POLY-P-XYLYLENE

POLY-P-XYLYLENE 化学特性,用途語,生産方法

• 化学的特性

  The most significant property of poly-p-xylylene is its thermal stability. The crystalline melting point is 375-425°C and in an inert atmosphere the material is claimed to have a useful life of 10 years at 220°C. The thermal stability in air is not exceptional. Poly-p-xylylene also maintains useful properties at temperatures as low as - 200°C. The polymer has outstandingly good electrical insulation characteristics and is used as a dielectric in special capacitors.
  It may be noted that poly-p-xylylene is considerably less stable than polyp- phenylene owing to the presence of the relatively weak dibenzyllinkages. It may also be noted that the isomeric polyxylylenes have been prepared but poly-o-xylylene has a polymer melt temperature of 110°C whilst poly-mxylylene has a softening temperature of only 60°C; these polymers are therefore of no immediate interest.

• 製造方法

  When di-p-xylylene is pyrolysed, both methylene bridges are homolytically cleaved to give the reactive intermediate p-xylylene which spontaneously forms the linear polymer on cooling. Generally, the polymer is deposited (in the polymerization chamber) on to a cold condenser and then removed as film; alternatively, the polymer is deposited directly on to an object which is required to be coated. Typically, an average molecular weight of about 500000 is attained.
  

  

POLY-P-XYLYLENE 生産企業

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