BS 4407:1988 download free.Methods for Quantitative analysis of fibre mixtures.
1 Scope
BS 4407 describes methods for the quantitative analysis of textile fibre mixtures after identification of the fibre components of the mixture, including the composition of the individual yarns. Any non-fibrous matter is removed by a suitable pretreatment. If the fibre components do not form an intimate mixture and can be readily separated by hand, the analysis is carried out by the procedure given in section 3.
If part or the whole of the textile consists of an intimate mixture of two fibre types (binary mixture) one of the components is removed using a suitable method2 following the appropriate procedure given in section 4, and the proportion of this component is calculated from the loss in mass. Wherever possible it is preferable to remove the fibre present in greater proportion, thus obtaining the fibre present in the smaller proportion as residue.
If part or the whole of the textile consists of an intimate mixture of three fibre types (ternary mixture) the above process is repeated using a second reagent. Suitable methods for the analysis of specific ternary mixtures are given in Appendix A.
NOTE 1 To obtain a reliable result, at least two determination should be made, either by manual separation or by chemical separation, if the results of duplicate tests differ by more than 2 %, two repeat determinations should be made. NOTE 2 The titles of the publications referred to in this stand are listed on the inside back cover.
2 Definitions
For the purposes of BS 4407, the definition given in BS 4815 apply.
3 Apparatus
3.1 Glass-filter crucibles, with sealed-in sintered
disc filters of porosity grade P160 complying with
BS 1752 and provided with either ground-glass
stoppers or watch glass covers.
3.2 Soxhiet extractor, complying with BS 2071.
3.3 Weighing bottles.
3.4 Ventilated oven for drying specimens
at 105±3°C.
3.5 Desiccator containing self-indicating silica gel.
3.6 Analytical balance, accurate to ± 0.0002 g.
3.7 Vacuum flask.
3.8 Additional apparatus as specified in the
appropriate clauses of this standard.
4 Reagents
4.1 Light petroleum, redistilled, boiling range 40°C
to 60 °C.
4.2 Water complying with grade 3 of BS 3978.
4.3 Other reagents as specified in the appropriate
clauses of this standard.
5 Conditioning and testing atmosphere
Dry masses are determined and therefore it is unnecessary to condition the specimen. The analysis is carried out under ordinary room conditions.
6 Sample
Take a sample that is representative of the hulk and sufficient to provide all the specimens, each of at least I g, that are required. Follow the sampling procedure as described in BS 4658.
7 Pretreatment of sample
Extract the air-dry sample in a soxhiet apparatus (3.2) with light petroleum for I h at a minimum rate of 6 cycles/hour. Allow the light petroleum (4.1) to evaporate from the sample. Then extract it by immersing the sample in water at room temperature for 1 h and then immersing it in water at 65 ± 5 °C for a further hour, agitating the liquor from time to time. Use a liquor to sample ratio of 100: 1.
Where non-fibrous matter, e.g. size or special finish, cannot be extracted with light petroleum and water, remove it by substituting for the water treatment described above, a suitable method that does not substantially alter any of the fibre constituents. However, for some unbleached, natural vegetable fibres (e.g. jute, coir) note that normal pretreatment with light petroleum and water does not remove all the natural non-fibrous substances. Do not apply additional pretreatment unless the sample does contain finishes insoluble in both light petroleum and water. Include full details of the methods of pretreatment used in the analysis report.
8 Test procedure
8.1 General instructions
8.1.1 Drying. Conduct all drying operations for not less than 4 h and not more than 16 h at 105 ± 3 °C in a ventilated oven with the oven door closed throughout. If the drying period is less than 14 h, weigh the specimen or residue to check that its mass has become constant. The mass may be considered to have become constant if, after a further drying of 60 mm, its variation is less than 0.05 %. Where apparatus other than a filter crucible is used, conduct drying operations in the oven in such a way as to enable the dry mass of the fibres to be determined without loss of fibre.
8.1.2 Drying of specimen. Dry the specimen in a weighing bottle with its stopper beside it. After drying, stopper the weighing bottle before removing it from the oven and transfer it quickly to a desiccator.
8.1.3 Drying residue. Dry the residue in the filter crucible with its stopper or cover beside it. After drying, close the crucible and transfer it quickly to a desiccator.
8.1.4 Cooling. Conduct all cooling operations in the desiccator, the latter being placed beside the balance, until complete cooling of the weighing bottles is attained, and in any case for not less than 2 h.
8.1.5 Weighing. After cooling, complete the weighing of the weighing bottle or crucible within 2 mm of its removal from the desiccator.
NOTE Do not handle the crucibles, weighing bottles, specimens or residues with bare hands during the drying, cooling and weighing operations.
Where a special pretreatment is used the values b1, b9 and h.3 should be determined, if possible, by submitting each of the pure fibre constituents to the pretreatment applied in the analysis. Pure fibres are those free from all non-fibrous material except those which they normally contain (either naturally or because of the manufacturing process) in the state (unbleached, bleached) in which they are found in the material analysed.
Where no clean separate constituent fibres used in the manufacture of the material to be analysed are available average values of b1, b2 and b:i, as obtained from tests performed on clean fibres similar to those in the mixture under examination. should be used.
If normal pretreatment by extraction with light petroleum and water is applied b1, b2 and b3 may generally be ignored, except in the case of unbleached cotton, unbleached flax and unbleached hemp where the loss due to pretreatment is usually accepted as 4 % and in the case of polypropylene as 1 %.
In the case of other fibres, losses in the pretreatment are usually disregarded in calculations.
10 Report
10.1 State that the analysis was conducted in accordance with the appropriate method(s) of this standard.
10.2 State whether the result relates to the overall composition of the assembly or to an individual component of the assembly.
10.3 Give details of any special treatment for the removal of size or finish given in substitution for or addition to the specified pretreatment.
10.4 State the number of individual determinations made. Give the individual results and the arithmetic mean, each to an accuracy of 0.1 %.
10.5 State whether the result is based on:
a) clean dry mass;
b) clean dry mass with agreed allowances for moisture and other matter and also, where appropriate, for non-fibrous matter removed in the pretreatment, and state the values of the allowances used.
10.6 Whenever possible, state the precision of the
method for each component for ternary mixtures.
Calculate the precision according to Table 1
(see clause 16).