Cambered and Non-flat Polyethylene Webs Induced by Thickness Variation

Abstract

One of the most common web defects is web bagginess. Although it appears in most web materials, it is very difficult to categorize since its appearance changes from one case to the other; hence it has been given different definitions by different people. The most general way to define a baggy web is a web that does not lie flat/straight and has an intrinsic length difference across the width of the web. In this study, polyethylene webs were used as the main material to develop an understanding on some of the web bagginess cases through experimentation. Viscoelastic material properties behavior of polyethylene web was also characterized using time-temperature superposition. Digital image acquisition was used to detect web bagginess. With these results, it is now possible to correctly model this defect using a numerical simulation under development by the Web Handling Research Center.