Infrared spectrometry of high polymers in the overtone and combination regions

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Virginia Polytechnic Institute


Recently, there has been an expanding interest in the packaging industry concerning thermoplastic film laminations. These types of materials provide a packaging material that can be tailored to the consumers' needs. An understanding of the bonding mechanisms between plastics might prove useful in the improvement or development of film lamination.

Infrared spectrometry has been used to study the structures of plastics in the 3.0 - 100 micron region. It was decided that a study of infrared spectrometry in the 1.0 - 3.5 region could provide a tool for studying bonding mechanisms between thermoplastic material.

The results of the qualitative study of the structural groups of nine polymers showed that the spectral identification in the 1.0 - 3.5 micron region was possible. These results could provide a means of determining the groups involved in bonding mechanisms.

Beer's law has normally been applied to the quantitative analysis of homogeneous gaseous and liquid mixtures. A study shewed that Beer's law was applicable, with limited quantitative accuracy, to solid thermoplastic mixtures. The results indicate that a base-line analysis technique, based on Beer's law can be used to determine concentration gradients. A study of such concentration gradients across the interface of a lamination could indicate the types of bending mechanisms.

All samples were analyzed in the form of films with a Beckman DK-2 ratio recording spectrophotometer. An improved method for the preparation of film samples was developed. Thermoplastic resins were pressed between 10 mil Mylar and Teflon FEP films on a Carver laboratory press.