Polycarbonate sheets, properties

ISO 1628-4 1999 Plastics - Determination of the viscosity of polymers in dilute solution using capillary viscometers - Part 4 Polycarbonate (PC) moulding and extrusion materials ISO 7391-1 1996 Plastics - Polycarbonate (PC) moulding and extrusion materials - Part 1 Designation system and basis for specifications ISO 7391-2 1996 Plastics - Polycarbonate (PC) moulding and extrusion materials - Part 2 Preparation of test specimens and determination of properties ISO 11963 1995 Plastics - Polycarbonate sheets - Types, dimensions and characteristics. 

Abrasion-Resistant Polycarbonate Sheet. Abrasion-resistant polycarbonate sheet retains the extremely high impact properties and also provides resistance to abrasion. The surface coating also gives some added protection against weathering. 

In 1954 the surface fluorination of polyethylene sheets by using a soHd CO2 cooled heat sink was patented (44). Later patents covered the fluorination of PVC (45) and polyethylene bottles (46). Studies of surface fluorination of polymer films have been reported (47). The fluorination of polyethylene powder was described (48) as a fiery intense reaction, which was finally controlled by dilution with an inert gas at reduced pressures. Direct fluorination of polymers was achieved in 1970 (8,49). More recently, surface fluorinations of poly(vinyl fluoride), polycarbonates, polystyrene, and poly(methyl methacrylate), and the surface fluorination of containers have been described (50,51). Partially fluorinated poly(ethylene terephthalate) and polyamides such as nylon have excellent soil release properties as well as high wettabiUty (52,53). The most advanced direct fluorination technology in the area of single-compound synthesis and synthesis of high performance fluids is currently practiced by 3M Co. of St. Paul, Minnesota, and by Exfluor Research Corp. of Austin, Texas. 

Whilst conventional polycarbonate based on bis-phenol A is essentially linear, branched polymers have recently been introduced. These materials have flow properties and a melt stability that makes them particularly suitable for large (20 litre) water and milk containers. Branched polymers have also been used in the manufacture of twin-walled sheet for the building industry. 

Engineers like to design machines that take plastics and inject them into molds, extrude them into filament, sheets, rods, and film, or blow-mold them into shapes. They want these plastics to have a terrific balance of mechanical, electrical, and chemical properties. That s why they have attached their name to engineering resins, a set of plastics unlike thermosets that they can remelt and further process mechanically. Nylon, polycarbonates, and polyesters are the three most popular engineering resins. 

Property Summary Acrylics recommended for general-purpose applications, especially for optical decorative, and outdoor use. In sheet stock, cast acrylic has greater strength and transparency extruded acrylic costs less (especially in thin members), and has better formability. Polycarbonates for maximum strength, as in explosion shields. Butyrates for excellent impact resistance, and deep formability. Vinyls for maximum formability and printability. Acetates and vinyls for flexible glazing and guards. Medium-impact styrene and rigid vinyls for lowest-cost molded transparent parts. 

Impact Failure. Standard notched Izod impact measurements have been made over wide temperature ranges on specimens cut from compression molded %-inch thick sheets of BPA polycarbonate and two BPA carbonate-silicone block polymers (Figure 4) (see Table I for compositions and properties). In the homopolymer a ductile-brittle transition occurs at 0° to —15°C, as reported previously (4, 5). Introduction of 15 and 25% silicone lowers the transition to —45° and —110°C (block polymers A and B). As indicated in Table I, this increase in toughness at low temperature is accompanied by the reduction of modulus and yield stress. 

At present, there is only one commercial source of the polyamide/polycarbonate blends (Dexcarb , Dexter Corp.). According to their patent, the blend was compatibilized by using a combination of a polyesteramide elastomer and a maleated olefinic polymer, such as male-ated polypropylene or EP rubber [Perron, 1984 1988]. However the degree or the efficiency of compatibilization achieved is unknown, since the added components are not known to be miscible or compatible with the polycarbonate. Nevertheless, the data sheet indicated good properties including a high notched Izod impact strength of > 700 J/m (Table 15.24). 

For the investigation into the Influence of u.v. radiation on the dielectric properties of polycarbonate, pressed sheets of the material were irradiated at room temperature in air by a standard Hanovia mercury lamp. The lamp provided a spectrum of wavelengths within the range 254 to 546 nm and sample intensities of 2.47 mW cm and 0.91 mW cm respectively at the principal wavelengths of 365 nm and 254 nm. A voltage-stabilized power supply assisted consistency of spectral output. 

The complex three-layer membrane of Bangkok Airport s membrane roof is illustrated in Fig. 12.9. Here and as explained before, the high and lasting solar reflection of 70% of the outer waterproof PTFE/glass layer is also an important feature. To improve the acoustic properties of the roof, an additional middle layer has been included which consists of a cable net covered with transparent polycarbonate (PC) sheets. This, in conjunction with the translucent inner membrane liner, acts as a baffle. Figure 12.10 provides an interior view of the concourses with the innovative membrane envelope. 

The polymers used in thermoforming must be of fairly high relative molecular mass since the heated sheet must be form stable. The significant property is melt elasticity. The elastic effects are produced by entropy-elastic forces between physical cross-links (molecular entanglements). The polymers used include polystyrene, ABS, acrylics, polycarbonate, PVC, polypropylene, and linear potyethylene. 

Polycarbonate (PC) is a clear, colorless polymer used extensively for engineering and optical applications. It is available commercially in both pellet and sheet form. Outstanding properties include impact strength and scratch resistance. The most serious deficiencies are poor weatherability and chemical resistance. Some typical properties are Glass Transition Temperature, Tg = 145° C Melting... 

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