I ' i LL '^-^' ^ I ^ / / , Ali^^n, *r!: ^^ '" ^"V •nfo^mation so classS^^;3^^'°''"'''^^ ^^ '^^• sons m the milit^iffl^l slT '?"'^ *° ''^'■ States apprariiiK^SSn n« ^^'"^^^ °f the United tne fedeaJcEBlfeZ^t 2 !^ "'^ ''"^ employees of theiailSllVEr^t^t ° r r "^ '^g'*''^"ate interest jSSion wh^ f ^ ^'^'""' °f '^"own loyalty (.•*eT,on Who of necessity must be .nformed '^£ST»Me^£Q No. 1292 L_. U.S. Dth'OSiTO'-T UNITED STATES DEPARTMENT OF AGRICULTURE FOREST SERVICE FOREST PRODUCTS LABORATORY Madison, Wisconsin In Cooperation with the University of Wisconsin mm. cf K ' ^'^m Digitized by the Internet Archive in 2013 http://archive.org/cietails/neutralOOfore ACID AND NEUTR/IL SULFITE SE!,IICHS!'ICAL PULPINC- OF SIX .iJlFA^NSAS DELTA ^-^ASDTO^DS By J. N. I^Cf>OVSR]\T, Assistant T^^chnolof^ist and G. H. CHIDESTER, Senior Engineer Forest Products Laboratory,- Forest Service U. S. Department' of Agriculture ABSTRACT Semichemical pulping processes, using both acid and neutral sul- fite liquors, were applied to the following six Arkansas Delta hardwoods: black willow, southern cottonwood, America.n elm, sugarberry, green ash, and bitter pecan. Pulping conditions for yields of 75 to gO percent were determined and the properties of both the pulps and nine-point boards pro- duced from them were evaluated. The general results were as follows: (1) Both the acid and neutral sulfite processes caused greater lignin removals from willow and cottonwood yet the pulps had lower lignin contents and higher alpha and total cellulose contents than did the pulps from the other woods. (2) The neutral sulfite pulps from willow, cottonwood, and sugar- berry had strength properties suoerior to those of the pulps from the other woods. (3) The acid sulfite process caused greater removal of lignin and. cellulose but less removal of material soluble in 1 iiercent caustic soda than did the neutral sulfite process. The pulps from the acid -orocess had lower strength values than those from the neutral process. (U) The proper- ties of nine-Tooint corrugating boards made from the neutral sulfite pulps, especially those from willov:, cottonwood, and sugarberry, were equal or superior to the properties of many commercial boards. (5) The nine-point boards made from acid sulfite pulps were inferior to those from the neutral sulfite pulps. I!TTRODUCTION A vital problem in forest utilization exists today in the produc- tive use of the hardwoods which compose a predominant part of many of our forests. In the lower South, for example, 5I percent of the forest area is occupied by hardwood forest types and 63 percent of the total volume of usable v^ood is contained in hardwood trees, as revealed by the recent Federal Forest Survey (l). These figures make apparent the critical need for effective hardwood utilization in that region. r !;!aintained at I.'adison, T7is. , in cooperation vrith the University of Wisconsin, RI292 A logical outlet for many of the hardwoods appears to "be in the form of pulp^'ood, and the possibilities of hardvoods for pulping purposes have been recently outlined by the Forest Products Laboratory (2) . The production of pulp from hardwoods is particularly significant at this time in view of the threatened shortage of wood pulp in the United States. The Forest Products Laboratory has recently investigated the pulp- ing of six species from Phillips County, Arkansas. This delta region sup- ports almost pure stands of bottomland hardwoods. The species studied were black willow ( Salix nigra ) , southern cottonwood ( Populus deltoides virginiana ) American elm ( Ulmus americana ) , sugarberry ( Celtis laevigata ) , green ash ( Fraxinus pennsylvanica lanceolata ) , and bitter pecan ( Hicoria texana ). These representative species have been subjected to various pulping processes, including the acid and neutral sulfite semichemical pulping procedures with which this report is especially concerned. The neutral sulfite semichemical pulping, in particular, was applied to these woods because it had been pre- viously found (1_) that pulps prepared according to this process had promis- ing outlets for news, board, and liner and, after further purif ica.tion, for high-grade pulps. The immediate objectives in the pulping of these woods by the acid and neutral sulfite semichemica.1 procedures were (l) to establish suit- able digestion conditions for yields in the range 75 to 80 percent and to evaluate the pulps so produced; (2) to produce pulps in semicommercial quantities for conversion into nine-point corrugating board and to evaluate the boards so produced; and (3) to compare the acid sulfite and the neutral sulfite semichemical pulps, and the nine-point bo.ards made from both. EXPERII.fflMTAl PART For the pulping experiments each of the six hardwoods was converted into standard 5/g-inch chips. Preliminary trials to establish cooking con- ditions suitable for a yield from 75 to gO percent were made in a I.5 cubic- foot, alloy-clad, steam- jacketed autoclave. Larger-scale digestions to furnish material for nine-point boards were conducted in an alloy-lined, steam- jacketed, tumbling digester having a capacity of I3 cubic feet. The preliminary neutral sulfite digestions were designated as series I, the lai-ger-scale neutral sulfite digestions as series II, the preliminary acid sulfite digestions as series III, and the larger-scale acid sulfite diges- tions as series IV. The neutral sulfite liquors were prepared by dissolving sodium sulfite and sodium bicarbonate in water and diluting to the desired concen- tration. Fresh liquor was used for each of the digestions in series I, whereas in series II after the first digestion with fresh liquor the blow- back liquor from the previous digestion was utilized in making up the liquor for each succeeding digestion. The concentration of the neutral sulfite liquors was approximately 75 grams per liter of sodium sulfite and 15 grams per liter of sodium bicarbonate (calculated as the carbonate) for practically all digestions. RI292 -2- The acid sulfite liquors ^ure rirc-pared by loassinp; sulfior dioxide from p cylinder into millr-of-liine . The concentration for p11 digestions was 6 percent total with O.9O percent combined sulfur dioxide. The digestions vith the neutral sulfite liquor were carried out as follows: The chips in the nutoclave or digester were steamed at atmos- pheric pressure for one-half hour. The impregnation liquor was then charged and the temperature raised by indirect and direct steam to approx- im'^tely 120° C The rise required ik minutes in series I and 32 minutes in series II. The temperature was maintained at this level for from. U5 to 60 minutes, dioring which time the pressure was held at 100 pounds per square inch by rrieans of steam introduced at the top of the autoclave or digester. Upon completing the impregnation period, all excess liquor was blown from the digester and the temperature raised to approximately 170° C. by indirect and direct steam. The rise required 11 minutes in series I and IS minutes in series II. The cooking period was continued for from U5 to 9c minutes at this temperature level, after which the steam vras shut off and the pressure relieved. The chips were d^jmped from the digester and washed thoroughly with hot water. The chemical absorbed by the chips during the impregnation period v/as determined by the difference between the amount of chemical in the blowback solution and that in the initial liquor charged. The method of analyzing the liouors has been described previously (3_) • The digestions with the acid sulfite liquor follo-ed usual sulfite pulping T^rocedure, except for a shortened cooking schedule. The tempera- ture '"as raise'^. to 110° C. in ? hours, followed by a rise to 130° C. in ? hours more. In the first trial digestion the temToeratiore was held at 130° C. for 1 hour before starting the -oressure relief; in all other digestions the pressure relief '-'as started '-'hen the maximum temperature of 130° C. 'T'as reached in k hours. The -Dressure relief required 13 minutes in series III and from h^ to 60 minutes in series IV., The chips were removed from the autoclave or digester by dum.ping, after which they were '-ashed '-ith water. The yields of the pulps were based in all instances on the moisture-free weights of the -oulps defiborcd in a 5-pound beater. All the chips from the autoclave digesters were dcfibered in the beater, whereas only a sample of digested chips fromx the larger-scale digestions was thus defibcred. The remaining chips from the larger-scale digestions were processed in a Bauer mill. Strength and chemical tests were made on the beator-defibered material in the case of the autoclave pulps and on the Bauer-milled material for the larger-scale pulps. The strength char- acteristics of the pulp v'ore determined by tost beater processing. The nine-point boards made from Bauer-milled pul^os '-ere also tested for strength and in addition the color was measured by the blue reading on an Ives photometer. All tests '-'orc made according to standard Forest Products La.b oratory methods. RI292 -3- DISCUSSION The Wood The six hardwoods employed in these experiments had certain material differences in their physical and chemical properties. The data presented in tahle 1 v^ere taken from a more complete report describing these woods (U). The most notable differences between the woods occurred in their densities and cellulose contents, which covered a considerable range. The variation in density was perhaps the most pronounced of all the properties, the range being from 23 pounds for the comparatively light willow and cottonwood to 36 pounds per cubic foot for the relatively heavy pecan. The density was therefore considered the basic variable for purposes of later comparisons between the woods. While all , the woods were classed as young and rapid growing, the v;illow and cottonwood were out- standing in this respect, being comparable to rapid-growth southern pine. The data in table 1 also indicated that some of the logs ^'ere larger in diameter than is common for pulpwood. It is interesting to note that the sugarberry and green ash contained no heartwood. The total cellulose contents of the hr^rdwoods differed to a considerable extent, varying from 5^ percent for green ash to 63 percent for ccctonwood. There was a trend to'-'ard increasing cellulose content with decreasing density. The three lightest ^-oods had relatively high alpha cellulose contents in comparison ^-ith the three heaviest v'oods. Except for the lo^- lignin content of the sugarberry, this component in- creased roughly ^ith density. The pentosan contents shored no definite change from species to species, except that that of the sugarberry was somewhat higher than the others. With the exception of ether solubility, the ash and sugarberry had generally a higher solubility in the various solvents than the other woods. The material soluble in ether was low while that soluble in 1 percent caustic soda was relatively high for all species. Neutral Sulfite Semichemical Pulping Series I. Preliminary Autoclave Experiments Several trials were necessary with sugarberry, the first wood tested, in order to establish impregnation and cooking conditions suitable for yields in the range of 75 to 80 percent. It was found that relatively moderate conditions produced a pulp having a yield in the desired range. Briefly, the general conditions found to be satisfactory were an impreg- nation at 120° C. for U5 minutes with a liquor containing 75 grams of sodium sulfite and I5 grams per liter of sodium bicarbonate (as the RI292 -U- carbonate) and a cooking period of U5 minutes at 170° C. These general conditions were applied to all the woods with two exceptions. In the case of the hitter pecan (No. 319, tahle 2) an increased impregnation time of 60 compared with U5 minutes was required for sufficient chemical absorption because of the relatively high density of this species. In the case of the American elm (No. 33U, table 2) a cooking time of 60 instead of U5 minutes was needed for a yield in the desired range. There was no apparent reason why the lignin and hemicellulosic matter, the main con- stituents besides extractives removed during pulping, should be more difficult to remove from elm than the other species. Certain differences in the absorption of chemical during impreg- nation and in the strength properties pnd chemical analyses of the pulps from the various woods were noted from the results of the digestions per- formed as described above. Some of these differences could be related to the physical and chemical characteristics of the woods themselves. The data are given in tables 2, 3) and U. With impregnation conditions approximately the same for the six species, the volume of neutral sulfite liquor retained, and to a lesser extent the total chemical absorbed, de- creased with an increase in wood density, as shown in table 2, series I. It is to be noted that, even with a slightly longer impregnation time, the least amount of chemical vras absorbed by the most dense v/ood, bitter pecan, and yet a sufficient amount was present to bring about the desired pulping. Except for a practically constant residual sulfite content in the spent liquor, all of the chemical absorbed during the im.pregnation period was ccn-sumed during the cooking stage, regardless of the amount initially presen':- The yields of defibered pulp from the six hardvvoods fell in the relatively narrow range of jG to 79 percent when the cooKing conditions were ci-sely alike, except for the differing amounts of chemical present at the start of cooking. It appeared, therefore, that only a certain min- imum of chemical was needed to pulp these woods to a definite yield. The small yield variation also indicated that the sum of the lignin, cellu- losic, and extractive material removed during cooking was approximately the same for all species. The .percentages of each chemical constituent present in the different pulps and the percentages of the original con- stituents remuved varied, however, with species, as shown in table 3. series I. The chemical analyses of the pulps showed tha.t their lignin con- tents fell in the same order as those of the respective v^oods, except for the sugarberry, whose pulp lignin content was high in relation to its wood lignin content. The percentage of the original lignin content removed from Cottonwood and willow, however, was considerably higher than that from the other woods; approximately 50 for the former as compared to 30 for the latter. This higher percentage of lignin removed from cottonwood and willow would be important where subsequent purification to a more deligni- fied pulp is desired. As v;ith the lignin, the total cellulose contents of the pulps fell roughly in the same order as those of the woods, again with the exception of the sugarberry, which had a pulp value higher than might be predicted on the RI292 _5_ basis of the cellulose content of the rood. The v.'illov ajid cottonrood pulps have outstandingly high cellulose contents comppred ^-ith the others. The percentage of the original total cellulose removed varied "betveen 2 and 6 percent, vith no particular order in regard to other properties. This relatively lov cellulose removal illustrated the mild action of the neutral sulfite liquor. Excluding the elm, the alpha cellulose values of the pulps had the sam.e order as this constituent in the ori^rinal roods. The alpha cellulose values rere higher for the cottonv:ood and vrillov: than for the others. The percentage of alpha cellulose material removed during cooking V7as "belov 1 percent, except for the elm and pecan, vhich had rela- tively high values of 6.6 and U.O percent, respectively. The pentosan values for the pulps from the different \70ods did not differ greatly, but the percentage of original pentosan material removed by cooking varied be- tween 22 and 37 percent. The percentage removal of material soluble in 1 percent caustic soda, a measure of the hemicellulosic constituents removed during pulping, '-as high, running from approximately 60 for cottonvood to over 80 percent for green ash. The varying distribution, '"ith species, of the amounts of the chief constituents removed during tJulping is illustrated in table 3> series I ,• under the heading, "Amounts Removed from 100 Pounds of Wood." Whereas the total removal of lignin and cellulosic material varied by less than 3 pounds (apToroximately the same vririation as for yield of defibered material), the actual amounts removed varied from a lov; lignin and high hemicellulose removal in the case of sugarberry to a high lignin and lor hemicellulose removal in the case of the cottonrood. In addition, the elm and pecan under'-ent a certain removnl of material of the alpha cellulose type. The strength properties of the neutral sulfite senichemical pulps, tabulated in table U, series I, covered the range typical for this type of pulp. The bursting, tearing, and tensile strength values placed the pulps from the rillor and cotton^-ood ahead of the others, those from the sugar- berry intermediate, and those from the ash, pecan, and elm last. The last three also required longer beating times to attain a given freeness and had lo-'er solid fraction values than the others. Series II. Digester Experiments Application of the neutral sulfite scmichernical pulping condi- tions developed in series I to the larger-scale digestions in series II produced results closely paralleling those discussed in the foregoing paragraphs. The actual digestion conditions used for series II, horever, differed in some respects from those used for series I. The conditions and results can be compared in tables 2, 3. and U. The weight of wood in the digester charged to capacity was proportional, of course, to the density of the species. With proportionally larger wood charges in the larger-scale digestions as compared to the preliminary ones, the impregnation stages for the former were made with lower liquor-rood ratios and showed lower chemical absorptions. Nevertheless, sufficient chemical was present in all cases to perform the desired cooking. All of this chemical, except a small residue RI292 -6- in the spent liquor, -ras consumed, rsf^prdless of the ?.iiiount present. A shorter cooking time v/as employed for the digestion of the elm in series II than in series I; the shorter time led to an increased yield of pulp from the elm. The pulps in series II showed the same trends ^"-ith species as those in series I vith regard to chemical analyses, percentages and amounts of wood constituents removed by cooking, and strength properties. Tnese are given in tables 3 ^'^^ ^• Nine-point Corrugating Board The pulps described in series II on conversion into nine-point corrugating board had the characteristics given in table 5* The strength properties of these boards follored the same general order of species as established for the pulps in series I and II in that the vrillovr, cotton- T70od, and sug?irberry vere superior to the others in bursting, tearing, and tensile strengths. The color of the boards was in direct relation "^ith the color of the original v/oods; the ash giving the lightest color and the willow the darkest. On the basis of the physical properties, the boards made from willow, cottonwood, and sugarberry T^rere equal or superior to boards previously made at the Forest Products Laboratory from sweetgum and blackjack oak, and also '-'ere superior to commercial boards from pine ground- wood, chestnut chips, a.nd stra'.' that have been tested at the Laboratory. Acid Sulfite Semichemical Pulping Series III and IV. Pulping Experiments In a trial digestion with sugarberry using conditions calling for a total time of 5*2 hours, as outlined earlier, a pulp yield of 59*9 percent was obtained. By eliminating the time of 1 hour at the maximum temperature of 130° C. , or shortening the total time to k.2 hours, the yield was raised to 76.1 percent. These latter conditions were then applied in trial diges- tions with willow and cottonwood. The chemical analyses and strength tests of the pulps from the three woods are given in series III, tables 6 and J, The same conditions, except for the longer blowdown period, were also applied in the large-scale digester experiments to willow, cottonwood, and sugar- berry. These results are given in series IV, tables 6 and 7* The yields from the three species in series III cooked under the same conditions covered the rather narrow range of from jh.? to 77*7 percent (table 7) and were apparently little affected by the species used, checking a similar observation in the neutral sulfite semichemical pulping experi- ments. Because of the extended and variable blowdown period for the diges- tions in series IV, the yields v^ere somewhat lower than those in series III. RI292 -7- The chemical analyses of the pulps in both series III and IV (table 6) showed the same species relationship as v^as observed in the neutral sulfite semichemical pulping exT>eriments. The yrillow and cottonwood pulps had lower lignin contents than the sugarberry pulp, although the latter wood was lower in lignin than the other two. The pulp analyses show that the willow and cottonwood also had more lignin removed during pulping than the sugarberry, but the difference was not so great as that found previously in the neutral sulfite experim.ents. The total and alpha cellulose contents of the willow and cottonwood pulps were considerably higher than those of the sugarberry pulps, following the relations for these constituents in the woods. The percentages of total and alpha cellulose removed during pulping were approximately the same for all species, averaging 11 and 1 percent, respectively. The pentosan content of the sugarberry pulp v;as higher than that of the willow and cottonv;ood pulps, as was the case in the respective Vfoods. The percentage of pento-san material removed during pulping, however, v/as less for the sugarberry than for the others. With the exception of a higher solubility in 1 percent caustic for the sugarberry pulp, the other resT^ective solubility values were about the same for the three species. The high values for solubility in 1 percent caustic soda for all the pulps indicated the presence of a considerable amount of hemicellulosic type material which was insoluble in the acid sulfite liquor. Part of this material was present in the vrood originaJ-ly and part v/as formed by degrada- tion of the cellulose. The strength properties of the three pulps prepared in series III ' and IV, respectively, showed no difference between the willow, cottonwood, and sug-.rberry, except possibly lo'-^er tensile strength and solid fraction values "^or the sugarberry pulps. The data are given in table 7* However, certain differences were noted between the pulps from series I which had been deiibered in a beater and the pulps from series II '-hich had been de- fibered in a Bauer mill. The normal initial freeness values for the pulps defibered in the beater indicated that the refining action vras solely that of separating the fibers, whereas the relatively low initial freeness values for the pulps defibered in the Bauer mill indicated a combination of fiber- separating and hydrating actions. Furthermore, the values for the developed strengths of the pulps from series IV were somewhat higher than the corre- sponding values in series III, possibly becaiise of the particular refining treatment received by the pulps from series IV. Nine-point Corrugating Board The properties of the nine-point corrugating boards from willow and cottonwood acid sulfite semichemical pulps are given in table g. The data showed that these boards vrore slightly superior in bursting and tensile strength to commercial corrugating boards made from pine groundv/ood, chestnut chip, and straw that have been tested at the Laboratory, but were somewhat inferior to these boards in tearing strength and stretch. The board from the cottonwood had a fairly high value for Ives blue color read- ing. None of the boards was outstanding in any of its properties. RI292 -g- ComiDarison of Acid and Neutral Sulfite Pulps and Boards An 3vera,?;e of the results from the autoclave- scale semichemical pulping; experiments applying neutral and acid sulfite liquors to black willow, Cottonwood, and suf^arberry, series I and III respectively, furnished a good comparison of the action of the two processes on the three species. The averages axe found in table 9* The average yields obtained by the two processes were much the same, 7^.0 percent for the acid and 77* 1 percent for the. neutral sulfite, so that the comparisons may be considered as being made on practically an equal yield basis. The bursting, tearing, and ten- sile strength values from beater tests for the acid si-ilfite pulps defibered in a beater v/ere considerably lower than those for the neutral sulfite pulps similarly defibered. The solid fraction values were also somewhat lower for the acid sulfite pulps. The low strength values for the acid sulfite pulps were considered due to the acid condition during the pulping treatment. The pulps of both processes that had been defibered in a beater showed no differ- ence in the test beating times to attain a given freeness value. It was mentioned previously, however, that the action of defibering the acid sulfite pulps in a Eauer pulper caused a considerable drop in freeness, whereas the neutral sulfite pulps likewise treated showed no effect except for a slight freeness drop in one case, the sugarberry pulp. The hydrating tendency for the acid sulfite pulps was apparently caused by presence of relatively large amounts of hemicellulosic constituents. The chemical analyses of the tv;o tj'pes of pulps and the percentages of wood components removed during pulping given in table 9 also showed the effect of the acid as compared to the neutral sulfite semichemical pulping conditions. Although the average yields gained by the t^o processes v;ere quite alike, the acid process pulps had somewhat lower contents of materials analyzing as lignin, cellulose, and pentosans, but considerable higher amounts of material soluble in 1 percent caustic soda than the neutral process pulps. In terms of percentages of the original constituents removed during pulping, the acid process caused a greater removal of lignin, total cellulose, and pentosan (furfural-produ.cing) material than the neutral process, but a considerably lower removal of material soluble in 1 percent caustic soda. It is possible that the relatively large amount of material soluble in 1 percent caustic soda in the case of the acid pulp was composed of degraded products from the cellulose-analyzing component of the wood, altered pentosans materials not producing furfural according to the test procedure, and hemicellulosic materials soluble in the alkali but not in the acid cooking liquor. The nine-point boards from the neutral and acid sulfite semichemical pulps differed in strength in the same manner as described for the pulps from T;hich they were made. This is shown by comparing the respective values in tables 5 and g. The acid sulfite boards were definitely inferior to the neutral sulfite boards. RI292 -9. LITERATURE CITED (1) Eldred^e, I, F. Southern Forest Experiment Station. Occasional Paper No. ^Z (Uaj l6, 1939). (2) Bray, U. W. , and Chidester, G. H. Paper Hill 63 (U6) ik, I6, 18, 20 (I'lovember I6, I9U0) . Curran, C. E. Pulp and Paper Mag. Canada kl_ (10) 665-8 (September 19^0). (3) McGovern, J. ¥., Evert, J. N. , and Chidester, G, H. Paper Trade J. (U) Pew, J. C. , and Schafer, E. P. Forest Products Laboratory mimeogrophed report. Problem r-lS9( project II68-5 (J"une I9UI). 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H r^ o Of u o 4-) c C o c (£1 u -4 p« 4-1 c: J3 a < ♦J u c P © « o u (> r ♦^ c 4J c: 1 4)X CJ OO « L Cl >> 1 o z u *J 1 & o Ut ^ I r-t 4*1 3 1 U c A H 1 t> « a O 1 :: C) rH u -1 ,J (11 u* , r-( o C K a 0) 41 (U a c u r-l g ■<^ 0, *J c •;! n ** o t. «H &^ c to n 0^ j:] CJ 01 O o 0« « a •35 « O r-4 u fr* r-< 4J C c tA t. 4) ^ 0« • • •4 O s. a r*- H m TO rH K\ H r^ OJ ^ CU (\J (\J CJ OJ ^ W K\ J* OJ ^ C\J ON r4 r^ ITV C\J VO VO IXN ^0 l*N (\» K\ OJ v^ -^ '^ ^D ,-- -^ TO ^ K> K\ K\ 10 TO ^ rH O r^ r^ i-l TO CA Oj ;* O r- r— lA '-D vo rw vi) r*^ i*N K\ r— r^ r- fH cr* c\i f*^ CM r^ c\j -^ — * O iH — ' ^-^ TO C\i ir\ l*N K\ l*N C\j ITV ^ r (^ -P to I I EH 0) U o o o c\j M If) (D B o ^l Vh w > -P M -P CO CO 0) •H o CO i-H M •H CD • •H 0) . a 0) PQ d o •H o •H o a El 4-3 a CD ;h C« •H 03 (D ■P -p to Pi (-1 CO I I w ■t:) Q) •H CD P P ^1 Ph P (D P 0) -P cd o ■ H CD U CM C\J CM C\J cT\ 60 cr> cr\ CT^ cp\ rH^ CM CM r-H rH VvD LTN r^vD r — r — CM CJ> O LC^ rH CO r^CM^ CM J- J- r^ r<-Nbo co-:^- t-^ ^ ^ CM r^ r^r^ O J- ^ li^ O VD LT^ r^ r^CM r^CM CM o 0) p^ rH ;:) Pj CD pq •H TJ CD o CD 000000 Ti 000000 O ctn cvj UD cr\ r — co PJ vn Lr\ CM J- CM CM rH ^ 000000 O O O O Q O f-t O f^J^ jrt ^ ^ a) »►«»..« -(J -r^ r^ rH CM rH rH CO CD f^Cl •H O CM CM CM r— CM CO cj> r— r — >vD r — -t^ o o o o • H CM Lr> CM CM CM LO o o r — CO vD v£> o rH r-H * * * * K^ rH ►H 000 1^^*^ f"^ *"• r-- CO J 'vX) J- j=f CO O CD •H {-, CD CO O ^ r— LO r^ r— VX) L^^ CM ^ CM CM CD o o & c o -IJ ■p o o o CD ft fn a (D C\j -P ^ J-( -H W ci! fq O O O O U^O (^ r^vD I — r — r^ CO CO CO r^- CO CO 1^^ O U) UD O ^ rH I . O U3 rH iH rH . r^ CM r-- CO r— CM LOl rH r-- r— CO . f^ r<~\ CM • CM CM '. 000000 O LO o O Lr^ o r — CO C3^ CTN CO rH '^ VX) r^ LTn CM CM 000 000 r-^CM I — o o o o -=|- o CO CO c^vX) r— cr« 1 — to r-i to rH r^ '. CO . VXI M3 rH r-i cr\ CM r-- CO t^O r^ u^ LO CO J- r^ CO CM CM '. CM LTMO r^ . CM CM • o rH Td rH O • H O o •4J P o PP o o a O 1) ft -Ic^ f^ CD c23 pq Table 5* — Properties of nine-point boards from neutral sulfite semi chemical pulp 3 Species : bursting : strength : Tearing : : strength: Tensile strength : Stretch: Solid fraction iCaliper ; Color •Points per ^:ound per ream— : Grams per:P : ■Dound : :per ream—: ounds per .Percent : Points: Parts^ blue - square inch Black willow 0.65 : I.OU : 7,iUo . 3.15 : 0.55 . 9.6 : ^3 Cottonwood .50 : l.OU : 5,oUo 2.95 : .U5 g.3 ■: 50 Sugarberry .U7 : 1.12 : U,700 3.60 : .Uo 8.9 : 50 American elm .36 : .gl : 3,250 . 2 . Us .; • Ul 9.3 : 50 Bitter pecan: .29 .67 ■: 3,260 2.60 : .U5 • 7.9 : 39 Green ash : .15 .52 : 1,920 : 2.10 : ,3S .: 9.5 : 53 -25 X UO - 500 ream. 2 Ives photometer. RI292 VX .H OO XI u. m 3 ifv r^ ftj *j o o 4^ I 6- C tf o as y o 1) s •t3 (0 o c o o » o K\ <\|I K\ BO <7\ «) ^ lA O -4 r- Q K\ w «p in iTv J- ir» ^ ^ r'N --* o -^ .\j> oj cul • CVJl • • ^ ^^ CVi w K\ in 0) ■p C/3 I I EH 0) o o o rvj w -p to Q) ;-! 1) -p k3 0) S o u 0) > -p a (D !h -p CO •l-l o © CO 1—1 a; . Q) CO •rH -P 0) o •H -P o ai •H o CO -p U -P w CD Eh -P C o ;-i -p w C ■ H Eh -p a 0) !h -p O •rM P V) CO I I C/J CO CD CD CD I I CO I I w CO (D CD CD U I I at w CD c; (D Q) ^1 CO I 1 w if) CD d CD u o CJ o o o o o GO o o o o o o o CO o o o in LPn o o o o 50 o o o o o o o C)0 o o o O O o o to R1292 Ul fl) T-J ^1 ri^ % ^H crt C) CD ;=! G 'A CT ■ H (^ w tn -l. CT •H (Jh to to Ti CD i-^ ^1 f-< CT^ CD p fH p U e> p a) Pj w Tl CD ^i M !h cri ;rj Jh P !-< cii P Q) fy to 1 p TJ a) ^ M C fn •H CD p P f-t 1^ P Q) P\ to p Tj a ?H C •H CD p .-^ |Jh Pl CD ^1 CD •H HH CD PJ P^ ury lO m r^ fH cr« CTn cr\ BO aj C)0 C\J o CM CJ> o CO o C\J o o CD -rf rH CVI CT^ (AJ (\J J- CO o> C\J CM O CM CM m VD VD LTN Lr> CT> ■H C5 ^H CJ> bO CM CD -=!■ CM r — c:> CT\ rH ^D co CM CO i-H ^1 PJ rH ::< PJ (D (^ a •H Xi S-H ^ ■H V^ CO P^ rH P< P^ U P t/; •H -P o o <+H o I J- rHl CTN r^ CM rHi rH| CO o O o ^1 rHi & I-H t:) >. rH fn •H (h ^ .^ a rQ Ai ^H -p 01 CO -p ql) r^ ^ m CO ^ rH TJ S r-^ ^1 ■ H ^-1 ^ t5 C ^ .M ^1 C) P cvi «1 -P WJ rH T^ (/J o o o o CO c w a ^1 si •H -P •H c Table 8. — Properties of nine-point boards from acid sulfite semichemical pulps Property Species Black : Cottonwood willow O.3U : 0.33 .59 .65 kl20 : U9U0 2.1 : 2.3 .^47 .56 g.g : g.5 3^ : U9 Bursting strength — Points per pound per ream- Tearing strength — G-rams per pound per ream- Tensile strength — Pounds per square inch Stretch — Percent Solid fraction Caliper — Points p Color — Parts blue— "25 X UO - 500 ream. ~Ives photometer. 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P! fl 1 -p -p -P (U q; (D a) 5 I 1 1 ftH 0) PirH rH PnrH P3 PnrH P> m: Ph rH rH nJ CO rH n3 (D n-i 03 fl.) r-\ 03 • H r-i 03 P) > > pi > Ph pi > ,-( 03 pi > rt Ph rH Ph Ph Ph •H ^25 Ph •H a pi a 05 a <-i a ^ a G c: (D rA C! ^ fi 0) a rt CD pi -P d t>fl n rt r-K HH p^ p I-H « -p I-H -Th r~i ^ l-A c^l •H 0) rH H^l -Ij EH (n • • • • • • • • • • * • - • • • • • • • • • r^^ ^D fH r^rH r-\ Lr> r — cr\ CO r^J- % • t • • • • r^ cr\ (T\ r^ C\J C\J LO, r^LOi • • • • • • • • • • • • • • • • - • • • •• 0>VX) (T\ r^\ r— r->, OJ LO,.zt CM aj • • • • • * • VD c\j 'X) r— CM LO cr« h- p p: o Ph Ah Td >-i Pi Ph O Ph Pi P O Ah 1 O cJ 1 O O +^ O LO t>DCO LO I P- I P CO CO CO tu) P) c •rH Pi a ro Pi Pi P, O P Pi P-; Pi P! •H Pi I CO p. © Ph m I CJ o o o I o o ^ O LO P> CO LO I I I i CO p. pi pq t/5 CO d Ph 1^ Ph P. +-> c« •H Pi 03 en o o ^ O LO 4J CO I LO Fm F'h d Ph -P CO CO d EH O O O O O O O LO CO LO d o 1 1 •rH I 1 P O CA C/5 o5 CO CO Pi ■hh d d xj •rH tn Ph rH Ph Ph O HJ p^ d O CJ o o s o o O LO I CO LO I I I I I a ■ H CO CO -P to CO t»D d d d •rl P Pi Ph cti Ph Th 0) W T3) o o +J d d +:> •H -P CO d • g ^H ct3 Pi H^ ^ LO g 1 c:3 1 d -rf -d l--^ CO LO OS C\J Fl C\J UNIVER; irv OF FLORIDA 3 1262 08866 6069