BS ISO 2302:2020 pdf download.Isobutene-isoprene rubber (IIR) —Evaluation procedure.
1) Discharge the batch and immediately check the temperature with a suitable measuring device.
g) The final temperature of the discharged batch after the cumulative mixing time of 5 mm shall not exceed 120 °C. lilt does, discard the hatch and repeat the procedure with a different hatch mass or starting temperature.
h) Pass the batch through a mill set at SO °C ± 5 °C twice with a 3,0 mm mill opening.
i) Check the batch mass (see ISO 2393) and record. If it differs from the theoretical value by more than + %, discard the batch and re-mix.
j) Cut out a test piece for determining the vulcanization characteristics in accordance with ISO 6502-2 or ISO 6502-1, if required. Condition the test piece for 2 h to 24 h at 23 °C ± 3 °C before testing.
k) If required, sheet the batch to approximately 2,2 mm for preparing test sheets or to the appropriate thickness for preparing ISO ring or dumbbell test pieces in accordance with ISO 37. To obtain the effects of mill direction, pass the folded batch four times between mill rolls set at 50 °C ± 5 °C and at the appropriate mill opening. Cool on a flat, dry surface.
I) After mixing and prior to vulcanizing, condition the hatch for at least 2 h hut not more than 24 h, if possible at standard laboratory temperature and humidity as defined in ISO 23529.
For a miniature internal mixer having a nominal mixing capacity of 65 cm3, a batch mass corresponding to 0,47 times the formulation mass (i.e. 0,47 x 156,75 = 73,67 g) has been found to be suitable.
Mix with the head temperature of the miniature internal mixer maintained at 60 °C ± 3 °C and a starting (unloaded) rotor speed of 6,3 rad/s to 6,6 rad/s (60 rev/mm to 63 rev/mm).
Prepare the rubber by passing it once through a laboratory mill with the roIl temperature set at 50 °C ± S °C and an opening of 0,5 mm. Cut the sheet thus produced into strips 25 mm wide.
For an internal mixer having a nominal capacity of 1170 cm3 ± 40 cm3, a batch mass corresponding to (8,5 x 156,75 g = 1 332 g) has been found to be suitable.
The speed of the fast rotor shall be set at 7 rad/s to 8 rad/s (67 rev/mm to 87 rev/mm).
6.2.2.4 Method C — Two-stage mixing using a laboratory internal mixer for initial mixing and a mill for final mixing
6.2.2.4.1 General
The mixing technique shall he such as to obtain a good dispersion of all the ingredients.
The temperature of the batch discharged on completion of mixing shall be between 150 °C and 170 °C.
If necessary, adjust the batch mass or the mixer head starting temperature so that this condition is met.
During final mixing, a good rolling bank at the nip of the rolls shall be maintained. If this is not obtained
with the nip setting specified, small adjustments to the mill openings may be necessary.
A general mixing procedure for the laboratory internal mixer is given in 6.2.2.4.2 and 6.2.2.4.3.BS ISO 2302 pdf download.