Earliest Production:
PVC is one of the oldest polymers in the world. Regnault, a French
scientist, first produced the vinyl chloride monomer in 1835. In 1872, a
man named Baumann exposed sealed tubes containing vinyl chloride to
sunlight, and thus recorded the polymerization of PVC. The first patent
for PVC manufacturing in the United States was issued in 1912. However,
the first production of the material did not come until the 1930s,
simultaneously at plants in Germany and the United States.
Production/Structure:
PVC is made from hydrocarbon polymers that have been chlorinated. It's
structure is almost identical to that of polyethylene, but the alternating
carbon atoms in the main sequence have one of the hydrogen atoms in the
polyethylene replaced by a chlorine atom in the PVC structure. The making
of PVC involves opening the double bond in the vinyl chloride molecules to
allow combinations from surrounding molecules to produce the long chain
molecule. The chlorine is produced from sodium chloride that is
electrolysed.
In production of the material, the ethene, made from hydrocarbon raw
materials, is reacted with the chlorine to yield 1,2-dichloroethane, which
is called ethylene dichloride. The actual chemical formula for the
original reaction is:
C2 H4 (ethene) + Cl2 (chlorine) = C2 H4 Cl2 (1,2-dichloroethane)
The 1,2-dichloroethane is heated in a furnace and decomposed into vinyl
chloride and hydrogen chloride. The hydrogen chloride that is produced is
reacted with more ethene in a process called oxychlorination, which
produces even more 1,2-dichloroethane. This is further decomposed into
vinyl chloride and hydrogen chloride again. The final equation for the
material can be shown as:
2 C2 H4 + Cl2 + 1/2 O2 = 2 C2 H3Cl + H3O
Physical Properties:
PVC can be made into two different forms based on the type and amount of
materials used in the manufacturing process. The two types are chlorinated
Polyvinyl Chloride (CPVC) and Rigid Polyvinyl Chloride (RPVC).
LEGEND
A = amorphous - Cr = crystalline - C = clear - E = excellent - G =
good - P = poor - O = opaque - T = translucent- R = Rockwell - S = Shore
RPVC CPVC
SPECIFIC DENSITY: 1.35 1.56
WATER ABSORBTION RATE (%): 0.2 0.15
ELONGATION (%): 20 40
TENSILE STRENGTH (psi): 6500 8700
COMPRESSION STRENGTH (psi): 11000 14500
FLEXURAL STRENGTH (psi): 12100 15500
FLEXURAL MODULUS (psi): 400000 435000
IMPACT (IZOD ft. lbs/in): 5 12
HARDNESS: R105 R110
FABRICATION
- BONDING: G G
- ULTRASONIC WELDING: G P
- MACHINING: G P
DEFLECTION TEMPERATURE (F)
- @ 66 psi:
170 162
- @ 264 psi:
162 140
UTILZATION TEMPERATURE (deg. F)
- min:
14 N/A
- max:
140 178
MELTING POINT (deg. F): 176 175
COEFFICIENT OF EXPANSION: 0.000045 0.00004
UV RESISTANCE: G P
CHEMICAL RESISTANCE
- ACIDS: P E
- ALKALIS: E E
- SOLVENTS: G G
Uses of PVC:
We all use PVC in our daily lives for countless things. It brings water to
our homes, covers our walls and floors, and does countless other important
tasks.
Fire and Safety:
PVC is difficult to ignite, and even when it does, it releases little heat
compared to other materials, making it excellent for fire protection. To
minimize fires from light fixtures, PVC is used in fluorescent light
diffuser panels. Many window frames are now made of PVC because they
withstand fires. Other uses include: wiring and cable covering, shrink-on
seals on medicine and food containers, shatter-proof bottles, protective
clothing, life rafts, life jackets, sporting goods, conveyor belts in coal
mines, non-slip flooring, and foam cores of some sailing boats.
Health and Hygiene:
PVC uses in this area include sealing floor and wall coverings to prevent
infection of other patients in hospitals, medicine containers, blood bags,
modified atmosphere packaging for fresh foods, and reservoirs and pipes to
provide a safe water supply to communities.
The following chart shows the uses of PVC in Europe according to the different markets it is used in:
Building and construction 53%
Packaging 16%
Wire cable and electrical 9%
Leisure 4%
Transport 3%
Furniture/office equipment 3%
Clothing/footwear 3%
Household appliances 1%
Other uses 8%
PVC is also used in many areas of the automobile, including the skin of the dashboard, window encapsulation, trim, sun visors, and gear shift lever. Some other unique uses of the material include credit cards, smart cards, identity cards, telephone cards, lifevests, rain jackets, and imitation leather apparel.