LOSS OF BALSA WOOD CORE STRUCTURAL INTEGRITY DURING FIRE EXPOSURE OF SANDWICH COMPOSITES

摘要

The thermal degradation and combustion of E-glass/vinyl ester balsa core sandwich structures were investigated using chemical analysis techniques in coordination with mechanical testing to determine loss of balsa wood core structural integrity. The structure and chemical composition of balsa wood core was found to govern the overall fire resistance characteristics and compressive stiffness of the sandwich structure. Wood-to-char conversion through-the-thickness of the balsa wood occurred in up to 67% of the core depth at the end of an 80 kW/m{sup}2, 800°C, 30 min fire exposure. In addition, the post-fire balsa wood core stiffness was significantly compromised as a result of increasing fire exposure time. The post-fire compressive modulus of the sandwich structures were found to decrease at a rate of 2.85 MPa/s as a result of an 80 kW/m{sup}2, 800°C fire exposure for up to 200 s.