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1998 Spotlight on Graduate and Undergraduate Research at ESF
Paper Science Engineering Abstracts

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.


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.


Page maintained by Russell Briggs.
Last modified July 19, 1999


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