DEGRADATION OF PLASTICS IN THE ENVIRONMENT - Plastics and Environmental Sustainability - page 237

Figure 6.8 compares the change in tensile elongation at break (or
extensibility) of LDPE and the ECO copolymer films at different exposure
durations. For clarity, the logarithm of tensile extensibility is plotted in
the figure. Steeper the gradient of the linear plots, faster is the rate of
degradation. The ratio of the gradients is a measure of the degree of
“enhancement” afforded by the ECO copolymer over conventional LDPE.
The data in the figure for exposure in Miami, FL, in (summer) show an
enhancement (Andrady et al., 1993a) factor of 5 for the photodegradable
ECO material. Table 6.2 compares the values of gradient B (days −1 ) in plots
of changes in tensile elongation at break for copolymer of ethylene with
(1%) carbon monoxide (ECO) and that for the control LDPE film of the
samethickness (60mil),atdifferent locations intheUS.TheECOlaminates
used are of the same grade as in photodegradable six-pack rings and were
supplied by the manufacturer (ITW HiCone Company). The ratio of the
values of gradient ( B */ B ) is an approximate measure of the enhancement of
degradation using this approach and ranges from 5 to 20 depending on the
location (Andrady et al., 1993a).