Answer 1:
PVC (poly-vinyl chloride) is a polymer that
mimics polyethylene but is much easier to produce
and is almost universal in application. Vinyl
chloride is singly chlorinated ethylene. Most
polymerization processes make use of reduction of
a double bond to a single bond by means of a free
radical, and PVC is the prototypical version of
this process. Essentially, the double bond is
broken in the ethylene to allow two single bonds
to neighboring monomers to make a chain that can
be thousands of molecules long. (In general,
longer strands improve many of the properties of
the material -- for example tensile strength
versus brittleness.
While PVC is very stable and is widely used in
health care applications (it is easy to
sterilize), vinyl chloride is a known
carcinogen and is relatively dangerous. A
particular danger is from smoke inhalation of
burning byproducts of PVC. (I must point out that
burning creosote is even more dangerous to
breathe!) Despite similarities to other
chlorinated organics (such as chlorinated phenols
which were used for years as anti-bacterial
agents), PVC's are themselves stable, non-toxic,
plastics with minimal out gassing if manufactured
correctly. There are lots of sites on the web
regarding plastics, some are quite factual -- some
are not. |
