ISO 2303:2019 pdf free.Isoprene rubber (IR)一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 cm3 to about 2 000 cm3, 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 mm 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 blender1) has been found suitable for this method. Caution: if mixed longer than 3 s, the stearic acid might melt and prevent good dispersion.
Remove sufficient material from the batch for evaluating the vulcanization characteristics in accordance with ISO 6502-1 or ISO 6502-2. Condition this material for 2 h to 24 h, if possible at a standard temperature and humidity as defined in ISO 23529, before testing. Sheet the batch to approximately 2,2 mm for preparing test slabs or to the appropriate thickness for preparing ISO ring test pieces in accordance with ISO 37. Condition the batch for 2 h to 24 h prior to vulcanizing, if possible at a standard temperature and humidity as defined in ISO 23529.
Rest the batch for at least 30 mm, or until it reaches room temperature, before proceeding with the final mixing stage. 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.
When a LIM is used, adjust, if necessary, the batch mass, the head temperature and/or the rotor speed so that this condition is met. When mill mixing is used, set the surface temperature of the rolls to 70 °C ± S °C and maintain it at this temperature during mixing. The standard laboratory mill batchmass, in grams, shall be based on two times the formula mass. A good rolling bank at the nip of the rolls shall be maintained during mixing. If this is not obtained with the nip settings given hereunder, small adjustments to the mill openings may be necessary.ISO 2303 pdf download.