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Mechanical properties of polybenzoxazine syntactic foams
Author(s) -
Santhosh Kumar K. S.,
Reghunadhan Nair C. P.,
Ninan K. N.
Publication year - 2008
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.27030
Subject(s) - syntactic foam , glass microsphere , materials science , ultimate tensile strength , composite material , flexural strength , compressive strength , compaction , volume (thermodynamics) , specific gravity , scanning electron microscope , volume fraction , microsphere , chemical engineering , physics , quantum mechanics , engineering
Syntactic foams of polybenzoxazine, containing moderately high volume percentage of glass microballoons, were prepared. The specific gravity decreased with increase in microballoon content. The disproportionate decrease in specific gravity was ascribed to entrapment of air voids during compaction. The high content of microballoon increased the possibility for air voids that tended to get accumulated. The effect of microballoon concentration on tensile, compressive, and flexural strengths of the foams was studied. Tensile and compressive properties were optimized at about 68% by volume of microballoon while flexural strength decreased marginally on increasing the microballoon content. Althought the specific tensile and compressive strength showed a maximum followed by a decrease, the specific flexural strength systematically increased with microballoon content. The increased packing density of syntactic foam of a given constituent composition increased the compressive strength. The property variation was corroborated by morphological features, as evidenced in scanning electron micrographs. The syntactic foams showed “multiple resin‐neck formation” and “disc‐shaped microballoon regions.” The crushing of microballoons during molding was inevitable when compaction was effected to achieve a density beyond the theoretical one. Low‐density syntactic foams tend to fail at lower loads because of fracturing of microballoons. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008