PC Polycarbonates

CD-ROM not erasablenot rewritable technology identical with audio compact disk (CD-DA) substrate and information layer from polycarbonate (PC)... 

Polycarbonate (PC) Resins. Polycarbonates (qv) based on bisphenol A are sold in large quantities. Other bisphenols can be incorporated, but do not give the same favorable combination of properties and cost (82). Small quantities of PC based on tetramethylbisphenol A are used as blending resins (83) and polyester carbonate copolymers are used for appHcations requiring heat-deflection temperatures above those of standard PC resins (47). 

In a molded polymer blend, the surface morphology results from variations in composition between the surface and the bulk. Static SIMS was used to semiquan-titatively provide information on the surface chemistry on a polycarbonate (PC)/polybutylene terephthalate (PBT) blend. Samples of pure PC, pure PBT, and PC/PBT blends of known composition were prepared and analyzed using static SIMS. Fn ment peaks characteristic of the PC and PBT materials were identified. By measuring the SIMS intensities of these characteristic peaks from the PC/PBT blends, a typical working curve between secondary ion intensity and polymer blend composition was determined. A static SIMS analysis of the extruded surface of a blended polymer was performed. The peak intensities could then be compared with the known samples in the working curve to provide information about the relative amounts of PC and PBT on the actual surface. 

Friedrich et al. also used XPS to investigate the mechanisms responsible for adhesion between evaporated metal films and polymer substrates [28]. They suggested that the products formed at the metal/polymer interface were determined by redox reactions occurring between the metal and polymer. In particular, it was shown that carbonyl groups in polymers could react with chromium. Thus, a layer of chromium that was 0.4 nm in thickness decreased the carbonyl content on the surface of polyethylene terephthalate (PET) or polymethylmethacrylate (PMMA) by about 8% but decreased the carbonyl content on the surface of polycarbonate (PC) by 77%. The C(ls) and 0(ls) spectra of PC before and after evaporation of chromium onto the surface are shown in Fig. 22. Before evaporation of chromium, the C(ls) spectra consisted of two components near 284.6 eV that were assigned to carbon atoms in the benzene rings and in the methyl groups. Two additional... 

In this section, we examine fibrillation behavior of a polycarbonate (PC)-TLCP blend by injection molding. 

Polycarbonates (PC) are another group of condensation thermoplastics used mainly for special engineering purposes. These polymers are considered polyesters of carbonic acid. They are produced by the condensation of the sodium salt of bisphenol A with phosgene in the presence of an organic solvent. Sodium chloride is precipitated, and the solvent is removed by distillation ... 

Fig. 50. Yield for chain scission as a function of strain rate for different fractions of polycarbonate (PC) in benzyl alcohol/dioxan (90 10 v.v) at 20 °C. A normal PC with Mp = 417000 B normal PC with Mp = 321000 C normal PC with Mp = 256000 D PC with weak bonds, Mp = 217000 Mp molecular weight at peak maximum sc critical strain rate for chain scission (extrapolated from the linear portion of the degradation curve)...

Polycarbonate (PC) serves as a convenient example for both, the direct determination of the distribution of correlation times and the close connection of localized motions and mechanical properties. This material shows a pronounced P-relaxation in the glassy state, but the nature of the corresponding motional mechanism was not clear 76 80> before the advent of advanced NMR techniques. Meanwhile it has been shown both from 2H NMR 17) and later from 13C NMRSI) that only the phenyl groups exhibit major mobility, consisting in 180° flips augmented by substantial small angle fluctuations about the same axis, reaching an rms amplitude of 35° at 380 K, for details see Ref. 17). 

A method of converting polycarbonate (PC) to bishydroxyethyl ether of bisphenol A (BHE-BPA) was studied, with a view to recycling PC plastic wastes. Treating PC in ethylene glycol with a catalytic amount of sodium hydroxide produced the monohydroxyethyl ether of bisphenol A (MHE-BPA, 42%), BHE-BPA (11%) and BPA (42%). BHE-BPA was produced quantitatively when 1.6 mol. equiv. ethylene carbonate was added to this reaction system. The reaction of BPA with EC produced both BHE-BPA and MHE-BPA, indicating that ethylene carbonate was formed as an intermediate in the base catalysed reaction of PC with ethylene glycol. A large proportion of this ethylene carbonate formed from PC was, however, lost by decarboxylation so additional ethylene carbonate must be provided for the quantitative preparation of BHE-BPA. 12 refs. 

Other commercial thermoplastics include acrylonitrile butadiene styrene (ABS), cellulose acetate butyrate (CAB), polycarbonate (PC), nylon (PA), and acetals. These resins are frequently used in consumer applications. 

Boronic acids (69 and 70) (Fig. 45) with more than one boronic acid functionality are known to form a polymer system on thermolysis through the elimination of water.93 Specifically, they form a boroxine (a boron ring system) glass that could lead to high char formation on burning. Tour and co-workers have reported the synthesis of several aromatic boronic acids and the preparation of their blends with acrylonitrile-butadiene-styrene (ABS) and polycarbonate (PC) resins. When the materials were tested for bum resistance using the UL-94 flame test, the bum times for the ABS samples were found to exceed 5 minutes, thereby showing unusual resistance to consumption by fire.94... 

The photochemical degradation of bisphenol-A polycarbonate (PC) has been the subject of a number of investigations.-3 ... 

Engineering polymers are often used as a replacement for wood and metals. Examples include polyamides (PA), often called nylons, polyesters (saturated and unsaturated), aromatic polycarbonates (PCs), polyoxymethylenes (POMs), polyacrylates, polyphenylene oxide (PPO), styrene copolymers, e.g., styrene/ acrylonitrile (SAN) and acrylonitrile/butadiene/styrene (ABS). Many of these polymers are produced as copolymers or used as blends and are each manufactured worldwide on the 1 million tonne scale. 

As an example of the form of the information that may be derived from a pyrolysis-MS, Figure 26 [69] shows the structure of the polycarbonate (PC) and the EI-MS spectra of pyrolysis compounds obtained by DPMS of poly(bisphenol-A-carbonate) at three different probe temperatures corresponding to the three TIC (total ion current) maxima shown in Figure 27(b) Figure 27 compares the MS-TIC curve with those obtained from thermogravimetry. (The TIC trace is the sum of the relative abundances of all the ions in each mass spectrum plotted against the time (or number of scans) in a data collection sequence [70].)... 

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