A common practice in the field of forensics is to place samples in reusable bags often under brand names such as Ziploc®.
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Polyolefin Films & Slip Agents
Slip agents vary, but one commonly observed slip agent is a fatty acid amide known as stearamide
< Figures 1 and 2 >
- Figures 1 & 2: A customer submits an unknown polymer for testing to determine the material composition
- Figure 3: After analysis using FTIR-ATR the sample was determined to be polytetrafluoroethylene (PTFE), but additional absorptions are present that do not correlate with PTFE
- Figure 4: An additional analysis was performed on the reusable bag which the unknown polymer was received in. The reusable bag was identified as the polyolefin known as polyethylene using FTIR-ATR
- Figure 5: Again additional absorptions were present that do not correlate with polyethylene. A slip agent was suspected, isolated, analyzed using FTIR-ATR, and was identified as stearamide
- Figure 6: A final comparison spectra of the unknown polymer, a reference of PTFE, and a reference of stearamide displays the contamination of the slip agent from the reusable bag onto the sample submitted for testing (Figure 6).
Figure 3 & 4
Figures 5 & 6
1. Chen, J., Li, Hu, & Walther. (2007). Fundamental study of erucamide used as a slip agent. Journal of Vacuum Science & Technology A: Vacuum, Surfaces, and Films, 25(4), 886-89
2. Zahedi, A., Ranji, A., & Asiaban, S. (2006). Optimizing COF, Blocking Force, and Printability of Low Density Polyethylene. Journal of Plastic Film & Sheeting, 22(3), 163-176.