Polariscopic imaging and vibrational characterization of hybrid films for packaging (original) (raw)
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The Journal of Chemical Physics, 2000
We present reflectance anisotropy spectroscopy ͑RAS͒ data for aligned films of luminescent conjugated polymers. Ultrathin films ͑5-10 nm͒ spin-cast onto friction-deposited poly-tetrafluoroethylene ͑PTFE͒ show birefringence and dichroism indicating alignment of the polymer chains with the PTFE axis. The observed dichroism agrees very well with recently published polarized ultraviolet absorption spectra. In particular, the spectrum of a derivative of poly ͑para-phenylene͒ shows the onset of a perpendicular-polarized absorption feature at 5 eV, consistent with recent theoretical predictions. Thick films, prepared by gel-processing in polyethylene ͑PE͒, also show characteristic optical anisotropy, and the RAS results are interpreted in terms of the ellipsometric functions, ⌿ and ⌬.
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Thin Solid Films, 2008
Polymer sheets are currently used worldwide in a wide range of applications. The manufacturing process of these sheets involves extruding machines that stretch the material in both lateral and longitudinal directions with respect to the machine direction, thus inducing birefringence. In most cases, the film obtained is optically biaxial. Polarimetric spectroscopy (Ellipsometry and Mueller Matrix) combined with conoscopic observation are the methods of choice to study these properties. In this work we report an analysis of commercially available polyethylene terephtalate (PET) films used as substrate for food packaging as well as for embedded electronic devices such as solar cells or flexible displays. Initial observation of these films through polarizing microscope in conoscopic mode reveals first the trace of optical axis plane with respect to the film surface and second, whether the optical axis is acute or not. This preliminary study allows optimal sample positioning for further polarimetric studies. The measurements and modelling are done in both reflection and transmission mode on several spectroscopic polarimetric setups from UV to NIR. The models give as a main result, the dielectric tensor of the film as well as its orientation with respect to the laboratory reference frame.
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Polymer Engineering and Science, 1979
The modules and birefringence of oriented polymers are known to couple through the structural and intrinsic properties of the polymer. Recent developments in both optical and mechanical theories have allowed this coupling to be expanded so that it includes predictions of modulus and refractive indices of uniaxially-oriented polymer films at various angles to the draw direction. The validity of these theories has been tested in this study by predicting the angular dependence of the optical and mechanical properties of seven uniaxiallyoriented films of isotactic polypropylene. The present study also provides intrinsic material properties associated with the crystalline and noncrystalline components of the polymer, and consequently allows the identification of the structural parameters that control the properties of ultra-high oriented isotactic polypropylene.
Vibrational Spectroscopic Analysis on the Deformational Behavior of Hybrid Polymers
Under this equipment grant, we are to acquire a unique characterization facility needed for determining sub-molecular level changes in the atomic bonding responsible for the enhanced performance of materials reinforced with a new class of nano-structured, hybrid chemicals; polyhedral oligomeric silsesquioxanes (POSS). This facility is vital to the PI's current AFOSR and AFRL-PRSM projects because it will expand the use of POSS in both high temperature polymeric matrix composites and engineering elastomers. This effort is needed for a fundamental advancement of our understanding for the synergistic performance enhancement in the use of nano-structured hybrid chemicals with organic materials. Under this effort, we had purchased 1) an upgrade the existing Fourier transform infrared spectrometer (FT-IR) equipped with a new detector, 2) a micro-Raman spectrometer with 3 different excitation lasers covering from UV to near-IR range, and 3) a custom heated deformation stage. This uniqu...
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Vibrational spectroscopies, including infrared and Raman techniques, are important tools for the characterization of chemical composition, molecular structures, and chain orientation under mechanical deformation of polymeric materials. The development of fiber-optic-based spectrometers has broadened the use of vibrational spectroscopy for process monitoring in various fields including polymerization, curing, and manufacturing processes. Combined with chemometrics, near-infrared (NIR) spectroscopy is now recognized as one of the most important techniques for polymer analyses. Infrared and Raman studies also offer invaluable means for the analysis of inorganic particles used as reinforcing fillers for polymers. The characterization of surface species and the nature of interfacial bonding between the organic and inorganic phases are important issues for the understanding of composite properties. Infrared spectroscopy is particularly convenient for the detection and analysis of hydroxyl...
Rheo-Optical Fourier Transform Infrared and Raman Spectroscopy of Polymers
Applied Spectroscopy, 1993
This article is intended to review recent results of simultaneous mechanical and Fourier transform infrared spectroscopic—so-called rheo-optical—measurements for polymer deformation studies. The technique will also be discussed in terms of the application of Fourier transform near-infrared light-fiber and Raman spectroscopy. Specifically, data on the bidirectional drawing of poly(ethylene terephthalate) and the strain-induced conformational changes of poly(vinylidene fluoride) will be presented.
Applied Spectroscopy, 1996
The linear diphenyl polyene Φ–(C=C–)4Φ has been investigated as a resonant Raman-active probe for molecular orientation, suitable for incorporation into polymers prior to melt extrusion and drawing. By examination of the polarization properties of the Raman scattered radiation, it is possible to determine the P200 and P400 orientation parameters for the dye molecule as a function of draw ratio. Assuming that the dye resides only in amorphous polymer regions, it is expected that the data will give insight into the orienting forces present in the amorphous phase during processing. Expressions were derived relating P200 and P400 to the polarized Raman intensities. An expression for Hermans' orientation parameter was also derived—it was shown that f was always slightly higher than P200 when evaluated from the same Raman data. These Raman measurements were illustrated by using the example of uniaxially drawn poly(ethylene) (PE) tubing. As an alternative approach, FT-IR dichroic ratio...
Polarization modulation Fourier transform infrared ellipsometry of thin polymer films
Applied Spectroscopy, 1986
Polarization modulation infrared ellipsometric spectra were collected on an FT-IR spectrometer, with the use of two linear polarizers and a photoelastic modulator. Samples consisted of thin poly(vinyl acetate) and poly(methyl methacrylate) films on gold substrates. The relative phase retardation (delta) and relative amplitude (psi) were derived from these measurements. These spectra were superior to those from static infrared ellipsometry measurements on the same samples. The thickness and optical constants of the films were calculated from the ellipsometric measurements and compared with reference optical constant spectra.