Fig. 1. SEM photographs of EPP beads withdifferent expansion ratio(a : X 15, b : X 30, c: X 45)
Fig. 2. Frequency response of PP samples of at HF Range
Fig. 3. Schematic of dental hand piece and its operating principle
Fig. 4. UV laser aided micro-cell opened EPP Foam
Fig. 5. Comparison of SEM images with (a) original EPP foam and (b) cell-opened EPP foam
Fig. 6. Micro muffler
Fig. 7. Sound absorption test for a hand piece with micro muffler
Fig. 8. Comparison graph of experimental data
Table 1. Experimental data of sound absorption test
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