3. Plastic
Molecular unit (Carbon, Hydrogen)
repeated and formed chains
Man-made
“first plastic” :celluloid
In1860s’
To replace Ivory
4. Types of plastic
Resin identification code
Lots of types of plastic
Different molecular unit
Different chemical and physical
feature
♵
PVC
5. PolyVinyl Chloride (PVC)
Molecular unit
Light and High Toughness
Colorless
Not easy to be corrode
by acid or base
Fire Retardant
Add Plasticizer to change its hardness
Vicat softening point : 65- 100
6. PolyVinyl Chloride (PVC)
Cheap
Easy to produce
Wildly used
Add Plasticizer to change its
hardness
Plastic Wrap, tube…
7. PVC Production In Hong
Kong
Sunny Hose Company Limited
In Tai Po
Produce Tubes
For water supply or sprinkle
9. Processes
Cracking and Polymerizatio
Molding
Chlorination n
VCM(Vinyl PVC(Polyv
Petroleum chloride inyl Products
monomer) chloride)
10. Cracking and Chlorination
Petroleum heated with catalyst, high
pressure and without air
Produce Ethene and “light”
hydrocarbons
Chlorination to ethene
Thermal cracking
Chloroethene
Vinyl chloride monomer
11. Polymerization of PVC
Condition : UV light or heat and
pressure
Organic peroxide compounds(initiator)
Monomer(VCM)
Addition polymerization
Free radical addition
13. Polymerization of PVC
Molecule masses vary with the
temperature
Exothermic reaction
Strong intermolecular force
Dipole-dipole between
polymer chains
15. 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
17. Environment & human
Wholeproduct life cycle:
production use disposal
Production:
Releases of EDC and VCM carcinogens
during process;
Release of heavy distillate material
18. Use:
Release of toxicants in PVC products
Disposal:
landfill cause leachates
incinerated generate dioxin
19. Production
vinyl chloride monomer
(VCM) & ethylene dichloride
(EDC) are by-products of PVC
On human:
highly volatile VCM jeopardise workers’ health
( risk of liver / brain cancer)
colourless EDC , inhalation/ direct contact may
have toxic effect
20. 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
21. 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
22. 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
23. 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
Editor's Notes
Over time, these additives leach out of vinyl products. Phthalates are typically present in indoor air at much higher concentrations than outdoor air due to their high concentrations in consumer products and building materials.