ISO 2453-2020 pdf free.Rubber, raw styrene-butadiene,emulsion-polymerized — Determination of bound styrenecontent— Refractive index method.
Sheet out 2 g to 6 g of rubber, selected and prepared in accordance with IS0 1795.Cut into piecesno larger than 2 mm x 2 mm or strips no longer than 10 mm and not wider than 5 mm. Weigh a testportion of approximately 2 g to the nearest 0,001 g.
Place a circular filter paper in the bottom of the wide-mouthed conical flask (6.1), and add 100 cm3of ETA extraction solvent (5.1) for all rubbers except alum-coagulated rubbers.For alum-coagulatedrubbers, use acidified ETA (5.2).
Introduce the rubber pieces separately into the flask, swirling after each addition, so that the rubberpieces are thoroughly wetted with solvent and sticking is minimized.
Fit the reflux condenser (6.2) to the flask and boil the solvent very gently under reflux for 1 h.Replacethe solution with another 100 cm3 of ETA or acidified ETA and extract for an additional hour. Rinse therubber pieces with three successive 10 cm3 portions of extraction solvent.
NOTE As an alternative, the weighed rubber pieces can be wrapped in filter paper and placed in a Soxhletextractor and extracted with ETA or acidified ETA under reflux for a minimum of 4 h.
Remove the rubber pieces from the flask and dry them to constant mass in the vacuum oven (6.4)maintained at a pressure of about 1 300 Pa1) and a temperature of 100 °C±5 °C.
lt is important that the rubber pieces be extracted and dried thoroughly since either residual solvent orincompletely extracted materials will result in erroneous readings of the refractive index.
Avoid plasticizing of the sample by overheating.
After the test pieces have been thoroughly dried, more than one technique is suitable for pressingthe test piece. The method of pressing may be modified to suit the type of rubber and the type ofequipment available.The pressure and the time of pressing at 100 °C may be varied. The test piece maybe cooled to room temperature under pressure, or removed from the press while hot. The time of hotpressing shall never exceed 10 min, and should preferably be 5 min.
The conditions shall be chosen so that the pressed test piece is homogeneous and so that a distinct linecan be observed dividing the light and dark fields of the telescope field when the refractive index isdetermined.ISO 2453 pdf download.