Polycarbonates Lexan

Fig. 5.2 Type III isotherms, (a) n-hexane on PTFE at 25°C (b) n-octane on PTFE at 20 C (c) water on polymethylmethacrylate at 20°C (d) water on bis(A-polycarbonate) (Lexan) at 20°C. The insets in (c) and (d) give the curves of heat of adsorption against fractional coverage the horizontal line marks the molar heat of liquefaction. (Redrawn from diagrams in the original papers, with omission of experimental points.)...

Problem 16.98 (a) Show the mers of the following condensation polymers, formed from the two indicated monomers (i) Polycarbonate (Lexan). phosgene, CLC=0 + (HOC H ),C(CH ), (tough and optically clear) (ii) Kodel,... 

The basic working station is a box constmcted of metal or plastic with an appropriate transparent window onto which replaceable rubber gloves are mounted. This configuration enables all areas within the box to be reached and viewed. The best materials for constructing the box are aluminum or stainless steel. Aluminum is preferred for most of the applications since it is lighter, easier to handle, and is probably cheaper. Polycarbonate (lexane) is the best material for the window. 

The mechanical properties of a craze were first investigated by Kambour who measured the stress-strain curves of crazes in polycarbonate (Lexan, M = 35000) which had first been grown across the whole cross-section of the specimen in a liquid environment and subsequently dried. Figure 25 gives examples of the stress-strain curves of the craze determined after the 1st and 5th tensile loading cycle and in comparison the tensile behavior of the normal polymer. The craze becomes more and more elastic in character with increasing load cycles and its behavior has been characterized as similar to that of an opencell polymer foam. When completely elastic behavior is observed the apparent craze modulus is 25 % that of the normal poly-... 

Results of some of these short-term tests are shown in Table II. A comparison is given between PPS and five other plastics nylon (Zytel 101), polycarbonate (Lexan 141), polysulfone (Bakelite Polysulfone), polyphenylene oxide (Noryl), and polyetherimide (Ultem 2300). The data presented are based upon retention of tensile strength for all plastics except the Ultem 2300, which is based upon retention of flexural strength. Unsuccessful attempts were made to injection mold ASTM Type IV tensile bars out of the Ultem compound, but flexural strength bars could be made. Experience has shown that chemical resistance tests monitored by flexural strength retention are comparable to those monitored by retention of tensile strength. 

In the fall of 1966, researchers at North Star Research Institute began a search for compression-resistant microporous substrates.19 This effort resulted in the development of microporous sheets of polycarbonate (Lexan) and poly-sulfone (Udel).20 Figure 5.4 shows a graph comparing the flux levels and flux stability for three membranes made at that time (a) float-cast cellulose acetate on microporous polysulfone, (b) float-cast cellulose acetate on a mixed cellulose ester microfilter support and (c) a standard asymmetric cellulose acetate membrane. The improvement in membrane fluxes was readily apparent, when switching from cellulosic substrates to the microporous polysulfone substrate. 

Polyesters with two ester groups bonded to the same carbon are known as polycarbonates. Lexan is produced by the reaction of phosgene with bisphenol A. Lexan is a strong, transparent polymer used for bulletproof windows and traffic-light lenses. In recent years, polycarbonates have become important polymers in the automobile industry as well as in the manufacture of compact discs. 

Biomaterial-induced microemboli were obtained as follows Vk-in. sheets of Plexiglass G (DuPont), polystyrene (Dow Resin F70502.00), or polycarbonate (Lexan, General Electric Co.) were cut, drilled, and mounted into the parallel-disc configuration shown in Figure 2. The surfaces were soaked in ethanol (95% for the polycarbonate and polystyrene and 50% for the Plexiglass) for at least 24 h, and then in saline solution for 12-18 h at 37°C just prior to exposure to the blood samples. 

ACRONYM, ALTERNATIVE NAME, TRADE NAMES PC, bisphenol-A polycarbonate, Lexan (GE), Makrolon (Bayer)... 

Polyesters (Dacron) Polycarbonates (Lexan ) Polyurethane (Lycra )... 

Polycarbonate (Lexan) resin can be cemented using epoxy systems containing room temperature curing hardeners such as diethylene triamine or with systems containing elevated temperature curing hardeners such as anhydrides . 

Type 23 Screw Threed Size Polycarbonate (Lexan) Boss Dimensions, in. ... 

Machine screws commonly are used to assemble components made of GRTP. Recommended clearance hole diameters are provided by material suppliers. Those for polycarbonate (Lexan) are given in Table 5-7. To insure optimum component reliability, screw torque must be specified after careful consideration of the following ... 

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