Polycarbonate physical properties

Table 1. High heat polycarbonate physical properties...

Unless great care is taken in control of phenol/acetone ratios, reaction conditions and the use of catalysts, a number of undesirable by-products may be obtained such as the o-,p- and o-,o- isomers of bis-phenol A and certain chroman-type structures. Although tolerable when the bis-phenol A is used in epoxy resins, these have adverse effects on both physical properties and the colour of polycarbonate resins. 

Hydrolysis studies compared a polycarbonate urethane with a poly(tetramethyl-ene adipate) urethane and a polyether urethane based on PTMEG. After 2 weeks in 80°C water, the polycarbonate urethane had the best retention of tensile properties [92], Polycarbonates can hydrolyze, although the mechanism of hydrolysis is not acid-catalyzed, as in the case of the polyesters. Polycarbonate polyurethanes have better hydrolysis resistance than do standard adipate polyurethanes, by virtue of the highest retention of tensile properties. It is interesting to note in the study that the PTMEG-based urethanes, renowned for excellent hydrolysis resistance, had lower retention of physical properties than did the polycarbonate urethanes. 

Nearly all of the polymers produced by step-growth polymerization contain heteroatoms and/or aromatic rings in the backbone. One exception is polymers produced from acyclic diene metathesis (ADMET) polymerization.22 Hydrocarbon polymers with carbon-carbon double bonds are readily produced using ADMET polymerization techniques. Polyesters, polycarbonates, polyamides, and polyurethanes can be produced from aliphatic monomers with appropriate functional groups (Fig. 1.1). In these aliphatic polymers, the concentration of the linking groups (ester, carbonate, amide, or urethane) in the backbone greatly influences the physical properties. 

How does the molecular architecture of the bisphenol molecule affect the physical properties of the final polycarbonate polymer ... 

Meldrum s acid chemistry, 21 151,152, 153 Melengesterol acetate (MGA), 10 871 Melissic acid, physical properties, 5 30t Melt behavior, of polycarbonates, 19 805 Meltblown fabrics, 17 478-479, 495 Meltblown fibers, 11 237, 240-241 Melt casting, 14 230 Melt crystallization, 3 137—141... 

Requirements for CD-quality material are polycarbonate with low levels of chemical impurities, low particle levels, thermal stability, excellent mold release, excellent clarity, as well as constant flow and constant mechanical behavior (for reproducibility). There exists a time/cost balance. High molecular weight polycarbonate offers a little increase in physical property but the flow rate is slow, making rapid production of CDs difficult. The molecular weight where good mechanical strength and reasonable flow occurs, and that allows for short cycles, is in the range of 16,000-28,000 Da. 

Thorat SD, Phillips PJ, Semenov V, Gakh A (2003) Physical properties of aliphatic polycarbonates made from CO2 and epoxides. J Appl Polym Sci 89 1163-1176... 

Table 15.7 Thermal and Physical Properties of Polycarbonates (Typical Values)...

TABLE 1. Physical Properties of Polycarbonate Prepared Using Bisphenol A, 3,3-bis(4-hydroxy-phenyl)-l-phenyl-lH-indol-2-one, and Phosgene Dissolved in C Cb/Chlorobenzene at Ambient Temperature... 

Further, methods for producing a thermoplastic resin with good physical properties and appearance properties and weatherability as well, use a three component blend of ASA, PMMA, and polycarbonate) (20). 

The gas-polymer-matrix model for sorption and transport of gases in polymers is consistent with the physical evidence that 1) there is only one population of sorbed gas molecules in polymers at any pressure, 2) the physical properties of polymers are perturbed by the presence of sorbed gas, and 3) the perturbation of the polymer matrix arises from gas-polymer interactions. Rather than treating the gas and polymer separately, as in previous theories, the present model treats sorption and transport as occurring through a gas-polymer matrix whose properties change with composition. Simple expressions for sorption, diffusion, permeation and time lag are developed and used to analyze carbon dioxide sorption and transport in polycarbonate. 

Test methods used to determine the uniformity of substrates are numerous and vary with the type of material. They are generally the same tests used to characterize the material or to determine its fundamental physical properties. Tests that are commonly employed are hardness, tensile strength, modulus, and surface characteristics such as roughness or contact angle with a standard liquid. Often a test similar to the nonvolatile test mentioned above is used to determine if there are any compounds in the substrate that are capable of out-gassing on exposure to elevated temperatures. Moisture content of certain hydroscopic polymers, such as nylon and polycarbonate, is also known to affect adhesion. 

The most popular materials are styrenics and olefins, and engineering plastics such as modified polyphenylene ether or polycarbonate (Chapter 2). Fillers for enhanced physical properties, UV stabilizers, and flame retardants are common additives. 

Physical properties of polycarbonates derived from diphenyl carbonate, and isosorbide and/or bisphenol and those derived from bismethylsalicylcarbonate, (1), bisphenol A and/or isosorbide are provided in Tables 1 and 2, respectively. 

TABLE 2. Physical properties of polycarbonates obtained from the reaction of bisphenol A and isosorbide with bismethylsalicylcarbonate, (I). 

Poly(L-arginine)6o-Wocfc-poly(L-leucine)2o (PLArg-/ -PLLeu, Fig. lOg) showed similar physical properties as PLLys60-fe-PLLeu2o and also formed micrometersized vesicles in aqueous solution. These vesicles were able to entrap water-soluble species, such as dextran, and could be extruded through polycarbonate filters to yield stable, low-polydispersity vesicles of controllable diameter down to 50 nm [53]. 

Because of its excellent physical properties, polycarbonate is specified for a number of engineering uses. Some of these may involve significant exposure to light. As an aromatic polymer, polycarbonate absorbs significantly in the near UV and is thus susceptible to photodegradation. 

The results from this survey indicate that a wide variety of reactions occur in the photodegradation of polycarbonate under natural weathering conditions. Both oxidative and non-oxidative processes are involved, but the oxidative reactions probably cause greater loss in physical properties. Accelerated aging studies should take into account the variables tested here. In particular, acceleration should not be accomplished by the use of very short wavelength light. 

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