Rotational molding molecular requirements

The reason for the extremely high modulus of oriented polyethylene in comparison to typical specimens ( 1 GPa for injection-molded high density polyethylene [24]) is simple. The tensile deformation of isotropic samples at low strains principally involves the distortion of molecules whose trajectories approximate to a random coil, which is largely accommodated by bond rotation. This requires much less force than the molecular stretching required to extend the all-trans configuration, which involves bond elongation and an increase in the C—C—C dihedral bond angle. 

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