Paper samples of three different qualities were extrusion coated with low-density polyethylene (LDPE) and high-density polyethylene (HDPE). The morphological phases of the polyethylene layers have been quantified by C-13 solid-state high-resolution NMR. Shear forces in the process initiate the formation of the monoclinic crystallites. The surface tensions of the high-density papers have influence on the degree of interaction between the two materials and how these shear forces work. The paper surface properties will thus have an influence on properties and the size of the monoclinic crystalline mass fraction of the polyethylene coating. (C) 2003 Wiley Periodicals, Inc.