BS ISO 2303:2019 pdf download – Isoprene rubber (IR) — Non-oil-extended, solution- polymerized types — Evaluation procedures 6.2.3 Laboratory internal mixer (LIM) mixing procedure 6.2.3.1 General For a LIM having a nominal mixing capacity of 65 cm 3 to about 2 000 cm 3 , the batch mass shall be equal to the nominal mixer capacity, in cubic centimetres, multiplied by the compound density. The LIM conditions shall be the same for each batch mixed during the preparation of a series of identical mixes. At the beginning of each series of test mixes, a machine-conditioning batch shall be mixed using the same formulation as the mixes under test. The LIM shall be allowed to cool down to 60 °C between the end of one test batch and the start of the next. Temperature control settings shall not be altered during the mixing of a series of test batches. 6.2.3.2 Single-stage mixing procedure The mixing technique shall be such as to obtain a good dispersion of all the ingredients. The final temperature of the batch discharged after mixing shall not exceed 120 °C. If necessary, adjust the batch mass, head temperature and/or rotor speed so that this condition is met. NOTE 1 Compounding materials other than rubber, carbon black and oil can be added to LIM batches more precisely and with greater ease if they are previously blended together in the proportions required by the formulation. Such blends can be made using a mortar and pestle, by mixing for 10 min in a biconical blender with the intensifier bar turning, or by mixing in a blender for five 3 s periods and scraping the inside of the blender to dislodge materials stuck to the sides after each 3 s mix. A Waring blender 1) has been found suitable for this method. Caution: if mixed longer than 3 s, the stearic acid might melt and prevent good dispersion. NOTE 2 An example of a mixing procedure for a LIM is as follows: a) Load the rubber, lower the ram and allow the rubber to be masticated. 1,0 1,0 b) Raise the ram and add the pre-blended zinc oxide, sulfur, stearic acid and TBBS, taking care to avoid any loss. Then add the carbon black, sweep the orifice and lower the ram. 1,0 2,0 c) Allow the batch to mix. 7,0 9,0 d) Turn off the motor, raise the ram, remove the mixing...
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