Polyethylene articles

摘要

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.

主权项

1. 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).