| Thermosetting epoxy resin E-51 used as matrix, K-25 hollow grass microspheres (HGM) from 3M Ltd. as light-weight filler andμm-Degree SiO2 powder as modifying agent, light-weight syntactic foam ith different SiO2 content was prepared, whose density was all about 0.5g/cm3.The initiating temperature(Ti), peak temperature (Tp) and final temperature(Tf) of the curing reaction can be derived from the non-isothermal DSC curing curves of E-51/594 system with various curing agent content. The apparent activation energy of curing reaction was calculated by KAS differentiation and FWO integration, respectively. And the different trends of the curing reaction difficulty reflected by the two calculating method were also compared. The results indicated that there was a deviation between two calculating values, but the trend was consistent. Moreover, the optimized curing condition can be determined by DSC results. Curing kinetics model investigation indicated curing kinetics curve obtained by Malek maximum probable function method was well accordant with experimental curves, which can be used to predict partial experimental results except some deviations in later curing period.The actual density of the syntactic foam, the volume fractions of HGM and air bubbles were also tested and calculated. The results showed that more pore lead to remarkable deviation between the true density and theoretical one. The influence of SiO2 content on the mechanical properties of the composites was also studied. It showed the compression and bending strength were significantly improved when the mass fraction of SiO2 was 4%.The SEM photographs of the sample fracture surfaces indicated, the break of HGM was most responsible for the fracture of the syntactic foam. In the same time, the more HGM may also lead to non-wetting between expoxy resin and HGM. In addition, investigation indicted that the SiO2 particles play a "nail anchor" role for the crack in the syntactic foam. |
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