CEN/TC 249/SC 1/WG 13 - Thermosets

ISO 8988:2006 specifies three methods for the determination of the hexamethylenetetramine ("hexa") content of phenolic resins:
a Kjeldahl method;direct titration with perchloric acid;potentiometric titration with hydrochloric acid.

ISO 8987:2005 specifies methods for the determination of the B-transformation time of phenolic resins at a specified temperature and under specified conditions on a heated test plate.
Two methods are described, each with a different test plate:
Method A -- plate with depressions in the form of segments of spheres;
Method B -- flat plate without depressions.

ISO 8619:2003 specifies a method for the determination of the flow distance of powdered heat-setting phenolic resins for production and control. With reference to tablet formation, test temperature and angle of inclination of the glass plate, measurement of the flow distance involves arbitrarily defined conditions.
The flow distance is dependent on the reactivity and melt viscosity of the resins. Rapid solidification and high melt viscosity shorten the flow distance.

Liquids simulating fodd and beverages are placed in contact with mouldings of the sample material, under defined conditions. The formaldehyde content of the liquid is then determined and the quantity of formaldehyde extracted per unit area of content is calculated. Two spectrophotometric methods for the determination of formaldehyde in the liquid, using chromotropic acid disodium salt or acetylacetone as reagents, are given.

Specification of two methods for the determination of chlorine: Oxidation of the test portion with sodium peroxide (method A) in a Parr bomb or with gaseous oxygen (method B) in a flask, followed by electrometric or volumetric titration of the resulting chlorides. Blank tests shall be carried out by using the same quanities of reagents as in the determination.

This International Standard specifies a method for the determination of the epoxy equivalent and is applicable to all epoxy compounds. In the case of epoxyamines, it is necessary to apply the modification specified in annex A.

The principle of the method specified is measuring the heat flux supplied to a test sample as a function of time or temperature, while the test sample is subjected to a temperature schedule under a specified atmosphere. A reaction is marked by the release of energy from the sample, resulting in an exothermic peak in the heating curve. Integration of the recorded peak area as a function of time gives a measure of the energy of the reaction. Applies to phenolic resins with exothermic behaviour, such as resols or mixtures of novolaks with hexamethylenetetramine or other curing agents.

Gives a method for the determination of the miscibility of water with liquid phenolic resins depending on the conditions and on the degree of condensation of the resin. Replaces the first edition.

Specifies three chromatographic methods for the separation of phenolic resins into their component compounds according to molecular size or molecular weight and polarity: gel-permeation chromatography, high-performance liquid chromatography on polar and on non-polar columns. Applies to phenolic resins that are soluble in the solvents and solvent blends used. This test is useful for characterization of products and for research.

Specifies a method for the determination of the primary, secondary and tertiary amine group nitrogen content of aliphatic or aromatic amine hardeners for epoxy resins.

The method specified determines the percentage mass of moulding material that is transferred through two apertures in the punch of a disc mould during a moulding process carried out under defined conditions. It is intended only for production control and should not be used as part of a mandatory material specification.

Specification of a semi-quantitative method. The content of free ammonia in a moulded article is of importance, when corrosion of metal inserts or contamination in contact with the article has to be considered. Distillation of the aqueous extract from a powdered test portion, coloration of the distillate by reaction with Nessler reagent and comparison of the colour with that of standard matching solutions.

A semiquantitative method for the determination of the amount of free phenols in phenolic mouldings. Hot water extraction of free phenols from a powdered test portion, iodination of the water extract and backtitration of the excess of iodine with standard volumetric thiosulfate solution.

Specification of a qualitative method of detecting the presence of free ammonia or other volatile bases in phenol-formaldehyde mouldings by the exposure of an indicator paper to the vapour from a moistened powdered sample. It may be used when the absence of free ammonia is a requirement.

Specification of a gravimetric method for the determination of the amount of matter that can be extracted by boiling acetone from a sample of finely divided phenolic moulding material. The extract is dried under controlled conditions and the mass of residue determined by weighing. The amount of acetone soluble matter (apparent resin content) is expressed as percentage by mass of the original test portion.

Specifies a method for the determination of the reactivity of unsaturated polyester resins as characterized by the maximum temperature reached when heated with catalyst in a water-bath at 80 °C and by the time taken for the temperatur of the mixture to rise from 65 °C to this maximum temperature. As the test results depend very much on the conditions under which the test is carried out, these conditions are described in detail.

The principle of the method specified is reacting a small amount of free acid present in a test portion of acid anhydride hardener or accelerator with rhodamine 6G to colour the test solution pink, measuring the absorbance of the coloured solution at a wavelength of about 510 nm using a spectrometer, determining the free-acid content from a calibration curve. The method is suitable for most anhydrides except for polyester and oligomeric anhydrides which may give too wide a scatter of results.

Cancels and replaces the first edition (1989). Specifies a method for determining the exothermic reactivity of thermosetting liquid phenolic resins when mixed with an acid hardener under specified conditions. The results of the determination are used as a means of assessing the behaviour of the resin during processing.

Important for applications in which such resins are used as impregnating materials. The principle is based on addition of an acetone/water mixture to a solution of the resin. The precipitate thus produced is allowed to settle, and the conductance of the suspension remaining above the resin is measured. The conductivity, expressed in microsiemens per centimetre, is then calculated from the measured conductance.

Specifies a method for the determination of the apparent density of a moulding powder or a granular material. The sample is pured through a specified funnel into a measuring cylinder of 100 cubiccentimeter capacity, the excess is removed with a straightedge and the mass of the contents is determinded by weighing. Expression of the apparent density in grams per millilitre.

A test sample of 5 g is weighed into a weighing bottle and spread evenly over the bottom. The bottle is dried at 55 C. After 3 h the sample is remove from the open, cooled to room temperature and conditioned. The volatile matter is given as a percentage by mass.

Migrated from Progress Sheet (TC Comment) (2000-07-10): 1st FV on 1994-04; 2nd FV decided by BT C 179/1995.

Migrated from Progress Sheet (TC Comment) (2000-07-10): 1st FV on 1994-04; 2nd FV decided by BT C 179/1995.