Showing papers on "Polycarbonate published in 1976"

Impact strength of polymers: 1. The effect of thermal treatment and residual stress

Abstract: The effect of thermal annealing and quenching on the notched Izod impact strength of several polymers has been studied. Primary emphasis was placed on polycarbonate, but ABS, PVC, polysulfone, and polymethylmethacrylate were also studied. It was determined that residual stresses created by thermal quenching from above the glass transition temperature can have a great effect on impact strength for the polycarbonate, PVC, and polysulfone polymers studied. In fact, it is shown that the thickness transition observed in impact strength for polycarbonates is governed by the residual stresses and not by thickness. In polycarbonates, quenched sheets up to 3/8 in. in thickness have shown impact strengths of 18 ft-lb/in. whereas sheets 1/8 in. in thickness can be embrittled by annealing, showing an impact strength of 2 ft-lb/in. However, it has been shown that this embrittlement results from the absence of residual stress. Residual stresses having maximum values up to 3000 psi (in Compression) have been determined at the polycarbonate sheet surface using birefringence measurement techniques. The existence of these compressive stresses is postulated to restrict the extent of craze growth at the notch tip, and the impact specimen can yield rather than fail in a brittle manner if the stress state is sufficient.

Thermoplastic resin composition comprising methyl methacrylate resins and a polycarbonate

Abstract: A thermoplastic resin composition consists essentially of from 10 to 95 parts by weight of a methyl methacrylate resin and from 90 to 5 parts by weight of a styrene-methyl methacrylate copolymer resin with or without from 5 to 150 parts by weight of a polycarbonate resin. A molded product from the composition has a beautiful, pearlescent luster and a high impact strength.

Stabilized polycarbonate composition

Abstract: A stabilized polycarbonate composition comprising in admixture an aromatic carbonate polymer and a stabilizing amount of a cyclic diphosphite. The composition may additionally contain co-stabilizers such as epoxides or silanes.

Abrasion resistant coating for polycarbonate substrates

Abstract: A process is disclosed for applying an adherent, optically clear, abrasion resistant coating to polycarbonate substrates such as lenses. The process includes: (a) forming a coating solution containing 25-75% of a hydrolyzed C 1 -C 2 alkyltri(lower alkoxy)silane, such as methyltriethoxysilane, in a water-miscible, volatile, organic solvent, and also containing small amounts of an abrasion-resistance enhancer and a stabilizing weak acid; (b) applying a thin, uniform coating of the coating solution to a clean surface of the polycarbonate substrate; and, (c) dehydrating the coated substrate under low humidity conditions at an elevated temperature below the temperature at which the substrate degrades until an adherent, abrasion resistant coating is formed.

Preparation of microporous polycarbonate resin membranes

Abstract: A casting process is set forth for the preparation of microporous membranes from polycarbonate resin material. The polycarbonate resin is dissolved in an organic casting solvent to produce a solution stable at room temperature. The solution is cast as a thin film on a smooth substrate and is permitted to desolvate for at least a few seconds. Film and substrate are immersed in a bath characterized by the capabilities for swelling the polycarbonate resin, and for dissolving the first solvent, while not dissolving the polycarbonate resin. After formation of the film is initiated, the film and substrate are removed from the quenching bath and the film is either water-washed or air dried to attain the full mechanical strength thereof.

Crystallization of bisphenol‐A polycarbonate. I. Influence of trimellitic acid tridecyloctyl ester on the kinetics of crystallization

Abstract: The crystallization of bisphenol-A polycarbonate plasticized by trimellitic acid tridecyloctyl ester (Morflex 525) has been studied. A half-crystallization time of 100 min is observed at 170°C with 10% of plasticizer compared with a figure of 18,000 min for the unplasticized material. The kinetic study is limited to the primary crystallization process which can be described by an Avrami equation; however, the Avrami coefficients are much higher than usual. Studies on the effect of the preparation procedure of the samples and of premelting indicate that nucleation is at least partially heterogeneous.

Some new aspects of the crystallization of bisphenol-A polycarbonate

Abstract: This paper concerns the action of plasticizers and nucleating agents on the crystallization of bisphenol-A polycarbonate. The influence of plasticizers is to increase the rate of crystallization to a great extent using 10 percent of a plasticizer such as trimellitic acid, tridecyloctyl ester. The influence of nucleating substances on plasticized and undiluted polycarbonate is investigated. A large number of substances have been found capable of nucleating polycarbonate crystallization. The un-plasticized semi-crystalline polycarbonate is characterized by a much higher melting point (300°C) than the plasticized semi-crystalline systems (210–245°C). The stability of bisphenol-A polycarbonate in the presence of nucleating salts is also examined. We observe a substantial decrease in the molecular weight in the presence of a great number of nucleating substances. The modulus-temperature curves of two semi-crystalline polymers are reported in the last series of experiments.

Isothermal and nonisothermal dielectric relaxation studies on polycarbonate

Abstract: Dielectric relaxation measurements at very low frequency were carried out on polycarbonate. Two prominent peaks were resolved from the broad β-relaxation peak with activation energies of 0.28 and 0.52 eV, respectively. Thermally stimulated discharge current was also studied and compared to the results obtained from the dielectric relaxation measurements.

Process for manufacturing thin, non-porous gas permeable polycarbonate films

Abstract: Non-porous, thin, polycarbonate films and a process for their production. Solutions of polycarbonates in concentrations of less than 5 parts solids per 100 parts solvent are applied to the surface of liquids immiscible, or sparingly miscible with, the solvent for the polycarbonate. The solvent is then evaporated, and the resultant film removed. The films are useful for the separation of gas and liquid mixtures and for electrical insulating purposes.

Glass fiber-reinforced polycarbonates with improved mechanical properties containing 0.5 to 5.0% of organopolysiloxane

Abstract: Glass fiber reinforced polycarbonate molding compositions are taught which have improved mechanical properties. This improvement is achieved by incorporating between about 0.5 to 5 wt.% of organopolysiloxanes into the composition. The compositions of this invention have improved impact, notched impact and elongation properties without a loss in elastic modulus.

Polycarbonate polyurethanes based on particular aliphatic/cycloaliphatic polycarbonates

Abstract: Energy-absorbing laminates for use as automobile windshields or other safety glass applications comprising a polycarbonate urethane and a sheet of glass are disclosed. The polyurethane is formed from a cycloaliphatic diisocyanate, a compound containing at least two active hydrogens per molecule and having a molecular weight below 250, and a special polycarbonate diol synthesized from a mixture of linear aliphatic and cycloaliphatic diols.

Thermoplastic polycarbonate moulding compositions with improved ease of mould release

Abstract: The invention relates to a thermoplastic moulding composition comprising a high molecular, thermoplastic aromatic polycarbonate based on an aromatic dihydroxy compound and containing 0,01 to 0.5% by weight of an ester of a saturated aliphatic carboxylic acid with 10 to 20 C. atoms per molecule and an aromatic hydroxy compound with from 1 to 6 OH groups.

Method for producing a polycarbonate oligomer

Abstract: Polycarbonate oligomer having uniform qualities is prepared by reacting an aqueous alkaline solution of 2,2-(4,4'-dihydroxydiphenyl) propane with phosgene in the presence of methylene chloride and as a characteristic point of this method, in the presence of an inert gas in an amount of 1 to 10 mol % based upon the phosgene.

Polycarbonate molding materials

Abstract: This invention relates to thermoplastic polycarbonate molding materials having improved flame resistance and hydrolysis resistance. These materials comprise intimate blends of aromatic high molecular weight polycarbonates and about 0.5 to 50 wt. % of polyphenylene sulphides. This invention also relates to a process for improving the flame resistance and hydrolysis resistance of aromatic polycarbonates by intimately blending them with about 0.5 to 50 wt. % polyphenylene sulphide.

Copolycarbonates of phenolphthalein polycarbonates and other polycarbonates

Abstract: Novel copolycarbonates exhibiting generally improved impact resistance, clarity and flame resistance are prepared by blending a polycarbonate of a trityldiol such as phenolphthalein and a polycarbonate of another diol such as bisphenol-A under conditions of temperature and/or shear sufficient to cause reaction of the polycarbonates.

Polycarbonate resin shaped articles having improved abrasion resistance

Abstract: A polycarbonate resin shaped article having a cured coating of a melamine-type resin on its surface through a primer layer resulting from the solidification or curing, in the presence or absence of a crosslinking agent and a crosslinking catalyst, of a primer comprising a polymer containing a carboxyl or carbamoyl group or a polymer containing a hydroxyl and carboxyl, amino, substituted amino, epoxy or tetrahydrofuryl group; a primer coating composition useful for the surface treatment of the above shaped article; and a method for producing the coated polycarbonate resin shaped article.

Thermoplastic copolymers of polysiloxane polycarbonate and polyester constituents

Abstract: There is disclosed thermoplastic silicone copolymers having polyarylcarbonate and polyarylester constituents covalently bound to a polydiorganosiloxane constituent. The copolymer is produced by reacting a dihydric phenol with a difunctional polydiorgano siloxane, an organo-diacid halide or with alkyl or aryl ester of an organo-diacid, and with phosgene or other suitable carbonate precursors. The reactions are carried out in suitable organic solvents that solubilize the reagents and the resulting copolymer, in the presence of conventional catalysts. In another embodiment a solvent system is eliminated and the condensation polymerization is carried out in a molten system.

Reinforced thermoplastic compositions of polyester resins and a polycarbonate resin

Abstract: Reinforced thermoplastic compositions are provided comprising a poly(1,4-butylene terephthalate) resin, a poly(ethylene terephthalate) resin, a polycarbonate resin and a fibrous glass reinforcement. The compositions are moldable to articles having improved resistance to heat distortion or warpage in comparison with molding compositions of glass reinforced poly(1,4-butylene terephthalate).

Brillouin scattering from amorphous bisphenol-A polycarbonate

Abstract: Brillouin scattering has been studied from amorphous bisphenol-A polycarbonate in the temperature interval 60–240°C. Both longitudinal and transverse Brillouin peaks are observed over the entire range. The behavior of both types of Brillouin splittings, Δωl and Δωt, in the region of the glass–rubber relaxation is typical of an amorphous polymer. Equilibrium values of Δωl and Δωt were obtained 20°C below the glass-transition temperature Tg determined at cooling rates of 20°C/hr. Comparison of the present results with previous ultrasonic data reveals a considerable dispersion in the longitudinal phonon velocity below Tg. The origin of the large transverse Brillouin intensities is related to the structure of polycarbonate.

Coated polycarbonates and acrylics

Abstract: Improved coatings on polycarbonate or acrylic articles are provided with the coating consisting essentially of the heat cured reaction product of the combination of a prescribed solvent-soluble further-curable organopolysiloxane, an alkylated melamine formaldehyde partial condensate resin and a prescribed composition which contains a linear diol, a thermosetting acrylic, a crosslinking agent, and an effective ultraviolet stabilizing amount of an ultraviolet stabilizer

Flame retardant polycarbonate having improved critical thickness

Abstract: Polycarbonates are provided having improved critical thickness values based on an aromatic diphenol, a halogenated dihydric phenol and an aromatic diphenol thioether By incorporating an effective amount of the aromatic thiodiphenol based on the total diphenol content into the polymer the critical thickness and flame retardant characteristics of the polycarbonate is substantially improved

Production of films and sheets of polyester-polycarbonate blends

Abstract: This invention provides a film or sheet capable of being thermoformed into a shaped article and being formed from a blend of about 60 to 85 parts by weight of a polyethylene terephthalate polymer having an intrinsic viscosity of at least about 0.90 and correspondingly about 40 to 15 parts by weight of a polycarbonate polymer, the polyethylene terephthalate portion of the film or sheet having a degree of crystallinity in the range of about 20 to 40%. The film is essentially non-oriented. The present invention also provides shaped articles thermoformed from such film or sheet, such as cook-in-trays. Moreover, this invention provides a process of forming such film or sheet which comprises the steps of blending about 60 to 85 parts by weight of a polyethylene terephthalate polymer having an intrinsic viscosity of at least about 0.90 with correspondingly about 40 to 15 parts by weight of a polycarbonate resin, extruding the resultant blend at a temperature of above about 500°F onto a moving support such as a casting roll while maintaining the surface of the support at a temperature of about 225° to 380°F whereby a film or sheet of the blend is formed, and collecting the thus formed film or sheet.

Stabilized polycarbonate resin

Abstract: An aromatic polycarbonate composition that is color stable, which composition consists of an aromatic polycarbonate resin having in admixture therewith 0.005 - 0.5 weight percent of a phosphine and with or without an epoxy compound and a pigment.

Electron microscopy and small angle x-ray studies of amorphous polymers

Abstract: The small-angle X-ray scattering (SAXS) from polycarbonate, polymethyl methacrylate, and polyethylene terephthalate seem inconsistent, both in the magnitude of the SAXS intensity and in its variation with scattering angle, with nodular features as representative of the bulk polymers. Rather than nodules, the SAXS data indicate the presence of thermal density fluctuations frozen-in at the glass transitions, together with a small concentration of large heterogeneities (hundreds to thousands of angstroms in size). Electron microscopy (EM) of amorphous polycarbonate provides further support for the suggestion that nodular features are not representative of the bulk material. The only structure seen in bright field is the “salt and pepper” background common to all materials. In dark field, very small structures (<30 A in size) occupying small volume fractions were observed. These results are at variance with previously reported EM observations of nodular features in polycarbonate. It is suggested that...