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1. • CommentAuthorGeorge Bayer
   • CommentTimeFeb 14th 2008

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   Fourier transform infrared (FTIR) spectrometers record the interaction of infrared radiation (light) with experimental samples, measuring the frequencies at which the sample absorbs the radiation and the intensities of the absorptions. Determining these frequencies allows identification of the sample’s chemical makeup, since chemical functional groups are known to absorb infrared radiation at specific frequencies. In addition to identifying the plastic or the polymer matrix in a composite, FTIR can identify organic contaminants, and some inorganic fillers. FTIR can also be quite useful in indicating whether the material has degraded, for example changes in the IR absorption of certain organic functional groups due to ultraviolet or chemical degradation. The Attenuated total reflectance mode (ATR) is generally the preferred method for FTIR analysis of solids, liquids, gels and pastes.
   
   Differential scanning calorimetry (DSC), Thermomechanical analysis (TMA) and Thermogravelmetric analysis (TGA) are used to document and analyze the thermal history of the polymer (DSC), to determine of thermal the glass transition and coefficient of thermal expansion (TMA) for the material, the volatile content, the filler content and onset of decomposition (TGA). Differential scanning calorimetry is most often used in the analysis of polymers for determining the polymer melting temperature, glass transition temperature, degree of crystallinity, heat of fusion, and degree of cure. It is an excellent analytical technique for investigating the failure of polymers and polymers because of the very small sample size required; typically on the order of 10 milligrams. By its ability to measure the glass transition temperature (of an amorphous plastic like polystyrene, polycarbonate, epoxies) or crystalline melting temperature (of semi-crystalline polymers like polypropylene) of the polymeric material, it can provide information about the manufacturing process used to produce the sample or the effects of temperature on the material during service. Again, it is important to analyze the failed sample and a non-failed sample to make the proper conclusions about the material.