A nanocomposite concentrate composition comprising about 10 weight percent to about 90 weight percent of a layered silicate material and about 10 weight percent to about 90 weight percent of a matrix polymer comprising about 90-99.5% by weight of a polyolefin and about 0.5% to about 10%, preferably about 1% to about 6% by weight, of a maleic anhydride-modified polyolefin, based on the total weight of polyolefins, wherein the layered silicate material is dispersed uniformly throughout the matrix polymer. Shearing of the concentrate and later (after shear) addition of an added matrix polymer avoids thermal degradation of the added matrix polymer and optimizes the dispersion of the nanomer throughout the matrix polymer; provides increased tensile strength; and reduces degradation of the polymer by melt formation of a concentrate thereby decreasing heat degradation of added matrix polymer.