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Ramie hemicellulose as beater additive in paper making from jute-stick kraft pulp
INDUSTRIAL CROPS ANDPRODUCTS ANINTERNATIONALJOURNAL
Industrial Crops and Products 4 (1995) 79-84
Ramie hemicellulose as beater additive in paper making from jute-stick kraft pulp S.K. Bhaduri *, I.N. Ghosh, N.L. Deb Sarkar Chemisty and Microbiology Division, Jute Technological Research Laboratoties (ICAR), 12, Regent Park, Calcutta 700040, India
Received 13 June 1994; accepted 27 February 1995
Abstract A degraded hemicellulose obtained from degumming liquor of ramie fibre was used as an additive during the beating operation of jute-stick pulp. Pulp properties, such as freeness, beating energy, etc., and the strength properties of the paper sheets were evaluated. It was found that the additive had a significant effect in reducing the energy consumption during the beating operation and in improving the strength properties of paper sheets made from the pulp. Keywords: Ramie hemicellulose;
Degummed ramie liquor; Beater additive; Jute stick; Kraft pulp; Paper making
1. Introduction
Various agricultural residues, such as straw, stalk, bagasse, cereal, etc., and waste materials like waste cotton, waste paper, etc., have taken a significant place in supplementing the dwindling supply of conventional forest raw material for catering the. ever-increasing demand on the pulp and paper industry. With the increasing use of short fibres, such as hard wood and agricultural residues in admixture with conventional raw materials, like bamboo and soft wood in paper making, the paper industry is facing the difficulty to meet the consumers’ specifications for different varieties of paper and board. In this context, chemicals and additives play a vital role in the process of paper making by imparting some improved properties in the pulp. Different chemicals and additives like synthetic resins, starch and modi* Corresponding
author.
fied starches, vegetable glues, etc., have been tried (Fahmy and Mobarak, 1972; Bakshi et al., 1982) in order to improve the properties of paper and board. Hemicelluloses extracted from plant raw materials have adhesive properties and their role as additive in paper making has been stressed by several authors (Mobarak et al., 1973). We report here the effect of an additive, a degraded hemicellulose obtained from the waste degumming liquor of ramie fibre, on the beating characteristics and strength properties of paper made from the pulp of jute stick, an agrowaste of jute cultivation. 2. Materials and methods 2.1. Isolation and characterisation of degraded hemicellulose The isolation of the degraded
0926-6690/95/$09.50 0 1995 Elsevier Science B.V. All rights reserved. SSDI 0926-6690(95)00018-6
and chemical characterisation hemicellulose from degumming
80
S.K. Bhaduri et aL I Industrial Crops and Products 4 (1995) 79-84
liquor of ramie fibre was reported earlier (Bhaduri et al., 1992). Decorticated ramie (gum content 25%) was degummed by open digestion for 2 h with 1% sodium hydroxide solution at 93-98°C (Das Gupta et al., 1976). The degraded hemicellulose was obtained as a light brown precipitate from the digestion liquor neutralized with dilute sulphuric acid and the addition of ethanol. It was washed with alcohol, acetone and ether and dried in vacuum (yield 10%). The polysaccharide, after purification by reprecipitation from its aqueous solution by ethanol, was analysed for its ash, lignin and uranic anhydride contents by standard methods (TAPPI, 1972). It was hydrolysed according to the method of Jeffery et al. (1960) and neutral sugars in the hydrolysate were analysed by chromatography of their alditol acetates using a gas-liquid chromatograph (HP Model 5830A) equipped with f.i.d. Resolutions were performed on a stainless steel column (180 cm x 0.5 cm) containing 3% ECNSS-M on Gas-Chrome Q (loo200 mesh) using nitrogen as carrier gas. 2.2. Preparation of kraft pulp of jute stick The pulp was made by digesting 1 kg of jutestick chips (2-3 cm size) in a cylindrical rotary digester using a solution of sodium hydroxide and sodium sulphide of about 18% strength and 25% sulphidity at 170°C for 4 h. After washing with water, the pulp was beaten in a PFI 1 mill at 10% consistency under a definite beating pressure. 2.3. Bleaching of jute-stick kraft pulp A portion of the raw kraft pulp was bleached using the CEH sequence (chlorination, extraction and hypochlorite treatment) to moderate brightness. Lignin contents of both unbleached and bleached pulps were estimated by the TAPPI, 1972 standard method using 72% sulfuric acid. 2.4. Preparation and testing of paper sheets Paper sheets were made from both unbleached and bleached pulps under control condition as 1Papirindustriens
Fhkningsinstitutt.
well as using the degraded hemicellulose as additive in different concentrations during the beating operation. Hemicellulose was added in the following different concentrations, viz. 0.5%, 1.0% 1.5% and 2.0%, on the basis of oven-dry pulp weight to a pulp slurry of 10% consistency containing 50 g dry pulp. The pulp samples were beaten in the PFI mill at different revolutions and the corresponding changes in freeness and beating energy were noted and compared with those of the control sample (without hemicellulose). The beating energy of pulp was noted from the energy-consumption meter attached to the PFI mill. Pulp freeness was measured by using a Schopper-Reigler freeness tester. Standard paper sheets of about 60 g were made from each pulp using a sheet-making machine according to British standard. Strength properties, viz. tensile index, folding strength (double fold), and burst index of the paper sheets were measured according to the TAPPI, 1972 standard method using a tensile-strength tester, folding-strength tester (double fold), and bursting-strength testing equipment. The density of the paper sheets was calculated by measuring the thickness, using a dial thickness gauge, and basis weight of the paper sheets. 3. Results and discussion Jute stick, an agrowaste of jute cultivation, contains about 41% at-cellulose, 23% lignin and 24% pentosan in addition to other minor constituents. Its potential as raw material in pulp for making various grades of paper, such as writing and printing paper, wrapping and packaging paper, corrugated medium, etc., had been demonstrated earlier by several workers (Jain, 1960; Guha et al., 1962, 1965a, b). Ghosh et al. (1983) studied mixed pulping of jute stick with other conventional raw materials. Due to the short fibre and slow drainage of jute-stick pulp, the strength properties of paper made from the pulp alone is not up to the desired level. To improve the strength properties of paper made from jute-stick kraft pulp, a degraded hemicellulose obtained from the waste liquor during degumming of ramie fibre was used as beater additive. The degraded hemicellulose
S.K. Bhaduti et al. I Industrial Crops and Products 4 (1995) 79-84
had the following chemical composition (Bhaduri et al., 1992): ash, 18%; lignin, 6.7%; uranic anhydride, 14%; residues of rhamnose, 38%; arabinose, 9.7%; galactose, 46.9%; and glucose, 5.4%. The hemicellulose was light brown in colour, water soluble and strongly acidic in nature. The addition of a small amount (0.5 to 2%) of hemicellulose in jute-stick kraft pulp causes very little change in colour of the paper sheets. A portion of the unbleached kraft pulp (lignin, 16%) was bleached to moderate brightness, using the CEH sequence (lignin, 6%, brightness, 70% Elrepho). Strength properties of paper sheets made from the bleached pulp with additive were also evaluated. The effect of addition of the degraded ramie hemicellulose during the beating operation at different PFI revolutions on the strength properties of paper sheets made from both unbleached and bleached jute-stick kraft pulps are shown in Tables 1 and 2. It was observed that: (a) the density and strength properties, e.g. tensile index, fold-
Table 1 Effect of beating Sample No.
on strength
Pulp type
and other properties PFI revolutions
Beating energy
of jute-stick Freeness (“SW
(kwh)
81
ing strength (double fold), and burst index of paper sheets made from both unbleached and bleached pulps increased with addition of hemicellulose in the pulp during the beating operation; (b) for a particular beating experiment with the PFI mill, the pulp freeness, beating energy and strength properties of paper sheets made from both bleached and unbleached pulps increased with an increase in PFI revolutions, irrespective of addition of hemicellulose; (c) with an increase in additive percentage, lesser beating energy is required thereby reducing the time of beating operation. Addition of hemicellulose during the beating operation thus helps the pulp to achieve the desired strength values with less energy consumption in a shorter time period. The physical properties of the unbleached and bleached pulps and paper sheets made of them with and without the additive are represented with the change in PFI revolutions in Figs. l-6. The curves give us information regarding the effect of
kraft pulp with additive Strength
properties
tensile index
of resulting double
fold
paper burst index (kPa m’/g)
(N m/g)
Density paper (glcm3)
A
Control
1000 2000 3000 4000
0.025 0.035 0.045 0.055
13 20 30 38
28.4 35.4 44.0 52.9
84 114 190 204
1.90 2.16 2.35 2.65
0.22 0.27 0.34 0.51
B
Pulp + 0.5% additive
1000 2000 3000 4000
0.025 0.030 0.040 0.050
15 22 33 40
32.7 41.2 51.2 56.2
90 130 200 249
1.92 2.53 3.24 3.50
0.21 0.28 0.42 0.58
C
Pulp + 1.0% additive
1000 2000 3000 4000
0.020 0.025 0.030 0.045
14 25 36 42
35.6 47.6 55.7 61.1
90 150 240 285
1.90 2.65 3.41 3.68
0.25 0.33 0.51 0.60
D
Pulp + 1.5% additive
1000 2000 3000 4000
0.020 0.020 0.030 0.040
16 26 38 43
36.2 49.6 58.8 63.7
100 168 268 330
2.00 2.65 3.53 4.12
0.28 0.40 0.58 0.63
E
Pulp + 2.0% additive
1000 2000 3000 4000
0.017 0.020 0.025 0.035
18 27 38 45
38.0 50.0 67.6 71.2
105 173 275 360
2.07 2.79 3.82 4.74
0.27 0.40 0.61 0.70
of
S.K. Bhaduri et al. IIndustrial Crops and Products 4 (1995) 79-84
82
Table 2 Effect of beating on strength and other properties of bleached jute-stick kraft pulp with additive Sample No.
Pulp type
Control
A
PFI revolutions
Beating energy
Freeness
Strength properties of resulting paper
Density of
(“SW
tensile index
burst index (kPa m’/g)
paper (s/cm?
1000
0.025 0.030 0.030 0.031
18 21 29 31
33.4 35.3 40.7 45.0
60 69 18 85
1.77 1.96 2.26 2.55
0.24 0.33 0.45 0.55
0.020 0.025 0.030 0.031
20 29 31 33
37.2 38.2 43.8 46.7
15 81 96 105
2.09 2.45 2.88 3.05
0.31 0.35 0.52 0.64
(kwh)
2000 3000 4000
double fold
(N m/g)
B
Pulp + 0.5% additive
C
Pulp + 1.0% additive
0.015 0.030 0.035 0.032
22 32 34 36
38.5 41.2 44.0 49.0
78 90 100 114
2.62 2.94 3.24 3.37
0.33 0.40 0.60 0.70
D
Pulp + 1.5% additive
0.010 0.015 0.020 0.029
24 33 36 40
41.2 42.9 45.6 50.0
87 96 105 120
3.06 3.24 3.70 3.90
0.38 0.42 0.63 0.72
E
Pulp + 2.0% additive
0.010 0.020 0.030 0.032
25 37 40 42
40.6 43.8 49.0 51.3
95 105 114 125
3.04 3.41 3.94 4.51
0.40 0.45 0.65 0.77
1000
5ol 40.
i
a -
30.
2 al
z
E 20’ 10
I I
2000
1000 PFI
3000
4 000
Revolution-
Fig. 1. Freeness vs PFI revolution. a = jute-stick pulp, b = jute-stick pulp + 2% additive, c = bleached jute-stick pulp, d = bleached jute-stick pulp + 2% additive.
additive and the rate of beating at which the pulp develops its properties. This is given by the PFI revolutions to reach the desired degree of freeness or strength. It is one of the most important properties evaluated because of its effect on power consumption. Addition of hemicellulose favours interfibre bonding due to its hydrophilic properties which cause greater swelling of cell walls in water imparting fibre flexibility. This helps in better fibre conformation and more interfibre bonding during sheet formation. Thus the strength properties of paper correlated to interfibre bonding (Rydholm, 1965), viz. tensile index, folding endurance, etc., are improved. In addition, hemicellulose may contribute more hydrogen bonding per unit area than do cellulose surfaces (Robinson, 1980). The degradation of hemicellulose during isolation, and its addition to the pulp effecting in concentrated absorption on external fibre surfaces (Mobarak et al., 1973), are also reasons for its effect as additive in fibre bonding.
S.K. Bhaduri et al. /Industrial Crops and Products 4 (1995) 79-84
83
80
.06
r
70
60
b
1 1000
2000 PFI
3000
4000 I
Revolution
Fig. 2. Beating energy vs PFI revolution. a = jute-stick pulp, b = jute-stick pulp + 2% additive, c = bleached jute-stick pulp, d = bleached jute-stick pulp + 2% additive.
2000
1000 P F
3000
4000
I Revolution
Fig. 3. Tensile index vs PFI revolution. a = jute-stick pulp, b = jute-stick pulp + 2% additive, c = bleached jute-stick pulp, d = bleached jute-stick pulp + 2% additive.
4. Conclusions 500 -
The
degraded hemicellulose obtained from degumming liquor of ramie fibre was an acidic polysaccharide having rhamnose and galactose as predominant sugars. When the hemicellulose was used as additive in small concentrations (0.5% to 2.0%) during the beating operation of jute-stick kraft pulp in a PFI mill, it helped to reach improved strength properties of the pulp with less energy consumption, thereby reducing the time of beating operation. Strength properties, such as tensile index, folding endurance and burst index of paper sheets made from the jute-stick pulp with the additive were also improved significantly. The beneficial effect of added hemicellulose on strength properties of paper is attributed to its hydrophilic properties imparting fibre flexibility due to greater swelling of cell wall which, in turn, favours interfibre bonding. In addition, increased concentration of added hemicellulose on the external fibre surfaces and degradation of the
400
.
300
-
200
.
100
-
9 9 2 2 P
I 1000
2000 PFI
3000
4000
Revolution
Fig. 4. Double fold vs PFI revolution. a = jute-stick pulp, b = jute-stick pulp + 2% additive, c = bleached jute-stick pulp, d = bleached jute-stick pulp + 2% additive.
84
S.K. Bhaduti et al. IIndustrial
Acknowledgements
5.0 v
4.0
Crops and Products 4 (1995) 79-84
The authors are thankful to the Director of the Jute Technological Research Laboratories (ICAR) for providing work facilities.
’
N$ p
References
3.0.
1 x 4 g
e In !s In
2.0 -
1.0
-
1000
2000 P F I
RavolutiMl
3000
4000
-
Fig. 5. Burst index vs PFI revolution. a = jute-stick pulp, b = jute-stick pulp + 2% additive, c = bleached jute-stick pulp, d = bleached jute-stick pulp + 2% additive.
1000 PF
I
2000 3000 Revolution
4 000 L
Fig. 6. Density vs PFI revolution. a = jute-stick pulp, b = jute-stick pulp + 2% additive, c = bleached jute-stick pulp, d = bleached jute-stick pulp + 2% additive.
hemicellulose during isolation have also significant effect in raising its adhesive property for fibre bonding.
Bakshi, B.K., Gandhi, OP., Meshramkar, PM., Deb, U.K. and Jaspal, N.S., 1982. Chemicals and additives in paper making - experience at the West Coast Paper Mills Ltd. lppta, 19: 40-48. Bhaduri, SK., Day, A., Mondal, S.B. and Sen, S.K., 1992. Degraded gum from ramie in binder composition for jute stick particle board. Bioresour. Technol., 40: 87-89. Das Gupta, PC., Sen, K. and Sen, S.K., 1976. Degumming of decorticated ramie for textile purposes. Cellulose Chem. Technol., 10: 285-291. Fahmy, Y. and Mobarak, E, 1972. Influence of starch addition on filler retention and paper properties of straw and wood pulps. Cellulose Chem. Technol., 6: 67-70. Ghosh, I.N., Roy, A.K. and Banerjee, SK., 1983. Mixed pulping of jute stick with other cellulosic raw materials. Indian Text. J., 94: 151-153. Guha, S.R.D., Mathur, G.M. and Mukherjea, VN., 1962. Production of cheap grade paper from jute stick by cold caustic soda process. Indian Pulp Pap., 17: 153-154. Guha, S.R.D., Sharma, Y.K. and Mukherjea, V.N., 1965a. Jute stick pulp for writing and printing papers by sulphate process. Indian Pulp Pap., 19: 729-730. Guha, S.R.D., Mukherjea, V.N. and Sharma, Y.K., 1965b. Pilot plant production of printing papers from jute stick and bagasse by mechano-chemical process. Indian Pulp Pap., 19: 551-552. Jain, S.C., 1960. Pulp from jute stick by nitric acid pulping process. Indian Pulp Pap., 15: 161-169. Jeffery, J.E., Partlow, E.V. and Polglase, W.J., 1960. Chromatographic examination of wood cellulose hydrolysates - a routine reflectance method. Anal. Chem., 32: 17741777. Mobarak, F., El-Ashmany, A.E. and Fahmy, Y., 1973. Hemicelluloses as additive in paper making, Part II. The role of added hemicelluloses and hemicellulose in situ on paper properties. Cellulose Chem. Technol., 7: 323-325. Robinson, J.V., 1980. Fibre bonding. In: J.I? Casey (Editor), Pulp and Paper Chemistry and Chemical Technology, Vol. 11. John Wiley and Sons, New York, 3rd ed., pp. 940-941. Rydholm, S.R., 1965. Pulping Processes. Interscience Publishers, New York, 1159 pp. TAPPI, 1972. Standard and Suggested Methods. Technical Association of the Pulp and Paper Industry, New York.
Industrial Crops and Products 4 (1995) 79-84
Ramie hemicellulose as beater additive in paper making from jute-stick kraft pulp S.K. Bhaduri *, I.N. Ghosh, N.L. Deb Sarkar Chemisty and Microbiology Division, Jute Technological Research Laboratoties (ICAR), 12, Regent Park, Calcutta 700040, India
Received 13 June 1994; accepted 27 February 1995
Abstract A degraded hemicellulose obtained from degumming liquor of ramie fibre was used as an additive during the beating operation of jute-stick pulp. Pulp properties, such as freeness, beating energy, etc., and the strength properties of the paper sheets were evaluated. It was found that the additive had a significant effect in reducing the energy consumption during the beating operation and in improving the strength properties of paper sheets made from the pulp. Keywords: Ramie hemicellulose;
Degummed ramie liquor; Beater additive; Jute stick; Kraft pulp; Paper making
1. Introduction
Various agricultural residues, such as straw, stalk, bagasse, cereal, etc., and waste materials like waste cotton, waste paper, etc., have taken a significant place in supplementing the dwindling supply of conventional forest raw material for catering the. ever-increasing demand on the pulp and paper industry. With the increasing use of short fibres, such as hard wood and agricultural residues in admixture with conventional raw materials, like bamboo and soft wood in paper making, the paper industry is facing the difficulty to meet the consumers’ specifications for different varieties of paper and board. In this context, chemicals and additives play a vital role in the process of paper making by imparting some improved properties in the pulp. Different chemicals and additives like synthetic resins, starch and modi* Corresponding
author.
fied starches, vegetable glues, etc., have been tried (Fahmy and Mobarak, 1972; Bakshi et al., 1982) in order to improve the properties of paper and board. Hemicelluloses extracted from plant raw materials have adhesive properties and their role as additive in paper making has been stressed by several authors (Mobarak et al., 1973). We report here the effect of an additive, a degraded hemicellulose obtained from the waste degumming liquor of ramie fibre, on the beating characteristics and strength properties of paper made from the pulp of jute stick, an agrowaste of jute cultivation. 2. Materials and methods 2.1. Isolation and characterisation of degraded hemicellulose The isolation of the degraded
0926-6690/95/$09.50 0 1995 Elsevier Science B.V. All rights reserved. SSDI 0926-6690(95)00018-6
and chemical characterisation hemicellulose from degumming
80
S.K. Bhaduri et aL I Industrial Crops and Products 4 (1995) 79-84
liquor of ramie fibre was reported earlier (Bhaduri et al., 1992). Decorticated ramie (gum content 25%) was degummed by open digestion for 2 h with 1% sodium hydroxide solution at 93-98°C (Das Gupta et al., 1976). The degraded hemicellulose was obtained as a light brown precipitate from the digestion liquor neutralized with dilute sulphuric acid and the addition of ethanol. It was washed with alcohol, acetone and ether and dried in vacuum (yield 10%). The polysaccharide, after purification by reprecipitation from its aqueous solution by ethanol, was analysed for its ash, lignin and uranic anhydride contents by standard methods (TAPPI, 1972). It was hydrolysed according to the method of Jeffery et al. (1960) and neutral sugars in the hydrolysate were analysed by chromatography of their alditol acetates using a gas-liquid chromatograph (HP Model 5830A) equipped with f.i.d. Resolutions were performed on a stainless steel column (180 cm x 0.5 cm) containing 3% ECNSS-M on Gas-Chrome Q (loo200 mesh) using nitrogen as carrier gas. 2.2. Preparation of kraft pulp of jute stick The pulp was made by digesting 1 kg of jutestick chips (2-3 cm size) in a cylindrical rotary digester using a solution of sodium hydroxide and sodium sulphide of about 18% strength and 25% sulphidity at 170°C for 4 h. After washing with water, the pulp was beaten in a PFI 1 mill at 10% consistency under a definite beating pressure. 2.3. Bleaching of jute-stick kraft pulp A portion of the raw kraft pulp was bleached using the CEH sequence (chlorination, extraction and hypochlorite treatment) to moderate brightness. Lignin contents of both unbleached and bleached pulps were estimated by the TAPPI, 1972 standard method using 72% sulfuric acid. 2.4. Preparation and testing of paper sheets Paper sheets were made from both unbleached and bleached pulps under control condition as 1Papirindustriens
Fhkningsinstitutt.
well as using the degraded hemicellulose as additive in different concentrations during the beating operation. Hemicellulose was added in the following different concentrations, viz. 0.5%, 1.0% 1.5% and 2.0%, on the basis of oven-dry pulp weight to a pulp slurry of 10% consistency containing 50 g dry pulp. The pulp samples were beaten in the PFI mill at different revolutions and the corresponding changes in freeness and beating energy were noted and compared with those of the control sample (without hemicellulose). The beating energy of pulp was noted from the energy-consumption meter attached to the PFI mill. Pulp freeness was measured by using a Schopper-Reigler freeness tester. Standard paper sheets of about 60 g were made from each pulp using a sheet-making machine according to British standard. Strength properties, viz. tensile index, folding strength (double fold), and burst index of the paper sheets were measured according to the TAPPI, 1972 standard method using a tensile-strength tester, folding-strength tester (double fold), and bursting-strength testing equipment. The density of the paper sheets was calculated by measuring the thickness, using a dial thickness gauge, and basis weight of the paper sheets. 3. Results and discussion Jute stick, an agrowaste of jute cultivation, contains about 41% at-cellulose, 23% lignin and 24% pentosan in addition to other minor constituents. Its potential as raw material in pulp for making various grades of paper, such as writing and printing paper, wrapping and packaging paper, corrugated medium, etc., had been demonstrated earlier by several workers (Jain, 1960; Guha et al., 1962, 1965a, b). Ghosh et al. (1983) studied mixed pulping of jute stick with other conventional raw materials. Due to the short fibre and slow drainage of jute-stick pulp, the strength properties of paper made from the pulp alone is not up to the desired level. To improve the strength properties of paper made from jute-stick kraft pulp, a degraded hemicellulose obtained from the waste liquor during degumming of ramie fibre was used as beater additive. The degraded hemicellulose
S.K. Bhaduti et al. I Industrial Crops and Products 4 (1995) 79-84
had the following chemical composition (Bhaduri et al., 1992): ash, 18%; lignin, 6.7%; uranic anhydride, 14%; residues of rhamnose, 38%; arabinose, 9.7%; galactose, 46.9%; and glucose, 5.4%. The hemicellulose was light brown in colour, water soluble and strongly acidic in nature. The addition of a small amount (0.5 to 2%) of hemicellulose in jute-stick kraft pulp causes very little change in colour of the paper sheets. A portion of the unbleached kraft pulp (lignin, 16%) was bleached to moderate brightness, using the CEH sequence (lignin, 6%, brightness, 70% Elrepho). Strength properties of paper sheets made from the bleached pulp with additive were also evaluated. The effect of addition of the degraded ramie hemicellulose during the beating operation at different PFI revolutions on the strength properties of paper sheets made from both unbleached and bleached jute-stick kraft pulps are shown in Tables 1 and 2. It was observed that: (a) the density and strength properties, e.g. tensile index, fold-
Table 1 Effect of beating Sample No.
on strength
Pulp type
and other properties PFI revolutions
Beating energy
of jute-stick Freeness (“SW
(kwh)
81
ing strength (double fold), and burst index of paper sheets made from both unbleached and bleached pulps increased with addition of hemicellulose in the pulp during the beating operation; (b) for a particular beating experiment with the PFI mill, the pulp freeness, beating energy and strength properties of paper sheets made from both bleached and unbleached pulps increased with an increase in PFI revolutions, irrespective of addition of hemicellulose; (c) with an increase in additive percentage, lesser beating energy is required thereby reducing the time of beating operation. Addition of hemicellulose during the beating operation thus helps the pulp to achieve the desired strength values with less energy consumption in a shorter time period. The physical properties of the unbleached and bleached pulps and paper sheets made of them with and without the additive are represented with the change in PFI revolutions in Figs. l-6. The curves give us information regarding the effect of
kraft pulp with additive Strength
properties
tensile index
of resulting double
fold
paper burst index (kPa m’/g)
(N m/g)
Density paper (glcm3)
A
Control
1000 2000 3000 4000
0.025 0.035 0.045 0.055
13 20 30 38
28.4 35.4 44.0 52.9
84 114 190 204
1.90 2.16 2.35 2.65
0.22 0.27 0.34 0.51
B
Pulp + 0.5% additive
1000 2000 3000 4000
0.025 0.030 0.040 0.050
15 22 33 40
32.7 41.2 51.2 56.2
90 130 200 249
1.92 2.53 3.24 3.50
0.21 0.28 0.42 0.58
C
Pulp + 1.0% additive
1000 2000 3000 4000
0.020 0.025 0.030 0.045
14 25 36 42
35.6 47.6 55.7 61.1
90 150 240 285
1.90 2.65 3.41 3.68
0.25 0.33 0.51 0.60
D
Pulp + 1.5% additive
1000 2000 3000 4000
0.020 0.020 0.030 0.040
16 26 38 43
36.2 49.6 58.8 63.7
100 168 268 330
2.00 2.65 3.53 4.12
0.28 0.40 0.58 0.63
E
Pulp + 2.0% additive
1000 2000 3000 4000
0.017 0.020 0.025 0.035
18 27 38 45
38.0 50.0 67.6 71.2
105 173 275 360
2.07 2.79 3.82 4.74
0.27 0.40 0.61 0.70
of
S.K. Bhaduri et al. IIndustrial Crops and Products 4 (1995) 79-84
82
Table 2 Effect of beating on strength and other properties of bleached jute-stick kraft pulp with additive Sample No.
Pulp type
Control
A
PFI revolutions
Beating energy
Freeness
Strength properties of resulting paper
Density of
(“SW
tensile index
burst index (kPa m’/g)
paper (s/cm?
1000
0.025 0.030 0.030 0.031
18 21 29 31
33.4 35.3 40.7 45.0
60 69 18 85
1.77 1.96 2.26 2.55
0.24 0.33 0.45 0.55
0.020 0.025 0.030 0.031
20 29 31 33
37.2 38.2 43.8 46.7
15 81 96 105
2.09 2.45 2.88 3.05
0.31 0.35 0.52 0.64
(kwh)
2000 3000 4000
double fold
(N m/g)
B
Pulp + 0.5% additive
C
Pulp + 1.0% additive
0.015 0.030 0.035 0.032
22 32 34 36
38.5 41.2 44.0 49.0
78 90 100 114
2.62 2.94 3.24 3.37
0.33 0.40 0.60 0.70
D
Pulp + 1.5% additive
0.010 0.015 0.020 0.029
24 33 36 40
41.2 42.9 45.6 50.0
87 96 105 120
3.06 3.24 3.70 3.90
0.38 0.42 0.63 0.72
E
Pulp + 2.0% additive
0.010 0.020 0.030 0.032
25 37 40 42
40.6 43.8 49.0 51.3
95 105 114 125
3.04 3.41 3.94 4.51
0.40 0.45 0.65 0.77
1000
5ol 40.
i
a -
30.
2 al
z
E 20’ 10
I I
2000
1000 PFI
3000
4 000
Revolution-
Fig. 1. Freeness vs PFI revolution. a = jute-stick pulp, b = jute-stick pulp + 2% additive, c = bleached jute-stick pulp, d = bleached jute-stick pulp + 2% additive.
additive and the rate of beating at which the pulp develops its properties. This is given by the PFI revolutions to reach the desired degree of freeness or strength. It is one of the most important properties evaluated because of its effect on power consumption. Addition of hemicellulose favours interfibre bonding due to its hydrophilic properties which cause greater swelling of cell walls in water imparting fibre flexibility. This helps in better fibre conformation and more interfibre bonding during sheet formation. Thus the strength properties of paper correlated to interfibre bonding (Rydholm, 1965), viz. tensile index, folding endurance, etc., are improved. In addition, hemicellulose may contribute more hydrogen bonding per unit area than do cellulose surfaces (Robinson, 1980). The degradation of hemicellulose during isolation, and its addition to the pulp effecting in concentrated absorption on external fibre surfaces (Mobarak et al., 1973), are also reasons for its effect as additive in fibre bonding.
S.K. Bhaduri et al. /Industrial Crops and Products 4 (1995) 79-84
83
80
.06
r
70
60
b
1 1000
2000 PFI
3000
4000 I
Revolution
Fig. 2. Beating energy vs PFI revolution. a = jute-stick pulp, b = jute-stick pulp + 2% additive, c = bleached jute-stick pulp, d = bleached jute-stick pulp + 2% additive.
2000
1000 P F
3000
4000
I Revolution
Fig. 3. Tensile index vs PFI revolution. a = jute-stick pulp, b = jute-stick pulp + 2% additive, c = bleached jute-stick pulp, d = bleached jute-stick pulp + 2% additive.
4. Conclusions 500 -
The
degraded hemicellulose obtained from degumming liquor of ramie fibre was an acidic polysaccharide having rhamnose and galactose as predominant sugars. When the hemicellulose was used as additive in small concentrations (0.5% to 2.0%) during the beating operation of jute-stick kraft pulp in a PFI mill, it helped to reach improved strength properties of the pulp with less energy consumption, thereby reducing the time of beating operation. Strength properties, such as tensile index, folding endurance and burst index of paper sheets made from the jute-stick pulp with the additive were also improved significantly. The beneficial effect of added hemicellulose on strength properties of paper is attributed to its hydrophilic properties imparting fibre flexibility due to greater swelling of cell wall which, in turn, favours interfibre bonding. In addition, increased concentration of added hemicellulose on the external fibre surfaces and degradation of the
400
.
300
-
200
.
100
-
9 9 2 2 P
I 1000
2000 PFI
3000
4000
Revolution
Fig. 4. Double fold vs PFI revolution. a = jute-stick pulp, b = jute-stick pulp + 2% additive, c = bleached jute-stick pulp, d = bleached jute-stick pulp + 2% additive.
84
S.K. Bhaduti et al. IIndustrial
Acknowledgements
5.0 v
4.0
Crops and Products 4 (1995) 79-84
The authors are thankful to the Director of the Jute Technological Research Laboratories (ICAR) for providing work facilities.
’
N$ p
References
3.0.
1 x 4 g
e In !s In
2.0 -
1.0
-
1000
2000 P F I
RavolutiMl
3000
4000
-
Fig. 5. Burst index vs PFI revolution. a = jute-stick pulp, b = jute-stick pulp + 2% additive, c = bleached jute-stick pulp, d = bleached jute-stick pulp + 2% additive.
1000 PF
I
2000 3000 Revolution
4 000 L
Fig. 6. Density vs PFI revolution. a = jute-stick pulp, b = jute-stick pulp + 2% additive, c = bleached jute-stick pulp, d = bleached jute-stick pulp + 2% additive.
hemicellulose during isolation have also significant effect in raising its adhesive property for fibre bonding.
Bakshi, B.K., Gandhi, OP., Meshramkar, PM., Deb, U.K. and Jaspal, N.S., 1982. Chemicals and additives in paper making - experience at the West Coast Paper Mills Ltd. lppta, 19: 40-48. Bhaduri, SK., Day, A., Mondal, S.B. and Sen, S.K., 1992. Degraded gum from ramie in binder composition for jute stick particle board. Bioresour. Technol., 40: 87-89. Das Gupta, PC., Sen, K. and Sen, S.K., 1976. Degumming of decorticated ramie for textile purposes. Cellulose Chem. Technol., 10: 285-291. Fahmy, Y. and Mobarak, E, 1972. Influence of starch addition on filler retention and paper properties of straw and wood pulps. Cellulose Chem. Technol., 6: 67-70. Ghosh, I.N., Roy, A.K. and Banerjee, SK., 1983. Mixed pulping of jute stick with other cellulosic raw materials. Indian Text. J., 94: 151-153. Guha, S.R.D., Mathur, G.M. and Mukherjea, VN., 1962. Production of cheap grade paper from jute stick by cold caustic soda process. Indian Pulp Pap., 17: 153-154. Guha, S.R.D., Sharma, Y.K. and Mukherjea, V.N., 1965a. Jute stick pulp for writing and printing papers by sulphate process. Indian Pulp Pap., 19: 729-730. Guha, S.R.D., Mukherjea, V.N. and Sharma, Y.K., 1965b. Pilot plant production of printing papers from jute stick and bagasse by mechano-chemical process. Indian Pulp Pap., 19: 551-552. Jain, S.C., 1960. Pulp from jute stick by nitric acid pulping process. Indian Pulp Pap., 15: 161-169. Jeffery, J.E., Partlow, E.V. and Polglase, W.J., 1960. Chromatographic examination of wood cellulose hydrolysates - a routine reflectance method. Anal. Chem., 32: 17741777. Mobarak, F., El-Ashmany, A.E. and Fahmy, Y., 1973. Hemicelluloses as additive in paper making, Part II. The role of added hemicelluloses and hemicellulose in situ on paper properties. Cellulose Chem. Technol., 7: 323-325. Robinson, J.V., 1980. Fibre bonding. In: J.I? Casey (Editor), Pulp and Paper Chemistry and Chemical Technology, Vol. 11. John Wiley and Sons, New York, 3rd ed., pp. 940-941. Rydholm, S.R., 1965. Pulping Processes. Interscience Publishers, New York, 1159 pp. TAPPI, 1972. Standard and Suggested Methods. Technical Association of the Pulp and Paper Industry, New York.