The objective of our research was to extend the use of the single fiber fragmentation test to include fast reacting resin systems and to determine the effect of gelation time on interfacial shear properties. To do this work, we developed a processing system capable of producing single fiber fragmentation samples with gelation times ranging from 45 minutes to 2 minutes. This development allowed us to assess interfacial properties of resins used in fast molding applications. We examined the interfacial properties between E-glass fibers and a vinyl ester resin by performing single fiber fragmentation tests. In this work, we found the vinyl ester resin catalyzed with methyl ethyl ketone peroxide and promoted with cobalt naphthenate and dimethyl aniline gelled in two minutes and had an estimated interfacial shear strength of 105 MPa. Specimens cured without the promoter gelled in 45 min and had an interfacial shear strength of 72 MPa. Further postcuring of the unpromoted specimens resulted in an increase in shear strength to 96 MPa. Although the mechanical properties were similar, near infrared spectroscopy results showed little correlation between the amount of vinyl groups converted and mechanical propeties. Of special note with these systems were the extensive damage zones along the fiber matrix interface that surrounded the breaks in the fiber.
Citation: Adhesion Society
Pub Type: Journals
gel time, interface, processing, single fiber fragmentation, spectroscopy, vinyl ester