract: Polycarbonate resins can be stabilized against the adverse influence of UV light by incorporating either directly into the resin or by means of a coating on the surface of the polycarbonate resin, an effective amount of a dicyano stabilizer.

Effect of processing parameters on morphology and thermal properties of electrospun polycarbonate nanofibers

Abstract: In the present contribution, it has been reported about the effect of solvent, solvent concentration, flow rate and applied voltage on the fabrication of electrospun polycarbonate (PC) nanofibers. The morphology of fibers was studied by optical and scanning electron microscope. It is observed that morphology of fibers depends upon the concentration of PC or viscosity of the solution, vapor pressure and diffusion coefficient of solvent. In fact, when viscosity of the solution is very low, beads or droplets are formed instead of fibers. The same problem arises when the viscosity of the solution is too high due to high surface tension. In this case, jet formation will not be observed and the solution will coagulate at the tip of needle. Tetrahydrofuran (THF) easily diffuses with polymer, at higher concentration of PC and at higher flow rate of solution; fibers of micron size are formed because of high vapor pressure of THF. On the other hand, in case of mixed solvents (DMF and THF), by controlling processing parameters one can get fiber diameter up to 200 nm. The study of Differential Scanning Calorimetry (DSC) indicates that less amount of heat energy is absorbed during endothermic reaction and there is a slight increase in glass transition temperature of nanofibers. Thermogravimetric analysis (TGA) shows an increase in thermal stability of PC nanofibers by 40oC as compared to PC granules. This is due to the alignment of PC polymeric chains during stretching and whipping that occurs while electro spinning process. Copyright © 2010 VBRI press.