ISO 8130-3:1992 download free.Coating powders Part 3 : Determination of density by liquid displacement pyknometer.
This part of ISO 8130 specifies a liquid displacement pyknometer method for the determination of the density of coating powders. The method is based on a determination of the mass and the volume of a test portion.
The apparatus specified Is relatively inexpensive, but the liquid displacement pyknometer method is liable to give erroneous results, particularly if the powder swells In contact with the dIsplacement liquid used or the displacement liquid does not totally displace the air between the powder particles. The liquid displacement method is much slower in execution and less accurate than the gas comparison pyknometer method specified in ISO 8130-2 and is only to be used if it can be shown that the same resuits will be obtained as for the gas comparison pyknometer method.
2 Normative references
The following standards contain provisions which, through reference In this text, constitute provisions of this part of ISO 8130. At the time of publication, the editions indicated were valid. All standards are subject to revision, and parties to agreements based on this part of ISO 8130 are encouraged to investigate the possibility of applying the most recent editions of the standards indicated below. Members of IEC and ISO maintain registers of currently valid International Standards.
ISO 787-10:1981, General methods of test for pigments and extenders — Part 10: Determination of density — Pyknometer method.
ISO 842:1984, Raw materials for paints and varnishes
— Sampling.
ISO 3696:1987, Water for analytical laboratory use — Specification end test methods.
ISO 8130-2:1992. Coating powders — Part 2: Determination of density by gas comparison pyknometer (referee method).
3 PrInciple
The density of the coating powder is determined in a liquid displacement pyknometer in accordance with ISO 787-10, using a liquid that completely wets the product under test without swelling or dissolving
4 MaterIals
4.1 Water, or at least grade 3 purity as defined in ISO 3696, freshly boiled and cooled.
4.2 Displacement liquid: any suitable aliphatic hydrocarbon or mixture of aliphatic hydrocarbons, free from aromatic compounds, with a boiling point withln the range 80 °C to 140 C.
n-Heptane hac been found to be suitable in many Instances for the determination of the density of thermosetting coating powders. However, if there is an interaction between n-heptane and the product under test or its components, a suitable alternative liquid shall be used.
4.3 Acetone, analytical grade.
5 Apparatus
5.1 Pyknometer complying with ISO 787-10.
5.2 Vacuum pump with rubber pressure tube attachment.
5.3 Balance, capacity 2009, capable of weighing to
I mg or less.
6 SamplIng
Take a representative sample of the product to be tested, as described in ISO 842.
7 Proc.dur.
Carry out the determination in duplicate at
(23 ± 0,5) °C. Weigh to the nearest I mg.
7.1 Determination of the density of the
displacement liquid
Weigh the empty clean pyknometer (5.1), liii IL to the mark with the displacement liquid (4.2) and reweigh. Empty the pyknometer, wash it with three separate portions of acetone (4.3) and dry it under vacuum. Refill the pyknometer with water (4.1) and reweigh.
Calculate the density , in grams per millilitre, of the displacement liquid at 23 °C, using the equation
where
n is the mass, In grams, or the empty pyknometer;
m is the mass, in grams, of the pyknometer containing the displacement liquid;
in2 Is the mass, in grams, of the pyknometer containing water,
is the density, in grams per milIliltre, of the water. (For the purposes of this part of ISO 8130, take the density of water at 23 °C as 0,998 g/mi.)
7.2 DetermInation of the density of the coating powder
Empty the pyknometer, wash it with three separate portions of acetone and dry it under vacuum. Introduce a test portion of the sample of between 3 g and 4 g Into the pyknomctcr and rcwelgh. Add sufficient displacement liquid to wet the test portion and just
cover It. Attach the opening of the pyknometer to the proosuro tubo connoctod to the vacuum pump (5.2). Reduce the pressure in the pyknometer to a maximum of 1.2 kPa” and shake until there Is no further emission of air from the powder/liquid mixture. Carefully allow the pressure in the pyknometer to rise to atmospheric pressure. Then fill the pyknometer to the mark with displacement liquid, taking care not to disturb the sedimented powder. Take care also on filling In order to avoid powder remaining in the neck of the pyknometer. Reweigh the filled pyknometer.
8 ExpressIon of results
8.1 Calculation
Calculate the density p, in grams per millilitre, of
the coating powder at 23 °C, using the equation:
n is the mass, in grams, of the empty pylcnometer,
m1 Is the mass, In grams, of the pyknome.ter containing the displacement liquid
m3 is the mass, in grams, of the pyknometer containing the test portion;
m4 is the mass, In grams, of the pyknometer containing the test portion and the displacement liquid:
is the density, in grams per millilitre, of the displacement liquid at 23 °C.
If the two determinations differ by more than 0,04 g/ml, repeat the determination (7.2).
Calculate the mean of two valid determinations and report the result to the nearest 0.01 gIml.
8.2 PrecisIon
Only limited precision data are currently available. As a rule, a reproducibility of 0,05 g/ml can be expected.
9 Test report
The test report shall contain at least the following information:
a) all details necessary to Identify the product tested;
d) the result of the test (ndividuaI values and mean value):
e) any deviation from the test method specified;
f) the date of the test.