Spectra cellophane

A Beckman Model 25 UV-Visible Spectrophotometer was used to determine the ultraviolet spectra of the Cellophane samples. Sample and reference films were held in custom-made sample holders. Scans of the UV-Visible spectrum indicated an absorption peak at about 265 nm. Therefore, all further measurements were made, at the wavelength of maximum absorption in the 255 - 270 nm region. 

Figure 3. Changes in the 1500 - 1900 cm l Region of the Infra-Red Spectrum of Cellophane Film (C) baked for 150 hr at 140 °C, then (B) washed or (A) treated.

Figure 5. Changes in the Ultra-Violet Spectrum of Cellophane Film...

Dialysis membranes can be animal membranes and cellophane, but mostly used membranes are made of cellulose. Now, various-sized dialysis tubes, made by the American Union Carbide and American medical spectrum, are commonly used. The MWCO of the tubes are usually around 10,000. In order to improve the efficiency of dialysis, a variety of devices can also be used, including various types of Zeineh dialyzer (Biomed Instruments Inc. US), by which the speed and efficiency of dialysis can be greatly increased. 

A good illustrative example of the value of ATR sampling is a cellophane overwrap from a package of chewing gum. That the primary component is cellophane (a cellulose derivative with a glycerol plasticizer) can be easily established from the transmission spectrum (see Figure 10.8). 

If the spectrum of the outside surface is obtained by ATR/MIR, however, we obtain the spectrum shown in Figure 10.9, and that is not a spectrum of cellophane but rather of nitrocellulose. There are no bands in this spectrum corresponding to cellophane at all. The spectrum, not shown, from the inside of the same overwrap was also obtained by ATR/MIR, and this latter spectrum very closely matched that of a reference secondary amide, a commonly used vehicle for printing inks. It also appears that dioctylphthalate (or perhaps camphor) was used as a plasticizer on both the inside and outside surfaces. 

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