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Glass melting temperature

Irregularities such as branch points, comonomer units, and cross-links lead to amorphous polymers. They do not have true melting points but instead have glass transition temperatures at which the rigid and glasslike material becomes a viscous liquid as the temperature is raised. [Pg.1006]

This type of adhesive is generally useful in the temperature range where the material is either leathery or mbbery, ie, between the glass-transition temperature and the melt temperature. Hot-melt adhesives are based on thermoplastic polymers that may be compounded or uncompounded ethylene—vinyl acetate copolymers, paraffin waxes, polypropylene, phenoxy resins, styrene—butadiene copolymers, ethylene—ethyl acrylate copolymers, and low, and low density polypropylene are used in the compounded state polyesters, polyamides, and polyurethanes are used in the mosdy uncompounded state. [Pg.235]

In the area of moleculady designed hot-melt adhesives, the most widely used resins are the polyamides (qv), formed upon reaction of a diamine and a dimer acid. Dimer acids (qv) are obtained from the Diels-Alder reaction of unsaturated fatty acids. Linoleic acid is an example. Judicious selection of diamine and diacid leads to a wide range of adhesive properties. Typical shear characteristics are in the range of thousands of kilopascals and are dependent upon temperature. Although hot-melt adhesives normally become quite brittle below the glass-transition temperature, these materials can often attain physical properties that approach those of a stmctural adhesive. These properties severely degrade as the material becomes Hquid above the melt temperature. [Pg.235]

Polymer systems have been classified according to glass-transition temperature (T), melting poiat (T ), and polymer molecular weight (12) as elastomers, plastics, and fibers. Fillers play an important role as reinforcement for elastomers. They are used extensively ia all subclasses of plastics, ie, geaeral-purpose, specialty, and engineering plastics (qv). Fillets are not, however, a significant factor ia fibers (qv). [Pg.368]

Other uses of Snp2 are in the synthesis of fluorophosphate glasses having low melting temperatures (13—15), in formation of transparent film (16), and in the preparation of optically active alcohols (17). [Pg.253]

Eig. 15. Time—temperature transformation ia a thin-phase change layer during recording/reading/erasiug (3,105). C = Crystalline phase A = amorphous phase = melting temperature = glass-transition temperature RT = room temperature. [Pg.149]

Properties. One of the characteristic properties of the polyphosphazene backbone is high chain dexibility which allows mobility of the chains even at quite low temperatures. Glass-transition temperatures down to —105° C are known with some alkoxy substituents. Symmetrically substituted alkoxy and aryloxy polymers often exhibit melting transitions if the substituents allow packing of the chains, but mixed-substituent polymers are amorphous. Thus the mixed substitution pattern is deUberately used for the synthesis of various phosphazene elastomers. On the other hand, as with many other flexible-chain polymers, glass-transition temperatures above 100°C can be obtained with bulky substituents on the phosphazene backbone. [Pg.257]

Qiana, introduced by Du Pont in 1968 but later withdrawn from the market, was made from bis(4-aminocyclohexyl)methane and dodecanedioic acid. This diamine exists in several cis—trans and trans—trans isomeric forms that influence fiber properties such as shrinkage. The product offered silk-like hand and luster, dimensional stabiUty, and wrinkle resistance similar to polyester. The yam melted at 280°C, had a high wet glass-transition temperature of - 85° C and a density of 1.03 g/cm, the last was lower than that of nylon-6 and nylon-6,6. Qiana requited a carrier for effective dyeing (see Dye carriers). [Pg.260]

A reexamination of polycarbonate chemistry was carried out about 50 years after the first aromatic polycarbonates of resorcinol and hydroquinone were discovered. In independent investigations at Bayer AG and General Electric, it was discovered that the polycarbonates of BPA could be prepared (eq. 2). Unlike the ahphatic polycarbonates prepared earlier, which were either hquids or low melting sohds, the aromatic polycarbonates were amorphous sohds having elevated glass-transition temperatures. [Pg.278]

Glass-Transition Temperature and Melt Behavior. The T of BPA polycarbonate is around 150°C, which is unusually high compared... [Pg.280]

Polycarbonate—polyester blends were introduced in 1980, and have steadily increased sales to a volume of about 70,000 t. This blend, which is used on exterior parts for the automotive industry, accounting for 85% of the volume, combines the toughness and impact strength of polycarbonate with the crystallinity and inherent solvent resistance of PBT, PET, and other polyesters. Although not quite miscible, polycarbonate and PBT form a fine-grained blend, which upon analysis shows the glass-transition temperature of the polycarbonate and the melting point of the polyester. [Pg.290]


See other pages where Glass melting temperature is mentioned: [Pg.143]    [Pg.247]    [Pg.248]    [Pg.144]    [Pg.228]    [Pg.123]    [Pg.32]    [Pg.1328]    [Pg.143]    [Pg.247]    [Pg.248]    [Pg.144]    [Pg.228]    [Pg.123]    [Pg.32]    [Pg.1328]    [Pg.130]    [Pg.433]    [Pg.393]    [Pg.451]    [Pg.284]    [Pg.302]    [Pg.305]    [Pg.305]    [Pg.305]    [Pg.306]    [Pg.310]    [Pg.335]    [Pg.335]    [Pg.338]    [Pg.375]    [Pg.539]    [Pg.66]    [Pg.67]    [Pg.69]    [Pg.127]    [Pg.201]    [Pg.44]    [Pg.463]    [Pg.427]    [Pg.135]    [Pg.235]    [Pg.246]    [Pg.248]    [Pg.267]    [Pg.286]    [Pg.301]   
See also in sourсe #XX -- [ Pg.776 ]

See also in sourсe #XX -- [ Pg.199 , Pg.242 ]




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