The effect of heat treatment on the adhesion and rheological behavior of polysulfone

Shear adhesive strength (τ) was investigated for polysulfone (PSK-1) and steel wire (d=150 μm) joints. The rheological behavior of polysulfone melts and thermogravimetry was also studied at 260–300 °C during a long period of heating (up to 3 h). It was found that at a constant temperature of heat treatment Tf the dependence of τ on treatment time tf was described by a curve with a maximum, and Tf affected the time required to reach the maximal adhesion. The adhesive strength of the joints prepared during the two-step formation coincided with τ of the joints prepared during one-step heating. The thermogravimetric measurements showed that the isothermal heating of the melts was not accompanied by heat-evolution and weight losses. The frequency dependencies of storage modulus, loss modulus and complex viscosity showed that structuring of the polymer occurred during heat treatment. It is assumed that structuring is due to chemical cross-linking. The mechanisms were proposed to explain the non-monotonic dependence of the interfacial strength on time of joints formation in polysulfone/steel wire joints.