At stretching ratio of 30%, the lamellar
structure shows maximum periodicity. By further stretching to
130%, the secondary signal decreases, meaning that higher
stretching ratio deteriorates the lamellae periodicity, in agreement
with the above SEM results. Combined with the SEM results, it can
be deduced that at the stretching ratio of 30%, some connecting
bridges appear and the possible lamellae slipping improves the
periodicity, but at higher stretching ratio, although more connecting bridges are formed, the periodicity becomes worse.