| Summary: | The primary research interest of this project was the structural properties of an epoxy-based composite reinforced with thermite powders. The thermite powder, Al-Fe2O3, was being incorporated in the epoxy. Al-Fe2O3-epoxy with 85wt% of epoxy and 15wt % of Al-Fe2O3 was casted using a rectangular mold.
The structural characterization focused on the changes in static structural properties when powders are incorporated in the matrix. Other than Al-Fe2O3-epoxy, pure epoxy and Al-epoxy were prepared for the comparative structural studies. The characterization was carried out by comparing the structural properties of 1) Al-Fe2O3-epoxy with pure epoxy and 2) Al-Fe2O3-epoxy with Al-epoxy. Al-Fe2O3-epoxy was compared with pure epoxy to study the changes in structural properties when Al-Fe2O3 powders are incorporated in the epoxy matrix. Al-Fe2O3-epoxy was compared with Al-epoxy to study the changes in structural properties when Fe2O3 powders are added. The structural properties were assessed via static mechanical tests; tensile, compression and hardness tests.
Analyses of the structural tests showed powder-reinforcement effects in Al-Fe2O3-epoxy under compression and surface deformation. Under compression loading, the Al-Fe2O3 powders were believed to have provided extra resistance to Al-Fe2O3-epoxy as compared to pure epoxy. In addition, the presence of the hard Fe2O3 provided extra resistance resulting in higher stiffness and strength in Al-Fe2O3-epoxy as compared to Al-epoxy.
However, under tensile load Al-Fe2O3-epoxy exhibited less favorable properties in terms of ultimate tensile strength and ductility. The presence of Al-Fe2O3 resulted in lower ultimate tensile strength and ductility in Al-Fe2O3-epoxy compared to pure epoxy. This could be attributed to the presence of powders that interrupted the discontinuity between the polymer chains. Furthermore, the presence of the hard Fe2O3 made Al-Fe2O3-epoxy more brittle than Al-epoxy and pure epoxy.
It should be noted that sedimentation was present in the rectangular Al-Fe2O3-epoxy sample that was characterized. There were attempts to solve this sedimentation by pre-synthesizing the Al-Fe2O3 powders before incorporating them into the epoxy matrix. The two synthesis methods were 1) milling and 2) using poly-4-vinylpyridine (PVP) as a binding agent for Al-Fe2O3. Although these two methods were employed, the sedimentation problem could not be eliminated from the rectangular composites. Owing to time constraint and the fact that tensile test characterization requires rectangular samples, structural characterization on rectangular Al-Fe2O3-epoxy samples despite presence of sedimentation.
However, further homogeneity studies were carried out using cylindrical samples of Al-Fe2O3-epoxy, Al-Fe2O3(milled)-epoxy and Al-Fe2O3(PVP)-epoxy to investigate the sedimentation problem. The studies concluded that minimizing the movement of the pre-coupled Al-Fe2O3 powders was the key to solving the sedimentation problem. Future synthesis of such rectangular samples could look into this area for solutions.
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