ISO 17278-2020 pdf free.Rubber, raw natural -Determinationof the gel content of technically specified rubber (TSR).
This document specifies a method for the determination of gel content for technically specifiedrubbers (TSR).
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 2000:2014,Rubber, raw natural —Guidelines for the specification of technically specified rubber (TSR)IS023529,Rubber —General procedures for preparing and conditioning test pieces for physical test methods
For the purposes of this document, the following terms and definitions apply.
technically specified rubberTSR natural rubber obtained from the latex of Hevea brasiliensis (typically processed into block rubber), andhaving properties complying with the criteria for the grade concerned
ATSR sample is dissolved in toluene under specified conditions, and the gel content is calculated as thepercentage mass fraction of the insoluble part of the rubber.Use only reagents of recognized analytical grade.
CAUTION -The solvent might evaporate from the flask or tube when it is handled. Therefore,handling this solvent should be done only when permitted and only in a well-ventilatedappropriate place.After this period, shake the tube up and down for 60 s to disperse the jelly-like precipitate onthe bottom.
Before placing the tubes in the centrifuge machine, all tubes shall be filled up with fresh toluene, so thatthe volume of solution is the same in all tubes.
NOTE A centrifuge tube is usually filled up with solution to minimize the dead space created at the top ofthetube because of the vacuum-pressured environment during rotation.Place the tubes in the centrifuge machine and operate the machine at 14 000 r/min for 2 h.
If the rotating capacity of the centrifuge machine is below 14 000 r/min,operate the machine at 8 000 r)min for 6 h.
A set temperature of centrifuge is usually indicated in the operation manual for safety reasons.If not ,itmay be set to between 0 C and 25 °C.
Remove the tube from the machine and pipette the liquid from the tube held at approximately45.Caution shall be taken to prevent pipetting the precipitate.ISO 17278 pdf download.