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Contents
NEW
TECHNIQUES OF FRACTIONATING PULP FIBERS. Hemant Gupta and B. V. Ramarao, Paper Science
and Engineering, 308 Walters Hall, SUNY- College of Environmental Science and Forestry,
Syracuse, NY 13210.
PHOSPHORESCENT BETA RADIOGRAPHIC IMAGING OF PAPER FOR THE
CHARACTERIZATION OF FORMATION. Joel J. Pawlak and D. Steven Keller, Faculty of Paper
Science and Engineering, SUNY-College of Environmental Science and Forestry, Syracuse, New
York, 13210.
AN INVESTIGATION OF THE RISING AND ROUGHENING OF PAPER SURFACE BY THE
INKJET PRINTING. Yong-Joo Sung and D. Steven Keller, Faculty of Paper Science and
Engineering, 417 Walters, SUNY College of Environmental Science and Forestry, Syracuse, NY
13210.
DIRECT MEASUREMENT OF THE METHOXYL GROUP CONTENT WITH GAS
CHROMATOGRAPHY IN AQUEOUS SOLUTION. Rallming Yang and Y.-Z. Lai, Faculty of Paper
Science and Engineering, 425 Walters Hall, SUNY College of Environmental Science and
Forestry, NY 13210.
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Abstracts
NEW TECHNIQUES
OF FRACTIONATING PULP FIBERS. Hemant Gupta and B. V. Ramarao, Paper Science and
Engineering, 308 Walters Hall, SUNY- College of Environmental Science and Forestry,
Syracuse, NY 13210.
The fractionation of secondary pulp fibers into two or
more streams on the basis of either fiber length or chemical composition and morphology
has been long sought after process, with the view to selectively induce favorable pulp in
the recycle furnish. Two new methods have been investigated to determine the extent of
separation on the basis of fiber length and the difference in chemical composition of the
chemical and mechanical pulps.
Elutriation of fiber fines from a conical spouted bed of
recycled pulp (elutriation spouting) was conducted experimentally to remove small fiber
particles (fines) from the slurry. Pulp suspension was fluidized at different flow rates
of water. The length of the fibers in the overflow and the bed was determined by using
fiber length analyzer Kajaani FS-100 and subsequent comparison was made with the original
pulp mixture.
In another set up, experiments were conducted with the aim
to separate mechanical pulp from the chemical pulp using column flotation. It is well
established that the difference in the chemical composition of chemical and mechanical
pulp influences the wettabilty of the fibers and render them hydrophobic or hydrophilic.
Different dosages of surfactant was examined, which enabled to create the froth and helped
in entraining hydrophobic pulp (mechanical) in the bubble swarm. The more hydrophilic pulp
(chemical) was left behind.
PHOSPHORESCENT BETA RADIOGRAPHIC IMAGING OF PAPER FOR THE
CHARACTERIZATION OF FORMATION. Joel J. Pawlak and D. Steven Keller, Faculty of Paper
Science and Engineering, SUNY-College of Environmental Science and Forestry, Syracuse, New
York, 13210.
Mass distribution variability has significant impact on
paper properties such as print mottle, directionality, and dimensional stability. It is
therefore important to be able to characterize this variability. There currently exist a
number of methods for determining the mass variation within a sheet of paper. These
methods include light transmission, point by point beta particle transmission, and beta
radiography. The ability to efficiently capture an image of the mass distribution poses a
number of advantages. The objective of this investigation is to characterize a phosphor
storage system for use with a beta radiographic technique.
Traditional beta radiography involves capturing an image of
a sample using transmitted beta particles and x-ray film. The use of x-ray film has a
number of difficulties associated with it. The nonlinear response of the film, the
variability of the developing process, the absorption efficiency of the emulsion, and the
need for a darkroom are just a few of the drawbacks to x-ray film. By introducing a
phosphor storage system we have eliminated these difficulties.
The phosphor storage system consists of BaFBr:Eu+2 crystals in a matrix of polymer attached to an aluminum plate. When exposed to high-energy
radiation the crystals are oxidized. The crystals remain in this state until they are
excited by laser radiation at 633 nm, which causes the crystals to phosphoresce releasing
photons in the blue light region. The intensity of this blue light is proportional to the
amount of high-energy radiation passing through the sample.
Our studies have shown that a phosphor storage system can
replace x-ray film in beta radiography. It is possible to construct a master calibration
curve for the phosphor storage system due to its linear response, uniform time constant,
and stationary absorption coefficient. This adds a great deal of convenience to the
detector system.
Mylar films were used to characterize the variability of the
phosphor storage system with respect to grammage. The variability of the detector response
is characteristic of a binomial distribution. The co-variance decreases with time as would
be expected from the binomial distribution. These studies also indicate that variability
is not constant over a range of grammages. This instability is due to the changes in the
flux of the beta particle transmitting through the mylar.
The phosphor storage system is linear over four orders of
magnitude. While this creates a large basis weight gradient, it is shown that the limiting
factor for basis weight resolution is the Kaiser detection limit. Spectral analysis
indicates that it may be possible to filter the background noise from images of paper.
This would shorten the exposure time required for a certain paper sample.
AN INVESTIGATION OF THE RISING AND ROUGHENING OF PAPER SURFACE BY THE
INKJET PRINTING. Yong-Joo Sung and D. Steven Keller, Faculty of Paper Science and
Engineering, 417 Walters, SUNY College of Environmental Science and Forestry, Syracuse, NY
13210.
In this work, we evaluated the surface roughening of
paper caused by the wetting with ink by using a laser profilometer. Variation in surface
topography was measured to a resolution of 1 m m in 3 dimension
so that the contour of individual fibers could be mapped.
This instrument utilizes a triangulation technique that uses
a laser beam with a spot size of 10-15m m in diameter. The
sample is passed beneath the sensor using precision positioning stages with m m resolution. The laser range sensor had a z-directional resolution
of 0.5m m over range of 150m m. The
mean roughness of the surface in the z-direction rising and the increase in roughness(RMS)
values, before and after ink jet printing were compared. Difference can be attributed to
bond breakage, stress relaxation, and fiber swelling in the presence of water-based ink,
which are not completely reversed on drying.
DIRECT MEASUREMENT OF THE METHOXYL GROUP CONTENT WITH GAS
CHROMATOGRAPHY IN AQUEOUS SOLUTION. Rallming Yang and Y.-Z. Lai, Faculty of Paper Science
and Engineering, 425 Walters Hall, SUNY College of Environmental Science and Forestry, NY
13210.
A new method was established for the quick measurement of
methoxyl group content with gas chromatography (GC) in an aqueous solution. The principle
reaction involved in the method is hydriodic acid demethylation. Gas chromatograph
equipped with Tenax packed column was successfully applied to detect the released methyl
iodide in aqueous solution. Model compounds study shown that the reaction is
pseudo-first-order. The monitor of the liberated methyl iodide against time indicated that
the reaction finished in thirty minutes for both of the lignin and model samples. Having
been applied to test the lignin and model samples, the proposed method was proved to be a
simple and precise way for the measurement of methoxyl group content. |
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