Polyester (PET) single fiber FT-IR dichroism: Potential individualization

1998 ◽  
Author(s):  
Liling Cho ◽  
David L. Wetzel ◽  
John A. Reffner
Keyword(s):  
Single Fiber ◽  
Ir Dichroism ◽  
Ft Ir

Polarized microbeam FT-IR analysis of single fibers

1996 ◽  
Vol 54 ◽  
pp. 206-207
Author(s):  
Liling Cho ◽  
David L. Wetzel
Keyword(s):  
Molecular Orientation ◽  
Transition Point ◽  
Polymer Fibers ◽  
Single Fiber ◽  
Wire Grid ◽  
Polyester Fibers ◽  
Ft Ir ◽  
Ir Analysis ◽  
The Relationship ◽  
Wire Grid Polarizer

Polarized infrared microscopy has been used for forensic purposes to differentiate among polymer fibers. Dichroism can be used to compare and discriminate between different polyester fibers, including those composed of polyethylene terephthalate that are frequently encountered during criminal casework. In the fiber manufacturering process, fibers are drawn to develop molecular orientation and crystallinity. Macromolecular chains are oriented with respect to the long axis of the fiber. It is desirable to determine the relationship between the molecular orientation and stretching properties. This is particularly useful on a single fiber basis. Polarized spectroscopic differences observed from a single fiber are proposed to reveal the extent of molecular orientation within that single fiber. In the work presented, we compared the dichroic ratio between unstretched and stretched polyester fibers, and the transition point between the two forms of the same fiber. These techniques were applied to different polyester fibers. A fiber stretching device was fabricated for use on the instrument (IRμs, Spectra-Tech) stage. Tension was applied with a micrometer screw until a “neck” was produced in the stretched fiber. Spectra were obtained from an area of 24×48 μm. A wire-grid polarizer was used between the source and the sample.

Study on Structure and Property of Broussonetia papyrifera (BP) Fiber

2010 ◽  
Vol 146-147 ◽  
pp. 1593-1596 ◽  
Author(s):  
Xin Zhang ◽  
Li Jun Qu ◽  
Xiao Qing Guo
Keyword(s):  
Mechanical Properties ◽  
Chemical Composition ◽  
Cross Section ◽  
Single Fiber ◽  
Cellulose Content ◽  
Broussonetia Papyrifera ◽  
X Ray ◽  
Structure And Property ◽  
Morphology And Structure ◽  
Ft Ir

The morphology and structure of Broussonetia papyrifera(BP) bast and fiber were investigated by SEM, OM, FT-IR and X-ray analysis, and chemical composition of BP bast was analyzed. The results show that the cellulose content in the BP bast can be as high as 63.76%. BP fibers arrange parallel in the bast, which are linked by pection. The cross-section of PB fibers are irregular round with lumens that are almost invisible in the completely mature fibers. The crystallinity of the fiber could reach 83.26%. Most impurities such as hemi-cellulose, lignin, pectin could be effectively removed by degumming, while cellulosic structure is not changed. BP fiber has good mechanical properties, but the single fiber is too short to spin alone.

Microbeam polarization infrared spectroscopy: single fiber discrimination

1995 ◽  
Vol 53 ◽  
pp. 494-495
Author(s):  
Liling Cho ◽  
David L. Wetzel
Keyword(s):  
Infrared Spectroscopy ◽  
Phase Measurement ◽  
Single Fiber ◽  
Synthetic Fiber ◽  
Liquid Crystal Phase ◽  
Synthetic Fibers ◽  
Polyester Fibers ◽  
Fixed Reference ◽  
Ft Ir ◽  
Ir Microspectroscopy

FT-IR microspectroscopy of single fiber can produce useful information to distinguish among synthetic fibers. Certain fibers can be readily discriminated on the basis of spectra obtained by this technique. Polarization infrared spectroscopy has been used to measure macromolecular properties such as precipitate crystallinity, polymer film draw ratio, and liquid crystal phase. Measurement of IR dichroism requires light polarized both parallel and perpendicular to a fixed reference direction of the sample. Dichroism may be used to compare and discriminate between different polyester fibers and possibly to establish new groups within a subclass. Four fundamental bands (872, 973,1505 and 1579 cm-1) and two overtone bands (1960 and 3435 cm-1) were chosen because they were relatively free from overlapping bands, and they were weak enough not to be over-absorbing in the spectra of thick, unflattened fibers. During industrial production, the process of drawing can impart many useful properties to a synthetic fiber. When this occurs, molecular chains may become oriented in the long direction of the fiber.

scholarly journals Fibres from polypropylene/polyamide 6 blends: Application of FT-IR Dichroism for study of fibre molecular orientation

1992 ◽  
Vol 11 (3) ◽  
pp. 193-203 ◽  
Author(s):  
O. Ďurčová ◽  
I. Gróf ◽  
M. Jambrich ◽  
P. Mizerák
Keyword(s):  
Molecular Orientation ◽  
Polyamide 6 ◽  
Ir Dichroism ◽  
Ft Ir

FT-IR microspectroscopic analysis of diseased white matter brain tissues

1995 ◽  
Vol 53 ◽  
pp. 968-969
Author(s):  
Steven M. Le Vine ◽  
David L. Wetzel
Keyword(s):  
White Matter ◽  
Gray Matter ◽  
Twitcher Mouse ◽  
Grid Pattern ◽  
Marked Contrast ◽  
Spatially Resolved ◽  
Ft Ir ◽  
Ir Microspectroscopy ◽  
Chemical Evidence

In situ FT-IR microspectroscopy has allowed spatially resolved interrogation of different parts of brain tissue. In previous work the spectrrscopic features of normal barin tissue were characterized. The white matter, gray matter and basal ganglia were mapped from appropriate peak area measurements from spectra obtained in a grid pattern. Bands prevalent in white matter were mostly associated with the lipid. These included 2927 and 1469 cm-1 due to CH2 as well as carbonyl at 1740 cm-1. Also 1235 and 1085 cm-1 due to phospholipid and galactocerebroside, respectively (Figs 1and2). Localized chemical changes in the white matter as a result of white matter diseases have been studied. This involved the documentation of localized chemical evidence of demyelination in shiverer mice in which the spectra of white matter lacked the marked contrast between it and gray matter exhibited in the white matter of normal mice (Fig. 3).The twitcher mouse, a model of Krabbe’s desease, was also studied. The purpose in this case was to look for a localized build-up of psychosine in the white matter caused by deficiencies in the enzyme responsible for its breakdown under normal conditions.

Ultra-spatially resolved synchrotron powered FT-IR microspectroscopy of individual cells of biological material

1995 ◽  
Vol 53 ◽  
pp. 884-885
Author(s):  
David L. Wetzel ◽  
John A. Reffner ◽  
Gwyn P. Williams
Keyword(s):  
Thermal Noise ◽  
Spot Size ◽  
Acquisition Time ◽  
Thermal Source ◽  
Signal To Noise ◽  
Spatially Resolved ◽  
Good Spatial Resolution ◽  
Small Spot ◽  
Ft Ir ◽  
Ir Microspectroscopy

Synchrotron radiation is 100 to 1000 times brighter than a thermal source such as a globar. It is not accompanied with thermal noise and it is highly directional and nondivergent. For these reasons, it is well suited for ultra-spatially resolved FT-IR microspectroscopy. In efforts to attain good spatial resolution in FT-IR microspectroscopy with a thermal source, a considerable fraction of the infrared beam focused onto the specimen is lost when projected remote apertures are used to achieve a small spot size. This is the case because of divergence in the beam from that source. Also the brightness is limited and it is necessary to compromise on the signal-to-noise or to expect a long acquisition time from coadding many scans. A synchrotron powered FT-IR Microspectrometer does not suffer from this effect. Since most of the unaperatured beam’s energy makes it through even a 12 × 12 μm aperture, that is a starting place for aperture dimension reduction.

FR-IR Molecular Microanalysis System

1990 ◽  
Vol 48 (2) ◽  
pp. 270-271
Author(s):  
John A. Reffner ◽  
William T. Wihlborg
Keyword(s):  
Fourier Transform ◽  
Fourier Transform Infrared ◽  
Integrated System ◽  
Morphological Examination ◽  
Fully Integrated ◽  
Ir Microscopy ◽  
Normal Functions ◽  
Infrared Microspectroscopy ◽  
Infrared Spectral ◽  
Ft Ir

The IRμs™ is the first fully integrated system for Fourier transform infrared (FT-IR) microscopy. FT-IR microscopy combines light microscopy for morphological examination with infrared spectroscopy for chemical identification of microscopic samples or domains. Because the IRμs system is a new tool for molecular microanalysis, its optical, mechanical and system design are described to illustrate the state of development of molecular microanalysis. Applications of infrared microspectroscopy are reviewed by Messerschmidt and Harthcock.Infrared spectral analysis of microscopic samples is not a new idea, it dates back to 1949, with the first commercial instrument being offered by Perkin-Elmer Co. Inc. in 1953. These early efforts showed promise but failed the test of practically. It was not until the advances in computer science were applied did infrared microspectroscopy emerge as a useful technique. Microscopes designed as accessories for Fourier transform infrared spectrometers have been commercially available since 1983. These accessory microscopes provide the best means for analytical spectroscopists to analyze microscopic samples, while not interfering with the FT-IR spectrometer’s normal functions.

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