ISO 1218:1975 pdf free
ISO 1218:1975 pdf free.Plastics – Polyamides – Determination of “melting point”
Before using the apparatus for the first time, and whenever the thermometer is changed, calibrate the apparatus following the procedure given in 6.2 to 6.7, but using, instead of the polyamide specimen, one or more of the appropriate standards from clause 3, melting close to or covering the range of the melting points to be measured.
Insert the thermometer in position in the apparatus.
Insert the capillary tube containing the test specimen in the apparatus and heat with maximum power.
When the temperature is about 10 °C below the expected melting point, reset the rheostat to reduce the rate of temperature rise to 2±0,5 °C per minute.
Switch on the iluminating 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 temperature at which the sharp edges of the specimen disappear.
Repeat the operations described above using a second test specimen. If there is a difference of more than 5 °C between the two determinations, these results shall be disregarded and two additional specimens tested.
Record as the “melting point” the arithmetic mean of the temperatures observed in accordance with 6.6 for the two test specimens.
If, when calibrating (with tin and bismuth or another standard of known melting point), a difference of more than 1 C has been found from the theoretical melting point of the standard, apply a similar correction to the reading recorded for the test specimens.
If the polyamide sample is not available in the form of powder, cut, by means of the microtome (11.5), a slice of about 0,1 mm thickness. From this slice cut, using the punch (11.8)， some disks of about 1,6 mm diameter and divide each disk into four parts by means of the razor blade (11.5). Use one of those quarters as test specimen.
Before using the apparatus for the first time, and whenever the thermometer is changed, calibrate the apparatus’ following the procedure given in 13.2 to 13.10,but using, instead of the poly amide specimen, one or more of the appropriate standards from clause 10, melting close to or covering the range of the melting points to be measured. Care should be taken to interpose a cover-glass (11.4) between the metallic grain and the hot stage when metallic standards are used. This precaution is not necessary with the polyamide specimens since mel ting temperatures obtained with or without this cover-glass are practically the same. ISO 1218 pdf download.
