Polycarbonate

About: Polycarbonate is a research topic. Over the lifetime, 14032 publications have been published within this topic receiving 141740 citations. The topic is also known as: PC & Polycarbonate, PC.

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.

Biodegradable polymers based on renewable resources. VI. Synthesis and biodegradability of poly(ester carbonate)s containing 1,4:3,6-dianhydro-D-glucitol and sebacic acid units

Abstract: Poly(ester carbonate)s with different compositions were synthesized by bulk polycondensation of 1,4:3,6-dianhydro-D-glucitol with diphenyl sebacate and diphenyl carbonate in the presence of zinc acetate as a catalyst. Most of the poly(ester carbonate)s as well as the corresponding polycarbonate were amorphous, except the poly(ester carbonate) with a small carbonate content and the corresponding polyester, which are semicrystalline. All these poly(ester carbonate)s are soluble in chloroform, pyridine, dimethylformamide, dimethyl sulfoxide, and N,N-dimethylacetamide. Soil burial degradation tests, biochemical oxygen demand (BOD) measurements in an activated sludge, and enzymatic degradation tests indicated that these poly(ester carbonate)s are potentially biodegradable. The biodegradability was found to be maximum for the poly(ester carbonate)s with carbonate contents of 10–20 mol % and to decrease markedly for the poly(ester carbonate)s with the carbonate content above 50 mol %. The biodegradability of the poly(ester carbonate)s is discussed in terms of the crystallinity, glass transition temperature, and surface hydrophobicity of the polymer films. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 872–880, 2002

A new synthetic route to polycarbonate

Abstract: A detailed study has been carried out on the new synthetic reaction of poly(p-xylylene carbonate) from potassium carbonate and p-xylylene dibromide by using a variety of crown ethers as a catalyst, which was recently found by the present authors. Crown ethers having 18-member ring showed the best catalytic property of the various crown ethers, and the reaction was conducted in various solvents at 50–160°C by using 18-crown-6-ether. Both the polymer yield and the molecular weight of the polymer increased in proportion to the amount of potassium carbonate, and they increased rapidly and reached constant values with increasing the concentration of 18-crown-6-ether. They also depended significantly upon the reaction temperature as well as the solvent used. A maximum yield with the highest molecular weight was obtained from the reaction at 100–120°C in diglyme solvent. The spectroscopic analysis of the polymer indicated that all the end groups of the resulting polymer had the structure of benzyl bromide. From these results, a plausible mechanism was proposed for the reaction. Similar reactions were also conducted by using several aliphatic dibromides, Br(CH2)xBr, in place of p-xylylene dibromide. The products were strongly dependent of the value of x: polycarbonate was obtained from dibromides with ≧4, and cyclic carbonates from dibromides with ≦3.

Ab initio study on thermal degradation reactions of polycarbonate

Abstract: An ab initio study on thermal degradation of polycarbonate, poly(bisphenol A carbonate), PC, was carried out using Hartree-Fock (HF) and density functional (B3LYP) methods. The polycarbonate chain was modelled by a dimer unit (PC-2), which represented a fragment of the polymer chain. The main emphasis was on the determination of reaction enthalpies and Gibbs energies for the different degradation reactions, which were calculated at a standard state (298.15 K) and at a higher temperature (673.15 K). On the basis of the calculated Gibbs energies, the various degradation paths were ranked according to their favourableness and spontaneity and found to agree well with experimental data. The CO 2 elimination reaction and substitution reaction with water were found to be the most favourable reaction paths.

Polycarbonate compositions with thin-wall flame retardance

Abstract: Polycarbonate compositions containing a specific combination of additives achieve desirable flame retardance characteristics when used in thin wall polycarbonate articles. These compositions contain a polycarbonate/siloxane component, containing a polycarbonate siloxane copolymer, or a mixture of a polycarbonate siloxane copolymer and polycarbonate resin; a mineral filler; and a flame retardant The composition contains at least 50% by weight of polycarbonate when the polycarbonate of the polycarbonate siloxane copolymer and any polycarbonate resin (linear or branched) are considered together; and the polycarbonate siloxane copolymer and the mineral filler are present in amounts effective to achieve a flex modulus of 29,000 kg/cm3 or greater, for example 30,000 kg/cm3 or greater, good flex-fold strength and good impact strength, for example a room temperature Notched Izod Impact Strength of 25 kgf-cm/cm or greater. The composition also includes a flame retardant to enable the composition to obtain a UL94 rating of V0 at test thicknesses of 1.2 mm.