Interfacial properties of polymer composites measured by push-out and fragmentation tests

The interfacial properties for E-glass/epoxy composites were measured using push-out tests and single fiber fragmentation tests. Theoretical models for both stress-based and energy-based criteria were used to interpret the experimental results. Fibers treated with gamma -aminopropyl-triethoxysilane (gamma -APS) showed higher bond strength (similar to 1.7 times higher) and interfacial toughness (similar to 1.9 times higher) than those of unsized E-glass based composites. However. the average interfacial toughness obtained from fragmentation tests was about six times higher than that obtained from push-out tests. Considering the analytical frameworks employed to interpret the values measured in the present work, the fragmentation test is a more appropriate method to obtain interfacial energy for polymeric composites, but both methods are appropriate for relative measurements of interface strength. (C) 2001 Elsevier Science Ltd. All rights reserved.