THERMOSTABLE ADHESIVES BASED ON MONOMERS WITH CN-MULTIPLE BONDS

The dependence of the adhesive strength (tau) of joints composed of mo dified polycyanurates (REOLANs) and polyisocyanurates (TRNPs) and a st eel wire on the adhesive composition, conditions of their synthesis, a nd test temperature has been studied. Measurements were conducted usin g the pull-out technique in the range 20-300 degrees C. The modificati on of REOLANs with a monomer additive (MA) and of TRNPs with low molec ular telechelic rubbers made it possible to increase the interfacial s trength. The dependence of tau on the amount of modifier added is desc ribed for both systems by a curve with a maximum; the maximum is obser ved at a low content (5-10 wt%) of the modifier. At room temperature, REOLANs exhibit a higher adhesive strength to the steel wire than TRNP s. As the test temperature is raised, the joints with REOLANs lose the ir strength much faster than TRNPs; however, up to 250 degrees C the v alues of tau for REOLANs exceed the adhesive strength of TRNPs. Compar ison of the temperature curves of the adhesive strength of the polymer s studied with analogous curves for polymers studied earlier demonstra tes the advantages of REOLANs and TRNPs as thermostable adhesives. Pos sible mechanisms that determine the observed dependence of the adhesiv e strength on the content of the modifier and temperature are discusse d.