Comparison of Mechanical Properties of Polymer-Based Multi-phase Particulate Composites
Multi-constituent particulate composites consist of individual particles of more than one material dispersed throughout and held together by a polymer binder. The mechanical and physical properties of the composite depend on the mechanical and physical pr
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Comparison of Mechanical Properties of Polymer-Based Multi-phase Particulate Composites Jennifer L. Jordan and Jonathan E. Spowart
Abstract Multi-constituent particulate composites consist of individual particles of more than one material dispersed throughout and held together by a polymer binder. The mechanical and physical properties of the composite depend on the mechanical and physical properties of the individual components, particularly the binder; their loading density; the shape and size of the particles; the interfacial adhesion; residual stresses; and matrix porosity. Multi-constituent composites with cast-cure epoxy binder have been presented recently. In this study, the microstructure is varied by injection molding PMMAbased composites. The dynamic mechanical properties of PMMA-based and epoxy-based composites are measured using a split Hopkinson pressure bar. The mechanical properties of these composites are compared. Keywords Particulate composite • PMMA • High strain rate
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Introduction
Polymer composites comprised of metallic particles distributed throughout a contiguous polymer matrix can often be modified to produce advanced composites that exhibit multifunctional characteristics. For example, epoxy with Ni and Al particles [1, 2] to produce high strength materials with exothermic reactive properties, or Teflon® (PTFE) can be reinforced with Al and W particles [3]. The properties of the particulate composites often depend on varying particle size, loading fractions, particle type, and the adhesion between the particulate and the matrix [2–6]. Several studies on epoxy-based composites with similar microstructures have been reported. These studies have shown that particle size [3, 7–9], shape [10], and concentration [11] and properties of the constituents can affect mechanical properties. In Al2O3 particle-filled epoxy (Epon 828/Z), increasing the particle concentration and decreasing the particle size is found to increase the stress corresponding to 4% plastic strain [12]. A study of aluminum particle filled epoxy (DGEBA/ MTHPA) composites has found that a small amount of filler (~ 5 vol.%) increases the compressive yield stress, but additional amounts of filler decrease the compressive yield stress [13]. However, tests on glass-bead-filled epoxy (DOW DER 331/bisphenol-A) found that increasing the volume fraction increased both the yield stress and fracture toughness of the material [14, 15]. In another study on a similar material, decreasing the aluminum particle size from micro to nano resulted in increased epoxy crosslink density and subsequently increased both static and dynamic strength [2]. This paper will present the experimental results comparing aluminum and nickel particles in PMMA prepared by injection molding with the same particles in epoxy prepared in a cast-cure process.
J.L. Jordan (*) Air Force Research Laboratory, AFRL/RWME 2306 Perimeter Road, Eglin AFB, FL 32542 e-mail: [email protected] J.E. Spowart AFRL/RXBC, Wright-Patterson AFB, OH 45433, USA V. Chalivendr
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