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Method of Depth Profiles for Porous Materials by Gravimetric Analysis

IP.com Disclosure Number: IPCOM000033681D
Publication Date: 2004-Dec-23

Publishing Venue

The IP.com Prior Art Database

Related People

Dave Biggs: AUTHOR [+3]

Abstract

A method to determine the composition of a porous material in the z-direction was developed. The method can be utilized to determine the uniformity of a material as well as to characterize and to identify interface structure. Alternatives to the method were considered including aspects of infiltration, embedding, cutting, testing conditions, removal of the embedding material, and gravimetric procedures. Analyses were performed to determine the effectiveness of the method. The results on a layered standard were presented. Data showed that the method successfully characterized and identified an interface within 400 microns. Also shown here is support that the method is accurate in determining the uniformity of a sample throughout the depth of the material within 2% by weight of the composition.

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Method of Depth Profiles for Porous Materials by Gravimetric Analysis

Dave Biggs*, Mike Shlepr*, and Janelle Warrick**

*Kimberly-Clark Corporation, Neenah, WI

**University of Wisconsin, Madison, WI

ABSTRACT

A method to determine the composition of a porous material in the z-direction was developed. The method can be utilized to determine the uniformity of a material as well as to characterize and to identify interface structure. Alternatives to the method were considered including aspects of infiltration, embedding, cutting, testing conditions, removal of the embedding material, and gravimetric procedures. Analyses were performed to determine the effectiveness of the method. The results on a layered standard were presented. Data showed that the method successfully characterized and identified an interface within 400-µm. Also shown here is support that the method is accurate in determining the uniformity of a sample throughout the depth of the material within 2% by weight of the composition.

KEYWORDS: Depth profile, porous material, z-directional profile, gravimetric analysis, thin-sectioning, uniformity, interface, reversible embedding

INTRODUCTION

Compositional depth profiles provide valuable insight into the details of material performance. For example, airlaid materials manufactured by multi-bank processes occasionally fail under nominal manufacturing tension. This failure might be the result of a lack of uniformity, particularity at the bank interfaces, and a procedure to test through-thickness composition would be beneficial.

The method discussed here embeds a sample of porous material in reversible embedding media to stabilize its three-dimensional structure. The embedded material is serially sectioned through the depth, and all sections are collected and labeled. The embedding media is removed and then sections analyzed for mass and composition. These data are related to depth to form a depth profile. The method is amenable to automation.

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MATERIAL AND METHODS Material In order to test the accuracy and repeatability of the method, a standard was devised. The standard was required to be of a thickness measurable by another reliable method and be of known composition. For this reason, a layered structure of pulp and meltblown polypropylene (MB) was chosen. Rolls of NB 416 pulp with a specified density of 1.20- g/cc and MB specified to be 0.45-ounces per square yard were used. Nine layers of this low basis weight MB were stacked to produce a MB layer. Pulp and MB-stacks were cut with a 2.5-cm square die cutter for use. One pulp square and two MB-stacks were used for the standard composite. Single MB-stacks were used in estimating weight-loss error for the entire method.

Two 3-cm x 3-cm x 0.3-cm aluminum plates were used to compress the sample. The bottom plate was stamped with a grating, which provided topography to stabilize the sample during sectioning. The upper plate had a 0.4-µm average surface roughness (Ra)...