Showing papers on "Polycarbonate published in 1986"

Refractive-index variations with temperature of PMMA and polycarbonate.

Abstract: J. M. Cariou, J. Dugas, L. Martin, and P. Michel Laboratoire de Physique des Solides, Associé au CNRS, Université Paul Sabatier, 31062 Toulouse CEDEX, France. Received 30 July 1985. 0003-6935/86/030334-03$02.00/0. © 1986 Optical Society of America. For polymers, the thermal volume expansion coefficient is always much higher than the coefficient for inorganic materials. We have recently shown that the variation of the refractive index of polymers vs temperature is essentially due to the variation of density. From the Lorentz-Lorenz relation, the function (n + 2)/(n 1) appears perfectly linear in the various temperature ranges where no phase transition occurs. The slope of the representative curve exactly follows the thermal expansion coefficient α which keeps a constant value in each temperature range. Thus, α may be easily deduced from the refractive-index measure­ ment at various temperatures. At the same time, the tem­ peratures where discontinuities of (n + 2)/(n 1 ) or its derivative appear conveniently fit with the transition tem­ peratures which may be so determined. A correct observation of such behavior is that the tempera­ ture variations are so slow that the material is continuously kept in thermal equilibrium. Indeed, it is well known that the various molecular processes which induce the transitions are characterized by very large relaxation times. If the material undergoes temperature changes too fast, it remains in a metastable state which is not a true equilibrium state. Waxier et al. have interferometrically measured some optical properties of Plexiglas and Lexan and determined the evolution of dn/dt, with the temperature between -160°C and +60°C. They obtained irregular but continu­ ous curves which do not evidence, even in a crude way, any systematic change in their behavior which may be related to a phase transition. Nevertheless, in the temperature range studied, at about -30°C PMMA (Plexiglas) undergoes the so-called β transition which is attributed to the beginning of the rotation of lateral chains of methacrylate radicals. A relevant discontinuity of the coefficient of thermal expan­ sion has been observed for PMMAs various tacticities. In the same way, for polycarbonate, the glass transition at 125°C is out of the temperature range studied by these authors. However a so-called α peak was observed at ~60°C and was widely discussed by Neki and Geil. No noticeable anomaly appears in the Waxier results. We have measured the refractive index of commercial samples of PMMA (Altuglas) and polycarbonate (Lexan) between about -100°C and +150°C. To avoid any stress which could take place by contact with another material, the measurement method chosen was the minimum deviation of a prism. The PMMA prism was drawn from bulk material

High strength, reduced heat distortion temperature thermoplastic composition

Abstract: New and improved thermoplastic compositions are disclosed comprising a blend of an aromatic polycarbonate and a copolymer derived from a glycol portion comprising 1,4-cyclohexanedimethanol and ethylene glycol present in molar ratios of 1:4 to 4:1 respectively and an acid portion comprising an aromatic dicarboxylic acid selected from terephthalic acid, isophthalic acid, and mixtures thereof. The compositions are compatible with, and advantageously contain impact modifiers and flame retardants. The copolymer of the subject invention has a heat distortion temperature of from 60° C. to 70° C. and when incorporated in the thermoplastic compositions of this invention provides polycarbonate-based compositions which exhibit lower heat distortion temperatures while retaining good tensile, flexural and impact strengths. The lower heat distortion temperatures of the compositions permits them to be molded and processed at lower temperatures thereby avoiding the degradation of the materials with concomitant loss in impact strength observed with higher conventional molding temperatures employed with earlier compositions.

Thermoplastic moulding compositions based on polysiloxane/polycarbonate block copolymers

Abstract: The present invention relates to thermoplastic moulding compositions containing (A) 20 to 80 parts by weight of a polydiorganosiloxane/polycarbonate block copolymer, (B) 70 to 5 parts by weight of a graft polymer in particle form and (C) 5 to 60 parts by weight of a rubber-free, thermoplastic vinyl polymer, the total of parts by weight of components (A)+(B)+(C) being in each case 100 parts by weight, and, if appropriate, other known additives.

Carbon dioxide as a monomer, 3. The polymerization of ethylene carbonate

Abstract: Polymerisation de melange oxyde d'ethylene-carbone dioxyde (ethylene carbonate) en presence de dibutyl (ethylenedioxy) etain

Molten bisphenol‐A polycarbonate‐poly(ethylene terephthalate) blends. I. Identification of the reactions

Abstract: This paper is devoted to the study of the reactions taking place in molten bisphenol-A polycarbonate-poly(ethylene terephthalate) mixtures. The analysis of the reaction products by infrared, proton and nuclear magnetic resonance spectroscopy, and by thermogravimetric analysis shows that the main reaction is an exchange reaction identical to that occurring in bisphenol-A polycarbonate-poly(butylene terephthalate) mixtures. However, some other reactions consecutive to this exchange reaction also take place, probably resulting from the instability of the ethylene carbonates produced by transesterification.

Thermoplastic polycarbonate moulding compositions

Abstract: The present invention relates to high-impact, flame-repellant thermoplastic polycarbonate moulding compositions consisting of halogen-free polycarbonates, halogen-free copolymers of styrenes and (meth)acrylonitrile, halogen-free phosphorus compounds of the formula (I) ##STR1## tetrafluoroethylene polymers and small amounts of graft polymers and, if appropriate, effective amounts of stabilizers, pigments, flow control agents, mould release agents and/or antistatics, and a process for their preparation.

Studies of surface composition and morphology in polymers. 2. Bisphenol A polycarbonate and poly(dimethylsiloxane) blends

Abstract: Etude par spectrometrie RX photoelectronique et spectrometrie de diffusion d'ions. Comparaison avec le copolymere

High molecular weight polycarbonate receiving layer used in thermal dye transfer

Abstract: A dye-receiving element for thermal dye transfer comprises a support having thereon a dye image-receiving layer comprising a polycarbonate, such as a bisphenol A polycarbonate, having a number average molecular weight of at least about 25,000. Use of this material reduces an undesirable relief image which otherwise tends to be obtained.

Polycarbonate blends having low gloss

Abstract: The present invention is directed to a thermoplastic molding composition comprising a blend of an aromatic polycarbonate, a graft copolymer and an impact modifier graft characterized by its properties wherein combined are low gloss and high impact strength.

Polyethylene-polycarbonate blends: Interface modification, phase morphology and measurement of orientation development during cast film and tubular extrusion by infrared dichroism

Abstract: The phase morphology and polymer chain orientation in polyethylene-polycarbonte blends is investigated. A blend with a dispersed polyethylene phase was found to exhibit phase growth under quiescent conditions. Addition of a styrene-(ethylene/butene) block copolymer controls the phase morphology and prevents phase growth. Melt spun tapes and tubular film have been prepared from polyethylene-polycarbonate blends. Orientation of the crystallo-graphic axes of the polyethylene and the chain axis of the polycarbonate were determined by infrared dichroism. The addition of polycarbonate to polyethylene is found to decrease chain orientation at the same drawdown stress.

Control of interchange reactions of polycarbonate/polyarylate blends and their influence on physical behavior

Abstract: Blends of polycarbonate of bisphenol A (PC) and a polyarylate of bisphenol A (PAr) are susceptible to showing interchange reactions in the melt state. The control of these reactions was carried out by means of the observation of the torque required to turn the Brabender and of its increase against the time due to copolymer formation in the processing equipment. Based on this variation and on glass transition temperature (Tg) measurements, the possibility of an exchange reaction in two steps in this blend was suggested. Tg measurements in melt- and solvent-cast blends also showed that this mixture is immiscible at all compositions and that, by copolymer evolution, a single Tg intermediate between those of the individual constituents can be found in all compositions. The influence of immiscibility on the mechanical properties of the blends was shown by the appearance of a minimum in large-strain properties at about 25% PAr. The behavior of the transesterified blends was very different showing a clear improvement of the tensile properties compared with those of the corresponding blends.

Polyurethane-based adhesive coating or film, and use of same in laminated glass panes

Abstract: A transparent adhesive coating or film based on polyurethane. A polyurethane formed from at least one aliphatic or cycloaliphatic diisocyanate, at least one polyol chosen from among the polyether diols, the polycaprolactone diols, the polycarbonate diols, and the polybutadiene diols, and at least one bifunctional chain-lengthening agent containing an aromatic nucleus.

Method for preparing cyclic polycarbonate oligomer mixtures

Abstract: Cyclic polycarbonate (or thiol analog) oligomer mixtures are prepared by the reaction of bishaloformates or their thio analogs, or mixtures thereof with dihydroxy or dimercapto compounds, with alkali metal hydroxides and various amines. The oligomer mixtures may be converted to polycarbonates or their thiol analogs by a method which is particularly adaptable to integration with polycarbonate processing operations. Polymerization may be conducted simultaneously with molding, extrusion and the like. The oligomer mixtures are adaptable to the preparation of filled prepregs.

Low temperature laminatable polyurethane

Abstract: A novel polyurethane can be used to form asymmetrical laminates with glass and plastics such as polycarbonate at temperatures below 150° F. The polyurethane is a reaction product of a diisocyanate, a high molecular weight polyether glycol or polyester glycol, and at least two different diols.

Polydiorganosiloxane/polycarbonate block copolymers

Abstract: The present invention relates to the preparation of thermoplastic poly-(diorganosiloxane)/polycarbonate block copolymers containing monoalkylphenyl or dialkylphenyl end groups by the phase boundary process, and to the block copolymers which can be obtained by the process.

High-melting bisphenol-A polycarbonate from annealing of vapor-induced crystals

Abstract: Polycarbonate is known to crystallize thermally, but only slowly and to a limited (25%) extent. The melting points reported exhibit a wide variation. We have found that the melting temperature of polycarbonate may be drastically increased by employing a sequence of vapor-induced crystallization and annealing treatments. The crystals formed by the treatment with organic vapor act as a nucleation or precursor state for further crystallization into larger, more perfect lamellae. An initial peak melting temperature of 195°C has been annealed up to 239°C, and then to 295°C by a double-heat treatment. This sample is 60% crystalline, based on heat-of-fusion calculations. An equilibrium melting point of 335°C has been obtained for PC from an extrapolation of reciprocal lamellar thickness.

Percolation threshold of conductive polycarbonate/carbon composites as revealed by electron microscopy

Abstract: Several reports have appeared recently on conductive polymeric composites based on mixtures of nonconductive polymers with conductive solid microadditives [1-4] Among the various combinations, polymer-carbon-black composites are of special interest because they combine the good application properties of commerical polymers (processability, low cost) with relatively high conductivity, thus offering an interesting type of light material The low concentration of the additive required to form a conductive network is specially attractive In a previous letter we have reported [5] on the electrical conductivity (a) variation ofpolycarbonate (PC)/carbon composites as a function of the concentration of the microadditive The influence of film thickness and temperature dependence on the conductivity level reached was also examined [5] In these systems the supermolecular structure of the polymer matrix has only a minor influence on the carrier mobility [6, 7] The conductivity mainly depends on the percolation threshold for the conducting particles In this system, carriers are transported above the percolation threshold through the carbon network predominantly involving a tunnelling conduction mechanism [6, 8] The specific type of initial chain-like carbon-black structure, defined through the aggregation of primary particles (few nanometres in size) in strongly bonded aggregates of several hundreds of nanometres and weakly bonded agglomerates of these aggregates of several micrometres, presumably plays an important part in defining the onset of the conductivity threshold [9] The purpose of the present letter is twofold: first, to report on the influence of the structure of carbon-black particles when transferred over into the polymer matrix on the conductivity level; secondly, to attempt to explain the change observed in the percolation threshold We have used two types of carbon-black materials: XE2 from Philips Petroleum (A) having a welldeveloped chain-like structure (dibutyl phthalate absorption (DBP) - 400 cc/100 g) and acetylene carbon black from SEA Tudor (B) with a lessdeveloped structure (DBP-~ 140 cc/100 g) Several mixtures of polycarbonate (bisphenol A) from Bayer with different carbon-black concentrations were prepared using a plastograph Polycarbonate was melted at the working temperature of 230 ° C Thereafter the filler was added and finally the mixture was mechanically stirred at 50 rpm, for 10 m until homogeneous materials were obtained Compressionmoulded films (T = 230°C, p = 50bar), 500#m thick and 2 x 2cm of lateral dimensions, were

Method for polymerizing aromatic bischloroformate composition to polycarbonate

Abstract: Bischloroformate oligomer compositions are prepared by passing phosgene into a heterogeneous aqueous-organic mixture containing at least one dihydroxyaromatic compound, with simultaneous introduction of a base at a rate to maintain a specific pH range and to produce a specific volume ratio of aqueous to organic phase. By this method, it is possible to employ a minimum amount of phosgene. The reaction may be conducted batchwise or continuously. The bischloroformate composition may be employed for the preparation of cyclic polycarbonate oligomers or linear polycarbonate, and linear polycarbonate formation may be integrated with bischloroformate composition formation in a batch or continuous process.

Laminate formed from a polyarylate sheet and a polycarbonate and/or polyester sheet

Abstract: Described herein are laminates formed from a layer of a polyarylate sheet and a layer of an aromatic polycarbonate, a polyester, or mixtures of these resin sheets. These laminates are suitable for use in glazing applications.

Single phase blends of polycarbonate and polymethyl methacrylate

Abstract: Clear, transparent, single phase blends of polycarbonate and a polyalkyl methacrylate in which the alkyl radical contains from 1 to about 10 carbon atoms, and in which the polycarbonate and the polyalkyl methacrylate are miscible in all proportions are obtained. Polymethyl methacrylate (PMMA) is the preferred polyalkyl methacrylate. These blends may be prepared by dissolving the two polymers in a mutual solvent having a boiling point of at least about 30° C. and evaporating the solvent at a temperature of from about 30° C. to the boiling point of the solvent. The preferred evaporation temperatures are from about 45° C. to the boiling point of the solvent. This is in contrast to presently known PC/PMMA blends, which are miscible only when the content is nearly all PC or nearly all PMMA. Preferred blends according to this invention contain from 10 to 80 percent by weight of PC and conversely 90 to 20 percent by weight of PMMA. The single phase blends are moldable and transparent.

Flame retardant polyetherimide-polycarbonate blends

Abstract: Flame retardant polyetherimide polycarbonate blend are prepared by incorporating therein a flame retarding modifier therefor selected from the group consisting of brominated polystyrenes and a mixture thereof with an acrylic rubber composite interpolymer.

Polycarbonate resin composition

Abstract: PURPOSE:To provide the titled composition having excellent heat resistance and mechanical properties, low molding shrinkage and high releasability, by compounding a specific amount of a fibrous reinforcing material or an inorganic filler together with a specific amount of a fluororesin to a base resin. CONSTITUTION:(A) 20-80(wt)% polycarbonate derived from a dihydric phenol of formula (X is 1-10C alkylene, -O-, etc.; R and R are halogen or 1-12C alkyl; m and n are 0-4; p is 0 or 1) (preferably bisphenol A) and a carbonic acid derivative (e.g. phosgene) with (B) 10-70% fibrous reinfocing material (e.g. glass fiber) or an inorganic filler (e.g. talc) and (C) 0.5-20% fluororesin (e.g. tetrafluoroethylene resin).

Oxygen barrier laminates

Abstract: A thermoplastic laminate comprises an oxygen barrier film, and a second film adhered to the oxygen barrier film and comprising a polymeric material which adds heat resistance and stiffness to the laminate. Such materials are preferably polycarbonate, polyamide, polypropylene, and polyester.

Poly(etherimide-carbonate)block copolymers and polymer blends containing same

Abstract: Novel block copolymers containing polyetherimide and polycarbonate segments are prepared from hydroxy terminated polyetherimide oligomers, a dihydric phenol and phosgene or a phosgene precursor. The segmented block copolymers exhibit improved toughness and are useful as engineering thermoplastics, alone, or in combination with other resins.

Dilation of polycarbonate by carbon dioxide

Abstract: A new technique is described for dilatometry under high pressure. The technique is based on optical interferometry and is analogous to measuring the thickness of thin, nonabsorbing films and coatings. The procedure is demonstrated for the well-characterized system of n-pentane sorption by polyisobutylene, and then results for the dilation of polycarbonate by the sorption of carbon dioxide are presented. The dilation of polycarbonate by CO2 is nearly linear with concentration; the partial molar volume of CO2 decreases slightly with increasing pressure. This result indicates that all sorbed CO2 molecules contribute equally to the dilation of the polymer matrix and that none reside in microvoids or in preexisting free-volume elements which do not contribute to volume expansion of the polymer.