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21 140 120 100 % Break Strain 80 60 y = 0.6014x + 29.214 40 R2 = 0.984 20 0 0 20 40 60 80 100 120 140 160 Filter Screen Size (Mesh) Figure 17. The effect of melt filtration on the percentage break strain of 100% MCRG. mesh size. The results for both sets of results are shown in The Effect of Silicone Rubber Figures 19 and 20. The tests run on the 100% MCRG were at 70C. One of the advantages of the BAM test is that the fractured The results of these experiments revealed that the degree of surface can be examined to see where the crack started. Exam- melt filtration is an important parameter for using recycled ples are shown in Figures 21 and 22. materials. It appears as if filtration at a mesh size in excess of The clear, rubbery material was identified as silicone rubber 100 mesh should be a minimum requirement. However, the by Fourier transform infrared (FTIR) analysis. The IR results results of the BAM test did not show as much improvement are shown in Figure 23. in the results with filtration as one might think. The reason Four different rubbery particles were tested, and they all for this is found in the next section. looked the same. It is not clear where the silicone rubber came 600 500 Break Strain (%) 400 300 200 y = 2.0632x + 158.23 2 100 R = 0.9937 0 0 20 40 60 80 100 120 140 160 Filter Mesh Size Figure 18. The effect of melt filtration on the percentage break strain of 50/50 MCRG/MDPE.

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400 350 300 Failure Time (Hrs) 250 200 150 100 50 0 0 20 40 60 80 100 120 140 160 Filter Mesh Size Figure 19. The effect of melt filtration on the BAM failure time of 100% MCRG at 70C. 120 100 BAM Failure Time (hrs) 80 60 40 20 0 0 20 40 60 80 100 120 140 160 Filter Mesh Size Figure 20. The effect of melt filtration on the BAM failure time of 50/50 MCRG/MDPE at 80C. Figure 21. BAM test fracture surfaces for failure times of 11 h (left) and 133 h (right) (unfiltered).

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23 Figure 22. BAM test fracture surfaces for failure times of 12 h (left) and 172 h (right) (100 mesh). %T CM1 Figure 23. Fourier transform infrared (FTIR) spectra for HDPE (top), the rubbery contaminant (middle), and the best library match, silicone rubber.