Nov_Dec_AMP_Digital

A D V A N C E D M A T E R I A L S & P R O C E S S E S | N O V E M B E R / D E C E M B E R 2 0 2 0 2 2 reflectance (ATR) attachment with a Ge crystal (Fig. 2). Individual peak analy- sis and the search software revealed that one side of the film is polyethylene, and the other is 84% petrothene NA 117 (mixture of polyethylene and mono- mer) and 16% polyamide. The FTIR microscope used can measure the sample in transmittance, reflectance, or ATR mode. A wide-field camera and 15x objective were installed to enable convenient sample image zooming from macro size (10 x 13 mm) to micro size (300 x 400 µm). The sam- ple stage canmove in a 70 x 30mmarea. Fig. 3 — Heat map of the mode at 2912 cm -1 . The aperture size of 10 x 50 µm ensures fine spatial resolution across the sample. Fig. 4 — IR mode at about 2912 cm -1 over the cross section of the sample. A monotonic intensity decrease was observed from the lower side to the upper side of the sample. Fig. 5 — Heat map of the mode at 1642 cm -1 over the cross section of the sample. FTIR spectra of the film’s cross sec- tion was acquired using compatible software. Using the line mode of the optional mapping software, a series of measurement spots was placed along the direction of a preset line. The aper- ture sizes were set as 10 x 50 µm to al- low fine spatial resolution across the cross section while maintaining a suffi- cient signal level (Fig. 3). The spectral difference from one side of the film to the other can be identified by comparing peak in- tensities of a few IR modes. The peak at about 2912 cm -1 was attri- Fig. 6 — IR mode at 1642 cm -1 over the cross section of the sample. Intensity increase was observed from the lower side to the upper side of the sample. buted to symmetric and antisymmet- ric stretching of the C-H bond. Be- cause a concentration gradient of –CH 2 - exists over the cross section, the peak intensity of this IR mode serves as a good indicator of varying chemical compositions. A monotonic change of the peak intensity was observed from one side of the sample to the other (Fig. 4). Peak intensity analysis can be applied to other IR modes as well. Peak intensity analysis was ap- plied to the C=O bond at 1642 cm -1 (Figs. 5 and 6). The monotonic peak in- tensity change was not as obvious as