Relationships between mechanical properties and microhardness of polyethylenes

The values of the elastic modulus (E) and the yield stress (Y) and the shape of the strain‐stress curves of different polyethylenes have been related to the microhardness (MH) of these materials, considering the roles that the crystalline, amorphous, and interfacial regions play in the deformation of semicrystalline polymers. Linear relations between microhardness and degree of crystallinity, (1 – λ) d , and between the logarithms of E and MH have been found. The variations of the parameters 100Y/E and σ min /Y (σ min is the relative minimum value of the nominal stress for elongations above the yield point) as a function of (1–λ) d follow different trends for linear and branched polyethylenes. Moreover, it has been found that the ratio MH/Y is smaller than three for these materials, approaching this theoretical value (Tabor relation) only for the highest crystallinity levels.