FTIR红外显微镜分析高分子聚合物饮料瓶

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Application Note Infrared Microscopy for the Analysis of Polymer2/3Laminates in Beverage Packaging Infrared Microscopy for the Analysis ofPolymer Laminates in Beverage Packaging Laminates are combinations of polymers that combine the benefits and properties of the variouspolymers used in the laminate to create a better material. Polymer laminates have a multitude ofuses including packaging for food and other products. Laminates act as moisture and/or oxygenbarriers and as such are commonly used to protect foods and chemicals. Analysis of laminates isoften required for quality control and to determine laminate adhesion problems. Introduction Modern polymers are seldom used as pure materials， more often mixtures of different polymers are combinedto give the desired physical characteristics. For example， the rigidity of polystyrene is often combined withan elastic polymer to produce stiff yet shock resistant materials. Polymeric laminates are important in themicroelectronics， medical， food packaging， and chemical industries. Since laminates act as moisture and/oroxygen barriers， they are commonly used to protect foods and chemicals. JASCO FT-IR Spectrometers There are many methods that can be used to generate these mixtures but one of the most commonis to simply assemble the polymers into layers and create alaminate. The most widely used structuralspectroscopic measurement for laminates is Fourier Transform infrared (FTIR). FTIR spectroscopy is a non-destructive technique that allows chemical identification of the component materials in the laminate. Infrared spectroscopy provides the ability to study the interactions of the vibrational and rotational energies ofatoms or groups of atoms within molecules and is a powerful qualitative and quantitative tool. Infrared spectrareflect vibrational motions that produce a change in the permanent dipole moment of the molecule. There isa large amount of information that can be gained by using infrared spectroscopy for the analysis of polymers.Minor changes to the molecular structure usually result in a spectrum that is clearly distinguishable from thespectrum of the original compound. Thus， the infrared spectra can be used to identify the presence of aspecific chemical compound or mixture of compounds. Several different polymer materials were selected for analysis including a prepared juice bottle and a plasticfood container. Laminate samples of controlled thickness were sectioned with a razor blade and the crosssection examined using the FT-IR microscope. Microscope apertures ranging from 15 x 15 microns to as largeas 50 x 50 microns were used to define sample areas for analysis. Analysis was performed using a JASCO FT/IR-620 and IRT-30 FT-IR microscope with a ceramic source， KBrbeamsplitter， and MCT detector. The resolution was 4 cm-1， with 64 co-added scans for the single-beambackground and sample spectra. The spectral range was from 4000-700 cm1. Figure 1. Juice bottle laminate examined using theFTIR microscope， visually， you can identify at least 4layers in this image. Figure 2. Infrared spectra of laminate polymers.Top： polypropylene Bottom： polyvinyl alcohol. Figure 3. Juice bottle laminate layers demonstrating the transition ofthe polymer layers from polypropylene to polyvinyl alcohol. JASCO INC. sco Initial investigation of the polymer laminate found that the primary components of the laminate werepolypropylene (PP) and polyvinyl alcohol (PVOH). Further study and careful examination of the laminatepolymer immediately adjacent to the PVOH layer revealed a gradient in the ratio of the polypropylene (PP) andpolyvinyl alcohol (PVOH) polymers. Laminate appears to comprise 6 layers. PP (polypropylene) and a highly hydrolyzed form of the PVOH(polyvinyl alcohol) were identified as the primary components based on the comparison of the infrared spectrato spectral libraries. There appear to be two slightly different PP types； PP1 and PP2 are probably m.wt.variants or PP1 may simply contain a small amount of an additive to provide the change in optical density.Additionally， it was determined that there was a mixing of the polymers at the interfaces. Infrared spectroscopywas not only able to identify the layers but also to give information on the polymer mixing occurring at theinterface. This valuable information will allow a more accurate determination of the physical properties of thepolymer and how it will handle stresses at the interface between the laminate layers. JASCO INC.Mary's Court， Easton， MD USATel：( Fax： ( pplication Library： http：//www.jascoinc.com/applications Mary’s Court， Easton， MD USATel： ( Fax： ( opyright O JASCO Corporation