Quality Control Practices 1. Obtain approximately 275 +/- 25 g of recycled rubber from the lot. See Practice E105). 2. Place a 1,000 cm3 +/- 0.1 cm3 cylindrical container on the scale and push the tare button. The scale should display zero. 3. Fill the cylindrical 1,000 cm3 +/- 0.1 cm3 container with enough sample to be higher than the edge of the container by pouring the sample into the center of the container from no higher than 50 mm above the rim of the container. 4. Depending on the particle sizes of the sample, this could be somewhere between 250 g to 500 g. 5. Level the overfilled container by a single sweep of the straightedge or spatula held perpendicular to and in firm contact with the lip of the container. 6. Record the weight (mass) of the rubber sample to the nearest 0.1 g. 2. Report a. Record the date of test b. Identification of samples c. Report the result to the nearest 0.1 kg/m3 Determination of Bulk Density The measurement of bulk density will provide a relative indication of uniformity of process samples. Control of the particle size will directly affect the bulk density of the processed sample. The more uniform large particles will have a lower bulk density than samples that contain a large number of fines/ fiber. The bulk density of recycled vulcanizate particulate rubber is determined from the mass of the particulate rubber contained in a cyclindrical container with the volume of 1000 +/- cm3. Calculation 1. Calculate the bulk density DB to the nearest 0.1 kg/m3 as follows: DB = W/Vc * 1000 where: DB = bulk density, in kg/m3 W = mass of recycled vulcanizate particulate rubber in the tared cylindrical container, in grams Vc = volume of cylindrical container, in cm3 Quality Control - Page 3
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