THERMOMECHANICAL ANAL Y SIS OF A TOUGH ENED

The ex per i men tal re sults of viscoelastic me chan i cal tests, at five dif fer ent lev els of con ver sion, are re ported for a thermoset com pos ite ma trix sys tem tough ened with an ap pro pri ate per cent age of a ther mo plas tic poly mer. The re sults from static tests are used to con struct the mas ter curves at a spe cific de gree of cure, while the shift fac tors are com pared with the cor re spond ing val ues from dy namic ex per i ments in or der to as sess the va lid ity of the time-tem per a ture su per po si tion for each con ver sion. Neat resin plates were cured ac cu rately, ac cord ing to the full ki net ics model for a dy namic and iso ther mal tem per a ture re gime; the con ver sion gra di ent in the plane and across the thick ness of the plates was as sessed by a ther mal anal y sis of sam ples taken from dif fer ent lo ca tions be fore ex tract ing the sam ples from them. The viscoelastic be hav iour of the resin ma trix showed a sen si ble dif fer ence in the re lax ation time spec trum upon con ver sion ac cord ing to the pro vi sional trend of mo - bil ity the ory; a higher con ver sion in duced a hor i zon tal shift of the prin ci pal re lax ation time for each level of con ver sion, which could be re lated very well to the glass tran si tion at the same con ver sion. Good re sults were also ob tained for the ul ti mate modulus of the resin at a tem per a ture just be fore the on set of the co-cur ing phase for partially cured samples.