Polyethylene articles
AssigneeMilliken & Company
InventorsDarin L. Dotson, Chi-Chun Tsai, Haihu Qin, John W. Miley, Mary Angela Cooley, Sanjeev K. Dey, Eduardo Torres, Francisco Alvarez
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Abstract
A polyethylene article comprises crystalline polyethylene in an orthorhombic unit cell. The b-axes of the crystalline polyethylene are substantially aligned with the machine direction of the article. In particular, the Herman's index of the b-axes in the machine direction is greater than zero and greater than the Herman's indices of the b-axes in both the transverse and normal directions. The unique physical attributes exhibited by a polyethylene article having this new morphology are also described.
Claims34
A polyethylene article produced from a molten polyethylene polymer, the article having a thickness, the article having at least one local machine direction (MDlocal) corresponding to a direction in which the molten polyethylene polymer flowed within a region in the article when the article was produced, the article having a corresponding local transverse direction (TDlocal) perpendicular to each local machine direction within the article, the article having a local normal direction (NDlocal) perpendicular to each local machine direction and corresponding local transverse direction and parallel to a line passing through the thickness of the article, the polyethylene polymer comprising a plurality of lamellae, each lamella comprising crystalline polyethylene, the crystalline polyethylene having a b-axis, the b-axes of the crystalline polyethylene in the lamellae having a Herman's orientation index at each local machine direction (F(MDlocal,020)), a Herman's orientation index at each corresponding local transverse direction (F(TDlocal,020)), and a Herman's orientation index at each corresponding local normal direction (F(NDlocal,020)), the b-axes of the crystalline polyethylene in the lamella being oriented within the article such that F(MDlocal,020)>0, F(MDlocal,020)>F(TDlocal,020), and F(MDlocal,020)>F(NDlocal,020).
A polyethylene article produced by extruding a molten polyethylene polymer through an orifice in a direction, the article having a thickness, the article having a machine direction (MD) corresponding to the direction in which the molten polyethylene polymer exited the orifice, the article having a transverse direction (TD) perpendicular to the machine direction and perpendicular to a line passing through the thickness of the article, the article having a normal direction (ND) perpendicular to the machine direction and the transverse direction and parallel to a line passing through the thickness of the article, the polyethylene polymer comprising a plurality of lamellae, each lamella comprising crystalline polyethylene, the crystalline polyethylene having a b-axis, the b-axes of the crystalline polyethylene in the lamellae having a Herman's orientation index in the machine direction (F(MD,020)), a Herman's orientation index in the transverse direction (F(TD,020)), and a Herman's orientation index in the normal direction (F(ND,020)), the b-axes of the crystalline polyethylene in the lamella being oriented within the article such that F(MD,020)>0, F(MD,020)>F(TD,020), and F(MD,020)>F(ND,020).
Dependencies are inferred from the claim text.