Amorphous polycarbonate, thermal

Variation of thermal diffusivity with temperature, for amorphous polycarbonate and semi-crystalline polyethylene. 

The data in Fig. 2.84 indicate that an amorphous polycarbonate sample as small as 50 pg could be heated at 400 C/min and yield a glass transition that is as discernible as that shown in Fig. 2.84 for the 1-mg sample of polycarbonate scanned at 20 C/min. These results indicate that it is now possible to determine thermal properties on polymeric samples that were previously deemed too small to analyze. 

The DRAW disc which offers the facility to make one recording consists of a plastic substrate such as polycarbonate (PC) or polymethylmethacrylate (PMMA) and a recording layer made in amorphous colourants. The thickness of the recording layer is approximately 30-100 nm. The principle of the optical DRAW disc memory, called heat mode system, is shown in Fig. 1. In this system, microscopic pits in the coloured recording layer of a disc are formed by thermal energy transformed from photo energy of a... 

Polycarbonates are tough, amorphous, and transparent polymers made by reacting bisphenol A and diphenyl carbonate. It is noted for its excellent mechanical and thermal properties (high Tgi 150°C), hydrophobicity, and antioxidative properties. 

Physical blends of bisphenol-A polycarbonate (PC) and a poly-arylate (PAr) exhibit by thermal analysis two amorphous phases a pure PC phase and a PAr-rIch miscible mixed phase. On controlled thermal treatment, transreaction between PC and PAr takes place mainly in the mixed phase, producing a new copolymer. Reaction progression from block to random copolymers has been traced by DSC, 13c NMR and CPC. The final product of transreaction is an amorphous copolymer showing a single T depending on the original binary composition. ... 

PROPERTIES OF SPECIAL INTEREST Polycarbonate engineering thermoplastics are amorphous, clear polymers that exhibit superior dimensional stability, good electrical properties, good thermal stability, and outstanding impact strength. They... 

Polycarbonate (PC) is the fourth largest volume material. It is an amorphous engineering thermoplastic with good thermal stability, transparency, impact resistance and the ability to be processed on conventional machinery. Its surface properties are important for many applications, including medical, optics and so on. Table 2.10 illustrates the properties of PC. 

Homopolymers derived from MDI and azelaic acid are semicrystalline engineering plastics with a Tg of 135°C and a Tm of 290°C (88). Copoljrmers of MDI with azelaic acid, containing 20-30 mol% of adipic acid show a eutectic Tm of approximately 240°C. These amorphous or slightly crystalline copolymers have mechanical properties comparable to transparent nylons or polycarbonates. Although injection molded samples are transparent, they will crystallize and turn opaque. Copolyamides derived from MDI and aromatic dicarboxylic acids are more difficult to prepare. Because of the very high Tm (420°C) of the isophthalic acid/MDI block it was necessary to prevent the formation of any appreciable ciystalline blocks, which was accomplished by prereacting a portion of the isophthalic acid (15-20 mol%) with 2,4-TDI. In this manner crystallization of the isophthalic acid/MDI blocks was surpressed (89). Thus, copolyamides containing IPA/azelaic acid (50 50) are obtained with thermal and mechanical properties similar to poly-sulfone. 

The degree of crystallinity of swollen polyfvinyl alcohol) has been measured by laser Raman spectroscopy from the relative intensity of the amorphous band at 1124 cm . The crystalline band, at 1147 cm, was not considered quantitative. Polyacetylene,poly(vinylidene fluoride), polyfdiphenyl siloxane), poly-(butylene terephthalate), poly(decamethylene oxide), polypropylene and copolymers, poly(methyl methacrylate), poly(ethylene terephthalate), polystyrene, polycarbonate, polyalkylene, poly(oxymethylene), and poly (ethylene oxide) have all been studied either by WAXS or thermal analysis. 

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