Chem 3/4
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Transcript of Chem 3/4
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PolyVinyl Chloride (PVC)
LAM Kwok Tung Kenny(52610985)Ngai Sau Man Carmen (52621860)
Lee Wing Man (52569943)Chow Lai Yin Kevin (52621822)
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INTRODUCTION
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Plastic Molecular unit (Carbon,
Hydrogen)repeated and formed chains Man-made
“first plastic” :celluloidIn1860s’ To replace Ivory
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Types of plasticResin identification codeLots of types of plastic Different molecular unit Different chemical and physical
feature
♵PVC
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PolyVinyl Chloride (PVC)Molecular unit Light and High Toughness Colorless Not easy to be corrode
by acid or baseFire RetardantAdd Plasticizer to change its
hardnessVicat softening point : 65- 100
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PolyVinyl Chloride (PVC)CheapEasy to produceWildly used Add Plasticizer to change its
hardnessPlastic Wrap, tube…
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PVC Production In Hong KongSunny Hose Company LimitedIn Tai PoProduce TubesFor water supply or sprinkle
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MANUFACTURING PVC(POLYVINYL CHLORIDE) PRODUCT
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Processes
PetroleumVCM(Vinyl chloride
monomer)
PVC(Polyvinyl
chloride)Products
Cracking and Chlorination
Polymerization
Molding
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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
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Polymerization of PVCCondition : UV light or heat and
pressureOrganic peroxide
compounds(initiator)Monomer(VCM)Addition polymerizationFree radical addition
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MechanismChain initiation :
Chain propagation :
Chain termination :
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Polymerization of PVCMolecule masses vary with the
temperatureExothermic reactionStrong intermolecular forceDipole-dipole between polymer chains
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Adding additivePlasticizer(塑化劑 )DEHP(di-2-ethyl hexyl phthalate)FillerStabilizerDyes or coloring
C6H4(C8H17COO)2 Bis(2-
ethylhexyl)phthalate(BEHP)
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MoldingUsing heat to soft the plastic,
pressure to squeeze and place to a mold, then cool down
Injection molding(a)Compression molding(b)
a b
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DANGER OF PVCBeyond your imagination !!!
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Environment & humanWhole product life cycle: production use disposal
Production: Releases of EDC and VCM carcinogens during process; Release of heavy distillate material
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Use: Release of toxicants in PVC products
Disposal: landfill cause leachates incinerated generate dioxin
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Production
vinyl chloride monomer (VCM) & ethylene dichloride (EDC) are by-products of PVCOn human: highly volatile VCM jeopardise workers’
health ( risk of liver / brain cancer) colourless EDC , inhalation/ direct contact
may have toxic effect
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VCM & EDC are genotoxic cause irreversible damage to
DNA (e.g. Birth defects/ genetic diseases of descendants)
On environment: improper treatment of VCM & EDC
or other by-products contaminate (underground)water and sediment (e.g. alluvial soil)
Case study:In Japan, consumption on rice irrigated by river water polluted by cadmium Kidney disease & Osteomalacia
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Use the use of PVC products threaten
human health On human: PVC additives phthalate plasticizers
increase risk of asthma PVC flooring persistent wheezing,
pneumonia, prolonged cough… etc metal stabilizers (e.g. lead) leach
into potable water
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Disposal
discarded PVC materials are hazardous
On human: phthalates and metals leach out of
disposed products into landfill leachate groundwater contamination
accidental PVC fire permanent respiratory disease
fire release dioxin reproductive disorders, immune suppression
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On environment: burning of chloride (major
component of PVC) during combustion of incineration
Release of toxic dioxin regarded as persistent organic
pollutants (POPs), dioxin accumulate in atmosphere
recycling of PVC is extremely difficult