Chem 3/4

PolyVinyl Chloride (PVC)

LAM Kwok Tung Kenny(52610985)Ngai Sau Man Carmen (52621860)

Lee Wing Man (52569943)Chow Lai Yin Kevin (52621822)

INTRODUCTION

Plastic Molecular unit (Carbon,

Hydrogen)repeated and formed chains Man-made

“first plastic” :celluloidIn1860s’ To replace Ivory

Types of plasticResin identification codeLots of types of plastic Different molecular unit Different chemical and physical

feature

♵PVC

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

PolyVinyl Chloride (PVC)CheapEasy to produceWildly used Add Plasticizer to change its

hardnessPlastic Wrap, tube…

PVC Production In Hong KongSunny Hose Company LimitedIn Tai PoProduce TubesFor water supply or sprinkle

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 PVCCondition : UV light or heat and

pressureOrganic peroxide

compounds(initiator)Monomer(VCM)Addition polymerizationFree radical addition

MechanismChain initiation :

Chain propagation :

Chain termination :

Polymerization of PVCMolecule masses vary with the

temperatureExothermic reactionStrong intermolecular forceDipole-dipole between polymer chains

Adding additivePlasticizer(塑化劑 )DEHP(di-2-ethyl hexyl phthalate)FillerStabilizerDyes or coloring

C6H4(C8H17COO)2 Bis(2-

ethylhexyl)phthalate(BEHP)

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

DANGER OF PVCBeyond your imagination !!!

Environment & humanWhole product life cycle: production use disposal

Production: Releases of EDC and VCM carcinogens during process; Release of heavy distillate material

Use: Release of toxicants in PVC products

Disposal: landfill cause leachates incinerated generate dioxin

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

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

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

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

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