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.

Effect of isopropylidene replacement on gas transport properties of polycarbonates

Abstract: The gas sorption and transport properties of a series of polycarbonates in which the isopropylidene unit of bisphenol A polycarbonate has been replaced with another molecular group are presented. Two new materials, bisphenol of norbornane polycarbonate (NBPC) and bisphenol Z polycarbonate (PCZ), are compared with several polymers which have been studied previously in this laboratory, including bisphenol A polycarbonate (PC), hexafluorobisphenol A polycarbonate (HFPC), and bisphenol of chloral polycarbonate (BCPC). The effect of molecular structure on chain mobility and chain packing is related to the gas transport properties. Dynamic mechanical thermal analysis and differential scanning calorimetry are used to judge chain mobility, while x-ray diffraction and free volume calculations give information about chain packing. Permeability measurements were made for He, H2, O2, N2, CH4, and CO2 at 35°C over a range of pressures up to 20 atm. Sorption experiments were also done for N2, CH4, and CO2 under the same conditions. The permeability coefficients of these polymers rank in the order HFPC ≫ NBPC>PC>BCPC ≫ PCZ for all of the gases. With the exception of BCPC, this order correlates well with fractional free volume. The low gas permeability of BCPC is attributed to a polarity effect. In general, bulky and relatively immobile substituents, as in HFPC and NBPC, can yield improved separation characteristics. The polar group of BCPC and the flexible cyclohexyl substituent of PCZ result in relatively low gas permeability.

Thermoplastic resin composition and molded article thereof

Abstract: Disclosed is a thermoplastic resin composition excellent in fluidity and mechanical characteristics. A preferred embodiment of this thermoplastic resin composition is also excellent in low warping property, laser transmission and laser weldability. Also disclosed is a molded article of such a thermoplastic resin composition. Specifically disclosed is a thermoplastic resin composition obtained by blending 0.1-4 parts by weight of a multifunctional compound (B) having three or more functional groups, wherein at least one terminal structure having a functional group includes an alkylene oxide unit, per 100 parts by weight of a thermoplastic resin (A). The thermoplastic resin (A) is preferably composed of one or more resins selected from polyester resins and polycarbonate resins. Also specifically disclosed is a molded article of such a thermoplastic resin composition.

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