2. The basic raw materials for PVC are derived from salt
and oil.
Chlorine is manufactured by the electrolysis of sodium
chloride, salt.
This is why the first PVC manufacturing plants were
located close to natural sources of salt.
The electrolysis of salt water produces chlorine.
The chlorine is then combined with ethylene that has
been obtained from oil.
3. The resulting element is ethylene dichloride, which is
converted at very high temperatures to vinyl chloride
monomer.(VCM)
These monomer molecules are polymerized forming
polyvinyl chloride resin.
For example rigid PVC like the one which is used in
windows frames is normally PVCU ("unplasticized"). On
the other hand flexible PVC is achieved by adding
plasticizers such as phthalates.
Furthermore, pure poly-chloroethene is unstable when
exposed to visible light or UV. In order to modify this
disadvantage and make it suitable for different
applications antioxidants are added.
4. First, the raw material VCM is pressurised and
liquefied, and then fed into the polymerisation reactor,
which contains water and suspending agents in
advance. Through high-speed agitation within the
reactor, small droplets of VCM are obtained.
Next, the initiator for polymerisation is fed into the
reactor, and PVC is produced by reaction under a few
bar at 40 - 60°C.
PVC obtained through suspension polymerisation is
suspended in water as particles of 50~200 μm
diameter (in slurry form).
5. Thereafter the slurry discharged from the
polymerization reactor is stripped of residual
monomer, dehydrated, dried and the particle size
controlled by screening to yield PVC in the form of a
white powder.
The un-reacted VCM is entirely recovered through the
stripping process, and after purification, recycled as
raw material for reuse in this process.
PVC resin produced via this ‘suspension’ process is
referred to within the industry using the abbreviation
S-PVC.
6. Emulsion polymerization and bulk polymerization are
alternative, much less extensively employed,
technologies to manufacture PVC.
Emulsion polymerization produces finer resin grades
having much smaller particles, which are required by
certain applications.
This type of resin is sometimes called ‘paste’ PVC and
referred to within the industry using the abbreviation
P-PVC to distinguish it from S-PVC.
7.
8. It is used:
For sewerage pipes and other pipe applications where cost
or vulnerability to corrosion limit the use of metal.
For making window and door frames.
In cabling applications as a wire insulator.
To make vinyl records.
More recent examples include wallcovering, greenhouses,
home playgrounds, foam and other toys, custom truck
toppers (tarpaulins), ceiling tiles and other kinds of interior
cladding.
Due to PVC piping being cheaper than metals used in
musical instrument making, it is a common alternative
when making instruments, often for leisure or for rarer
instruments such as the contrabass flute.
9. 1. Nylon 6,6:
It is prepared by the condensation
polymerization of hexamethylenediamine with
adipic acid under high pressure and at high
temperature.
10. 2. Nylon 6:
It is obtained by heating caprolactum with
water at a high temperature.
11. 1. Nylon 6,6 is used in:
Making sheets
Bristles for brushes
Textile industry.
1. Nylon 6 is used for the manufacture of:
Tyre cords
Fabrics
Ropes.
