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The physical properties of the isomers of xylene differ slightly. The melting point ranges from −47.87 °C (−54.17 °F) (m-xylene) to 13.26 °C (55.87 °F) (p-xylene)—as usual, the para isomer's melting point is much higher because it packs more readily in the crystal structure. The boiling point for each isomer is around 140 °C (284 °F).
for p-Xylene/Aniline [6] P = 745 mm Hg BP Temp. °C % by mole p-xylene liquid vapor 171: 7.5: ... data relate to Standard temperature and pressure. Reliability of ...
for m-Xylene/Toluene [7] P = 760 mm Hg BP Temp. °C % by mole toluene liquid vapor ... Except where noted otherwise, data relate to Standard temperature and pressure.
The p-xylene is then separated out in a series of distillation, adsorption or crystallization and reaction processes from the m-xylene, o-xylene, and ethylbenzene. Its melting point is the highest among this series of isomers, but simple crystallization does not allow easy purification due to the formation of eutectic mixtures.
This plastic is processed by injection molding or extrusion; depending on the type, the processing temperature is 260–300 °C. The surface can be printed, hot-stamped, painted or metallized. Welds are possible by means of heating element, friction or ultrasonic welding. It can be glued with halogenated solvents or various adhesives.
Terephthalic acid was produced by oxidation of p-xylene with 30-40% nitric acid. Air oxidation of p-xylene gives p-toluic acid, which resists further air-oxidation. Esterification of p-toluic acid to methyl p-toluate (CH 3 C 6 H 4 CO 2 CH 3) opens the way for further oxidation to monomethyl terephthalate. In the Dynamit−Nobel process these ...
Parylene was discovered in 1947 by Michael Szwarc as one of the thermal decomposition products of para-xylene H 3 C − C 6 H 4 − CH 3 above 1000 °C. Szwarc identified para-xylylene as the precursor by observing that reaction with iodine yielded para-xylylene di-iodide as the only product.
The melting point for average commercial low-density polyethylene is typically 105 to 115 °C (221 to 239 °F). These temperatures vary strongly with the type of polyethylene, but the theoretical upper limit of melting of polyethylene is reported to be 144 to 146 °C (291 to 295 °F). Combustion typically occurs above 349 °C (660 °F).