Rational for 4.1 We propose the removal of is not and replace it with may not be. We take issue with the word semi-quantitative in the context of the sentence. Semi-quantitative is a vague term. A quantitative method is believed to be substantially more precise and/or accurate than a semi-quantitative method. Therefore, our reasoning is based upon precision and accuracy arguments: The precision of the primary particle size measurement, within a laboratory skilled in the art of the measurement, is less than 1 nm (5% RSD), which is on par with the precision of STSA. Based on historical data generated from ASTM sponsored Round Robin studies, the precision problem is between laboratories and not within a given laboratory. Since the accuracy of TEM and STSA measurements for purposes of estimating primary particle size are both unknown one cannot make the claim that one method is semi-quantitative and the other is not. Rationale for 13.1: The way the standard is currently worded is misleading. Although the balloted method was voted on, the correlation itself was determined from one companys data. The wording can be interpreted that the greater than 700 data points were acquired from across the industry (carbon black manufactures and end-users). The committee has a duty to clarify the source of the data. Rationale for 18.3 Same as for 13.1, plus the following: Adding for non-porous carbon blacks is based on the following: In the cited publication (Hess and McDonald 1983 Improved Particle Size Measurements on Pigments for Rubber), the equation used is: fine-tuned using a series of non-porous carbon blacks with well-established size and surface area data from previous studies. It is not the relationship between size and surface area that is well-established, but rather it is the data for the carefully chosen non-porous carbon black samples that is well-established. Further, the paper was written specifically about pigments in rubber, which grades do have a tighter relationship between particle size and surface area than the wire and cable grades of interest for the application of D3849. Different companies have different processes, and the size-surface area relationship depends on the process of production as well as the measurement system. Therefore one companys data cannot adequately be used to qualify grades.
Keywordsaggregate size; automated image analysis; carbon black; electron microscopy; particle size; Primary aggregate dimensions; Aggregate; Aggregate dimensions; Carbon black; Electron microscopy; Image analysis;
Draft Under Development