ISO 1218-1975 pdf free.Plastics — Polyamides — Determination of “melting point”.
This International Standard specifies two methods fordetermining the “melting point” of polyamides.
The “meltingpoint” isan arbitrarilydeterminedtemperature which，in fact,lies in a range of temperaturewhich,for the homopolymers,covers a few degrees only.The determination of the “melting point”，however，isuseful for the characterization of polyamide homo-polymers. It is of less use for copolymers, which may havea much wider melting range.The two methods of test described in this InternationalStandard give results in close agreement in any one test,andquite good agreement between the two methods. Methodsdifferent from the two described in this document may givevery different results.
Before using the apparatus for the first time,andwhenever the thermometer is changed, calibrate theapparatus following the procedure given in 6.2 to 6.7, butusing,instead of the polyamide specimen, one or more ofthe appropriate standards from clause 3, melting close to orcovering the range of the melting points to be measured.Insert the thermometer in position in the apparatus.lnsert the capillary tube containing the test specimenin the apparatus and heat with maximum power.When the temperature is about 10c below theexpected melting point,reset the rheostat to reduce therate of temperature rise to 2±0,5 °C per minute.Switch on the illuminating lamps of the apparatus.Observe the specimen and record the temperature,indicated by the thermometer,at which the specimen melts. The melting point corresponds to that temperatureat which the sharp edges of the specimen disappear.Repeat the operations described above using a secondtest specimen. If there is a difference of more than 5°cbetween the two determinations,these results shall bedisregarded and two additional specimens tested.Record as the “melting point” the arithmetic mean ofthe temperatures observed in accordance with 6.6 for thetwo test specimens. lf,when calibrating (with tin and bismuth or anotherstandard of known melting point)，a difference of morethan 1°C has been found from the theoretical meltingpoint of the standard,apply a similar correction to thereading recorded for the test specimens.ISO 1218 pdf download.