For the evaluation of mechanical properties of semi-crystal
polymers, it is necessary to know that crystal fragments have
different mechanical properties from amorphous ones. Their
closer ordering leads to higher adhesive forces. Consequently,
the increasing percentage of crystals leads to increased strength,
mechanical stiffness and hardness by several degrees of
toughness. The amorphous segments are possible to imagine as
joints about which the crystals can rotate by deformation. It
contributes to improving toughness and elongation
(KREBS, 2006).With respect to the results of density and the
declared theory that, as the density (percentage of crystals) was
changed by more intensive cooling, so the mechanical properties
could be changed too. The tensile test didn´t confirmed this
premise, as can be seen in the figure 4 and figure 5. The
differences between the results are very small and could be with
relation to reached values of standard deviations neglected