Title:Fabrication and Mechanical Properties of POSS Coated CNTs Reinforced Expancel Foam Core Sandwich Structures
Volume: 4
Issue: 2
Author(s): Wanda Jones, Bedanga Sapkota, Brian Simpson, Tarig A. Hassan, Shaik Jeelani and Vijaya Rangari*
Affiliation:
- Department of Materials and Science Engineering, Tuskegee University, Tuskegee, AL36088,United States
Keywords:
Expancel foam, CNTs, POSS, sandwich structure, thermal properties, mechanical properties.
Abstract:
Background: Sandwich structures are progressively being used in various engineering
applications due to the superior bending-stiffness-to-weight ratio of these structures. We adapted a
novel technique to incorporate carbon nanotubes (CNTs) and polyhedral oligomeric silsesquioxanes
(POSS) into a sandwich composite structure utilizing a sonochemical and high temperature
vacuum assisted resin transfer molding technique.
Objective: The objective of this work was to create a sandwich composite structure comprising of a
nanophased foam core and reinforced nanophased face sheets, and to examine the thermal and mechanical
properties of the structure. To prepare the sandwich structure, POSS nanoparticles were
sonochemically attached to CNTs and dispersed in a high temperature resin system to make the
face sheet materials and also coated on expandable thermoplastic microspheres for the fabrication
of foam core materials.
Methods: The nanophased foam core was fabricated with POSS infused thermoplastic microspheres
(Expancel) using a Tetrahedron MTP-14 programmable compression molder. The reinforced
nanophased face sheet was fabricated by infusing POSS coated CNT in epoxy resin and
then curing into a compression stainless steel mold.
Results: Thermal analysis of POSS-infused thermoplastic microspheres foam (TMF) showed an increase
in thermal stability in both nitrogen and oxygen atmospheres, 19% increase in thermal residue
were observed for 4 wt% GI-POSS TMF compared to neat TMF. Quasi-static compression results
indicated significant increases (73%) in compressive modulus, and an increase (5%) in compressive
strength for the 1 wt% EC-POSS/CNTs resin system. The nanophased sandwich structure
constructed from the above resin system and the foam core system displayed an increase (9%) in
modulus over the neat sandwich structure.
Conclusion: The incorporation of POSS-nanofillier in the foam core and POSS-coated nanotubes
in the face sheet significantly improved the thermal and mechanical properties of sandwich structure.
Furthermore, the sandwich structure that was constructed from nanophased resin system
showed an increase in modulus, with buckling in the foam core but no visible cracking.
