No description available.

The nature of ballistic-type internal paper tear test methods has been reviewed. The kinetic energy of the tester sector is considered to be the prime contributor to paper rupture. In agreement with energy dissipation concepts and the principle of energy conservation, a mathematical model expressing tearing energy was derived based on kinetic energy variations in paper during tearing. It is shown that this mathematical model can be used to calculate the net energy of the tester sector, which is available for tearing paper, and the residual energy. Consequently, the difference between net and residual energy, or tearing energy, is that portion expended in the rupture process. Furthermore, the mathematical model relates tearing energy to velocity, hence can be used to examine the effect of tear rate and time-dependent properties of paper subjected to tearing stress. A method was devised for measuring the time required to tear standard samples. From an oscilloscope trace, the tear distance and time relationship was measured and represented by a quadratic equation. From this equation, sector swing and tearing velocities were calculated for computing various energy factors and their variation at any instant of the tearing process. Results have shown that ballistic-type tear test methods are time-dependent, in that time required to tear paper varies with the sample condition. The higher the number of plies torn simultaneously, the longer was the time required to tear a paper sheet. The energy required to tear paper was also time-dependent, increasing with decreasing tear rate. It was found that the direct relationship between tearing strength and number of plies torn simultaneously does not always hold, but that a constant direct relationship exists between tearing strength and tearing energy. Although the ballistic-type tear test is time-dependent, inherent specimen properties may have a profound effect on results. Test results with an Elmendorf tear tester on five paper grades varying in tearing strength from 14 to 156 g/sheet have confirmed that the energy dissipation concept is adequate. / Forestry, Faculty of / Graduate

Ever since newsprint was made on a mass production basis, there has been a real need for a simple and instantaneous measurement of the moisture content of the moving sheet. A knowledge of the moisture content is important both economically and technically to the mill operator. As newsprint is sold by weight, the moisture content of the paper must be maintained within a narrow specified range. The mill, naturally, strives to produce paper with as high a percentage of moisture as permissible. Without any scientific means to guide them, however, the machine operators tend to over dry the paper because an over dried sheet is not nearly so noticeable as one that is too moist. This means that less paper is being made than is practically possible for each cord of wood processed. In addition, the over dried paper is of inferior quality to that containing the proper amount of moisture. At present, the only reliable method of measuring moisture content in Canadian mills is the laborious oven method which, though undoubtedly very accurate, has the great disadvantage of time lag. The recent development of the Q-meter offers a method for the rapid measurement of the moisture content of the moving sheet by the dissipation factor method which has the advantage that no contact with the paper is required. The fact that the dielectric constant of water is very high compared to that of cellulose suggests that the dielectric losses in moist paper could be used to measure its moisture content. Tests were therefore conducted in the laboratory with a Boonton Q-Meter, type 160-A, to determine the dissipation factor of newsprint samples of various moisture contents. A pair of plates with the sample of newsprint between them, but not touching, constitutes the test condenser. The dissipation factor of this condenser depends largely upon the amount of moisture contained in the newsprint. To measure the dissipation factor, the test condenser is tuned to resonance with a high-Q inductor. The amplitude of resonance depends on its Q value which in turn is largely a function of the condenser losses. Hence the dissipation factor may be calibrated against the percentage moisture content. Results of laboratory tests at different humidities and various frequencies showed that the percentage moisture content can be measured with adequate accuracy. The speed tests showed that the speed of the paper up to a velocity of 1800 feet per minute between the condenser plates has no effect on the readings. All these preliminary tests in the laboratory indicate that it is feasible to apply the Q-meter for measuring the moisture content of the moving sheet by the dissipation factor method. Exhaustive field tests under actual mill production conditions should be made over a period of time to compile sufficient data for a fair appraisal of the practical value of this method. / Applied Science, Faculty of / Mechanical Engineering, Department of / Graduate

This study examines the hypothesis that coniferous wood fibre origin is maintained even when purified pulps are subjected to severe mechanical (beating) and chemical (decrystallizing) treatments. Four to five intra-incremental sulphate pulps obtained from each of three species, eastern larch (Larix lariaina (Duroi) K. Koch), Douglas fir (Pseudotsuga menziessii (Mirb.) Franco) and balsam fir (Abies balsamea (L.) Mill), were purified and machined to one or three levels EL (170 ± 45 ml Csf), DF (615 + 90 ml Csf; 328 + 43 ml Csf; 168 ± 62 ml Csf) and BF (190 + 30 ml Csf). Thereafter, cellulose supermolecular structures were altered by monoethylamine swelling, with changes (48 ± 2% vs. 68 ± 2%) quantified as fibre crystallinity index measured by X-ray diffractometry. Paper sheet apparent densities and tensile parameters (maximum strength, "stretch," modulus of elasticity and rupture energy) were determined. Fibre surface areas and sheet bonded states were estimated by light scattering coefficient measurements. The effects of wood origin on paper sheet physical-mechanical properties reported by other researchers were reaffirmed in this study, with all factors decreasing progressively across growth increments. The differences of wood intra-incremental, as well as species origins, were not removed by conventional pulping and papermaking processes, or additional treatments such as severe beating or major alteration of the basic cellulose structures as practiced in the study. Paper sheet tensile properties were related directly to sheet apparent density. Correlation coefficients as high as 0.979 and 0.989 were obtained for 00% and 82% monoethylamine decrystallized fibre sheets, respectively. Sheet density was inversely related to wood specific gravity and was found to be independent of wood species, degree of beating and decrystallization treatments. It is shown that fibre bonding potential is not the only factor influencing paper sheet strength. Intrafibre characteristics, such as cellulose supermolecular structures, have a highly significant effect on paper sheet strength as well. In addition, specific energy of "bond failure" (irreversible energy consumed per unit sheet surface formed as result of tensile straining) was higher for earlywood than for latewood sheets. This energy quantity depends on beating degree and differs according to species, as well as intra-incremental origin. The paper sheet light scattering coefficient (L.S.C.)-density relationship also depended on wood fibre origin. Earlywood sheet L.S.C. decreased with increased beating and sheet density, but latewood sheet L.S.C. remained almost unaffected. This observation explains why whole-wood fibre sheet L.S.C.-density relationships vary with pulp types as recorded in the literature. / Forestry, Faculty of / Graduate

No description available.

Laser ultrasonics has been used to measure the bending stiffness of paper products by measuring the dispersion of ultrasonic plate waves. In laser ultrasonics, ultrasound can be generated by absorption of pulsed laser spot while detection can be carried out by Laser Doppler Interferometry. The research presented in this paper describes a new method to detect ultrasonic plate waves using a recently developed acoustic transducer, more specifically an optical Micro ElectroMechanical System (MEMS) microphone with broadband capability. The MEMS device operates as a non-contact proximity probe placed less than ¼ a millimeter away from the plate. The signals are detected with a capacitive micromachined ultrasonic transducer (cMUT) in which the back electrode of the capacitive transducer on a transparent substrate is shaped as an optical diffraction grating. The displacement of the transducer membrane is determined using an optical interferometer. By applying voltage to deflect the membrane electrostatically, the detection sensitivity is kept at an optimum level. The main purpose of the research presented herein was to test this MEMSs ability to detect ultrasonic waves propagating through paper, to increase the signal-to-noise ratio (SNR), and to calibrate the device in order to quantify the limitations on sensitivity in the context of the detection of ultrasound in paper. Similar tests were conducted for comparison with a modified Mach-Zehnder Interferometer, a more traditional method used for laser ultrasonic detection, and its results are presented in this paper.

No description available.

Abstract This thesis presents an effective optical method for measuring liquid sorption into paper. From the two tested methods, based on a streak-camera and optical coherence tomography (OCT), the last-mentioned proved very promising for investigating dynamical paper-liquid interactions as spatially and temporally dependent processes. The streak-camera measurements were performed to explore the relationship between paper properties and light migration in dry and refractive index matched paper in general. Based on streak-camera measurements, a novel procedure for determining the average refractive index of cellulose fibre tissue was also presented here. In addition, the streak camera method lent itself to paper porosity determination. Results of the performed OCT measurements proved that liquids cannot penetrate into paper before filling the pores and pits of the paper surface. As a liquid penetrated into paper, the border between the wetted and dry area could be investigated in the depth direction. The liquid penetration velocity seemed to be slower at the beginning and end of the process. Liquid absorption into paper fibres could be investigated concurrently. For the first time, the location and moment of structural changes in paper could be determined during wetting, and the effect of three different coexistent subprocesses related to paper wetting could be detected. OCT only fell short of detecting the effect of liquid migration along fibres. Despite the limitations of the utilized method (resolution, probing depth and depth scanning rate), the obtained OCT measurement results are very promising for the development of an effective paper wetting measurement device for industrial applications. Even if this thesis focused on paper wetting, it is reasonable to assert that the presented ideas and obtained results have more general value in terms of explaining liquid penetration into porous structures and offer an alternative method of evaluating that process.

Due to the fact that only comparative results were sought, the investigation was greatly simplified. On a comparative basis, the effects of external influences were largely eliminated from positions of vital importance and the use of an elaborate test, circuit was unnecessary. The equipment consisted of a high-voltage test transformer which supplied the test voltage; an induction regulator, auto transformer and generator field rheostats for voltage control; overload relay and aircore inductances for circuit protection; motor-generator set for a source of 60 cycle alternating voltage. The electrodes were circular, square edge brass discs. Specimens were immersed in lubricating oil for periods up to 40 hours and then tested for puncture strength. Following this, specimens were immersed for one hour and 24 hours and each of the two groups tested at intervals of time up to 720 hours. In each test the voltage was raised in steps of 200 volts, starting at 1000 volts. The puncture strength of the untreated paper was determined by testing a sufficient number of specimens over a period of days. The results obtained indicated no immediate deleterious effects of lubricating oil on paper. On the contrary, there was an improvement in puncture strength, accounted for by the fact that the relatively low voltages-used did not make ionization a serious factor. The results of tho long-time tests were unsatisfactory, as explained previously. However, they did permit the conclusion that deterioration of paper impregnated with lubricating oil would become apparent much sooner than if insulating oil were used. Oxidation, although probably existing, was apparently too slow to affect the results. / Master of Science

The purpose of this study was to test whether the computer-administered College Level Examination Program (CLEP) General Examination in English Composition produced scores equivalent to those obtained from the traditional paper-and-pencil version. The CLEP examination and its adaptation for computer administration and the results of a pilot study are presented. The subjects in this study were volunteers who took the CLEP English Composition Examination in order to earn college credit and were randomly assigned to either the computer-first or paper-and-pencil-first groups. Each subject took both forms of the examination with approximately one half of the subjects taking each version first. Analysis of variance failed to detect a significant effect for test form or an interaction of test form and order of administration. Equivalence reliability coefficients and internal consistency coefficients also indicated that the computer administration did not significantly alter the results of the examination. In general, the results of this study support the hypothesis that the computer-administered version of the CLEP General Examination in English Composition produces results equivalent to those obtained from the traditional paper-and-pencil version.