Effective mechanical properties of multilayer nano-modified polymer composite laminates

This paper presents a method for determining theoretical in-plane and through-thickness elastic properties of laminates, consisting of isotropic layers. A multilayer nano-modified polymer film can be considered as an example of such laminate. A nano-modified polymer film consists of a number of polymer layers where at least one layer contains nanofillers. The properties of a single layer depend on the added nanofiller type, and it is considered that the nano-modified layer is isotropic. Although often disregarded, the through-thickness elastic properties are needed for modelling three-dimensional stress problems. Explicit relationships for the in-plane and through-thickness Young’s and shear moduli, Poisson’s ratios, and coefficients of thermal expansion (CTE) were derived. The obtained formulae are valid for both symmetric and unsymmetric laminate composition. Comparison of theoretical values of in-plane modulus and CTE with experimental data are presented for PE (polyethylene)-layered films nano-modified with MWCNT (multi-walled carbon nanotube) and PU (polyurethane)/PET (polyethylene terephthalate) films nano-modified with titanium carbide nanoparticles. The comparison results are satisfactory.