Relationship between the Contact Time of Polymer Surfaces and Their Bond Strength

Films of amorphous polystyrene (PS) (mono- and polydisperse polymers) and poly(phenylene oxide) (PPO) were brought into contact at a low pressure (0.8 MPa) under temperatures T _h from 62 to 156°C. The contact time t was varied from 2 min to 96 h. Partially healed PS-PS, PPO-PPO, and PS-PPO contacts were broken at room temperature and the shear strength in the contact zone was measured. The experimental -t curves were analyzed in double logarithmic coordinates. The value of for the three interfaces investigated was within 0.07-0.32 at T _h < T _g, where is the glass transition temperature. In the same way, the data on strength development taken from the literature for a number of polymer-polymer contacts formed both above and below T _g were analyzed, and the range of variations in proved to be roughly the same (0.05-0.35). The results obtained are discussed within the framework of theories of molecular dynamics for the polymer bulk and the interface.