ISO 22768-2020 pdf free.Raw rubber and rubber latex — Determination of the glass transitiontemperature by differential scanningcalorimetry (DSC)
This document specifies a method using a differential scanning calorimeter to determine the glasstransition temperature of raw rubber and rubber latex.
The following documents are referred to in the text in such a way that some or all of their contentconstitutes requirements of this document. For dated references, only the edition cited applies.Forundated references, the latest edition of the referenced document (including any amendments) applies.ISO 124:2014,Latex, rubber — Determination of total solids content
ISO 1407,Rubber — Determination of solvent extract
IS0 11357-1:2016, Plastics — Differential scanning calorimetry (DSC)—Part 1: General principles
ISO23529,Rubber —General procedures for preparing and conditioning test pieces for physical test methods.
For the purposes of this document, the terms and definitions given in ISO 11357-1 and the following apply.
Determine the mass of the test specimen to an accuracy of ±0,1 mg.Unless otherwise specified in thematerials standard, use a mass between 5 mg and 20 mg.The same nominal mass shall be used for alldeterminations. If possible, the specimen shall have a flat surface so as to give good thermal contactwith the bottom of the pan.
NOTE 1 Intimate thermal contact between the test specimen and the bottom of the pan is essential for goodrepeatability.
Place the specimen in the pan, using tweezers and seal with a lid.Place the sealed pan in the calorimeterusing tweezers.
Do not handle the test specimen or the pan with bare hands.
NOTE2 Placing an empty pan with a lid as a reference helps to obtain stable DSC thermograms.
Cool the test specimen to a temperature of approximately-140 °C at a rate of 10 C/min or 20 -C/min and hold at this temperature for 1 min to 10 min until the baseline becomes stable.
A starting temperature of -140 °C is required for the determination of rubbers and rubber latices withvery low glass transition temperatures,e.g. high-cis polybutadiene.For rubbers and rubber latices withhigher glass transitions, this temperature is not necessary.
Astarting temperature should be chosen so that a stable base line is achieved before the glass transitionregion, e.g.about 30 °Cto 40 C below the expected glass transition temperature.
lf the apparatus is not capable of maintaining the specified cooling rate, it should be adjusted to give arate as close as possible to that specified.
Perform the temperature scan at a heating rate of 20 °C/min, heating until a temperature about30 C above the upper limit of the glass transition range is reached.ISO 22768 pdf download.