All cookings in this report were performed under the following conditions except the addition of alkaline chemicals: Total:- SO2 2.5%, Liquor to wood ratio:- 5:1 Time required to raise from 20°C to 185°C (cooking temperature) 100 minutes Cooking time:-120 minutes in the case of cooking of the red pine 30 minutes in the case of cooking of the birch. For the first case we cooked the red pine and the birch without adding of alkaline chemicals, and the pulp yields from both woods resulted in 67%_??_68%. Then we added alkaline chemicals to the cooking liquor, and studied the effects of addition of chemicals upon the cooking state and the properties of paper made of the pulp obtained. (1) When the cooking liquor involves sodium hydroxide or sodium carbonate, the velocity of digestion is accelerated and sodium hydroxide shows faster cooking than sodium carbonate does. The cooking velocity is no more accelerated when sodium hydroxide of sodium carbonate is added over a certain limit. When sodium hydroxide is excessively added to the cooking liquor, it works as the cooking reagent and impedes sulfonation of lignin by sodium sulphite. (2) The alkaline chemical suitable for the purpose of buffering action is sodium bicarbonate, and sodium hydroxide and sodium carbonate indicate no buffering action and work only as pH controlling reagent which keep in order that the cooking liquor may no turn acidic while cooking. The addition of calcium carbonate to the cooking liquor shows also no buffering action. (3) When the concentration of sulphur dioxide in the cooking liquors is kept constant, the mechanical properties of paper made of pulp obtained are not affected by the amounts and kinds of added alkaline chemicals, but closely depend upon the yield of pulp. (4) In the range of semichemical pulp, Roe number is relative to the yield of pulp, but the change of Roe number is very small in comparison with the change of the yield of pulp. (5) In the definite cooking time, it is worth noticing that lignin content in pulp increases notwithstanding the decrease of yield, when alkaline chemical is added to the cooking liquor. (6) In the cooking of birch, the increase of cooking pressure caused by carbon dioxide gas from sidium carbonate or sodium bicarbonate is negligible, if they are not excessively added to the cooking liquor. (7) The color pulp cooked by the liquor without any alkaline chemical is the lightest, and the more alkaline chemical added to the cooking liquor, the worse becomes the color of the pulp. In this case, jt becomes more brown in the red pine and more reddish-brown in the birch.
In order to investigate the effects of hydrolysis at the latter stage of bisulfite cooking upon the fine structure of wood cellulose, the experiment stated as below was carried out. The holocellulose, which has been prepared from red pine in the same manner as previously reported in part IX, was hydrolyzed under following conditions, namely: temperature 100, 135 and 170°C, pH 7.0, 3.0, 1.5 and 1.0; retention time at elevated temperature 3 hrs. With each hydrolyzed holocellulose, its yield from original holocellulose, the amount of crystalline region in it, the rate of degradation of crystalline region, leveling-off DP etc. were determined. The results were as follows: 1. With the progression of acid hydrolysis, the holocellulose has gradually dissolved and decreased in its average DP and also in its leveling-off DP, while the content of crystalline region in it increased. These results were quite similar to that as previously reported in Parts I and IX. 2. With the hydrolyzed holocellulose, which has been degraded to the same average DP under different conditions, the higher the temperature the less its leveling-off DP and also its Kc. (degradation constant of crystalline region) 3. The hydrolyzed holocellulose with same average DP, has about the same amount of crystalline region in it, irrespectively of the temperature and pH during acid hydrolysis. However its yield from original holocellulose decreases under the higher temperature. From these results it could be presumed that the acid-hydrolytic reaction at the latter stage of commercial sulfite cooking has a fairly strong influence even upon the fine structure of wood cellulose according to the pH and temperature in its acid medium.
A tentative method of permeability mesurement of cocoon layer is described in this paper. Assuming the shape of cocoon is sphere, we introduced the fundamental equation governing the flow through the porous cocoon layer, and the following general relationship is found: where, Q: total flux, rw, re and Pw, Pe: inner and outer radii and pressures respectively. As the cocoon layer is much thinner than the apparent cocoon radius ro, we may regard re_??_rw, then we obtain: where A: surface area of cocoon, t: thickness of cocoon layer, ΔP: pressure difference. This relationship implies that, when the thickness of a cocoon layer is much thinner than its main radii, the flow through cocoon, having any shape is identical with the one of plain porous media as textile fabrics or paper. This fact simplifies the calculation of permeability of such media. If surface area of cocoon is calculated by Yanagisawa's formulae, we can obtain the permeability of cocoon with very simple treatment.
Sampilng method for counting fibres at cross-sections in blended yarn has been studied. The results obtained are as follows. In practical yarn, coefficient of auto-correlation is not any significant at intervals within mean fibre length L on each component fibre in case of continuous cut, and this shows that statistically independent sampling interval is obtainable even within L. Therefore it is found that the sampling method at 1″ interval described in the previous report (Part IV) has achieved the purpose of sampling. Further, for calculating blend irregularity, even if the sampling method for calculating yarn evenness were used just as it were, it would make no great difference.
(A) Colouring As is well known, the carroted fur colours - yellowish, brownish and/or orange - and the tone and deepness vary according to the treating conditions. The following results are obtained: (1) The hue of the carroted fur can be separated roughly into three groups, i.e. the orange (brownish yellow), the brown and the yellow. (2) As HNO3 content of the carrotting agent increases, the fur tends to become orange and the tone becomes deeper. (3) When the concentration of Hg(NO3)2 goes over 4.5% the fur tends to become brown. (4) As the carrotting temperature is raised, the proportion of the furs coloured yellowish or orange increase and at the same time the tones deepen more and more. (5) When the immersing time is longer, the orange colouring becomes predominant and the tone deepens. (6) The weight increase of the carroted fur of brownish and orange is remarkable, and becomes larger as the tone deepens more. On the contrary, the changes in the yellowed sample is negligible. (7) The concentration of NaNO2 does not affect significantly on the colouring at 5% level. (B) Crimp Increase The feltability of the more crimped animal fibre is greater than those of the poorly or noncrimped fibers. The crimp of the fur increases by carrotting, therefore it is often said that the effect of carrotting is to give more crimp on the poorly crimped fur (E. H. Mercer, 1954). So the authors measured the crimps of the carroted fur under various conditions reported in the previous paper (XIX), and the following results were obtained: (1) The crimp increases with the concentration of Hg(NO3)2 and HNO3 and with the immersing time and the temperature in the experimental design of 5×5 Hyper Graeco-Lation square. (2) In L27 (313) experiment the increase of crimp depends only on the concentration of HNO3. (3) The more the fur is crimped, the more its weight increases and its orange colour deepens.
In Report IV, the effects of moisture content in cut-material, and the weight of traveller upon the dry strength and elongation of the yarn while twisted were reported, and in this experiment then effects using the same samples upon the wet strength and elongation are tested. The result, showns that when the heavier traveller is used and the moisture regain of the cut-material is 50%, more wet strength can be obtained. Then the changes of strength and elongation of both the twisted and untwisted yarn were measured. when the yarn is more twisted or untwisted under the dry condition, the strength of yarn decreases. But when the moisture regain of cut-material is 50%, whether the yarn is twisted or untwisted with the possible heaviest traveller, the decrease of strength is very small, especially, of the wet strength. After testing the strength of commercial paper yarns and spun yarn under the same treatment, the results and then comparing them compared with those cited above show that decrease of the strength is caused by the decreased contact of the yarn.