A composite article includes a matrix having first and second opposing surfaces defining a transverse dimension and a filler material embedded in the matrix. The filler material presents a density gradient in the transverse dimension wherein a minimum filler density is at the first surface. In one embodiment, the composite article is a non-laminated article defining first and second regions wherein the first region encompasses the first surface. The first region has a filler-to-matrix ratio that varies along the transverse dimension, the filler-to-matrix ratio being at a minimum at the first surface. The first region can include one or more additives. A method for forming a composite article includes injecting first and second compositions into a die head at different points so as to produce a partially mixed composition that is discharged from the die head. The second composition contains less filler material than the first composition.