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Manufacturing PVC(Polyvinyl chloride) product
Processes
PetroleumVCM(Vinyl
chloride monomer)
PVC(Polyvinyl chloride) Products
Cracking and Chlorination Polymerization Molding
Cracking and Chlorination
• Petroleum heated with catalyst, high pressure and without air
• Produce Ethene and “light” hydrocarbons• Chlorination to ethene • Thermal cracking • ChloroetheneVinyl chloride monomer
Polymerization of PVC
• Condition : UV light or heat and pressure• Organic peroxide compounds(initiator)• Monomer(VCM)Addition polymerizationFree radical addition
Mechanism
• Chain initiation :
• Chain propagation :
• Chain termination :
Polymerization of PVC
• Molecule masses vary with the temperature• Exothermic reaction• Strong intermolecular forceDipole-dipole between polymer chains
Adding additive
• Plasticizer(塑化劑 )DEHP(di-2-ethyl hexyl phthalate)• Filler• Stabilizer• Dyes or coloring
C6H4(C8H17COO)2 Bis(2-ethylhexyl)phthalate(BEHP)
Molding
• Using heat to soft the plastic, pressure to squeeze and place to a mold, then cool down
Injection molding(a)Compression molding(b)
a b