Polycarbonate parameter

Fig. 22. Equatorial SAXS curves of pre-oriented polycarbonate. Parameter is the birefringence,...

Fig. 4 Vapor-liquid equilibrium of the polycarbonate/chlorobenzene system at 140°C. Symbols represent experimental data lines show predictions with SAFT [41]. Polycarbonate parameters were fitted to density data only...

Using these parameters for predicting the vapor-liquid equilibrium in the polycarbonate/chlorobenzene system kij = 0) at 140°C leads to results shown in Fig. 4. It is obvious that the results are very unsatisfactory a description of the experimental data also fails for any other value of the binary parameter Therefore, the polycarbonate parameters m (uncertain since the molecular weight for the density data was unknown) and s/k were refitted to the binary data in Fig. 5a. Using these new parameters m/M = 0.0080, e/A = 256.97 K and Vqo = 17.114 cm /mol, the experimental data can now be described very well. 

Although the polymer parameters were also fitted to binary data, they still have the character of the pure-component parameters. This is confirmed by calculations of other polymer/solvent systems, which are illustrated in Fig. 5b. Using the same polycarbonate parameters as determined for the chlorobenzene system, the... 

Figure 6 shows the field dependence of hole mobiUty for TAPC-doped bisphenol A polycarbonate at various temperatures (37). The mobilities decrease with increasing field at low fields. At high fields, a log oc relationship is observed. The experimental results can be reproduced by Monte Carlo simulation, shown by soHd lines in Figure 6. The model predicts that the high field mobiUty follows the following equation (37) where d = a/kT (p is the width of the Gaussian distribution density of states), Z is a parameter that characterizes the degree of positional disorder, E is the electric field, is a prefactor mobihty, and Cis an empirical constant given as 2.9 X lO " (cm/V). ...

A more interesting example is given with PVC and the polycarbonate of bis-phenol A, both slightly crystalline polymers. It is noticed here that whilst methylene dichloride is a good solvent and tetrahydrofuran a poor solvent for the polycarbonate the reverse is true for PVC yet all four materials have similar solubility parameters. It would seem that the explanation is that a form of hydrogen bonding occurs between the polycarbonate and methylene dichloride and between PVC and tetrahydrofuran (Figure 5.7). In other words there is a specific interaction between each solvent pair. 

In multiphase polymeric systems, the properties of the end products do not solely depend on the properties of the pure components, but other various parameters also have a great impact (Fig. 1). In order to emphasize these factors, the following systems are taken into consideration (I) elastomer toughened styrene system, (2) elastomer toughened polycarbonate blends, and (3) direct reactive blend processing. 

Of the instances of so-called solvent cracking of amorphous polymers known to the author, the liquid involved is not usually a true solvent of the polymer but instead has a solubility parameter on the borderline of the solubility range. Examples are polystyrene and white spirit, polycarbonate and methanol and ethyl acetate with polysulphone. The propensity to solvent stress cracking is however far from predictable and intending users of a polymer would have to check on this before use. 

Most of the engineering plastics reproduce faithfully and easily conform to the mold configuration, and when processing parameters are appropriately controlled, they will repeat with excellent accuracy tolerance wise, etc. As an example for the past many decades, we see plastic gears and other precision products made of acetal, nylon, polycarbonate,... 

Poisson s ratio depends on numerous parameters concerning the grade used and its processing, the temperature, the possible reinforcements, the direction of testing with regard to the molecular or reinforcement orientation. For given samples of neat and reinforced polycarbonates, it is evaluated at 0.38-0.39. This is only an example and cannot be generalized. 

Figure 3 Molecular relaxivities of liposomes with different Gd-containing membranotropic chelators. Liposomes (egg lecithin cholesterol chelator = 72 25 3) were prepared by consecutive extrusion of lipid suspension in HEPES buffered saline, pH 7.4, through the set of polycarbonate filters with pore size of 0.6, 0.4, and 0.2 mm. Liposome final size was between 205 and 225 nm. Gd content determination was performed by Galbraith Laboratories, Inc. The relaxation parameters of all preparations were measured at room temperature using a 5-MHz RADX nuclear magnetic resonance proton spin analyzer. The relaxivity of liposomes with polymeric chelators is noticeably greater because of the larger number of Gd atoms bound to a single lipid residue [16].

Aluminum isopropoxide has proved to be a very effective initiator for the polymerization of lactones pPL, 6VL, eCL, DXO, and pBL and dilactones D,L- and L-LA, and GA. It is worth noting that cycHc carbonates, e.g., 2,2-dimethyltri-methylene carbonate (DTC) and cycHc anhydrides such as adipic anhydride (AA) have also been polymerized by aluminum trialkoxides with the unique possibility to control the molecular parameters of the polycarbonate (PDTC) and polyanhydrides (PAA). This is illustrated in Scheme 2 and the preferred reaction conditions are given in Table 3. 

Although a majority of these composite thermistors are based upon carbon black as the conductive filler, it is difficult to control in terms of particle size, distribution, and morphology. One alternative is to use transition metal oxides such as TiO, VO2, and V2O3 as the filler. An advantage of using a ceramic material is that it is possible to easily control critical parameters such as particle size and shape. Typical polymer matrix materials include poly(methyl methacrylate) PMMA, epoxy, silicone elastomer, polyurethane, polycarbonate, and polystyrene. 

The helical parameters corresponding to the various skeletal conformations of the blsphenol A polycarbonate chain are calculated. Combining these results with the conformational energy calculations shows that flat-helical and extended conformations are of equal energy for this chain. In addition, cyclic structures are also found to be stereochemically possible. The small values of the characteristic ratio of the unperturbed end-to-end distance and its temperature coefficient are attributed to the equal energy of the flat-helical and extended-helical, as well as the nonhelical, conformers. 

The dipole moment of PMTC is determined. Theoretical calculations are performed using the RIS model with the scheme developed for polycarbonates. The calculated values of fieff are almost insensitive to the conformational parameters used in the calculations. 

This puts this polymer remote from the usual range of silicone rubbers, which have solubility parameters of about 15 (mJ m 3)l/2, and close to polycarbonates, which have a value of 19.4 (mJnT3)172, and nitrile rubbers and polyvinyl acetates, which are similar. 

CO2 in the mixed feed case are not affected measurably by the presence of the relatively non-interacting isopentane. The sorption and transport parameters for CO2 in the polycarbonate sample used in the above study are reported in Table 2. 

The solid line in Fig. 1 represents the sorption isotherm of carbon dioxide in polycarbonate calculated by fitting the solubility expression, eq. (11), to experimental data of Wonders and Paul (15). The best fit to the experimental data was achieved with the parameters ao=7.33cm3(STP)/cm3(polymer)-atm and a = 0.161 cm3(polymer)/cm3(STP). As can be seen in Fig. 1, eq. (11) describes the experimental data over the entire pressure range. The algorithm used to fit eq. (11) to the experimental data is described elsewhere (FI). 

Figure 1. Sorption isotherm at 35 °C for CO2 in polycarbonate conditioned by exposure to 20 atm CO2. The experimental data are from Ref. 15. The curves, based on the matrix model (solid line) and the dual-mode model (broken line), are calculated using the parameters given in the text.

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