Bisphenol-A polycarbonate film

Table III. Sensitivity of the IR-RA Measurement to Reduction in Initial Concentration of Several Functional Groups in Bisphenol-A Polycarbonate Films of Various Thicknesses ...

The photodegradation of unstabilized bisphenol A polycarbonate films is described as an autoaccelerating process initiated by formation of products arising from a formal photo-Fries reaction. Oxidation also contributes as an additional photodegradation pathway. Photosensitive polymers... 

FTIR spectroscopy was used to study the conformational changes in quenched bisphenol A polycarbonate films during physical ageing. The conformation changed gradually from the high energy trans-cis conformation to... 

Bulk spinodal decomposition in TMPC/PS [TMPC = poly(tetramethyl-Bisphenol-A-polycarbonate)] films was also studied by Cabral et ol. [151] using AFM. These authors were able to show that the topography observed by AFM is related to the spinodal morphology, although the periodicity of the structure determined by AFM appears to be larger than expected from LS measurements. Since the AFM structure factor is obtained by Fourier transform of an image of a cross-section (2D) whereas the LS data are 3D Fourier transform of the spinodal structure, such a discrepancy between AFM and LS results is not surprising. 

Bisphenol A Polycarbonate grade, no solvent required 150,000 Undisclosed Falling film USA General Electric... 

It was also found that the tensile heat distortion temperatures of films containing only a few mole per cent of these units were considerably higher than those found for bisphenol A polycarbonate. X-ray diffraction studies made on the test samples used in the tensile heat distortion apparatus could not demonstrate an increase in crystallinity of the samples. Only a slight indication of increase of orientation was apparent. Glass transition temperatures measured by the refracto-metric method were considerably lower than the heat distortion temperatures. 

Sears and Darby (7), in an extensive investigation of the plasticization of bisphenol A polycarbonate, reported that the tensile strength and modulus were increased somewhat and the elongation decreased when some plasticizers were present in relatively small amounts. According to a curve which showed the effect of one of these (iV-ethyl-0//>-toIuenesulfonamide) on film tensile properties, the maximum tensile strength and modulus occurred at an additive concentration... 

Figure 1 The absorption spectra of (4-(4-dimethylaminophenyl)-2,6-diphenyl-thia-pyrylium perchlorate) in dichoromethane, a homogeneous film of the perchlorate compound in bisphenol-A polycarbonate, and the aggregated dye produced by exposing the homogeneous film to dichloromethane vapors.

Extruded films of unstabilized bisphenol A polycarbonate (PC) were supplied by GE Plastics. The thickness of these films was approximately 0.2 mm. 

Contrary to other atmospheric gases like N2, O2 or CO2, the permeability of polymer films for SO2 is very high (Table III). Obviously the molecular size of SO2 is not the dominating factor for its permeation rate. As the permeability coefficient P is defined by the product of the diffusion coefficient, D, and the solubility, S, the SO2 solubility of the polymer films plays an Important role. In fact the few data published on solubility of SO2 in polymers corroborate this expectation. Equilibrium solubility of SO2 in polyacrylate was found to be as high as 21.5% by weight at 760 mmHgl. In case of a bisphenol A polycarbonate. 

The high impact strength, dimensional stability and optical clarity (low crystallinity) of bisphenol-A polycarbonate (PC) together with its low dielectric loss have led to a range of applications embracing optical components, CD-ROMs, film capacitors and safety-related products Subsequent market demands for enhanced physical properties has stimulated the development of a range of commercial blends of which rubber-modified bisphenol-A polycarbonate (PC) with polybutylene terephthalate (PBT) or polyethylene terephthalate (PET) are amongst the more successful ... 

The surface structure of melt-mixed blends of bisphenol A polycarbonate and PETP was investigated by FTIR attenuated total reflectance spectroscopy. Based on the peak intensity of the aromatic carbonate band for polycarbonate and the aliphatic ester band for PETP by using germanium and KRS-5 ATR crystals, the enrichment of the PETP component in the surface layer of the polycarbonate/PETP blend films was observed. 27 refs. 

Dutta et al. [16] reported the thermal expansion in prepreg film and crossply laminates of prepreg films. The films were prepared from a blend containing 10 wt% of thermotropic LC copolyester (Vectra A950) and 90 wt% polycarbonate (General Electric Corporation bisphenol-A polycarbonate, PC2). The highest order parameter of the PLC phase L57 (s = 0.45) was obtained at a draw ratio of the film 7.6. 

Bisphenol-A Polycarbonate obtained from Bayer AG was dissolved in CH2CI2 and a film cast. The films contained sphemlites. THF-treatment yielded a suspension of these superstmctures which were further extracted by THF-washing. 

Modified silicon-containing polycarbonates have been prepared in solution and their transition temperatures assessed. Block copolymers of bisphenol-A-polycarbonate-bisphenol-A-polysulphone and acrylates and methacrylates grafted onto polycarbonate film have also been prepared and evaluated, as have mixed polycarbonate systems based on 2,2 -bis(4-hydroxyphenyl)propane, 2,2 -bis(4-hydroxy-3,5-dibromophenyI)propaneandtetrabromophenophthalein. Molecular relaxations in aliphatic polycarbonates have been studied by the method of thermally-stimulated currents and the thermal ageing of polycarbonates based on polycyclic diphenols has been assessed by studies of mechanical properties. 

An amorphous polycarbonate (bisphenol A polycarbonate, Lexan ) film with a thickness of 30.5 pm was placed inside the lid of a WVT capsule. The lid had a 4.25-mm-diameter hole. The capsule was sealed with about 53 mg of water present. The TGA was held at 23 °C during the mass loss experiment. In this case the relative humidity inside the TGA was zero (i.e., p2 =0). The vapor pressure above the water drop inside the capsule (pi), was 21.1mm (2.11 cm) of mercury as found in a table of water vapor pressure values (Weast 1973). In Fig. 3.36 the mass loss of water in the sealed receptacle is plotted as a function of time. From these data it was determined that water vapor moved through the amorphous polycarbonate film at a constant rate of 0.062 0.001 mg/h for more than 275 min. This is equivalent to Ami At =0.44 mg/ (cm -h) in Eq. (3.33). 

Fig. 1S.12. Activation spectrum of a 700 pm filtered xenon lamp. Superimposed are the film of unstabilized bisphenol-A polycarbonate, spectral irradiance of the irradiation source based on the increase in absorbance at 310 nm and the UV-absorption spectrum of the after accelerated aging with a borosilicate-glass polymer redrawn from data in Ref. [35]).

Fig. 15.13. Action spectrum of a 700 pm film of bisphenol-A polycarbonate, based on the radiant energy required for a 10% decrease in transmittance at 360 nm (A) linear plot (B) semilogarithmic plot.

FTIR techniques in combination with or as complement to other measurement techniques have been used in a wide range of photochemistry studies on polymers. These include bisphenol-A polycarbonate [173], polycarbonate coatings on mirrors [174], PMMA [175], poly( -butyl acrylate) [176] and polypropylene [177]. DSC and FTIR studies have been used in conjunction to investigate the nature of y-radiation-induced degradation and its effect on the 19°C and 30°C phase transitions in PTFE [178]. IR studies of the hydrolysis of melamine-formaldehyde crosslinked acrylic copolymer films have shown that copolymer-melamine formaldehyde crosslinks are broken and that crosslinks between melamine molecules are formed [179]. The thermal and photo-degradation mechanisms in an IR study of cured epoxy resins were found to be related to the autoxidative degradation processes for aliphatic hydrocarbons [180]. 

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