Showing papers on "Polycarbonate published in 1990"

Remarkably selective formation of macrocyclic aromatic carbonates: versatile new intermediates for the synthesis of aromatic polycarbonates

Abstract: L'hydrolyse/polycondensation interfaciale catalysee par Et 3 N du bis-chloroformiate du bisphenol A donne selectivement des oligocarbonates cycliques avec des temps de reaction courts. Discussion du mecanisme. La polymerisation anionique de ces cyclooligomeres donne des polycarbonates de masse moleculaire elevee

Method of coloring polycarbonate extruded or molded products for optical members

Abstract: A method of coloring a polycarbonate extruded or molded product for optical members, which is colored by a liquid coloring process for obtaining a colored polycarbonate extruded or molded product for optical members by extrusion or injection molding. The process involves mixing a polycarbonate resin for optical members and a liquid coloring agent dispersion obtained by dispersing a coloring agent in a dispersing agent. The dispersing agent includes a specific saturated fatty acid ester or silicon oil. After mixing the polycarbonate resin and liquid coloring agent dispersion, the resulting mixture is melted and thereafter extruded or molded to form a product for optical members.

The compatibility and transesterification for blends of polyethylene terephthalate)/poly(bisphenol-A carbonate)

Abstract: A study has been made of the influence of transesterification on the miscibility in binary blends of poly(ethylene terephthalate) and poly(bisphenol-A carbonate). The blends were melt mixed in the range 260–300°C and studied by differential scanning calorimetry, dynamic mechanic analysis, and by Fourier transform infrared spectrometry. It was found that copolymer produced by a transesterification reaction can enhance the miscibility of this system. The new compositions were uniquely identified by FTIR. Gel permeation chromatography showed that molecular weight decreases were not the origin of miscibility. The ester exchange reaction itself was found to be initiated by the residual catalyst in the commercial polymers selected for study. This has been shown by the absence of reaction after polymer purification by solution and reprecipitation prior to melt mixing.

Polycarbonate/aromatic polyester blends modified with a grafted olefin copolymer

Abstract: A polycarbonate blend of good impact strength, solvent resistance and weldline properties is prepared by admixing with polycarbonate an aromatic polyester, a grafted olefin/carbon monoxide copolymer and, optionally, an elastomeric toughening agent such as a rubber, and, optionally, a filler

Anti-dazzling polycarbonate polarizing plate

Abstract: An anti-dazzling polycarbonate polarizing plate is formed with a polarizing thin layer composed of a polymeric film having a dichroic substance adsorbed on and oriented in the polymeric film, and a polycarbonate sheet having a retardation value of at least 2000 nm bonded to one or both surfaces of the polarizing thin layer.

Aromatic polycarbonate resin composition

Abstract: An aromatic polycarbonate composition contains aromatic polycarbonate in which a ratio of the phenolic end group to the non-phenolic end group is at least 1/19, and a copolymer having epoxy or oxazolinyl group, aromatic vinyl-diene-vinyl cyanide copolymer or aromatic polyester, or glass filler Compatibility between the specific aromatic polycarbonate and the other resin, weld strength, melt stability or adhesion to glass filler are improved

Compatibility studies of blends of polycarbonate and poly(ethylene terephthalate)

Abstract: Blends of bisphenol-A polyarbonate (PC) and poly(ethylene terephthalate) (PET) has been investigated by differential scanning calorimetry and scanning electron microscopy. Blends were prepared by screw extrusion and solution casting with weight fractions of PC in the blends varying from 0.90 to 0.10. From the measured glass transition temperature (Tg) and apparent weight fractions of PC and PET dissolved in each phase, it appears that PET dissolves more in the PC-rich phase than does the PC in the PET-rich phase. The composition-dependent values of the Flory–Huggins polymer–polymer–interaction parameter were determined and found to be from 0.054 to 0.037 for extruded blends at 275°C and from 0.058 to 0.040 for solution casting at 25°C. The interaction parameter decreases with increasing PET concentration. This result is consistent with the values of the Tgs, the microscopy study, and the measured extrudate swell ratios which show that compatibility increases more in the PET-rich compositions than in the PC-rich compositions. The PC–PET blends are not microscopically miscible for all the blend compositions.

Phase morphology coarsening and quantitative morphological characterization of a 60/40 blend of polycarbonate of bisphenol a (pc) and poly(styrene‐bco‐acrylonitrile) (san)

Abstract: A 60/40 polymer blend of polycarbonate of bisphenol A (PC) with a styrene-co-acrylonitrile (SAN) copolymer was prepared by melt compounding. Injection molded sheets of this, blend were annealed at 200°C as a function of time. The phase morphology of these sheets, studied using transmission and scanning electron microscopy, was found to coarsen as a function of the annealing time. Using the Chalkey procedure, the microstructure of the annealed blends was quantified. Initial tensile stress-strain data highlight the influence of microstructure on ductility for these co-continuous blends.

Reprocessing polycarbonate/acrylonitrile-butadiene-styrene blends: Influence on physical properties

Abstract: A commercial polycarbonate (PC)/acrylonitrile-butadiene-styrene (ABS) blend was reprocessed by injection molding to study the influence of reprocessing on the physical properties of the product. The modulus of elasticity and the yield stress are unaffected by reprocessing, whereas the break properties and the impact strength decrease. The effects observed are compared with those found in PC and ABS. The type of reactions taking place during reprocessing and the change of blend morphology are also discussed.

Filled polymeric blend

Abstract: Filled polymer blends comprising a polycarbonate, a rubber modified copolymer of a vinyl aromatic monomer and from 4 to 18 weight percent of an inorganic filler.

Phase behavior of blends of polycarbonate with partially miscible polymers

Abstract: Phase behavior of blends of bisphenol A polycarbonate (PC) with polystyrene (PS), poly(styrene-co-acrylonitrile) (SAN), poly(acrylonitrile-butadiene-styrene) (ABS), poly(methyl methacrylate) (PMMA), poly(ethylene terephthalate) (PET), and poly(butylene terephthalate) (PBT) has been investigated. Blends were prepared by screw extrusion and solution casting with weight fractions of PC in the blends varying from 0.90 to 0.10. From the phase diagram of the blends, it appears that PS, SAN, ABS, PMMA, PET, and PBT dissolve more in the PC-rich phase than does PC in the PS-, SAN-, ABS-, PMMA-, PET-, and PBT-rich phases. Also, from the measured glass transition temperature (Tg) of the screw-extruded blends and the solution-cast blends, it appears that compatibility increases more in the PS-, SAN-, ABS-, PMMA, PET-, and PBT-rich compositions than in the PC-rich compositions. Composition-dependent values of the polymer-polymer interaction parameters (g12) of various blends were calculated and found to be from 0.034 to 0.053 for equal weights of each of the polymers with PC.

Injection molding of polypropylene/polycarbonate blends

Abstract: This work deals with the effects of material and processing parameters on the mechanical behavior and morphology of noncompatlbilized polypropylene-polycarbonate (PP-PC) blends. The blends containing between 0 and 40 vol. percent of polycarbonate were compounded using a twin screw extruder and converted by injection molding using molds with rectangular as well as dogbone shaped cavities. The blends exhibit a complex skin-core morphology which evolves with the composition. Despite the absence of interfacial adhesion, the low strain modulus increases with PC concentration and follows approximately the Takayanagi model for systems with perfect adhesion. A slight increase of stiffness and strength with increasing PP/PC viscosity ratio is also observed. Weldline strength of these blends is generally poor and decreases with the increasing PC concentration.

Charge-transport processes in molecularly doped polymers: Binder effect

Abstract: Hole transport has been investigated in films of solid solutions of N,N′-diphenyl-N,N′-bis(3-methylphenyl)-[1,1′-biphenyl]-4,4′-diamine (TPD) in bisphenol A polycarbonate and polystyrene. Rather than being ‘inert’ as previously assumed, the binder plays a major role in influencing the rate of charge exchange between molecules. It is found that the absolute values of the drift mobilities, their electric-field dependence and the activation energies are strong functions of the binder polymer employed to cast the films. At equivalent low molecular concentrations, the hole mobility in films of molecular dispersions in polystyrene is two orders of magnitude higher than that observed in dispersions in polycarbonate, on which most investigations reported in the literature have been carried out. The increased mobility of dispersions in polystyrene is directly related to the reduction in the activation energies.

Blends of polyamide 6 with bisphenol-A polycarbonate. II. Morphology–mechanical properties relationships

Abstract: The relationships between morphology and mechanical properties in polyamide 6/bisphenol-A polycarbonate blends have been investigated by means of Scanning Electron Microscopy and tensile tests. The immiscibility of the two polymers gives rise to biphasic blends in which the polycarbonate constitutes the matrix when its concentration is higher than 35 wt %. The morphology of the blends is controlled by the thermal and rheological characteristics, as well as by the mixing conditions. In general, the adhesion at the interface between the phases is absent. Moreover, polycarbonate-rich blends can be considered as polycarbonate matrix with holes. As a consequence, the blends are mechanically much weaker than the pure components both in terms of Young's modulus and strength, at break. Blends very rich in polyamide, more than 90% by weight, behave differently, probably because of chemical, interchain interactions. This is reflected positively in the impact behavior, which was improved in this composition range.

Morphological studies on the blends of poly(butylene terephthalate) and bisphenol‐A polycarbonate

Abstract: The morphology of the blends of poly(butylene terephthalate) (PBT) and bisphenol-A polycarbonate (PC) crystallized from the melt were studied by density measurement and small angle light scattering techniques. Rate of crystallization of these blends was found to be slower with increasing amount of PC. The Avrami exponent n for the blends was calculated and related to the shape of superstructures formed. Hv and Vv scattering patterns as seen by small angle light scattering were analyzed to determine the nature, shape, and size of the superstructures. The changes in the superstructure formation with increasing amount of PC in these blends have been analyzed.

Polyurethane elastomers based on molecular weight advanced poly(ethylene ether carbonate) diols. I. Comparison to commercial diols

Abstract: Poly(ethylene ether carbonate)diols (2025 mol wt) have been made by the molecular weight advancement of lower molecular weight oligomers and have been fabricated into polyurethane elastomers by reaction with 4,4′-MDI and 1,4-butanediol using the prepolymer method. Polymer structure has been delineated by carbon-13 NMR. Comparisons have been made to a series of elastomers based on other polyester and polyether polyols (2000 mol wt) under conditions where the only variable was the soft segment structure. The poly(ethylene ether carbonate) diol gives a polymer with a partially phase mixed morphology, a higher ambient temperature modulus, and a lower ΔHm than the other polyester polyols. This lower ΔHm leads to a significantly lower rubbery plateau modulus than the other polyester polyols. Phase mixing is increased by post-curing at 150°C. Organic solvent resistance is the most outstanding property. The poly(ethylene ether carbonate) diol produces a polymer with predominantly polyester polyol features.

Ignition resistant polycarbonate blends

Abstract: Thermoplastic resinous blends are disclosed comprising a carbonate polymer; a rubber-modified styrene-acrylonitrile-type polymer (eg, ABS); an organophosphorus compound; a fluorinated-polymer; and a halogenated diphenol oligocarbonate The ignition resistant thermoplastic resin blends of the present invention exhibit surprisingly high resistance to combustion and/or ignition and are suitably employed for use in manufacturing pigmented or unpigmented molding useful as automobile parts, appliances, business and office equipment, photographic equipment and aircraft applications

Acoustic emission in single filament carbon/polycarbonate and Kevlar®/olycarbonate composites under tensile deformation

Abstract: An analysis of envelope signals of acoustic emission (AE) produced from carbon/polycarbonate and Kevlar®/polycarbonate composites undergoing tensile deformation has been carried out to identify the sources of emission. The Kaiser effect was reproduced to validate the AE technique. Two different fiber failure mechanisms, i.e., fiber fracture and fiber degradation in Kevlar®/polycarbonate composite have been identified. A one-to-one correspondence between acoustic emission signals and fiber fracture and degradation has been established. It is shown that the critical length of the fiber, evaluated by using acoustic emission signals, is helpful in understanding the fracture behavior of the composites, as affected by surface treatments of the fibers.

Glass transition temperature of glassy polymers plasticized by CO2 gas.

Abstract: Proposition d'une methode de mesure par DSC de la Tg de polymeres sous une pression allant jusqu'a 60 atm. Application au cas de polymeres plastifies par absorption de CO 2 sous 60 atm a 25°C

Interfacial adsorption and crystallization of polycarbonate in carbon fiber composites

Abstract: A polycarbonate (PC)/carbon fiber (CF) composite system has been examined with regard to interfacial adsorption and crystallization by altering times and temperatures of annealing. Times up to 180 min and temperatures of 245, 275, and 300°C have been investigated. Tranverse tensile, tranverse toughness, and scanning electron microscopy results on unidirectional, continuous-fiber composites indicate improved fiber/matrix adhesion at longer times and higher temperatures of annealing. Improvements in transverse toughness and transverse tensile strength of a factor of two is achieved. The data indicate that primarily adsorption rather than secondary interfacial crystallization is the likely mechanism for increased adhension. Isothermal transverse toughness values have been found to fit well to a Langmuir-type expression. The temperature dependence of adsorption as measured by transverse toughness is described well by an Arrhenius equation. The dependence of transverse toughness on PC molecular weights from Mw = 26,600 to 39,800 was found to be large, with higher molecular weights adsorbing more effectively.

Isothermal volume relaxation in aged polycarbonate measured by positron annihilation lifetime spectroscopy

Abstract: The positron annihilation lifetime spectroscopy (PALS) technique is used to measure volume relaxation in physically aged glassy polycarbonate. The relaxation times and activation energy calculated for the isothermal relaxations in the aged polycarbonate are greater than those parameters calculated for unaged polycarbonate. The activation energy of 8.2 kcal/mol in the aged polycarbonate is used to identify the phenyl group motion or the cooperative carbonate-phenyl interaction as the molecular features responsible for the thermally induced open volume relaxations. It is postulated that the open volume relaxation kinetics as measured by PALS can be used as a nondestructive indication of property differences between aged and unaged polycarbonate.

Preparation of branched polycarbonate from oligomeric cyclic polycarbonate and polyhydric phenol

Abstract: Branched polycarbonates are prepared by melt equilibration of aromatic cyclic polycarbonate oligomers with a polyhydric phenol having more than two hydroxy groups per molecule, preferably 1,1,1-tris-(4-hydroxyphenyl)ethane, in the presence of a carbonate equilibration catalyst, preferably tetrabutylammonium tetraphenylborate. In an additional embodimetn of the invention, a linear aromatic polycarbonate is added to the reaction mixture. Branched polycarbonates prepared according to this inventin have high melt strength and high shear sensitivity characteristics and are useful in extrusion and injection molding processing applications and particularly useful in blow molding applications for preparing relatively large articles and panels.

Process for continuously producing aromatic carbonate

Abstract: A process for continuously producing an aromatic carbonate or its mixture corresponding to the starting material comprising dialkyl carbonate, alkyl aryl carbonate or a mixture thereof and the reactant comprising aromatic hydroxy compound, alkyl aryl carbonate or a mixture thereof, said process comprising feeding the starting material and the reactant continuously to a continuous multistage distillation column to effect transesterification between them in the presence of a catalyst, and withdrawing the aromatic carbonate or its mixture formed as the high-boiling product in liquid form continuously from the lower part of the column, while withdrawing the by-products formed as the low-boiling products in gaseous form continuously from the upper part of the column by distillation to effect transesterification between the starting material and the reactant. This process makes it possible to produce efficiently at a high reaction rate and a high yield an aromatic carbonate which is useful as the starting material for producing an aromatic polycarbonate or various isocyanates without using toxic phosgene.

Blends of polycarbonate and poly(hexamethylene sebacate): IV. Polymer blend intrinsic viscosity behavior and its relationship to solid‐state blend compatibility

Abstract: The intrinsic viscosities of blends of bisphenol-A polycarbonate and poly(hexamethylene sebacate) have been measured in chloroform as a function of blend composition for a variety of molecular weight species. The compatibility of the polymer blend mixtures is characterized by the parameter δb, from the Krigbaum and Wall theory. Using Tg of the blend as a measure of bulk solid-state compatibility, a correlation is obtained with the Krigbaum and Wall parameter δb for each of the molecular weight pairs studied. Slopes of the correlation are invariant, as expected, as the chemical composition is the same for the different molecular weight pairs studied.

Dilation of substituted polycarbonates caused by high‐pressure carbon dioxide sorption

Abstract: Mass sorption/desorption and volume dilation/consolidation measurements are reported for tetramethyl and hexafluoro polycarbonate samples in the presence of carbon dioxide pressures up to 900 psia at 35°C. These results are combined with previous results for bisphenol-A-polycarbonate. The combined sorption and volume dilation measurements are used to analyze the thermodynamics of the three gas-polymer systems, and the partial specific volumes of carbon dioxide and the polymer are reported as functions of sorption level. Desorption and subsequent resorption measurements with the substituted polycarbonates show large and long-lived hysteretic effects similar to those seen with standard bisphenol-A-polycarbonate. Finally, assumptions inherent in the dual-mode model are shown to provide a satisfactory description of the volume dilation behavior for the substituted polymers.

Irradiated articles molded from polycarbonate-polyamide blends

Abstract: Thermoplastic articles molded from amorphous polyamide and polycarbonate resin blends exhibit improved color when irradiated with ionizing radiation.

Method for making end-capped polycarbonates from bisphenol monochloroformate polycarbonate oligomers with pH control system

Abstract: Aromatic polycarbonates are prepared by initially phosgenating a mixture of bisphenol and aqueous alkali metal hydroxide under interfacial reaction conditions to form an oligomeric bisphenol monochloroformate followed by the further introduction of phosgene and base and thereafter the elimination of reacted phosgene and the incorporation of endcapping phenol and tertiary organic amine and additional alkali metal hydroxide into the mixture. Reduced phosgene usage, the substantial elimination of emulsion formation, increased pH measurement accuracy and avoidance of production of diarylcarbonates are substantially provided.