JP2009002824A - Dry density measurement method and porosity measurement method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To measure easily the bulk density of a porous sample. <P>SOLUTION: This method has a mass measuring process for measuring the mass M of the porous sample 1; a liquid penetration process for allowing liquid 4 to penetrate into the sample; and a volume measuring process for inputting the sample 1 after the liquid penetration process into a sample chamber 31 into which a gas pressure is applied, and measuring the volume Vs2 of the sample 1 after the liquid penetration process based on a change of the gas pressure when the sample chamber 31 is communicated with an expansion chamber 32 through an on-off valve 33. In the method, the bulk density ρ2 of the sample 1 is measured based on the mass M measured in the mass measuring process and the volume Vs2 of the sample 1 after the liquid penetration process measured in the volume measuring process. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a dry density measuring method and a porosity measuring method for measuring the bulk density of a porous sample.

  A method for measuring the bulk density of a sample having a recess on the surface is known (see, for example, Patent Document 1). Here, the bulk density is a density obtained by dividing the mass of the sample by the entire volume including the concave portion of the sample surface. In the method described in Patent Document 1, after immersing a sample in a liquid of carbon fluoride and filling the concave portion with carbon fluoride, the carbon fluoride in the concave portion is solidified. Further, the sample after the coagulation treatment is placed in a fixed volume container containing water, the volume of the sample is obtained, and the bulk density is measured.

JP-A-1-185428

  However, the method described in Patent Document 1 is troublesome to measure the bulk density because the concave portion of the sample surface is filled with carbon fluoride and solidified.

The dry density measuring method according to the present invention includes a mass measuring step for measuring the mass of a porous sample, an immersion step for infiltrating the liquid into the sample, and the sample after the immersion step in the sample chamber where the gas pressure acts. And a first volume measuring step for measuring the volume of the sample after the liquid immersion process based on a change in gas pressure when the sample chamber and the expansion chamber are communicated with each other via an on-off valve, and a mass measuring step The bulk density of the sample is measured based on the mass measured in step 1 and the volume of the sample after the immersion step measured in the first volume measurement step.
The liquid to be permeated in the liquid immersion process is preferably isopropyl alcohol.
A second sample that measures the volume of the sample before the liquid immersion process based on a change in gas pressure when the sample before the liquid immersion process is put into the sample chamber and the sample chamber and the expansion chamber communicate with each other via the on-off valve. A volume measuring step is further provided, and the apparent density of the sample can be measured based on the mass measured in the mass measuring step and the volume of the sample after the liquid immersion step measured in the second volume measuring step.
The porosity of the sample can also be measured based on the bulk density and the apparent density measured by the measurement method.

  According to the present invention, the sample in a state in which the liquid is infiltrated is put into the sample chamber, and the volume of the entire sample including the gap is measured based on the change in gas pressure. The bulk density of the sample can be easily measured without performing the solidification process.

Hereinafter, an embodiment of a dry density measuring method according to the present invention will be described with reference to FIGS.
FIG. 1 is a diagram showing an entire apparatus for measuring density by a dry density measuring method according to an embodiment of the present invention. The sample 1 targeted by the present embodiment is a porous material such as cork having voids 1a such as recesses and pores on the surface and inside. The electronic balance 2 measures the mass M of the sample 1.

  The density meter 3 measures the volume of the sample 1 and measures the apparent density ρ1 and the bulk density ρ2 using the mass M measured by the electronic balance 2. Here, the apparent density ρ1 is a density obtained by dividing the mass M by the volume Vs1 excluding the void 1a of the sample 1 as shown in FIG. 2A, and the bulk density ρ2 is the density shown in FIG. ), The density obtained by dividing the mass M by the volume Vs2 of the sample 1 including the void 1a.

  The principle of density measurement by the density meter 3 will be described with reference to FIG. The density meter 3 is, for example, a dry density meter that encloses helium gas and measures the density, and includes a sample chamber 31, an expansion chamber 32, and a valve 33 that communicates and blocks the sample chamber 31 and the expansion chamber 32. .

  First, as shown in FIG. 3A, the valve 33 is opened to connect the sample chamber 31 and the expansion chamber 32, and the sample chamber 31 and the expansion chamber 32 are set to the same pressure Pa (atmospheric pressure) and temperature Ta. The volume of the sample chamber 31 is Vc, and the volume of the expansion chamber 32 is Ve.

Next, as shown in FIG. 3B, the sample 1 is put into the sample chamber 31 with the valve 33 closed, and the pressure in the sample chamber 31 is increased to P1. At this time, if the volume of the sample 1 is Vs1 (FIG. 2A), the volume of the sample chamber 31 is Vc−Vs1. Therefore, when the number of moles of gas in the sample chamber 31 is nc and the gas constant is R, the state equation in the sample chamber 31 is expressed by the following equation (I).
P1 (Vc−Vs1) = nc · R · Ta (I)
On the other hand, since the expansion chamber 32 is not pressurized, it remains at the atmospheric pressure Pa, and when the number of moles of gas in the expansion chamber 32 is ne, the internal state equation is expressed by the following equation (II).
Pa · Ve = ne · R · Ta (II)

Next, when the valve 33 is opened as shown in FIG. 3C, the pressure in the sample chamber 31 decreases, the pressure in the expansion chamber 32 increases, and the pressure in the entire system including the sample chamber 31 and the expansion chamber 32 is P2 and the state equation of the entire system is expressed by the following equation (III).
P2 (Vc−Vs1 + Ve) = nc · R · Ta + ne · R · Ta (III)
Here, when the relationship between the formulas (I) and (II) is applied to the above formula (III), the following formula (IV) is established, and the formula (IV) is further transformed to obtain the following formula (V).
P2 (Vc−Vs1 + Ve) = P1 (Vc−Vs1) + PaVe (IV)
Vs1 = Vc−Ve (P2−Pa) / (P1−P2) (V)

  From the relationship of the above equation (V), the volume Vs1 of the sample 1 can be obtained by measuring the pressures P1 and P2. Then, by measuring the mass M of the sample 1 with the electronic balance 2 in advance and dividing the mass M by the volume Vs1, the density (apparent density ρ1) of the sample 1 can be obtained.

  According to such a dry density meter, since gas enters the gap 1a in the sample, the volume of the gap 1a can be excluded from the volume of the sample 1, and the apparent density ρ1 can be accurately measured. On the other hand, it is difficult to measure the bulk density ρ2 because gas enters the gap 1a. Therefore, in the present embodiment, gas intrusion into the gap 1a is prevented as follows, and the bulk density ρ2 is measured by the same density meter 3.

  When measuring the bulk density ρ 2, first, as shown in FIG. 1, the beaker 5 is filled with a liquid 4 of isopropyl alcohol (isopropanol), and the sample 1 is immersed in the beaker 5. Next, the beaker 5 and the beaker 5 are put in the vacuum dryer 6 and decompressed for a predetermined time, and the liquid 4 is infiltrated into the gap 1 a in the sample 1. Thereafter, the sample 1 is taken out from the vacuum dryer 6, the sample 1 is put into the sample chamber 31 of the density meter 3, and the volume Vs2 of the sample is measured in the same manner as described above.

  In this case, since the liquid 4 is filled in the gap 1a in the sample, the gas does not enter the gap 1a and the volume Vs2 of the entire sample including the gap 1a can be measured by the density meter 3. And before immersing in the liquid 4, the mass M of the sample 1 is measured in advance by the electronic balance 2, and the bulk density ρ2 of the sample 1 can be obtained by dividing the mass M by the volume Vs2.

Using the apparent density ρ1 and the bulk density ρ2 thus determined, the porosity α of the sample 1 can be further determined by the following equation (VI).
α = (1- (ρ2 / ρ1)) × 100 (VI)
Thereby, the content rate of the pores inside the sample can be grasped, and useful information when the strength of the sample 1 is evaluated can be obtained.

  When the measurement of the bulk density ρ2 is completed, the liquid 4 that has penetrated into the sample volatilizes with time. Thereby, it returns to the state before being immersed in the liquid 4, and the sample 1 can be reused. In particular, in this embodiment, since isopropyl alcohol is infiltrated into the sample, the inside of the sample can be dried faster than in the case of infiltrating water, and the sample 1 can be easily reused. Since isopropyl alcohol is not as volatile as acetone, isopropyl alcohol does not volatilize from the sample during measurement of bulk density ρ2, and the bulk density ρ2 can be measured stably.

According to the above embodiment, the following effects can be obtained.
(1) Since the sample 1 was immersed in the liquid 4 of the beaker 5 and put into the vacuum dryer 6 so that the liquid 4 was infiltrated into the void 1a of the sample 1, the dry density meter 3 included the void 1a. The volume Vs2 of the entire sample can be measured, and the bulk density ρ2 of the sample 1 can be easily measured without performing a solidification process or the like of the liquid on the sample surface.
(2) Since the apparent density ρ1 and the bulk density ρ2 are measured by the density meter 3, the porosity α of the sample 1 can also be measured.
(3) Since the apparent density ρ1 and the bulk density ρ2 are measured by the same density meter 3, the porosity α can be measured with high accuracy.
(4) Since the sample is filled with isopropyl alcohol and the bulk density ρ2 is measured, the sample 1 can be easily reused.

  In the above embodiment, the mass M of the sample 1 is measured by the electronic balance 2 (mass measurement step), but the mass M may be measured by another measuring device. Although the sample 1 is immersed in the beaker 5 containing isopropyl alcohol and put into the vacuum dryer 6 to be infiltrated into the sample (immersion step), other liquid may be infiltrated into the sample. The volume of the sample 1 is measured based on the change in the gas pressure when the sample 1 is put into the sample chamber 31 where the gas pressure acts and the sample chamber 31 and the expansion chamber 33 are communicated with each other via the valve 33 (open / close valve). If it is to be performed, that is, if dry density measurement is performed by the constant volume expansion method, the configuration of the density meter 3 used in the first volume measurement step and the second volume measurement step may be any. That is, the present invention is not limited to the dry density measuring method of the embodiment as long as the features and functions of the present invention can be realized.

The figure which shows the whole apparatus for measuring a density with the dry-type density measuring method which concerns on embodiment of this invention. The figure explaining apparent density and bulk density. The figure explaining the principle of the density measurement by the density meter which concerns on embodiment of this invention.

Explanation of symbols

1 Sample 1a Air gap 2 Electronic balance 3 Density meter 4 Liquid (isopropyl alcohol)
6 Vacuum dryer ρ1 Apparent density ρ2 Bulk density α Porosity

Claims (4)

A mass measuring step for measuring the mass of the porous sample;
An immersion process for infiltrating the liquid into the sample;
The sample after the immersion step is put into the sample chamber where the gas pressure acts, and the sample after the immersion step is based on the change in the gas pressure when the sample chamber and the expansion chamber are communicated with each other via an on-off valve. A first volume measuring step for measuring the volume,
A dry density measuring method, comprising: measuring a bulk density of a sample based on a mass measured in the mass measuring step and a volume of the sample after the liquid immersion step measured in the first volume measuring step. In the dry density measuring method according to claim 1,
A dry density measuring method, wherein the liquid to be permeated in the liquid immersion step is isopropyl alcohol. In the dry-type density measuring method according to claim 1 or 2,
The sample before the liquid immersion process is put into the sample chamber, and the volume of the sample before the liquid immersion process is measured based on a change in gas pressure when the sample chamber and the expansion chamber are communicated with each other via an on-off valve. A second volume measuring step;
A dry density measuring method, wherein the apparent density of the sample is measured based on the mass measured in the mass measuring step and the volume of the sample after the immersion step measured in the second volume measuring step.   The porosity of the sample is measured based on the bulk density measured by the dry density measuring method according to claim 1 or 2 and the apparent density measured by the dry density measuring method according to claim 3. The porosity measuring method.

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