Document oebvrndD8K4o0nNGwywdGwbr3

FEB-02-2005 08 = 39 SfiE CUSTOMER SALES 724 776 0002 P.10 8 the asbestos fibril average diameter was determined to be 0.0337 Atm with distributions similar to that observed by other workers (10). From 45 fibrils of triple jet-milled chrysotile, the average diameter was determined to be 0.0316 pm, with a standard deviation of 0.0063 pm. ASBESTOS IDENTIFICATION Asbestos can be identified in the transmission electron micro scope in one of two ways. The first and absolute method is by electron diffraction. Such a diffraction pattern is pre sented as Fig. B-lMeasurement of diameters and correlation of these measurements with a known standard gives the interplanar spacings of the material. Comparison of these spacings with the ASTM file identifies the material as clino-chiysotile (asbestos). The second method of identification is by appearance. Fig. B-2A represents an image of asbestos obtained in the TEM. Fine lamellae are observed within the fibril which are parallel to the long axis. This appearance is characteristic of chrysotile asbestos fibrils. Because of the nature of the elec tron beam, radiation and heat damage can occur In the ma terial markedly altering the appearance. Such changes in as bestos are represented in Fig. B-2B- The fine linear appearance of the fibril of Fig. B-2A has been changed to a mottled struc ture. Sample Table B-l - Asbestos Concentration on Filters Concentration, Sample Identificationng/cm^ of filter A Test-normal stop-new brakes 15.32 B Background for A 1.06 C Test-normal stop-burnished brakes 7.98 D Background for C 4.64 E Te3t-high temperature stop-burnished 5.37 brakes F Background for E-not used, insufficient 1 sample - B|ank-unued filter 0.33 v Fig. B-l - TEM election diffraction pattern of chrysotile fibril Fig. B-2 TEM image of fibril; Arbefote, B-aftor electron beam damage