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The broader goal of this research is to develop a commercially viable material system and manufacturing method to mass produce functional parts using selective laser sintering, a rapid manufacturing method, for electrostatic charge dissipation applications. The specific objective of this research is to produce and characterize polyamide 11/ nanographene platelets nanocomposites that have improved electrical conductivity for electrostatic charge dissipation applications and better thermal stability to be used in selective laser sintering manufacturing. Polyamide 11 and nanographene platelets were blended using industry size co-rotating twin-screw extrusion. Four batches were prepared containing 1 wt%, 3 wt%, 5 wt% and 7 wt% of nanographene platelets. Microsctrucre of nanocompoistes was studied using scanning electron microscopy. Thermal characterization of nanocomposites was conducted using thermogravimetric analysis at three heating rates 5, 20, 40 C/min. Electrical resistivity was measured using the Hioki Megaohmmeter Instrument four probe method. Mechanical characterization includes tensile, flexure, and Izod-impact properties. Flammability property was measured using UL94 test.

Ablative nanocomposites were prepared by incorporating multiwall carbon nanotubes (MWCNT) into phenolic resin and then impregnating them into rayon-based carbon fabric. MWCNT were blended into phenolic resin at 0.5, 1, and 2 wt% loadings using a combination of sonication and high shear mixing to insure uniform dispersion of MWCNT. The composite test specimens were tested by using an oxyacetylene test bed (OTB) applying a heat flux of 1000 W/cm2 for duration of 45 seconds. Composite specimens with 2 wt% MWCNT showed reduction in mass loss, recession in length, and in situ temperatures compared to control composites.

The aim of this study is to investigate the influence of nanosilica on glass-reinforced epoxy composites under static mechanical and tension–tension fatigue loading. The glass-reinforced epoxy composites were manufactured with three different concentrations of nanosilica (6, 7, and 8 wt%). Static mechanical tests include tensile, flexure and short-beam strength. 6 wt% nanosilica composites showed the greatest enhancement in tensile strength, percentage elongation, and inter-laminar shear strength compared to the other concentrations and the control. Extensive tension–tension fatigue tests (R-ratio of 0.1 and frequency 2 Hz) were conducted on the control and 6 wt% nanosilica composites. In load-controlled and constant amplitude tests, a percentage of the ultimate tensile strength was applied to the specimens. Stress applied was from 80% of UTS, and reduced in steps of 10% until specimens survived 1 million cycles. In high-cycle and low-cycle fatigue tests, 6 wt% nanosilica composites showed 10 and 3 times improvement in fatigue life, respectively, compared to the control composites. Stiffness degradation curves were explained with three stages of damage mechanisms. The final failure occurred due to fiber breakage in the third stage. Both the control and 6 wt% nanosilica composites survived 1 million cycles at a maximum stress of 46.6 MPa, but at the end of 1 million cycles, control composites lost 65% modulus compared to 45% modulus loss in the 6 wt% nanosilica composites.

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