Introduction

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Introduction

 

Function

PoreXY, the successor to Pore-Comp and PoreXpand, is a processor for mercury porosimetry data that carries out six tasks, where applicable to the loaded experimental datafile:

 

(i)  corrects for a run with an empty sample chamber - i.e. the blank run, thus correcting for sample chamber (penetrometer) expansion,

(ii) compares the porosity listed on the datafile with that calculated from the sample's bulk porosity and maximum intrusion volume,

(iii) allows easy examination of parts of the porosimetry curves by means of a zoom-in function,

(iv) corrects for sample solid phase compressibility, allowing for compression of mercury,  and provides the user with the sample's solid phase bulk modulus,

(v) allows the user to trim the top and bottom of the intrusion curve if necessary, as PoreXpert models the full intrusion curve that is input, and extra 0% or 100% intrusion points weaken the model by extending the range of void sizes modelled beyond those that are valid, 

(vi) thins the data so that the intrusion points are equally spaced working along the intrusion curve, so that PoreXpert equally weights statistically all parts of the curve - rather than, say, being equally spaced with regards to pressure, which gives fewer points, and therefore under-weighting, at the important point of inflexion.

 

Even if you do not use PoreXpert routinely, PoreXY can be useful.  Quality control (but NOT void size estimation) can be carried by taking the first derivative (slope) of the intrusion curve, usually plotted with a logarithmic pressure (or size) axis.  PoreXY outputs fewer and more equally spaced points, and therefore leads to easier measures of slope. 

 

Input

As shown below, PoreXY inputs data from Thermo Fisher and BELPORE mercury porosimeters.  It also accepts PoreXpert csv format files, although they contain minimal information, so can only be trimmed and thinned. It also accepts two Micromeritics report (.RPT) format files as tutorial files.  To process other Micromeritics files, please contact us at support@porexpert.com .

 

Datafiles must be in UK format - specifically the decimal point separator must be a period / full stop (.) rather than a comma (,).

 

The example files below are loaded at instal time into a newly created directory named ...Documents/PoreXY/Example files .

 

In the case of the Micromeritics data files, as demonstrated by the two available tutorial files, they must be exported from the Autopore software in uncompressed (i.e. readable ASCII text) .RPT format, without the instrument software correcting for the blank or compression, as it is invalid if the data is corrected for compressibility twice.

 

The operations available to each type of datafile, together with the names of the example files, are shown below.

 

PoreXY_datafile_types_redacted

 

 

Output

 (i) PoreXY calculates the solid-phase bulk modulus (compressibility) of your sample (not the overall compressibility of the sample).  The solid phase compressibility is useful if, for example, you have a paper coating specimen or a fuel cell substrate, and need to know whether the binder (e.g. latex or PTFE) is sitting between the substrate particles or network as well as coating them/it, or only acting as a coating.

 (ii) The software outputs the processed data in the very simple PoreXpert format for direct entry into PoreXpert itself.

 

Caveat

The bulk modulus estimate derived from PoreXY demands that you have perfect porosimetry results, carried out slowly with no thermal heating effects, that are perfectly blank corrected.  The accuracy of the estimate decreases for higher bulk moduli (lower compressibility) because the calculation becomes increasing affected by the accuracy of the experimental data. You are unlikely to obtain a meaningful estimate of sample with bulk modulus above 30 GPa.   This decrease in accuracy is shown in the Results datafiles dropdown menu.

You need to follow best practice for mercury porosimetry to ensure you get good quality data. Not all of the recommendations are applicable to different instrument manufacturers.

 

Using PoreXY

To use PoreXY, carry out the relevant instructions that follow, in order.  There is no separate tutorial - if you wish to try out the program before using one of your own samples, then try the datafile type example most similar to your own.

 

Background information

The theory behind the compression correction and bulk modulus calculation performed by PoreXY is explained in more detail in the Theory of compression correction page.