Studies on effect of topology on pulp and paper characteristics ofEucalyptus camaldulenosis

Dharm Dulta', R S Malik", J S Upadhyayaa. C H Tyagi" & M K Upadhyaya''"Department of Paper Technology. Indian Institute of Technology Roorkee, Saharanpur Campus, Saharan pur 247001. India

"Global Board Ltd .. Mahad, Raigarh, India

Received 4 April 2004; revised received 4 February 2005; accepted 2 March 2005

Indian Journal of Chemical TechnologyVol. 12, May 2005. pp. 332-340

the tree's environment, brought about by deprivationof water, nutrients or light, would lead to suppression,accomplished by wood basic density, which washigher than normal I . Due to slow growth rate in E.grandis, E. diversicolor and E. religna, the wood waspink red in colour, ray cells partly penetrated into thevessels and hindered the movement of liquids indifferent processes". In E. robusta, the wood densitywas found to increase with decreasing growth rate.'.The wood density was more controlled byenvironmental factors and growth rate and i11 E.regnan, the availability of water in soil affected thewood density and growth rate".

It was reported that in wet areas of Tasmania thegrowth rate was observed to be good due to uptake ofstored water during summer to avoid reductions ingrowth rate due to drought stress:". Continuousirrigation or cycles of drought were observed to havea marked effect on tree growth, fiber length, andimproved tear and tensile indices of the cold causticsoak pulp". Eucalyptus globules and Eucalyptus nitensgrown in mild frost conditions were having improvedheight and diameter growth". Water stress hadirduced changes in tissue growth, which postponeddehydration and growth reduction in eucalyptusspecies growth during periods of drought9.

11.

The occurrence of tyloses formation had beenattributed to change in water potential. In area wherewater content in soil fell down, the turgor pressureinside a parenchyma cell became greater than the

The seedlings of Eucalyptus camaldulenosis of same genotype were grown at different geographical locations havingdistinct pre- and post-monsoon ground water levels. It is observed that as the ground water level recedes. balloon likestructures known as tyloses develop, which affect the plant anatomy, physico-chemical and pulp and paper makingcharacteristics of E. camaldulenosis. The aging of E. cainaldulenosis has marked adverse impact on morphological, physico-chemical composition, pulping and black liquor characteristics along with mechanical strength properties of paper.

Keywords: Ground water, pulp and paper, Eucalyptus canialdulenosisIPC Code: D21C 11/00: 9/00

Due to scarcity of wood fibers, Indian pulp and paperindustries have to rely on fast growing species likeeucalyptus along with non-woody and agro-basedfibrous raw materials. Local fanners and variousstates forest corporations of India are meeting thesustainable supply of eucalyptus. The quality ofeucalyptus received from different sources includingold stock of stack were observed to have low breakinglength, double fold, and bur.t index at the samefreeness level compared to eucalyptus from UPFC(Uttar Pradesh Forest Corporation). However, tearindex was observed to be at par. Moreover, the totalunbleached pulp yield of eucalyptus collected fromdifferent stacks was slightly better than that ofeucalyptus from Uttaranchal, local farmers, andUPFC. It was also observed that eucalyptus receivedfrom Haryana consumed more alkali to get the samekappa number than that of eucalyptus received fromUPFC. E. camaldulenosis received from Haryana wasreddish and darker in colour and contained tyloses,whereas E. camaldulenosis from UP was lighter andpale in colour and free from tyloses. Both the sampleswere recognized as E. camaldulenosis at WoodAnatomy Branch of Forest Research Institute, DehraDun.

It was observed that the growth rate of eucalyptuswas found lower than that which would be normal for

*For correspondence (E-rnail: dutl_dhann@yahoo.com;Fax: 91 1322727354)

DUTT et al.: EFFECT OF TOPOLOGY ON THE PULP AND PAPER CHARACTERISTICS OF EUCAL YPTUS 333

pressure potential of the adjacent vessel element,through embolism blockage or wounding of the vesselelement. Tyloses caused difficulties during woodpreservation, chemical pulping, match making andprevent water penetration into the woodJ2

-15

. Due toprotrusion of tyloses, extractive content and basicdensity of the wood was increased which were themost important parameters for predicting pulp

. 16-19properties .Trees growing in water deficient areas were

observed to have tyloses due to extension of rayparenchyma into vessel with part of cytoplasm andnucleus due to reduction of pressure; or to thecessation of conduction in the vessel. Thedevelopment of tyloses as a result of wounding wassaid to be due to difference in pressure in the cells oneach side of the pit membrane. They prevent rapidentrance of water, air, and fungal filaments byblocking the vessel lumina''v".

Yuzana Bo Ni conducted a project work at KungalTekniska Hogskolan (Royal Institute of Technology)Stockholm, Sweden in 1987 on E. camaldulenosis. Heobserved that in regions where water content suddenlyfell below normal, tyloses were found in the woodstructure. Tyloses were not only inhibited thepenetration of cooking liquor into the wood butcooking conditions were also disturbed.

The cells when first mature were most active, andthere was gradual slowing down of conduction untilfunctional activity ceased with aging. Aging of sapwoodcaused the transformation from sapwood to heartwood.A number of important changes occurred i.e. living cell,their protoplast and the cell sap was withdrawn,commonly the water current of the cell walls greatlyreduced, any food materials present in the living cellswere removed. Tyloses a characteristic of eucalyptuswood were formed; the partly lignified walls ofparenchyma cells might become more strongly lignified;deposition or formation of resins, tannins, aromaticsubstances and colouring materials occurred23-25.

Looking this anomaly in the behaviour ofeucalyptus, it was decided to grow seedlings of E.camaldulenosis of same genotype at differentgeographical locations having distinct ground waterlevels to know its impact on anatomy, morphology.and pulp and paper making characteristics. Also theimpact of aging after 4 and 7 years of cultivation onmorphology, physico-chemical and pulp and paperproperties, and black liquor characteristics of E.camaldulenosis were studied.

Experimental ProcedurePlantation establishment

A representative sample consisting of about tenseedlings of E. camaldulenosis of same genotypewere grown in various parts of the country havingdistinct ground water level. Ground water levels ofdifferent places were measured with the help ofIndian Irrigation Research Institute, Roorkee, duringthe course of study periods twice in a year i.e. pre-monsoon and post -monsoon, by digging welltechnique. The ground water levels of different placesalong with their geographical locations are reported inTable I. Variations in ground water level wereobserved only before and after rainy season. Theaverage temperature variation in Uttaranchal. UttarPradesh and Haryana lies between 1 and 45DC,whereas, in Ballarshah (Maharashtra), the temperaturevariation lies between 25 and 40DC.

Anatomical studiesA number of transverse and longitudinal wood

sections of thickness 25 urn from middle portion of E.camadulenosis collected from different regions werecut on Leitz base sladge microtome 1300. The glassslides for microscopic examinations were prepared asper standard method IS: 5285-1969. Themicrophotographs of the projected images of T.S. andC.S. of E. camaldulenosis were taken at amagnification of 400 x The microphotographs areshown in Micro A-F.

Proximate chemical analysisE. camaldulenosis .were cut after 4 and 7 years of

cultivation. The logs were chipped in NormanCarthage and Yeco plan chippers. The packingdensity, wood density and moisture contents ofscreened chips were determined in each case. Theproximate chemical analysis of E. camaldulenosis cutafter 4 and 7 years were carried out as per Tappi testmethods" and the results are reported in Table 2.

Pulping studiesThe logs of E. camaldulenosis harvested after four

and seven years of age were reduced into chips inNorman Carthage and Yeco plan chippers followedby screening. The screened wood chips in each casewere digested in WEYERK rotary digester of capacity0.02 rrr'. The pulps were made by kraft process using17 % active alkali (as Na20) with sulphidity of 20%using 1:3 wood to liquor ratio at 168 DC withfollowing time cycle: time to 105 DC: 90 min, timefrom 105 DC to 168 DC: 90 min and time at 168 DC: 90

-

[)

334 INDIAN J. CHEM. TECHNOL., MAY 2005

c

Microphotographs: Cross sectional view of E. camaldulenosis (A) after 4 years (Ballarshah) (B) after 7 years (Ballarshah) showingvessels complelely filled up with tyloses, medullary rays and few axial parenchyma (C) after 5 years (Khurishidabad) showing vesselsfilled with tyloses (D) after 5 years (Akabarpur) showing vessels filled with tyloses and tangential view of E. camaldulenosis from (E)Mala showing vessels filled with tyloses (F) Nazambad showing medullary rays and very few axial parenchyma (Magnification 400 X)

min. The pulp was washed on a laboratory flatstationary screen having 300 mesh wire bottom forthe removal of spent liquor, further disintegrated inthe WEVERK disintegrator and screened through aWEVERK vibratory screen and the screened pulp wasfurther evaluated. The pulp was then beaten to 30 and43 °SR to study the effect of ground water level onpulp and paper making characteristics. The laboratoryhand sheets of 60 g/m2 were prepared on Messmersemi automatic sheet former. The sheets were airdried, conditioned, and evaluated as per Tappi testmethods. The results of pulp evaluation are reported

in Tables 3, 4, 6 and 7 and Figs 1- 5. The results ofblack liquor analysis of E. camaldulenosis harvestedafter 4 and 7 years of age are reported in Table 5.

Results and DiscussionTable 1 indicates the pre- and post-monsoon

ground water levels of different geographicallocations where plantations of E. camaldulenosis wereundertaken. The average pre-monsoon ground waterlevels of different geographical locations vary from1.82 to 23.52 m, whereas average post-monsoonground water levels from 1.64 to 22.56 m.

DUll et al.: EFFECf OF TOPOLOGY ON THE PULP AND PAPER CHARACTERISTICS OF EUCALYPTUS 335

Table 1- Pre-monsoon and post-monsoon ground water level data for different locations of study along with their geographical locations

Year EucaLyptus camaldulenosis cultivation

Of Nizamabad Saharanpur Chidiapur' Zafarabad Khurshidabad Akabarpur Mala Yamuna Nagar Ballarshahstudy Range Local (180 km) (260 krn) (230 km) (630 km) (650 km) (300 km) (200 km) (1600 km)

Ground water level. m

II I II I II I II I II I II I II II I II

1995 2.50 2.00 6.50 5.76 1.98 1.82 7.50 5.70 19.79 18.50 19.25 18.73 8.52 8.00 6.85 5.32 24.52 23.22

1996 2.70 2.20 6.00 5.24 1.66 1.57 7.15 5.55 19.50 17.66 20.05 18.29 8.61 6.54 7.10 6.35 25.05 24.10

1997 2.10 1.50 6.20 5.65 1.90 1.62 6.25 5.35 19.73 18.34 19.90 18.63 8.77 8.34 6.50 6.05 23.62 22.34

1998 2.05 1.51 6.30 5.35 1.74 1.53 7.72 6.21 18.98 17.50 20.10 18.17 7.96 7.56 6.30 5.75 23.11 22.12

1999 22.51 21.98

2000 22.85 21.78

2001 23.00 22.51

Avg 2.34 1.85 6.25 5.50 1.82 1.64 7.15 5.70 19.25 18.00 19.82 18.46 8.47 8.11 6.69 5.87 23.52 22.56

I = Pre-monsoon. II = Post-monsoonAll distances (road) are given from New Delhi. the capital of India*Chidiapur is located near the bank of Ganga RiverNizamabad range 30 km away from Chidiapur

Table 2 indicates the effect of aging on chemicalcomposition of E. camaldulenosis collected fromBallarshah (Maharashtra) after 4 and 7 years of age.Ageing increases the bulk 'and basic densities of E.camaldulenosis by 17.29 and 8.97 %, respectively (ongreen wood basis). Alcohol-benzene soluble increasesby 45.24 %, whereas hot water soluble decreases by46.23 % due to effect of ageing. In the same patternholocellulose and lignin increase by 2.08 and 8.61 %,respectively with effect of ageing. The variations inchemical composition of E. camaldulenosis can beexplained based on anatomical changes occurred dueto pre- and post-monsoon ground water levels andageing effect. Microphotographs A and B clearlyindicate the presence of medullary rays and vessels,where vessels are plugged by tyloses. In such place.where ground water level recedes below normal. axialparenchyma protrudes into the vessel through pit, dueto a pressure difference' in vessel and axialparenchymatous cell on each side of a pit membrane.As protrusion of axial parenchyma cell into vesseladvances. it assumes the shape of balloon and itceases the conduction in vessel. Those trees. whichshow the characteristics of tyloses, normally consistof narrow medullary rays and parenchyma cells,which are evident by microphotograph A, havingnarrow medullary rays, and parenchyma cells.Microphotograph B shows that the tyloses becomevery large. extend into the vessel and become angularby compression. The density of tyloses increases withageing effect and is completely filled up withextractives. The cells in trees having tyloses have

Table 2- Effect of aging on chemical composition ofEucalyptus camaldulenosis analysis

SI.No. Particulars

1 Moisture, %

2 Basic density of wood,kg/rrr'

3 Bulk density of wood chipsOn green basis, kg/rrr' Ono.d. basis, kg/rrr'

4 Alcohol-Benzenesolubles,%

5 "Hot water soluble, %

6 1.0 % NaOH soluble, %

7 Holocellulose,%

8 a-cellulose. %

9 Pentosans, %

10 Lignin. %

•••= After extraction

4 years 7 years

31.3 29.3

702 765

295.0 346.0203.0 245.01.26 1.83

1.64 1.12

14.45 16.75

76.9 78.5

43.2 42.6

13.10 13.25

30.2 32.8

become more strongly lignified and woody portionbecomes reddish-brown in colour due to deposition ofvarious colouring and aromatic substances, tannins.resins, oils, gum etc. into the changing cells.

Table 3 shows the effect of ageing of E.camaldulenosis on pulping characteristics. Ageingeffect decreases unbleached screened pulp yield by4.3 % with an increase in screening rejects by 0.82 %.On the other hand, kappa number and permanganatenumber increase by 34.9 and 24.06 %, respectively.The change in pulping characteristics of E.camaldulenosis due to ageing effect can be explained

336 INDIAN J. CHEM. TECHNOL., MAY 2005

on the basis of change in physiological behaviour.The shape, size and number of tyloses due to recedingground water level and transformation of sapwoodinto heartwood have increased. The wall of tylosesbecome thickened and even lignified becomingwrinkled and partially collapsed in heartwood. Itcauses cessation of all physiological activities ofliving cells i.e. all living cells lose their protoplast; thecell sap is withdrawn, and commonly the watercontent of the cell walls is greatly reduced and partlylignified walls of cells may become more stronglylignified'". During pulping this balloon like structuresretard the penetration of cooking liquor into the chips.The disruption of cooking conditions results in low-screened pulp yield with high kappa number and morescreening rejects.

Table 4 shows the effect of ageing of E.camaldulenosis on paper properties. The initialfreeness level of E. camaldulenosis of 4 years old is22 "SR whereas freeness of 7 years old E.camaldulenosis is 17 °SR. It is also observed thatageing effect increases the beating time from 18 to 25min to attain a freeness level of 30 °SR and beatingtime 18 to 25 min to get a freeness level of 45 °SR.Burst factor and breaking length reduces by 13.33 and28.78 % at 30 °SR and 2.86 and 6.47 % at 45 °SRrespectively due to ageing effect. Ageing effectincreases the tear factor by 6.58 % at 30 °SR and5.71 % at 45 °SR respectively. The reason forchanging of physical properties of paper due to ageingis that the wood fibers' become thick walled andlignified which do not collapse readily to doublewalled ribbons on pressing. Therefore, they tend toretain their tubular structure and provide less fibersurface contact area for bonding. The sheet so formedwill be bulky, porous and opaque with high tear andlow bursting and tensile strength. The abnormalincrease of tyloses may pose problems to printers alsoas it leads a serious problem of picking during offsetprinting. This problem may be combated by treatingwood chips with hot black liquor (temperature100°C) or pre-steaming during pulping, whichfacilitates fast penetration of cooking liquor in thewood chips by bursting tyloses.

Table 5 shows the effect of aging on black liquorcharacteristics of E. camaldulenosis. The residualalkali decreases from 2.76 to 2.36 g/L (as Na20) at thesame cooking conditions. The total solids per tonne ofpulp increase from 1.55 .to 2.08 kg, and total solids inblack liquor also increase from 1.51 to 1.93 kg. The

Table 3- Effect of aging of Eucalyptus camaldulenosis onpulping and pulp characteristics

SI.No. Particulars 4 years 7 years

Total unbleached pulp yield, % 48.7 45.2

2 Unbleached screened pulp 48.3 44.0yield. %

3 Rejects, % 0.38 1.2

4 Kappa No. 24.9 33.6

5 Permanganate No. 18.7 23.2

Table 4- Effect of aging of Eucalyptus camaldulenosis on pulpevaluation characteristics

Sl. No. Particulars 4 years 7 years

InitialOSR 22 17

2 Defibration 15 15time, min

3 Beating time. 09 15 18 25min

4 FinaloSR 30 45 30 45

5 Basis weight, 61.5 62.6 60.5 64.5g/m2

6 Bulk, crn 'zg 1.32 1.27 1.34 1.28

7 Burst factor 45 70 39 68

8 Tear factor 76 70 81 74

9 Breaking 5650 8960 4250 8380length, meter

10 Double fold, 27 33 24 32No.

calorific value of black liquor decreases from 3964 to3848 kcal/g. These changes in black liquor propertiesare due to change in chemical composition as a resultof ageing.

Table 6 also shows the effect of pre- and postmonsoon ground water levels on anatomicalcharacteristics of E. camaldulenosis and its impact onputp and paper making characteristics.Microphotographs C and D show the cross sectionalview of E. camaldulenosis collected fromKhurshidabad and Akbarpur where average groundwater level is 18.00 and 19.82 m respectively.Microphotographs show that the vessels arecompletely filled up with tyloses. All the livingparenchymatous and vasicentric cells are convertedinto thick walled and highly lignified parenchymatousand vasicentric dead cells due to cessation of

DUTT et al.: EFFECT OF TOPOLOGY ON THE PULP AND PAPER CHARACTERISTICS OF EUCALYPTUS 337

Table 5- Effect of aging of Eucalyptus camaldulenosis onblack liquor characteristics

SI. No. Particulars 4 years 7 years

2

3

Residual alkali, g/L(as Na20)

pH

Total solids (w/v,%)

4 Organic: Inorganicratio

5 Calorific value,kcal/g

Total solidsl ton ofpulp

Total solid on blackliquor basis

6

7

2.76

12.6818.417.1

66.4: 33.6

3994

1.53

1.51

2.36

12.50

19.317.9

66.3: 33.7

3848

2.08

1.93

physiochemical actrvines of E. camaldulenosis. Itclearly indicates that these changes occur in regionswhere ground water level is below normal.

Table 6 indicates that basic density of woodincreases with receding ground water level ofdifferent geographical locations. Fig. 1 which showsthe curve between ground water levels and packingdensity follows the same pattern. Fig. 2 and 3 indicatethat screened pulp yield decreases with increasingpacking density while permanganate numberincreases with increasing packing density. Theincrease in packing density is due to accumulation ofextractives, lignin and pentose sugar content. Theabnormalities like in tyloses in E. camaldulenosis areobserved to increase with receding ground waterlevels. It disturbs the pulping

Table 6- Effect of soil quality and ground water level on the morphological and anatomical characteristics of Eucalyptuscamaldulenosis and its effect on pulping andpaper making characteristics

Sl. No. Particulars Eucalyptus camaldulellosis collected from different places after five years

Nizamabad Saharanpur ChidiapurRange Local

Water level (avg),m

Pre-monsoon

Post-monsoon'

Date of collection

2 Chipped at

3

4

Moisture, %

Basic density ofwood, kg/m'

Bulk density of,wood chips, kg/rrr'

Residual alkali,

g/L (as Na20)

Total unbleachedpulp yield, %

Screen rejects, %

Screened pulp yield,%

Permanganate No.

Brightness, °GE

Burst factor

Tear factor

Breaking length, m

Double fold, No

5

6

7

8

9

10

11

12

13

14

15

2.10

2.34

1.85

18.09.01

5.88

6.25

5.50

04.09.01

Veco plant

1.73

1.82

1.64

14.09.01

Norman

Carthage

31.9

510

233

47.3

0.1

47.2

15.3

27.5

30

76

4555

24

Zafarabad Khurshi- Akbarpurdabad

6.43

7.15

5.70

13.09.01

18.63

19.25

18.00

10.09.01

19.14

19.82

18.46

15.09.01

Norman

Carthage

15.0

748

300

2.2

46.9

2.3

44.6

19.4

20.0

32

72

4330

21

Mala

8.29

8.47

8.11

17.09.01

Norman

Carthage

31.7

689

271

1.9

47.9

0.8

47.1

15.8

26.5

39

78

4310

35

Yamuna Nagar

Heart SapWood wood

6.28

6.69

5.87

6.09.01

Vecoplant

Vecoplant

Norman

Carthage

33.0

625

50.5

495

orman Norman

47.2

589

46.5

450

265 221

Carthage

29.0

630

Carthage

19.4

740

321 221

2.8 4.8

264 299

3.4 0.8

48.4 46.4

3.7 2.8 2.8

47.6 48.3

0.2

48.2

0.1

• 46.3

47.1 47.1

2.4

45.2

0.1

48.2

18.2

23.0

16.3

29.0

0.9

46.2

3.1

43.4

19.7

24.0

14.5

31.0

42

76

6665

61

45

67

6890

65

19.2

25.5

21.2

23.4

38

73

5320

58

45

56

6330

71

32 28

69

4335

15

Cooking conditions: Active alkali = 16.0 % (as Na-O), Sulphidity = 20%, Time from room temp to 105°C = 60 min, Time from

105°C to 162°C = 60 min. Til1\e at 162°C = 75 min, bath ratio = 1:2.8, and digester pressure = 6.5 kg/ern".

Unbleached pulp evaluation: Final freeness = 30 °SR and basis weight of laboratory hand-sheet = 60 g/m2

5080

15

338 INDIAN J. CHEM. TECHNOL., MAY 2005

320 -- ••... -.--- .. - ••. - ••........ _ •.. _- ..•• _.-- - .•

300 ••

220L

200 ---~------.---------

'0

Ground water level (m)

,5

Fig. 1- Effect of ground water level on packing density of E.camaldulenosis

221

21i

20 ,

I'9

'8t 17c

'" 16

,5 :

14j

'3L12200 220 240 260 280

Packing density (K~ml)

300 320

Fig. 3- Effect of packing 'density on K number of E.camaldulenosis

conditions, which result in low pulp yield with highpermanganate number and more screening rejects.Figs 4 and 5 indicate that both breaking length andburst factor decrease with increasing packing densityof wood. Conversely, tear factor will increase withincreasing packing density of E. camaldulenosis.Microphotograph E shows tangential view of E.camaldulenosis collected from Mala. The vessels arecompletely filled up with tyloses. Theparenchymatous and vasicentric cells are thin walledand partly lignified. Table 6 also indicates that E.camaldulenosis collected from Mala produces 47.0 %screened pulp yield at permanganate number of 15.8.Microphotograph F shows the tangential view of E.camaldulenosis collected from Nizamabad rangewhere pre- and post-monsoon average ground water

49r

48

47

43j42l- ..... -~----

20

'50 170 '90 210 230 250 270

Packing density (Kglm3)

290 310 330

Fig. 2- Effect of packing density on screened pulp yield of E.camaldulenosis

7000 i··

6500 .

6000;

Ei5500 1j I

{ 500) i.~ I

'=j4000L

3500 ----------------~

..

200 220 240 260 300 320280

Pocking density (Kg/m')

Fig. 4- Effect of packing density on breaking length of E.camaldulenosis

50 r'" ._ - _ ',, .451

I

:; 40 j(; IJ! '

..-----!

~35

1

I

30 Ii

25 .•...1 -_------~----

•

200 220 240 280 280 300 320

Packing dens~y (K9'm')

Fig. 5-- Effect of packing density on burst factor of E.camaldulenosis

DUTT et al.: EFFECT OF TOPOLOGY ON THE PULP AND PAPER CHARACTERISTICS OF EUCALYPTUS 339

levels are 2.34 m and 2.85 m respectively. The vesselsare empty, thin walled medullary rays with few axialparenchymatous cells and resin ducts. E.camaldulenosis collected from Nizamabad rangeproduces maximum screened pulp yield withimproved strength properties.

Table 7 shows the impact of active alkali doses onE. camaldulenosis to get 16.5±0.5 permanganatenumber of rulp. E. camaldulenosis collected fromNizamabad range, Zafarabad, Khurshidabad andAkbarpur consumes 0.5, 2.0, 1.5 and 2.0 % moreactive alkali during pulping to get 16.5±0.5permanganate number. It is also observed thatmarginal improvements in strength properties occurwith increasing alkali dose to get equal permanganatenumber. However, a significant increase in pulp yieldand strength is masked by carbohydrate degradation,which is more pronounced at high alkali dose".

ConclusionThe chemical composmon of E. camaldulenosis

changes with aging. Wood density, packing density ofwood, alcohol-benzene soluble, holocellulose andlignin content of E. camaldulenosis increases withaging. On the other hand a-cellulose, pentosans andhot water soluble of E. camaldulenosis decreasesslightly with ageing.

In E. camaldulenosis, grown in locations whereground water level is below normal, vessel elementsare filled up with tyloses. Tyloses plug the porousstructure of wood, which retards the penetration ofcooking liquor into the chips, resulting in low-screened pulp yield, more screening rejects and highkappa number of pulp. The density of tylosesincreases with aging and filled up extractives, whichcontribute towards high alcohol-benzene soluble andone per cent NaOH soluble.

Table 7- Doses of active alkali to get equal pcrmanganate number l6.5±0.5 and its impact on pulp yield of E. camaldulenosis.

SI. No. Particulars Location of collection

Nizamabad Saharanpur Chidiapur Zafarabad Khurshidabad Akbarpur Malarange local

Basic density of wood, 625 495 510 630 740 748 689kg/rrr'

2 Bulk density of wood 265 221 233 264 299 300 271chips, kg/rrr'

3 Acitive alkali, % 16.5 16 16 18.0 17.5 18 16(as Na-O)

4 Total unbleached pulp 46.9 46.4 47.3 43.6 44.65 43.55 47.9yield, %

5 Screening rejects, %, 0.15 0.1 0.1 0.2 1.05 0.75 080

6 Screened pulp yield, % 46.8 46.3 47.2 44.2 43.5 42.8 47.1

7 Permanganate number 16.0 16.3 15.3 15.8 16.6 16.2 15.8

8 Brightness, °GE 26.3 29.0 27.5 28.4 24.6 22.2 26.5

9 Burst factor 47 45 30 36 32 35 39

10 Tear factor 72 67 76 68 72 75 78

11 Breaking length, m 6750 6870 4555 6164 4465 4395 4310

12 Double fold, No. 67 65 24 17 22 24 35

Cooking conditions: Sulphidity = 20%, Time from room temp to 105°C = 60 min, Time from 105°C to 162°C = 60 min. Time at

162 °c = 75 min, bath ratio = 1:2.8, and digester pressure = 6.5 kg/ern",

340 INDIAN J. CHEM. TECHNOL.. MA Y 2005

The fibers become thick-walled and lignified withaging and receding of ground water level. It results ina decrease in all the mechanical strength propertiesexcept tear factor of paper. Such type of pulp requirescomparati vely high refining energy. During pulpingballoon like structures of tyloses are separated asisolated elements, causing picking problems duringoffset printing.The black liquor solids of E. camaldulenosis

increase with ageing, whereas calorific value decreaseslightly. E. camaldulenosis collected from suchregions where ground water level is below normalconsumes more active alkali to get 16.5±O.5permanganate number of pulp during alkalinecooking.

ReferencesI Hillis W E & Brown A G. Eucalyptus FJr Wood Production

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