STUDY OF ELASTIC PROPERTIES OF POLYMERS FROM MICROHARDNESS TESTS

A numerical method of identification to derive the elastic properties of polymers from indentation experiments has been developed. Five diff erent polymers were tested: amorphous and semi-crystalline polyethylen e terephthalate (PET), semi-crystalline polyvinylidene fluoride (PVF2) , a copolymer of polyvinylidene fluoride and trifluorethylene, P(VF2/F 3E) 60/40, and high pressure crystallised polyethylene (PE). The elast ic properties of the polymers are calculated by two methods. On the ba sis of finite element solution, a simple function relating the load to the indentation depth and elastic modulus is first obtained. The elas tic properties are then derived from the load-indentation depth and el astic modulus is first obtained. The elastic properties are then deriv ed from the load indentation depth experimental data (loading curve). A second method to determine the elastic properties is based on using the experimental data of the unloading curve. Elastic properties obtai ned from loading and unloading curves are in good agreement.