ENSC 3313, Fall 2000
for a polymer
given the following
How many kg of S are needed to cross link 4% of the sites in 3000 kg of polyisoprene? Assume the S is
30% efficient. Isoprene is CSH8. The amu of S = 32.
To completely cross link, 2 of S link 2 mers of isoprene.
Isoprene is CsHgo
Hence, need 32 kg of S to com~letely cross link 68 kg of isoprene at 100% efficiency.
Thus, need ~x32xOo04
kg ofS to cross link 4% of the sites of3000 kg of isoprene -~kg.
But, s is 30% efficient, so need ~
reference to polymers,
the terms a) glass transition
c) HDPE and LDPE,
d) degree of polymerisation.
a) The glass transition
temperature is that temperature below which thermoplastic
because there is not enough thermal energy available
for chain segments to slide by one
b) Condensation polymerization,
in contrast to addition polymerization,
does not occur by adding small
molecules together, rather by a specific chemical reaction involving
Thus, the process
is not reversible. For example:
(poly) acid + (poly) alcohol ~ polyester + water