Showing papers on "Polycarbonate published in 2008"

Biodegradation of aliphatic and aromatic polycarbonates.

Abstract: Polycarbonate is one of the most widely used engineering plastics because of its superior physical, chemical, and mechanical properties. Understanding the biodegradation of this polymer is of great importance to answer the increasing problems in waste management of this polymer. Aliphatic polycarbonates are known to biodegrade either through the action of pure enzymes or by bacterial whole cells. Very little information is available that deals with the biodegradation of aromatic polycarbonates. Biodegradation is governed by different factors that include polymer characteristics, type of organism, and nature of pretreatment. The polymer characteristics such as its mobility, tacticity, crystallinity, molecular weight, the type of functional groups and substituents present in its structure, and plasticizers or additives added to the polymer all play an important role in its degradation. The carbonate bond in aliphatic polycarbonates is facile and hence this polymer is easily biodegradable. On the other hand, bisphenol A polycarbonate contains benzene rings and quaternary carbon atoms which form bulky and stiff chains that enhance rigidity. Even though this polycarbonate is amorphous in nature because of considerable free volume, it is non-biodegradable since the carbonate bond is inaccessible to enzymes because of the presence of bulky phenyl groups on either side. In order to facilitate the biodegradation of polymers few pretreatment techniques which include photo-oxidation, gamma-irradiation, or use of chemicals have been tested. Addition of biosurfactants to improve the interaction between the polymer and the microorganisms, and blending with natural or synthetic polymers that degrade easily, can also enhance the biodegradation.

A Novel Strategy to Incorporate Carbon Nanotubes into Thermoplastic Matrices

Abstract: Multiwalled carbon nanotubes (MWNT) are introduced into thermoplastic matrices (polycarbonate and polyamide) by melt blending using polyethylene (PE) based concentrates with high MWNT loadings (24-44 wt.-%). MWNT surfaces were treated with a metallocene-based complex to afford the in-situ polymerization of ethylene directly from the surface. The resulting concentrates showed excellent MWNT pre-dispersion. Due to the high interfacial energy between MWNT and PE, the nanotubes migrate into matrix polymers with lower interfacial energies, like polycarbonate and polyamide, and thereby remain in their excellent dispersion state. Thus, electrical percolation is achieved at lower MWNT contents as compared to direct incorporation. For polycarbonate it is shifted from 0.75 to 0.25 wt.-%.

Carbon Nanotube Polycarbonate Composites for Ultrafast Lasers

Abstract: Carbon nanotube polycarbonate composites with controlled nanotube-bundle size are prepared by dispersion with conjugated polymers followed by blending with polycarbonate. The composite has uniform sub-micrometer nanotube bundles in high concentration, shows strong nonlinear optical absorption, and generates 193 fs pulses when used as passive mode-locker in a fiber laser.

Mechanical and electrical properties of polycarbonate nanotube buckypaper composite sheets.

Abstract: The thermogravimetric, mechanical, and electrical properties of composite sheets produced by infiltrating single-wall carbon nanotube films (also known as 'buckypapers') with polycarbonate solution were characterized. The composite sheets showed improved stiffness and toughness, while the electrical conductivity decreased, as compared to a neat buckypaper. In addition, polycarbonate/buckypaper composite sheets showed higher resistance to handling and processing damages. Experimental results suggest the viability of the infiltration process as a means to toughen buckypapers and to fabricate polymer/carbon nanotube composites having high nanotube concentration and controlled nanotube structure.

Silver nanoparticle impregnated polycarbonate substrates for surface enhanced Raman spectroscopy

Abstract: The embedding of nanoscopic metal structures into polymeric matrices represents a convenient way to stabilise a controlled dispersion of protected nanoparticles whilst taking advantage of their physical characteristics. Supercritical carbon dioxide (scCO) has been used to produce silver nanoparticles in optically transparent polycarbonate (PC) matrices allowing fine scale dispersions of particles to be produced within a prefabricated polymer component. Characterization of these nanocomposites has been performed using transmission electron microscopy (TEM) and UV-vis spectroscopy. The substrates give excellent responses in surface-enhanced Raman spectroscopy (SERS) for both 4-aminothiophenol and rhodamine 6G target molecules. They offer significant benefits over more conventional SERS substrates in that they are cheap, flexible, mechanically robust and temporally stable. Post-processing the films via simple etching techniques, provides an additional degree of design control and the potential to fabricate devices with unique excitation and detection geometries for a wide range of applications.

Hydrothermal Treatment of Nanoparticle Thin Films for Enhanced Mechanical Durability

Abstract: The mechanical durability of nanoporous all-nanoparticle and polymer−nanoparticle layer-by-layer (LbL) films (80−150 nm thick) on both glass and polycarbonate substrates has been greatly enhanced by hydrothermal treatment (124−134 °C). Polymer−nanoparticle films were more durable than all-nanoparticle films after hydrothermal treatment. The optical properties of nanoporous antireflection (AR) films were exploited in an abrasion test (25−100 kPa normal stress) to quantify the extent of abrasive wear observed qualitatively by scanning electron microscopy (SEM). Marginal damage was observed under optimal reinforcement conditions. Untreated films not only delaminated from the surface completely but also damaged their underlying glass and polycarbonate substrates during testing. The nature of the substrate was found to play an important role in determining abrasion resistance, regardless of the level of particle fusion in the film. The low-temperature process enables in situ mechanical reinforcement of otherwi...

Migration of bisphenol A into water from polycarbonate baby bottles during microwave heating.

Abstract: A comprehensive migration database was established for bisphenol A from polycarbonate baby bottles into water during exposure to microwave heating Eighteen different brands of polycarbonate baby bottles sold in Europe were collected Initial residual content of bisphenol A and migration after microwave heating were determined Residual content of bisphenol A in the polycarbonate baby bottles ranged from 14 to 353 mg kg-1 Migration of bisphenol A was determined by placing a polycarbonate bottle filled with water in a microwave oven and heating to 100°C; the level of bisphenol A in the water was analysed by GC-MS The procedure of microwave heating and analysis was repeated twice for the same bottle and, thus, three migration extracts were prepared for each test specimen Migration of bisphenol A into water ranged from <01 to 07 μg l-1 There was no correlation between the amount of residual content of bisphenol A in the bottles and the migration of bisphenol A into water Furthermore, there was no correlation between the amounts of bisphenol A in consecutive migration extracts Data show that during three microwave-heating cycles of a baby bottle made from polycarbonate, microwave radiation had no effect on the migration of bisphenol A into water from polycarbonate All levels found were well below the specific migration limit of 06 mg kg-1 specified for bisphenol A in Commission Directive 2004/19/EC

Flame-retardant polycarbonate resin composition

Abstract: A resin composition which is excellent in appearance, impact strength, hydrolysis resistance and drip prevention properties The resin composition comprises (A) 100 parts by weight of an aromatic polycarbonate resin (component A), (B) 001 to 6 parts by weight of a polymer mixture (component B) obtained by suspension polymerizing a styrene monomer, a maleic anhydride monomer and an acrylic monomer in the presence of polytetrafluoroethylene particles, and (C) 001 to 30 parts by weight of a flame retardant (component C)

Effects of Surface Plasma Treatment on Tribology of Thermoplastic Polymers

Abstract: We have subjected polycarbonate (PC), low density polyethylene (LDPE), polystyrene (PS), polypropylene (PP), and Hytrel 1 (HY, a thermoplastic elastomer) to atmospheric pressure oxygen plasma treatment for varying amounts of time. Effects of the treatment have been evaluated in terms of the water wetting angle, dynamic friction, scratch resistance, and sliding wear. Although PS, PP, and HY do not undergo significant tribological changes as a result of the interaction with plasma, PC and LDPE show more pronounced and useful effects, such as a lowering of dynamic friction in PC and wear reduction in LDPE. These results can be explained in terms of the changes in chemical structures and increase of hydrophilicity. Based on the effects of oxygen plasma treatment on PC and LDPE, these two polymers have been subjected to longer oxygen plasma treatments and to argon, nitrogen, and air plasmas. Resulting effects on friction and scratch resistance are compared to determine the mechanisms responsible for the various surface behaviors. Chemical surface modification—as represented by changing contact angles—contributes to the tribological responses. POLYM. ENG. SCI., 48:1971–1976, 2008. a 2008 Society of Plastics Engineers

Polycarbonate resin composition

Abstract: A polycarbonate resin composition, which comprises a plant-derived component, has improved properties such as improved moldability, biodegradability, water-absorbing property, impact resistance, melt flow characteristics, density, transparency and the like, exhibits less environmental load and is excellent in recycling efficiency is disclosed. The polycarbonate resin composition of the present invention comprises 30 to 95 parts by weight of component A (a polycarbonate comprising a plant-derived component) and 5 to 70 parts by weight of component B (an acrylate resin, a biodegradable resin, an aromatic polyester, a polyolefin or a rubber-modified styrene resin) (provided that the total of the component A and the component B is 100 parts by weight).

Quantifying deformation and energy dissipation of polymeric surfaces under localized impact

Abstract: The mechanical response of polymeric surfaces to concentrated impact loads is relevant to a range of applications, but cannot be inferred from quasistatic or oscillatory contact loading. Here we propose and demonstrate a set of quantitative metrics that characterizes the ability of polymers to resist impact deformation and dissipate impact energy, as well as the strain rate sensitivity of these materials to contact loading. A model which incorporates nonlinear material behavior is presented and can predict the experimentally observed deformation behavior with high accuracy. The micrometer-scale impact response of several polymers has been investigated in the velocity range of 0.7–1.5 mm/s. Two semi-crystalline polymers – polyethylene (PE) and polypropylene (PP) – characterized above the corresponding glass transition temperature T g , and four fully amorphous polymers characterized well below T g – polystyrene (PS), polycarbonate (PC), and low and high molecular weight poly(methyl methacrylate) or PMMA termed commercially as Lucite® (LU) and Plexiglas® (PL) – have been considered. In an inverse application, the model and experimental method provide a tool for extracting the relevant material quantities, including energy dissipation metrics such as the coefficient of restitution e . This approach can be used to determine quantitatively the impact energy absorption of polymer surfaces at elevated temperatures through T g , as demonstrated for PS and PC over the range of 20–180 ° C.

Resin composition and resin molded article

Abstract: PROBLEM TO BE SOLVED: To provide a resin composition excellent in flowability, impact resistance, chemical resistance, moist heat-resistance and at the same time excellent in recycling characteristics. SOLUTION: The resin composition comprises an aromatic polycarbonate resin and a polyethylene terephthalate resin, wherein when the sum of the both is 100 pts.wt., the amount of the aromatic polycarbonate resin is 40-99 pts.wt. and the amount of the polyethylene terephthalate resin is 1-60 pts.wt., and the content of the germanium compound is 1-50 ppm as the germanium atom in the polyethylene terephthalate resin and the composition has 0.95-1.3 dL/g of intrinsic viscosity. COPYRIGHT: (C)2009,JPO&INPIT

A process for producing polycarbonates and a coordination complex used therefor

Abstract: The complex of the present invention containing an onium salt and a central Lewis acidic metal has a high catalytic activity at a high temperature for the copolymerization of an epoxide and carbon dioxide to produce a high molecular weight polycarbonate.

Preparation of Amylose/Polycarbonate Inclusion Complexes by Means of Vine-Twining Polymerization

Abstract: In this paper, we describe the preparation of inclusion complexes composed of amylose and hydrophobic polycarbonates by "vine-twining polymerization", which was achieved by means of the phosphorylase-catalyzed enzymatic polymerization of an α-D-glucose 1-phosphate from a maltoheptaose in the presence of the polycarbonates with appropriate methylene chain lengths. We found that the polycarbonate with the shorter methylene chain length such as poly(tetramethylene carbonate) was more favorable as the guest polymer to form the inclusion complex with amylose on vine-twining polymerization than that with the longer one.

Monomer recovery of waste plastics by liquid phase decomposition and polymer synthesis

Abstract: Polycarbonate was decomposed into phenol, bisphenol A and p-isopropenylphenol by the reaction at 130–300 °C in water. The decomposition reaction was accelerated by the addition of Na2CO3, and the yield of identified products reached 68% in the reaction at 250 °C for 1 h. By using the decomposed products, the prepolymer of phenol resin was synthesized.

Scratch-resistant flameproof thermoplastic resin composition with improved compatibility

Abstract: Disclosed herein is a scratch-resistant flameproof thermoplastic resin composition, the resin composition comprising a base resin including (A) about 50 to about 90% by weight of a polycarbonate resin; (B) about 1 to about 50% by weight of a methacrylic copolymer resin with a refractive index of about 1.495 to about 1.590; and (C) about 0 to about 49% by weight of a (meth)acrylic resin, and (D) about 5 to about 40 parts by weight of a flame retardant, based on about 100 parts by weight of the base resin comprising (A)+(B)+(C). The resin composition of the present invention can have good flame retardancy, scratch resistance, colorability, and good appearance due to its improved compatibility. The resin composition of the invention can be used to produce plastic molded articles which can exhibit better physical properties than products produced using conventional resin compositions.

Antireflection coating with UV-protective properties for polycarbonate.

Abstract: Polycarbonate is the chosen material for covers of automotive displays because it combines high transparency with high breaking strength. The requirements for coatings include an improvement of the scratch resistance and antireflection properties as well as high stability for challenging environmental conditions. A coating that involves all required properties has been developed and deposited onto polycarbonate by plasma-ion assisted deposition.

Method for producing polycarbonate and molding of polycarbonate

Abstract: PROBLEM TO BE SOLVED: To provide a method for producing polycarbonate exhibiting excellent mechanical strength, heat resistance, a small refractive index, a large Abbe number, small birefringence, and excellent transparency, and containing a raw material resulting from vegetables, and to provide moldings of the polycarbonate. SOLUTION: The method for producing a polycarbonate comprises a step of reacting a dihydroxy compound containing a dihydroxy compound having at least one connecting group represented by -CH 2 -O- in the molecule with a carbonic diester in the presence of a polymerization catalyst, wherein the content of formic acid in the dihydroxy compound having at least one connecting group represented by -CH 2 -O- in the molecule is less than 20 ppm. The moldings are made of either a polycarbonate which contains constituent units derived from a dihydroxy compound having at least one connecting group represented by -CH 2 -O- in the molecule and which exhibits an Abbe number of 50 or above and a 5% weight loss temperature of 340°C or above, or a composition comprising the polycarbonate. COPYRIGHT: (C)2009,JPO&INPIT

Mechanical properties of triple composites of polycarbonate, single-walled carbon nanotubes and carbon fibres

Abstract: The present work was undertaken to study the mechanical properties of reinforced polycarbonate systems, where the filler material consists of single-walled carbon nanotubes (SWCNTs), of carbon fibres (CF) or of both. The SWCNTs were taken from different sources, laser ablation and arc discharge, and carefully characterized before their incorporation into the matrix system. The loadings of the reinforcement material were varied from 1 to 35.5 wt% in the thermoplastic polymer. All composites were produced by melt extrusion. Experimental results show that small amounts of carbon nanotubes randomly distributed in thermoplastic matrix systems do not inevitably enhance the mechanical stability. Higher mechanical improvements could be attained by adding CF to the composite system. A triple composite of polycarbonate, PC/SWCNTs/CF reveals synergy effects in mechanical and electrical aspects. The composites were investigated by stress–strain measurements, dynamical mechanical analysis and hardness probing.

Thermoplastic polycarbonate/polyester blend compositions with improved mechanical properties

Abstract: Disclosed is a thermoplastic composition comprising a mixture of from 10 to 98 weight % of a polycarbonate polymer, from 2 to 90 weight % of a polyester polymer comprising structures derived from a diol compound having the structure (A) HO—Z—OH, wherein Z is a C1 to C36 linear aliphatic radical, a C3 to C36 branched aliphatic or cycloaliphatic radical, a C6 to C36 aryl radical, or a C7 to C36 alkylaryl radical, and a diacid compound having the structure (B) HOOC—CH2CH2—COOH, from 0 to 5 weight % of a polylactic acid polymer, wherein the sum of the polycarbonate polymer, the polyester polymer, and the polylactic acid polymer is equal to 100 weight %. The thermoplastic composition has improved mechanical properties.

Thermoplastic resin composition with improved compatibility

Abstract: Disclosed herein is a thermoplastic resin composition with improved compatibility by introducing a branched acrylic copolymer to a polycarbonate resin. The thermoplastic resin composition has good scratch resistance in addition to good colorability and appearance without a compatibilizer by improving compatibility.

Resin composition and molded body obtained by molding the same

Abstract: Disclosed is a resin composition which is excellent in mechanical strength, heat resistance, wet heat resistance and flame retardance, while having low dependence on petroleum products. Specifically disclosed is a resin composition containing a polylactic acid resin (A), a polycarbonate resin (B), a styrene thermoplastic elastomer (C), a monocarbodiimide compound (D), and a polyvalent carbodiimide compound (E). The mass ratio between the components (A) and (B), namely (A)/(B) is from 25/75 to 90/10.

Improvement of the surface properties of polycarbonate by organic–inorganic hybrid coatings

Abstract: Organic-inorganic hybrids (ceramers) were prepared through the sol-gel process with opportune alkoxysilane-terminated polymer chains as the organic phase and tetraethoxysilane as the inorganic network precursor. The consolidation process, used to reach a high degree of crosslinking between the two phases, was carried out with either conventional oven heating or microwave irradiation. High conversion degrees were obtained with both treatments even when microwave postcuring turned out to be much faster than conventional heating (5-10 s vs 40 min). Scratch-test and photooxidation investigations showed a significant improvement in scratch, yellowing, and photodegradation resistance for coated polycarbonate.

Resin composition, and molded article produced from the same

Abstract: Disclosed is a resin composition including a polylactic acid resin (A), a polycarbonate resin (B) and a methyl methacrylate copolymer (C). The mass ratio (A/B) between the resins (A) and (B) is 40/60 to 80/20. The ratio (MFR A /MFR B ) between the melt flow rate (MFR A ) of the resin (A) and the melt flow rate (MFR B ) of the resin (B) is less than 10 at 240°C under a load of 21.2 N. The copolymer (C) is a copolymer between methyl methacrylate and a (meth)acrylic acid ester, and the weight average molecular weight (Mw) of the copolymer (C) is 500,000 or more. The content of the copolymer (C) is 0.1 to 20 parts by mass in relation to 100 parts by mass of the total of the resins (A) and (B).