Showing papers on "Polycarbonate published in 1998"

Permeation Control through Porous Membranes Immobilized with Thermosensitive Polymer

Abstract: Permeation through a porous polycarbonate membrane, on which a thermosensitive polymer, poly(N-isopropylacrylamide), was immobilized, was investigated For photoimmobilization of poly(N-isopropylacrylamide), photoreactive azidophenyl group was connected to the polymer either at a chain terminal or in side chains The two types of derivatized polymers had different lower critical solution temperature (LCST) Prescribed amounts of the derivatized polymer were cast on the polycarbonate membrane and photoirradiated When a small amount of polymer was used, a thin layer of immobilized polymer was not enough to cover pores of the polycarbonate membrane, while a thick gel layer of immobilized polymer was formed on the polycarbonate membrane to cover pores when a large amount of polymer was used The former is represented by “porous membrane”, and the latter by “nonporous membrane” The rate of water permeation through the porous membranes changed at different temperatures, although permeation through nonimmobili

Mechanism of Exchange in PBT/PC and PET/PC Blends. Composition of the Copolymer Formed in the Melt Mixing Process

Abstract: Mechanisms operating in the exchange reactions occurring in the melt mixing processes of Bisphenol A polycarbonate (PC) with poly(butylene terephthalate) (PBT) and poly(ethylene terephthalate) (PET) blends have been investigated making use of appropriate polymer samples, capped or containing reactive chain end groups. The exchange process may proceed by two different mechanisms: a direct exchange reaction between inner functional groups located inside the polymer chains, i.e., inner−inner, or by attack of reactive chain ends functional groups (outer) on inner groups, i.e., outer−inner. It is shown that the distinction between the two processes can be conveniently made by determining the composition of the copolymer formed in the exchange reaction. The inner−inner mechanism occurs only in the reaction between end-capped or high molar mass PBT/PC or PET/PC samples, and it was found that the molar composition of the copolymer formed is always equal to the feed ratio of the two homopolymers and independent f...

Production of aromatic polycarbonate

Abstract: PURPOSE: To obtain the objective aromatic polycarbonate by determining the ratio, etc., of hydroxy terminals to total terminals in a prepolymer in the reaction of a specific dihydroxydiaryl compound with a diaryl carbonate and additionally polymerizing the compound according to the determined result. CONSTITUTION: An aromatic polycarbonate having desired hydroxyl-terminal ratio and number-average molecular weight is produced in high efficiency by prepolymerizing (A) a dihydroxydiaryl compound composed of ≥60mol% of a dihydroxydiarylalkane of formula (Ar 1 and Ar 2 are arylene; Y is alkylene, etc.) and ≤40mol% of other dihydroxydiaryl compound and (B) a diaryl carbonate until the number-average molecular weight of the prepolymer reaches 1,000-10,000, determining the number-average molecular weight, the ratio of hydroxyl terminals and that of aryl carbonate terminals to total terminal groups, adding diaryl carbonate to the system when the hydroxyl terminal ratio is higher than the desired level or adding dihydroxydiaryl compound when the ratio is lower than the desired level and continuing the polymerization reaction. COPYRIGHT: (C)1991,JPO&Japio

Phase equilibria of supercritical fluid–polymer systems

Abstract: Sorption and swelling of silicone rubber (SR), polyisobutylene (PIB), polycarbonate (PC), polymethyl methacrylate (PMMA), polystyrene (PS), and polyethylene terephthalate (PET) in the presence of sub- and supercritical carbon dioxide have been measured at pressures up to 30 MPa at 308.2 and 323.2 K. Rubbery polymers (SR and PIB) and PMMA showed a sigmoidal increase in sorption with pressure, while other glassy polymers such as PS and PC and a crystalline polymer, PET, showed the monotonic increase/level-off sorption behavior. The well-known dual-mode sorption mechanism was found to be inadequate to describe the sorption behavior of glassy polymers at high pressures. The amount of sorption was successfully calculated from the experimental swelling data for SR. Density representation of sorption was much better than the pressure representation. Other sorption and swelling behaviors have also been analyzed and discussed.

Polycarbonate compositions comprising polyester resins and ultraviolet light absorbers

Abstract: Weatherable polycarbonate compositions (formulations or blends) comprise polycarbonate, cycloaliphatic polyester resins, at least one of a benzotriazole, benzophenone, and triazine based UVA, and a catalyst quencher. The incorporation of the cycloaliphatic polyester resin and the benzotriazole, benzophenone, and triazine based UVA exhibits a synergistic effect, thereby resulting in unexpected enhanced protection of the polycarbonate compositions by imparting photostability to the polycarbonate formulations, thereby reducing yellowing or other forms of light induced degradation.

Ordered Structures in Polycarbonate Studied by Infrared and Raman Spectroscopy, Wide-Angle X-ray Scattering, and Differential Scanning Calorimetry

Abstract: Ordered structures in samples of Bisphenol A polycarbonate (BPAPC) prepared by varying thermal and solvent conditions were investigated by infrared and Raman spectroscopy, wide-angle X-ray scattering (WAXS), and differential scanning calorimetry (DSC). Based on the spectroscopic analysis and ab initio quantum mechanical calculations of diphenyl carbonate as a model compound, an assignment of the bands conformationally sensitive to the trans−trans and cis−trans structures is proposed. Temperature dependences of the vibrational spectra of BPAPC show that cis−trans structure is the energetically preferred conformation in the amorphous state and in solution and its population can be increased with decreasing temperature in amorphous BPAPC even below the glass transition temperature. Differences in the degrees of ordering in semicrystalline BPAPC assessed from the vibrational spectra, WAXS, and DSC indicate partial order in the interfacial region between the crystalline and amorphous phases. In some solvents (...

UV Curable Hard Transparent Hybrid Coating Materials on Polycarbonate Prepared by the Sol-Gel Method

Abstract: UV curable, hard, transparent inorganic/organic composites with covalent links between the inorganic and the organic networks were prepared by the sol-gel method. These hybrid coating materials were synthesized using a commercially available, acrylate end-capped polyester or polyurethane oligomeric resin (EBC80, EBC284), hexanedioldiacrylate (HDDA) as a reactive solvent, 3-(trimethoxysilyl)propoxymethacrylate (TMSPM) as a coupling agent between the organic and inorganic phase, and a metal alkoxide, tetraethylorthosilicate (TEOS). The materials were applied on primer or oxygen plasma pretreated polycarbonate sheets and UV cured, followed by a thermal treatment to give a transparent coating with a good adhesion and abrasion resistance. The high transmission and the thermogravimetric behavior indicate the presence of a nanoscale hybrid composite, as is confirmed by SAXS and TEM measurements. In a Taber Abrasion Test, uncoated polycarbonate sheets exhibit a 48% decrease in light transmittance at 600 nm after 300 wear cycles, whereas the EBC80 hybrid coating system containing 9 wt% SiO2 (EBC80/25Si) shows only 28% decrease in light transmittance. A maximal improvement of the abrasion resistance is achieved when 23 wt% SiO2 is incorporated (EBC80/60Si, EBC284/60Si) with only 20% decrease in light transmittance. The abrasion resistance of glass is not yet encountered. For optimal results, it is essential that the rate of condensation of the silanol groups is sufficiently high to form a dense three-dimensional network.

Synthesis and characterization of a series of poly(alkylene carbonate) macrodiols and the effect of their structure on the properties of polyurethanes

Abstract: A series of polycarbonate and copolycarbonate macrodiols was prepared by using an ester interchange reaction with ethylene carbonate and diols such as 1,6-hexanediol, 1,10-decanediol, 2,2-diethyl-1,3-propanediol, 1,4-cyclohexanedimethanol, and 1,3-bis(4-hydroxybutyl)-1,1,3,3-tetramethyldisiloxane. The diols were chosen to prepare a series of macrodiols with different structural features including linear, branched, rigid, and flexible. The macrodiols were characterized by 1H- and 13C-NMR spectroscopy and DSC. The commercial macrodiol based on 1,6-hexanediol exhibited a high level of crystallinity, while with the exception of 1,10-decanediol–based copolycarbonates all the others were completely amorphous. 1,10-Decanediol–based materials showed partial crystallinity under subambient conditions. A series of polyurethane elastomers with a constant hard segment percentage (40 wt %) was prepared using 4,4′-methylenediphenyl diisocyanate and 1,4-butanediol as the hard segment. Tensile test results and Shore hardness measurements demonstrated that polyurethanes based on polycarbonate macrodiols prepared from 1,3-bis(4-hydroxybutyl)-1,1,3,3-tetramethyldisiloxane had the lowest modulus and hardness of the series of polyurethanes. The remaining polyurethanes had high tensile strength with poor elasticity. The morphology of the polyurethanes, as determined by DSC analysis, varied from completely phase-mixed to well phase-separated structures. Polyurethanes based on macrodiols prepared from 1,3-bis(4-hydroxybutyl)-1,1,3,3-tetramethyldisiloxane showed good phase-separated morphology, with sharp hard segment melting endotherms and soft segment glass transitions close to that of the pure soft segment. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 69: 1621–1633, 1998

Structure of the interfacial region between polycarbonate and plasma-deposited SiN1.3 and SiO2 optical coatings studied by ellipsometry

Abstract: Fabrication of optical films on plastic substrates presents a considerable challenge due to the necessity of controlling adhesion and the optical properties of the interface. In the present work, the surface of polycarbonate (PC) substrates was pretreated in a microwave plasma in N2 and He gases, and amorphous hydrogenated silicon nitride (SiN1.3) and dioxide (SiO2) films were deposited in a dual-mode microwave/radiofrequency plasma. Using ex situ variable angle spectroscopic ellipsometry (VASE), spectrophotometry, and x-ray photoelectron spectroscopy, it was found that the plasma-treated PC contains a crosslinked surface layer which can extend to a depth of more than 50 nm, and which presents a refractive index increase of about 1%–2%. When PC is plasma treated and coated with SiN1.3 or SiO2, the interfacial region (interphase) is structured: it comprises the crosslinked layer, and a less dense transition region between the polymer and the film. The interphase may extend up to 100 nm. Some of the results...

Biostable polycarbonate urethane products

Abstract: Porous and non-porous polycarbonate urethane polymers having a set of properties suitable for long term implantation within the body of a mammal. The polycarbonate foams and elastomers comprise a polycarbonate material that is resistant to attack by in vivo agents over extended periods of time. The polycarbonate urethane polymers are prepared by reacting polycarbonate polyols with an isocyanate and a chain extender.

Compatibilized blends of non-polar thermoplastic elastomers and polar thermoplastic polymers

Abstract: The invention relates to compatibilized blends comprising a non-polar thermoplastic elastomer, a polar thermoplastic polymer selected from thermoplastic polyurethane (TPU), chloro containing polymers, fluoro containing polymers, polyesters, acrylonitrile-butadiene-styrene copolymers, styrene-acrylonitrile copolymers, styrene-maleic anhydride copolymer, polyacetal, polycarbonate, polyphenylene oxide, and a suitable compatibilizer.

Synthesis and Optical Properties of Fullerene-Functionalized Polycarbonates

Abstract: Fullerenation of polycarbonate (PC) is achieved by direct reaction of C60 with PC using AlCl3 as catalyst. Stirring a 1,1,2,2-tetrachloroethane solution of C60 and PC in the presence of AlCl3 under nitrogen at 140 °C for 24 h attached C60 to the PC chains, yielding fullerenated PCs (C60−PCs) with a C60 content up to 2.16 wt %. The C60−PCs are soluble in tetrahydrofuran (THF) and chloroform, and IR, UV, and NMR analyses suggest that they possess the molecular structure HxC60(PC)x with x < 1 on the average. The C60−PCs limit strong 532-nm optical pulses more effectively than the parent C60. Light transmission spectra of the C60−PC solutions red-shift with increasing concentration, with their cutoff wavelengths predictably tunable by simply changing their concentrations.

Modified weatherable thermoplastic resin molding compositions and articles molded therefrom

Abstract: A flame retarded resin molding compositions with enhanced weatherable properties, which comprise a polyester and polycarbonate blend modified with an organopolysiloxane-polycarbonate and a glycidyl ester impact modifier for enhancing weatherablity and a flame retarding amount of a halogenated flame retardant.

Flame-retardant polycarbonate resin composition and electrical and electronic components made by molding the same

Abstract: A flame-retardant polycarbonate resin composition, characterized by comprising a polycarbonate resin (A) and a composite rubbery graft copolymer (B), preferably one obtained by grafting a composite rubber having a structure constituted of 1 to 99 wt. % of a polyorganosiloxane rubber component and 99 to 1 wt. % of a polyalkyl acrylate rubber component, the two components being so interwisted with each other as not to separate from each other, and a mean particle diameter of 0.01 to 0.6 μm with one or more vinyl monomers, at an (A) to (B) weight ratio of 99:1 to 90:10, and by containing, per 100 parts by weight of the sum total of the components (A) and (B), 0.3 to 1.2 parts by weight (in terms of phosphorus) of a halogen-free phosphoric ester (C) and 0.01 to 1.0 part by weight of polytetrafluoroethylene (D), the weight ratio of the graft copolymer (B) to the phosphorus resulting from the phosphoric ester (C) lying within the range of 2 to 15; and housing of office automation equipment and electrical and electronic appliances and battery packs made by molding the composition. The composition is improved in mechanical properties such as impact resistance, is excellent in moldability and flowability, and exhibits high flame retardance even without resort to any bromine compound.

Chemical reactions occurring in the thermal treatment of PC/PMMA blends

Abstract: The chemical reactions occurring in the thermal treatment of bisphenol-A polycarbonate (PC) and poly(methyl methacrylate) (PMMA) blends have been investigated by nuclear magnetic resonance (NMR), mass spectrometry (MS), size exclusion chromatography (SEC), and thermogravimetry (TG). Our results suggest that in the melt-mixing of PC/PMMA blends, at 230°C, no exchange reactions occur and that only the depolymerization reaction of PMMA has been observed. In the presence of an ester-exchange catalyst (SnOBu2), an exchange reaction was found to occur at 230°C, but no trace of PC/PMMA graft copolymer has been observed. Instead, an exchange reaction between the monomer methyl methacrylate (MMA), generated in the unzipping of PMMA chains, and the carbonate groups of PC has been suggested. This is due to the diffusion of MMA at the interface or even into the PC domains, where it can react with PC producing low molar mass PC oligomers bearing methacrylate and methyl carbonate chain ends and leaving the undecomposed PMMA chains unaffected. The TG curves of PC/PMMA blends prepared by mechanical mixing and by casting from THF show two separated degradation steps corresponding to that of homopolymers. This behavior is different from that of a transparent film of PC/PMMA blend, obtained by solvent casting from DCB/CHCl3, which shows a single degradation step indicating that the degradation rate of PC is increased by the presence of PMMA in the blend. The thermal degradation products obtained by DPMS of this blend consist of methyl methacrylate (MMA), cyclic carbonates arising from the degradation of PMMA and PC, respectively, and a series of open chain bisphenol-A carbonate oligomers with methacrylate and methyl carbonate terminal groups. The presence of the latter compounds suggests a thermally activated exchange reaction occurring above 300°C between MMA and PC. The presence of bisphenol-A carbonate oligomers bearing methyl ether end groups, generated by a thermally activated decarboxylation of the methyl carbonate end groups of PC, has also been observed among the pyrolysis products. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 1873–1884, 1998

Optical recording medium

Abstract: PROBLEM TO BE SOLVED: To easily control the refractive index by constituting the medium in such a manner that a second substrate having a second recording face coated with a reflection film is disposed under a first substrate having a first recording face coated with a light-transmitting reflection film and that the light- transmitting reflection film consists of a metal compd. SOLUTION: A light-transmitting first substrate 11 comprising a polycarbonate has a first recording face 11a on its surface, and the recording face 11a is coated with a light-transmitting reflection film 12 comprising an amorphous metal compd. A second substrate 21 comprising a polycarbonate of the same size as the first substrate 11 has a second recording face 21a on its surface. The recording face 21a is coated with a reflection film 22 to constitute a second optical recording medium 20. It is preferable that the intensities of the reflected light of detecting light beams LB1 and LB2 are almost same. Therefore, the light-transmitting reflection film 12 which covers the first recording face 11a has preferably 15 to 4% reflectance for the detecting light beam LB1.

Aromatic polycarbonate resin composition

Abstract: An aromatic polycarbonate resin composition having hydroxyl groups as end groups is thermally stable and also offers excellent resistance to hydrolysis. The polycarbonate resin composition incorporates (A) an aromatic polycarbonate resin containing hydroxyl groups in the proportion of 5% or more of the total end groups and a metal impurity and (B) a deactivating agent selected from the group consisting of phosphorous acid, a thioether compound, a phosphite diester and a nitrogen-containing organic compound. The amount of deactivating agent is based on the amount of metal impurity in (A) and the type of deactivating agent.

Synthesis and Swelling of Poly(bisphenol A carbonate) Using Supercritical CO2

Abstract: Introduction. Among the advantages of traditional melt-phase polymerization processes is the potential to produce a high molecular weight polymer without the use of solvent. While solvent-free melt-phase polymerization methods avoid the use of environmentally detrimental solvent mixtures, it would be convenient to mediate the high viscosity of the polymer melt associated with the attainment of high molecular weight polymer, especially near the end of the polymerization. It has been noted previously that the condensate associated with certain step-growth polymerizations can be removed more effectively by swelling or plasticizing the polymer melt in some manner, thus increasing both chain mobility and free volume in the melt phase.1 Swelling agents should improve polymerization rates of step-growth polymerization processes by increasing the surface area available for condensate removal, but such a technique is not an advantage from a processing standpoint if it introduces to the reaction a swelling agent that is toxic, costly, or difficult to separate from the end product. Since many step-growth polymers are used for food and beverage packaging applications, absolute safety of any additive to the melt phase is imperative. Polycarbonates are an important class of polymers due primarily to their toughness and optical clarity. Two different, industrially suitable, synthetic routes were developed virtually simultaneously by Bayer A.G. and General Electric Co.2 The first route involves an interfacial reaction between 4,4′-isopropylidene bisphenol (bisphenol A) and phosgene using a biphasic system of methylene chloride and an alkaline aqueous phase with a phase-transfer catalyst. The other route involves a melt transesterification between a bisphenol and a diaryl carbonate, typically diphenyl carbonate. The former has become the predominant industrial route despite the drawbacks of the use of both phosgene and methylene chloride. The difference in pKa of various bisphenols, their partitioning between the two phases, and interaction with the phase-transfer catalyst reduce the utility of this route for producing a wide range of statistical copolymers.3 For this reason, as well as both the ease of synthesis of the monomer and satisfactory properties of the derived polymer, the industry has centered on the use of bisphenol A. Melt transesterification provides a useful route to a wide range of statistical copolymers, but the high viscosity of the melt limits the molecular weight that can practically be achieved. The high viscosity, which, for example, can reach 106 P for poly(4,4′-cyclohexylidene bisphenol) carbonate at the reaction/processing temperature of 280 °C, is the result of the polymer chain stiffness which also provides the desirable mechanical properties. Such viscosities necessitate the use of high temperatures, which, in turn, can lead to discoloration in the final product. Although CO2 is a nonsolvent for most polymers (exceptions include many fluoropolymers and silicones), CO2 has been found to be an excellent plasticizing agent.4-7 Thus, if the mechanism of a given polymerization process is compatible with CO2, many mass/bulk polymerization processes could benefit from the plasticization afforded by CO2. Recent work using liquid or supercritical carbon dioxide as a solvent medium has shown that supercritical CO2 is compatible with a number of polymerization types, including free radical,8 cationic,9 ring opening,10 and oxidative coupling.11 A number of small molecules display significant solubility in liquid or supercritical CO2, including a number of step-growth reaction byproducts. Although water has a low solubility in supercritical CO2, other common condensates, such as acetic acid, neopentyl glycol, and phenol, have the potential to be extracted from a reaction melt using supercritical fluid extraction methods that would drive the reaction to completion. Conventional methods of melt-phase step-growth polymerizations use vacuum techniques to remove condensates, but extraction of condensates using a SCFE method with CO2 has the added benefit of introducing a swelling agent into the polymer melt. In addition, the commercial scale use of vacuum methods requires tedious process controls and extensive capital investment in order to maintain vacuum integrity for extended periods of time (years) with little maintenance. The use of low-pressure CO2 as a continuous phase for bulk-phase polymerizations of polyesters and polyamides has been proposed,12 but the issue of the potential plasticization of the melt phase afforded by high-pressure CO2 has only been recently demonstrated.13 We are currently investigating the effects of CO2 as the swelling medium for melt-phase step-growth polymerizations. If the mechanism of polymerization is compatible with CO2, we anticipate that the swelling of the polymer melt by supercritical CO2 will lead to a reduction in the melt viscosity, which, in turn, may lead to increased reaction rates and increased production quality (color, higher purity lower residual monomer, etc.). Polymer Swelling Measurements. Measurements of polymer swelling with CO2 was performed in a specially designed high-pressure view cell, constructed of 316 stainless steel. The window of the cell consists of a steel plug in series with a brass O-ring, a 1 in. o.d., 0.5 in. thick sapphire window and a 0.002 in. thick Teflon gasket. High-pressure CO2 was introduced to the cell using a syringe pump (Isco 260D). A digital camera (Pulnix TM-7CN) outfitted with a 50 mm lens (Nikon f/1.4D) was used to view and record the swelling kinetics * To whom correspondence should be addressed. † University of North Carolina at Chapel Hill. ‡ North Carolina State University. § Presently at MiCell Technologies. ⊥ Presently at the Tokyo Institute of Technology. 9090 Macromolecules 1998, 31, 9090-9092

Nanoindentation on polycarbonate/polymethyl methacrylate Blends

Abstract: The combination of a scanning force microscope (SFM) with an integrated microindenter makes it possible to investigate mechanical properties of polymers and their blended systems with high spatial resolution The behaviour of the polymers polycarbonate (PC), polymethyl methacry- late (PMMA), and PC=PMMA blends were investigated using nanoindentation with different mechanical load, fre- quency, and development of inelastic deformation with time The results of the microscopic measurements were compared with macroscopic properties from tensile test experiments The relation of the Young's moduli of the macroscopic and microscopic tests of the neat polymers are comparable