Investigation of CO2 sorption in molten polymers at high pressures using Raman line imaging

Polymer melts (or polymer solutions) with a solubilized gaseous component (which occur under sufficiently high pressures, thus forming homogeneous mixtures), and polymer melts (or polymer solutions) with dispersed gas bubbles (thus forming heterogeneous mixtures of polymeric fluid and gas bubbles) are encountered in thermoplastic foam processing and polymer devolatilization. Thus, a good understanding of the rheological behavior of such mixtures is very important to the design of processing equipment and successful optimization of such polymer processing operations. From the 1950s through the 1970s, the dynamics of a single, spherical gas bubble dispersed in a stationary Newtonian or viscoelastic medium was extensively reported in the literature (Barlow and Langlois 1962; Duda and Vrentas 1969; Epstein and Plesset 1950; Folger and Goddard 1970; Marique and Houghton 1962; Plessst and Zwick 1952; Rosner and Epstein 1972; Ruckenstein and Davis 1970; Scriven 1959; Street 1968; Street et al. 1971; Tanasawa and Yang 1970; Ting 1975; Yang and Yeh 1966; Yoo and Han 1982; Zana and Leal 1975). While such investigations are of fundamental importance in their own right, they are not much help to describe bubble dynamics in thermoplastic foam extrusion or structural foam injection molding, for instance. There is no question that an investigation of bubble dynamics in a flowing molten polymer with dispersed gas bubbles is a very difficult subject by any measure. Thus, understandably, a relatively small number of research publications on bubble dynamics in a flowing molten polymer have been reported (Han and Villamizar 1978; Han et al. 1976; Yoo and Han 1981). The complexity of the problem arises from other related issues, such as the solubility and diffusivity of gaseous component(s) in a flowing molten polymer, which in turn depend on temperature and pressure of the system. Further, a gaseous component solubilized in molten polymer in the upstream side of a die, for instance, may nucleate as the pressure of the fluid stream decreases along the die axis, after which they could grow continuously as the molten polymer with dispersed gas bubbles flows through the rest of the die.

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Hyperspectral Raman Line Imaging of Syndiotactic Polystyrene Crystallinity

Applied Spectroscopy ◽

10.1366/0003702981942753 ◽

1998 ◽

Vol 52 (10) ◽

pp. 1264-1268 ◽

Cited By ~ 24

Author(s):

Shuliang L. Zhang ◽

Jerilyn A. Pezzuti ◽

Michael D. Morris ◽

Aruna Appadwedula ◽

Chang-Meng Hsiung ◽

...

Keyword(s):

Factor Analysis ◽

Raman Line ◽

The Other ◽

Moderate Intensity ◽

Syndiotactic Polystyrene ◽

Raman Intensity ◽

Structure Information ◽

Intensity Image ◽

Line Imaging ◽

Noise Factors

The crystallinity of syndiotactic polystyrene (sPS) is studied by hyperspectral Raman line imaging. Images of a 140 × 1200 μm region of an sPS test piece containing 39 200 pixels/image were generated from spectra taken over the wavenumber interval between 300 and 875 cm−1. The spectral region includes the moderate-intensity crystallinity-sensitive bands in the 770 800 cm−1 region, as well as other useful but weaker marker bands. Factor analysis was used to extract structure information from the set of spectra. Four non-noise factors were extracted; two were assigned to crystalline and amorphous sPS and the other two to background. Score images of the crystalline and amorphous sPS factors were used to visualize distribution of those species. The results were compared to the integrated Raman intensity image for the 773 cm−1 band of crystalline sPS.

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Raman line imaging for spatially and temporally resolved mole fraction measurements in internal combustion engines

Applied Optics ◽

10.1364/ao.38.001714 ◽

1999 ◽

Vol 38 (9) ◽

pp. 1714 ◽

Cited By ~ 55

Author(s):

Paul C. Miles

Keyword(s):

Raman Line ◽

Mole Fraction ◽

Internal Combustion Engines ◽

Internal Combustion ◽

Combustion Engines ◽

Line Imaging

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Practical applications in UV Raman line imaging of water vapor

10.1117/12.171303 ◽

1994 ◽

Author(s):

Peter A. DeBarber ◽

Cecil F. Hess ◽

Robert W. Pitz ◽

Sastri P. Nandula ◽

Thomas M. Brown III ◽

...

Keyword(s):

Water Vapor ◽

Raman Line ◽

Practical Applications ◽

Uv Raman ◽

Line Imaging

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Remote detection of liquids by Raman line imaging

10.1117/12.799832 ◽

2008 ◽

Author(s):

Chris R. Howle ◽

Christopher D. Dyer ◽

Kurt J. Baldwin ◽

Richard J. White

Keyword(s):

Raman Line ◽

Remote Detection ◽

Line Imaging

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Hyperspectral Raman Microscopic Imaging Using Powell Lens Line Illumination

Applied Spectroscopy ◽

10.1366/0003702981945138 ◽

1998 ◽

Vol 52 (9) ◽

pp. 1145-1147 ◽

Cited By ~ 58

Author(s):

Kenneth A. Christensen ◽

Michael D. Morris

Keyword(s):

Raman Line ◽

Signal To Noise Ratio ◽

Numerical Aperture ◽

Acquisition Time ◽

Charge Coupled Device ◽

Illumination System ◽

Image Acquisition Time ◽

Intensified Charge Coupled Device ◽

Line Imaging

The design and characterization of a simple and robust hyperspectral Raman line imaging illumination system with the use of a Powell lens is reported. The generated line uniformity is ±5% of total intensity with a laser power density of 12 mW/μm2 at the sample with a 50×/0.8 NA (numerical aperture) objective. Similar results were obtained by using other objectives. Linewidths remained near the diffraction limit for all objectives tested. Significant decreases in image acquisition time are also reported with the use of a Powell lens-illuminated hyperspectral Raman line imaging microscope equipped with an intensified charge-coupled device (CCD) detector. Hyperspectral images (100 × 350 pixels) were acquired in as little as 8 with a corresponding signal-to-noise ratio of 24.

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Hyperspectral Raman Line Imaging of an Aluminosilicate Glass

Applied Spectroscopy ◽

10.1366/0003702981942339 ◽

1998 ◽

Vol 52 (1) ◽

pp. 64-69 ◽

Cited By ~ 34

Author(s):

Nancy L. Jestel ◽

Jeremy M. Shaver ◽

Michael D. Morris

Keyword(s):

Factor Analysis ◽

Raman Line ◽

The Other ◽

Aluminosilicate Glass ◽

Nonbridging Oxygen ◽

Silica Network ◽

Data Set ◽

Dental Restorations ◽

Line Imaging ◽

Significant Factors

An aluminosilicate glass, which is a model for glass formulations used as dental restorations, was examined by hyperspectral Raman line imaging. The data set consisted of more than 30000 spectra, which were analyzed by using factor analysis. Nine score images were constructed from the nine significant factors identified. Three factors represent convolutions of noise, background, and offset. The other six factors represent Raman spectra of different bonding environments of the silicate tetrahedron. Three of those factors contain narrow Raman features. These are associated with a fully polymerized silica network, with a silicate tetrahedron with one nonbridging oxygen, and with an alumina-related inclusion or a silicate tetrahedron with two nonbridging oxygens. The last three significant factors contain broad Raman bands representing continua of slightly different bonding environments of silicate tetrahedra with 0–4 nonbridging oxygens. The score images reveal that the glass, although not homogeneous, has few regions with discrete heterogeneities. The different bonding networks commingle and could be interconnected.

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