Ind. Eng. Chem. Res. 2009, 48, 749–754
749
Cationic Alkoxylated Amine Surfactant as a Debonding Agent for Papers Made of Sulfite-Bleached Fibers Pedram Fatehi, Kevin Outhouse, and Huining Xiao* Department of Chemical Engineering and Limerick Pulp and Paper Centre, UniVersity of New Brunswick, Fredericton, New Brunswick, Canada E3B 5A3
Today, there is a steadily increasing demand for the application of surfactants as debonding agents in tissue manufacturing. The work presented herein focused on evaluating the debonding ability of cationic alkoxylated amine surfactant on unrefined and refined fibers. The results showed that, as the dosage of the surfactant was increased to 10 mg/g on unrefined pulps, the adsorption of the surfactant on the fibers increased to 5 mg/g, and the tensile and burst indices of the papers made of the modified fibers decreased by as much as 12.6% and 14.9%, respectively. Also, the roughness, strain, and moisture content of the papers were enhanced, whereas the apparent density was reduced. Furthermore, the tear index of the papers increased upon the application of surfactant (10 mg/g) at the expense of reductions in tensile and burst indices, as well as the apparent density at any pressure applied in wet pressing. Also, as the pressure was increased, the surfactant impacted the fiber bonding more significantly. On the other hand, the application of surfactant (10 mg/g) somewhat increased the light scattering coefficient of the papers, regardless of the refining load. Furthermore, the adsorption of the surfactant on refined fibers increased with increasing refining load. However, the influence of the surfactant on the tear, tensile, and burst indices and the apparent density was impaired with increasing refining load. Also, the zero-span tensile index and brightness of the papers varied negligibly upon surfactant application. 1. Introduction Recently, there has been an increasing demand for the use of debonding agents in the paper industries, especially in tissue manufacturing.1 The softness of tissue papers, which basically affects its folding and crinkling performance, can be improved by the mechanical or chemical treatment of papers.1 The mechanical treatment is conducted through creping and air-dry technology.1 However, the chemical treatment can be performed by using debonding agents, i.e., surfactants, on fibers.1 As the bonding of papers is reduced, the apparent density of the papers might be reduced, and papers could be more easily folded and crinkled. Several researchers have evaluated the adsorption characteristics of some surfactants on cellulose fibers.2-5 However, little information is available on the impact of such surfactants on paper properties. The adsorption of a chemical additive varies the hydrophilicity or surface charge of fibers and, hence, modifies the surface chemistry and/or morphology of the fibers.6 Because the surface charge and chemistry of fibers play crucial roles in the development of bonding, the application of a chemical additive might influence the bonding performance of fibers.7-9 Cationic alkoxylated amine is an environmentally friendly hydrophilic surfactant. Its effects on the water absorbency and pore sizes of papers were investigated in our previous studies.10,11 However, its debonding ability on papers has not yet been sufficiently investigated. Also, as refiners are often used in paper mills and the surface area and chemistry of fibers are changed by refining, it is of interest to assess the debonding ability of the surfactant on refined fibers. The debonding ability of a surfactant can be evaluated by analyzing the variations in the mechanical properties of papers caused by application of a surfactant. Page comprehensively described the parameters associated with the tensile strength of * To whom correspondence should be addressed. E-mail: hxiao@ unb.ca.
papers.12 These parameters can be categorized into two main groups: fiber bonding and fiber wall strength. The zero-span tensile strength of paper mainly represents the fiber wall strength.13 Therefore, assessments of the finite-span and zerospan tensile strengths of papers facilitate the estimation of fiber bonding according to Page’s tensile equation. Such an estimation could indicate the influence of the surfactant on the shear strength of fiber bonding. In this work, a surfactant was introduced into a suspension of unrefined or refined cellulose fibers under different treatment conditions, and then handsheets were made. Alternatively, some handsheets were made under different pressures of wet pressing. The adsorption and impact of the surfactant on the mechanical and optical properties of the handsheets were systematically investigated. The results of this work are directly related to the application of surfactants to papers, which is of great importance for tissue manufacturing. 2. Experimental Section 2.1. Raw Materials and Fiber Preparation. Cationic alkoxylated amine surfactant was kindly provided by Clariant Chemicals (Charlotte, NC) and diluted to 0.1 wt % before being used throughout the entire work. Sulfite-bleached softwood pulp was obtained from Fraser Paper Co. (Edmundston, NB, Canada). The pulp was washed thoroughly prior to use. The moisture content of the pulp was measured in accordance with TAPPI test method T 412. The fiber characteristics were analyzed using a fiber quality analyzer (OpTest Equipment Inc., Hawkesbury, ON, Canada). Also, the refining of pulp was carried out according to TAPPI test method T 248 with a PFI refiner (no. 158, PFI, Trondheim, Norway). The freeness of the pulps was tested using a Canadian standard freeness (CSF) tester in accordance with TAPPI test method T 227. 2.2. Surfactant Adsorption. About 1 g (oven-dry) of pulp fibers was first dispersed in a 125-mL Erlenmeyer glass flask
10.1021/ie800929p CCC: $40.75 2009 American Chemical Society Published on Web 12/02/2008
750 Ind. Eng. Chem. Res., Vol. 48, No. 2, 2009 Table 1. Properties of Papers Made of Unrefined Fibers Modified with Various Dosages of Surfactant dosage of surfactant (mg/g)
tensile index (N m/g)
burst index (kPa m2/g)
tear index (N m2/kg)
zero-span tensile index (N m/g)
brightness (% ISO)
moisture content (%)
0 2 4 6 8 10
48.1 ( 1.4 45.9 ( 1.9 45.1 ( 2.6 44.2 ( 2.4 43.7 ( 1.7 42.0 ( 1.1
3.55 ( 0.11 3.37 ( 0.13 3.34 ( 0.15 3.22 ( 0.14 3.15 ( 0.10 3.02 ( 0.12
14.8 ( 0.3 15.7 ( 0.4 16.1 ( 0.7 17.0 ( 0.5 17.2 ( 0.5 17.7 ( 0.4
164.5 ( 2.1 164.7 ( 2.3 161.2 ( 1.5 161.1 ( 1.8 159.4 ( 1.2 162.0 ( 1.9
87.8 ( 0.2 87.7 ( 0.3 87.8 ( 0.1 88.0 ( 0.4 87.7 ( 0.2 87.9 ( 0.2
5.8 ( 0.2 6.1 ( 0.3 6.4 ( 0.3 6.9 ( 0.4 7.2 ( 0.2 7.4 ( 0.3
Table 2. Mechanical Properties of Papers Made of Unmodified Fibers or Fibers Modified with Surfactant (10 mg/g) under Different Pressures tensile index (N m/g)
tear index (N m2/kg)
burst index (kPa m2/g)
zero-span tensile index (N m/g)
apparent density (kg/m3)
pressure (kPa)
blank
modified
blank
modified
blank
modified
blank
modified
blank
modified
150 250 480
39.7 ( 1.3 42.0 ( 1.8 49.5 ( 2.0
37.2 ( 1.7 39.5 ( 1.3 43.5 ( 1.5
17.9 ( 1.1 16.9 ( 2.0 13.3 ( 1.0
19.9 ( 1.5 18.6 ( 1.0 16.7 ( 1.2
2.68 ( 0.12 3.05 ( 0.14 3.81 ( 0.11
2.53 ( 0.14 2.88 ( 0.12 3.23 ( 0.10
160.2 ( 2.2 161.3 ( 2.0 170.1 ( 1.9
157.2 ( 2.3 158.1 ( 2.1 168.4 ( 1.9
618.7 ( 2.0 676.6 ( 2.1 745 ( 2.7
615 ( 1.5 660 ( 2.1 705 ( 1.8
Table 3. Characteristics of Refined Fibers refining loads (rev)
fiber length (mm)
fine (%)
curl index
CSF, ml
0 500 3000 5000 8000
1.95 ( 0.03 1.99 ( 0.04 1.66 ( 0.03 1.65 ( 0.03 1.59 ( 0.04
29.3 ( 2.2 30.9 ( 2.5 33.5 ( 2.6 34.9 ( 2.4 36.3 ( 1.9
0.141 ( 0.01 0.125 ( 0.01 0.110 ( 0.01 0.079 ( 0.01 0.075 ( 0.01
726 ( 3 686 ( 4 605 ( 6 526 ( 5 421 ( 3
at 3% consistency and 30 °C. Various dosages of the surfactant were added to the suspensions, as listed in Table 1, and then immersed in a water bath shaker and shaken at 200 rpm for 1 h. After that, the supernatants and fibers were separated by vacuum filtering. The supernatants were centrifuged at 3000 rpm for 30 min.2,4 Then, samples were taken from the top part of the centrifuged supernatant for analysis. A UV spectrometer (Thermo Electron Corporation, Genesys, Madison, WI) was employed to evaluate the concentration of the surfactant in the solutions.14,15 First, a calibration curve was prepared by plotting the variations in the predefined concentration of the surfactant in solution against the variations in the intensity of UV light at a wavelength of 212 nm. Finally, the concentrations of the surfactant in the solutions were determined by fitting the obtained UV intensities of the samples to the calibration curve. 2.3. Fiber Modification and Handsheet Preparation. Pulp fibers were first dispersed in distilled water in a 2-L three-neck glass flask at 3% consistency and 30 °C. In the first experiment, various dosages of the surfactant were applied to the suspensions of unrefined fibers, and the suspensions were stirred for 1 h (see Table 1). Then, the fibers were washed thoroughly with distilled water to remove unadsorbed surfactant. The handsheets were prepared in accordance with TAPPI test method T 205, pressed under 350 kPa pressure, and dried in a conditioning room in accordance with TAPPI test method T 402. In the second experiment, the surfactant, at a fixed amount of 10 mg/ g, was mixed with fiber suspensions under the same conditions as described above. After the removal of unadsorbed surfactant and the preparation of handsheets in a handsheet former (TAPPI test method T 205), different pressures (see Table 2) were applied to press the handsheets. Then, the handsheets were dried in accordance with TAPPI test method T 402. In the third experiment, 10 mg/g of the surfactant was applied to the suspensions of refined fibers under the same conditions (see Table 3). Then, the unadsorbed surfactant was removed from the fibers. After that, the handsheets were made in accordance with TAPPI test method T 205, pressed under 350 kPa pressure, and dried according to TAPPI test method T 402.
2.4. Paper Properties. The light scattering coefficient and the brightness of the handsheets were tested in accordance with TAPPI test methods T 425 and T 452, respectively, using a Technibrite Micro TB-1C optical tester (Technidyne, New Albany, IN). Finite-span tensile strength (simplified as tensile strength in this article) and tear strength were measured in accordance with TAPPI test methods T 494 and T 414, respectively, using Lorentzen & Wettre (L&W) tensile and tear testers (Kista, Sweden). The burst strength of paper was also measured in accordance with TAPPI test method T 403 using an L&W Burst-o-Matic burst tester. The roughness of the papers was examined using a monitor/print-surf roughness tester [model 58-01, Testing Machines Inc. (TMI), Ronkonkoma, NY] in accordance with TAPPI test method T 479. The zero-span tensile strength was measured using a Pulmac model FQT-E2-110 tester (Montreal, Quebec, Canada) in accordance with TAPPI test method T 494. The moisture content of the handsheets was also determined in accordance with TAPPI test method T 412, after they had been kept overnight in the conditioning room. It should be mentioned that each type of the test was conducted at least twice to ensure the repeatability and reliability of the results. 2.5. Fiber Bonding Estimation. The simplified form of Page’s tensile strength equation is as follows 1 1 1 ) + T F B
(1)
where T, F, and B represent the tensile index, fiber wall index, and fiber bonding index, respectively.12 Therefore, the fiber bonding index in eq 1 can be estimated by determining the tensile and zero-span tensile strengths of papers. 3. Results and Discussion 3.1. Adsorption Isotherm of Surfactant on Unrefined Pulp. Figure 1 shows the adsorption isotherm of the surfactant on unrefined pulp. As can be seen, an increase in the concentration of surfactant in the solution increased its adsorption on the fibers. However, the rate of adsorption decreased as the amount of surfactant adsorbed on the fibers increased. This decrease is probably due to the repulsive force developed between the already adsorbed surfactant on the fibers and the approaching surfactant molecules from the bulk or to the saturation of the fiber surface by surfactant. 3.2. Impact of Surfactant on Properties of Papers Made of Unrefined Fibers. Table 1 lists the properties of the papers made of the fibers modified with the surfactant. As can be seen, the tensile and burst indices of the papers decreased,
Ind. Eng. Chem. Res., Vol. 48, No. 2, 2009 751
Figure 1. Adsorption isotherm of surfactant on unrefined fibers.
Figure 2. Variations in tear, tensile, and burst indices of papers made of modified fibers as functions of surfactant dosage.
whereas the tear index increased upon application of the surfactant. The zero-span tensile index of papers changed only marginally, suggesting that the fiber wall strength was fairly unaffected by the surfactant application.13 Also, the brightness of the paper was almost unchanged. However, the moisture content of the papers increased as the surfactant dosage was increased. The increase in the water absorbency (rewetting ability) of papers upon use of this surfactant was reported in our previous work.10,11 Figure 2 shows the variations in the tear, tensile, and burst indices of papers upon application of the surfactant. It appears that the maximum enhancement in tear index was 20%. The maximum reductions in tensile and burst indices were 12.6%, and 14.9%, respectively, by applying 10 mg/g of the surfactant. Because the tensile index of papers varied significantly, whereas the fiber wall index was negligibly changed upon surfactant application, the variations in the tensile index represent variations in the fiber bonding according to eq 1. On the other hand, the tear index of paper is affected by many factors, e.g., fiber wall and bonding breakages and the friction between fibers.16,17 As reported earlier, the breaking of the fiber bonding requires more energy than the breaking of the fiber wall in the tear test.16 Therefore, more fibers are broken than pulled out in the tear test. Consequently, if the fiber bonding is reduced or the amount of fiber bonding breakage is increased, the tear index of the papers tends to increase, as shown in Figure 2. Figure 3 shows the final stress prior to the rupturing of papers modified with various dosages of the surfactant. Interestingly, as the dosage of surfactant was increased (to 10 mg/g), the final strain was enhanced (up to 11%). On the other hand, the moisture content of the papers increased upon application of the surfactant, as discussed earlier. It has been reported that an increase in the moisture content of paper is associated with an increase in the strain of paper.18 Therefore, the increase in the strain of the paper can be logically attributed to an increase in the moisture content of the fiber surface caused by application
Figure 3. Final strain of papers made of modified fibers as a function of surfactant dosage.
Figure 4. Roughness versus apparent density of papers made of fibers modified with surfactant.
of the surfactant. This increase probably contributes to the lubricating of the fiber surface, which results in easier pullingout of the fibers during the tensile test, as seen in Table 1 and proposed by Westerlind et al.19 Figure 4 shows the roughness and apparent density of the papers modified with the surfactant. Clearly, as the dosage of the surfactant was increased, the apparent density and roughness of the papers decreased and increased, respectively. The decrease in the apparent density of the papers was due to the reduction in the fiber bonding, as discussed above. These results support the findings in the literature.16,20,21 It has also been reported in the literature that, by increasing the fiber bonding, paper formation can be improved, i.e., the roughness of the paper can be reduced.22,23 Although the roughness measurement of papers does not directly probe the formation of the papers, variations in the paper roughness can indirectly reflect the changes that occur in the surface structure of the papers upon application of the surfactant. 24 Therefore, the increase in the paper roughness might be related to the debonding ability of the surfactant. 3.3. Impact of Surfactant on Paper Properties upon Varying the Contact Area of Fibers. To further investigate the debonding ability of the surfactant, we varied the contact area of the fibers by applying different pressures in wet pressing. Table 2 lists the mechanical properties of the papers made of fibers modified with the surfactant (10 mg/g) under different pressures. Similarly, the properties of the papers made of unmodified fibers and fibers modified with surfactant (10 mg/ g) and pressed at 350 kPa are listed in Table 1. As can be seen, the higher the pressure, the higher the tensile and burst indices and the apparent density, and the lower the tear index, regardless of surfactant application. In the literature, an increase in fiber bonding was proposed to be the main reason for such changes.25-27 Furthermore, the higher the pressure applied, the more intensely the fiber wall could be collapsed and cross-
752 Ind. Eng. Chem. Res., Vol. 48, No. 2, 2009
Figure 7. Adsorption of surfactant on refined fibers. Figure 5. Tear index versus tensile index for papers made of fibers modified with surfactant (10 mg/g) prepared under different pressures.
Figure 6. Bonding index versus light scattering coefficient for papers made of fibers modified with surfactant (10 mg/g) prepared under different pressures.
linked, leading to a higher fiber wall strength upon drying, regardless of surfactant application (Table 2). Figure 5 shows the tear index versus the tensile index of unmodified papers and papers modified with the surfactant (10 mg/g) prepared under different pressures. It appears that the surfactant did not change the tear-tensile correlation of the papers but shifted it to lower values for tensile index and higher values for tear index at any pressure. Figure 6 shows the bonding index versus the light scattering coefficient of the papers made of unmodified or modified fibers under various pressures. As can be seen, the bonding index was enhanced by increasing the pressure, whereas the light scattering coefficient was reduced, regardless of surfactant application. Such variations can be ascribed to an increase in the contact area of the fibers that causes higher fiber bonding development upon application of a higher pressure.25-27 Interestingly, at increased pressure, the bonding index of the papers made of unmodified fibers was more significantly increased than that of modified fibers. For the latter, the surface of the fibers was somewhat covered by the surfactant. Therefore, larger contact area of the modified fibers resulted in a greater impact of the surfactant on fiber bonding, which led to a more significant reduction in the fiber bonding (see Figure 6). Also, an increase
in the impact of the surfactant on the fiber bonding through an increase in pressure is perhaps the reason for the lower increase in the apparent density of the papers made of modified fibers compared to those made of unmodified fibers (see Table 2). 3.4. Impact of Surfactant on Paper Properties of Refined Fibers. Table 3 lists the characteristics of the refined fibers. Obviously, an increase in the refining load reduced the weighted length (LW) of the fibers and also increased the fine content of the pulps. Therefore, the available surface area of the fibers was increased by an increase in the refining load, as expected. Thus, it can be concluded that, as the refining load is increased, the fiber breakage increases significantly. Considering the reduction in the curl index of the fibers (Table 3), it can be suggested that fiber breakage was perhaps more dominant for curly fibers than for straight fibers. Additionally, the CSF analysis indicates that the flexibility of the fibers was increased by refining, as expected. Figure 7 shows the adsorption of the surfactant on the refined fibers. Clearly, an increase in the refining load tended to increase the adsorption of the surfactant on the fibers. This increase in adsorption is due to the enhancement in the fiber surface area, as described earlier. Table 4 lists the properties of the papers made of the refined fibers modified with surfactant. Regardless of surfactant application, an increase in the refining load tended to increase the tensile and burst indices, as well as the apparent density, and to decrease the tear index and brightness of the papers. Therefore, it can be concluded that the fiber bonding increased upon refining owing to larger fiber contacts. The larger fiber contacts are attributed to enhancements in the available surface areas of the fibers through fibrillation and in the flexibility of fibers.16,21 Also, an increase in the refining load reduced the difference between the apparent densities of the papers made of unmodified and modified fibers. On the other hand, Seth claimed that the reduction in the curl index of fiber is due to the straightening of fibers as the refining load is increased.25 This increase in fiber straightening might be a reason for the increase in the zero-span tensile indices of the papers made of unmodified or modified fibers even though the zero-span tensile index does not directly reflect the fiber wall strength.25
Table 4. Properties of Papers Made of Refined Fibers Modified with the Surfactant (10 mg/g) tensile index (N m/g) refining load (rev)
blank
500 3000 5000 8000
62.0 ( 2.0 83.2 ( 2.1 85.5 ( 1.9 91.1 ( 2.3
modified
tear index (N m2/kg) blank
modified
burst index (kPa m2/g) blank
58.1 ( 2.1 12.6 ( 1.1 14.5 ( 1.2 4.62 ( 0.14 80.3 ( 1.8 8.5 ( 0.7 9.4 ( 0.8 5.82 ( 0.14 83.9 ( 1.9 8.2 ( 0.9 8.7 ( 0.9 6.08 ( 0.12 90.0 ( 1.5 8.1 ( 1.2 8.3 ( 1.1 6.61 ( 0.09
zero-span tensile index (N m/g)
brightness (% ISO)
apparent density (kg/m3)
modified
blank
modified
blank
modified
blank
modified
4.21 ( 0.09 5.43 ( 0.13 5.82 ( 0.11 6.55 ( 0.10
173.6 ( 2.1 182.0 ( 2.0 186.5 ( 2.3 188.9 ( 1.7
170.9 ( 2.1 181.5 ( 2.3 185.2 ( 1.8 187.2 ( 1.6
86.6 ( 1.1 84.4 ( 0.8 83.9 ( 0.7 83.8 ( 0.9
86.8 ( 0.9 84.9 ( 1.0 83.7 ( 1.1 83.3 ( 1.02
762.5 ( 1.2 822.4 ( 2.1 862.4 ( 1.5 934.1 ( 0.8
739.1 ( 1.5 815.4 ( 2.0 852.3 ( 1.6 930.9 ( 2.3
Ind. Eng. Chem. Res., Vol. 48, No. 2, 2009 753
Figure 8. Tear versus tensile index for papers made of refined fibers modified with the surfactant (10 mg/g).
Figure 9. Final stress versus final strain for papers made of refined fibers modified with the surfactant (10 mg/g).
Figure 8 shows the tear index versus the tensile index of the papers made of the refined fibers modified with the surfactant (10 mg/g). It appears that the papers made of the modified fibers exhibited a higher tear index than the papers made of unmodified fibers. Also, increasing the refining load appears to have decreased the influence of the surfactant on the tear and tensile indices of the papers. Figure 9 shows the final stress versus the final strain of the papers prior to rupturing applied in the tensile test. Clearly, both the final stress and the final strain of the papers tended to increase with increasing refining load, regardless of surfactant application. These enhancements were due to the increase in the fiber bonding, which support the findings in the literature.16,21 Also, increasing the refining load decreased the difference between the strains of the papers made of unmodified and modified fibers. The results in Figures 8 and 9 suggest that an increase in the refining load decreases the debonding ability of the surfactant on papers even though the surfactant adsorption increased (Figure 7). As can be seen in Figure 7, when the refining load was increased, the total increase in the surfactant adsorption was about 1.5 mg/g, which could reduce the tensile or burst indices of the papers made of unrefined fibers by 4% (according to Figure 2). However, it appears that an increase in the available surface area of the fibers overwhelmed the effect of the surfactant on the fiber bonding. In other words, although the adsorption of surfactant increased as a result of refining, its surface coverage on the fibers might not have increased, and hence, this increase in adsorption could not compensate for the increase in the surface area and bonding of the fibers. Thus, its impact on the properties of the papers made of the refined fibers was impaired at increased refining loads.
Figure 10. Bonding index versus light scattering coefficient for papers made of refined fibers modified with the surfactant (10 mg/g).
Figure 10 shows the bonding index of the papers made of the refined fibers versus the light scattering coefficient. Obviously, when the refining load was increased, the fiber bonding and light scattering coefficients of papers increased and decreased, respectively. Regardless of the refining load, the light scattering coefficient of the papers was somewhat enhanced by surfactant application. Such behavior is in agreement with our previous study, in which an increase in the pore size of the papers was attributed to application of the surfactant.10,11 This phenomenon might be due to the repulsive force developed among fibers upon surfactant application.28 In other words, the stronger the repulsive force between the fibers, the smaller their contact areas, which results in larger voids in the paper matrix that lead to an increase in the light scattering of the papers (see Figure 10). 4. Conclusions Cationic alkoxylated amine surfactant is a promising debonding agent for reducing the tensile and burst indices of the papers made of the unrefined sulfite-bleached softwood pulps. As the dosage of the surfactant on unrefined pulps was increased to 10 mg/g, the adsorption of surfactant on the fibers increased to 5 mg/g. Also, the tensile and burst indices of the papers made of the fibers modified with surfactant decreased as much as 12.6% and 14.9%, respectively, and the tear index was increased to 20%. An increase in the dosage of surfactant tended to increase the roughness, strain, and moisture content of the papers but to decrease the apparent density of the papers. The tear index of the papers was increased by surfactant application (10 mg/ g), whereas the tensile and burst indices and the apparent density decreased at any pressure applied in wet pressing. Furthermore, as the pressure in wet pressing was increased, the impact of the surfactant on the fiber bonding of the papers became greater. The application of surfactant (10 mg/g) on the refined fibers led to an increase in the light scattering coefficient of the papers, regardless of the refining load. Additionally, increasing the refining load resulted in an increase in the adsorption of the surfactant on refined fibers. Otherwise, the influence of the surfactant on the tear, tensile, and burst indices and on the apparent density decreased as the refining load was increased. However, the zero-span tensile index and brightness of papers were changed only marginally by surfactant application. Acknowledgment The authors thank Fraser Papers and Clariant Chemicals for providing the pulps and surfactant, respectively. Also, the Atlantic Innovation Fund (AIF) and NSERC, Canada, are gratefully acknowledged for providing the funding for this research.
754 Ind. Eng. Chem. Res., Vol. 48, No. 2, 2009
Literature Cited (1) Liu, J.; Hsieh, J. Application of Debonding Agents in Tissue Manufacturing. In Proceedings of TAPPI Papermakers Conference Trade Fair; TAPPI Press: Atlanta, GA, 2000; Book 1, p 71. (2) Aloulou, F.; Boufl, S.; Beneventi, D. Adsorption of Organic Compounds onto Polyelectrolyte Immobilized-Surfactant Aggregates on Cellulosic Fibers. J. Colloid Interface Sci. 2004, 280 (2), 350. (3) Alila, S.; Aloulou, F.; Beneventi, D.; Boufi, S. Self-Aggregation of Cationic Surfactants onto Oxidized Cellulose Fibers and Coadsorption of Organic Compounds. Langmuir 2007, 23 (7), 3723. (4) Aloulou, F.; Boufi, S.; Belgacem, N.; Gandini, A. Adsorption of Cationic Surfactants and Subsequent Adsolubilization of Organic Compound onto Cellulose Fibers. Colloid Polym. Sci. 2004, 283 (3), 344. (5) Alila, S.; Boufi, S.; Belgacem, N.; Beneventi, D. Adsorption of a Cationic Surfactant onto Cellulosic Fibers I. Surface Charge Effects. Langmuir 2005, 21 (18), 8106. (6) Shirazi, M.; van de Ven, T. G. M.; Gargier, G. Adsorption of Modified Starch on Pulp Fibers. Langmuir 2003, 19 (26), 10835. (7) Pelton, R. On the Design of Polymers for Increased Paper Dry StrengthsA Review. Appita J. 2004, 57 (3), 181. (8) Lindstrom, T. The Role of Fiber Surface and Bulk Charge in Papermaking. In Proceedings of International Paper and Coating Chemistry Symposium; TAPPI Press: Atlanta, GA, 2003; p 1. (9) Laine, J.; Lindstrom, T.; Bremberg, C.; Gland-Nordmark, G. Studies on Topochemical Modification of Cellulosic Fibers. Part 5. Comparison of the Effects of Surface and Bulk Chemical Modification and Beating of Pulp on Paper Properties. Nord. Pulp Pap. Res. J. 2003, 18 (3), 325. (10) Shepherd, I.; Xiao, H. The Role of Surfactants as Rewetting Agents in Enhancing Paper Absorbency. Colloids Surf. A: Physicochem. Eng. Aspects 1999, 157 (1-3), 235. (11) Xiao, H.; Shepherd, I. Effect of Cationic Surfactant as Rewetting Agent on Paper Absorbency and Structures. J. Pulp Pap. Sci. 1999, 25 (5), 170. (12) Page, D. H. Theory for Tensile Strength of Paper. Tappi J. 1969, 52 (4), 674. (13) Wathen, R.; Rosti, J.; Alava, M.; Salminen, L.; Joutsimo, O. Fiber Strength and Zero-Span Strength StatisticssSome Considerations. Nord. Pulp Pap. Res. J. 2006, 21 (2), 193. (14) Ayranci, E.; Duman, O. Removal of Anionic Surfactant from Aqueous Solutions by Adsorption onto High Area Activated Carbon Cloth Studied by in Situ UV Spectroscopy. J. Hazard. Mater. 2007, 148, 75. (15) Fras-Zemljic, L.; Stenius, P.; Laine, J.; Stana-Kleinschek, K. The Effect of Adsorbed Carboxymethyl Cellulose on the Cotton Fiber Adsorption Capacity for Surfactant. Cellulose 2006, 13, 655.
(16) Seth, R. S. Fibre Quality Factors in PapermakingsI. The Importance of Fibre Length and Strength. In Proceedings of the Materials Research Society Symposium; Materials Research Society: Warrendale, PA, 1990; Vol. 197, p 125. (17) Ashkling, C.; Wagberg, L.; Rigdahl, M. The Effect of Additives on the Mechanical Properties of Dry-Formed Fiber Network. J. Mater. Sci. 1998, 33, 1997. (18) Seth, R. S.; Barbe, M. C.; William, J. C. R.; Page, D. H. Strength of Wet WebssA New Approach. In Proceedings of the Papermakers Conference; TAPPI Press: Atlanta, GA, 1981; p 13. (19) Westerlind, B. S.; Runslof, M.; Wagberg, L.; Bronkhorst, C. A. Influence of a Strength Additive and a Softener on Drying Stresses and Mechanical Properties for Laboratory Made Papers. In Proceeding of International Paper Physics Conference; TAPPI Press: Atlanta, GA, 2003; p 175. (20) Bushker, L. H. Effect of Wet Pressing on Paper Quality. In Proceedings of TAPPI Conference; TAPPI Press: Atlanta, GA, 1985; p 117. (21) Seth, R. S. Fibre Quality Factors in PapermakingsII. The Importance of Fibre Coarseness. In Proceedings of the Materials Research Society Symposium; Materials Research Society: Warrendale, PA, 1990; Vol. 197, p 141. (22) Nazhad, M. M.; Karnchanapoo, W.; Palokangas, A. Some Effects of Fiber Properties on Formation and Strength of Paper. Appita J. 2003, 56 (1), 61. (23) Nazhad, M. M.; Harris, E. J.; Dodson, C. T. J.; Kerekes, R. J. The Influence of Formation on Tensile Strength of Papers Made from Mechanical Pulps. Tappi J. 2000, 83 (12), 63. (24) Fatehi, P.; Xiao, H. The Influence of Charge Density and Molecular Weight of Cationic Poly (Vinyl Alcohol) on Paper Properties. Nord. Pulp Pap. Res. J. 2008, 23 (3), 285. (25) Seth, R. S. The Importance of Fiber Straightness for Pulp Strength. Pulp Pap. Can. 2006, 107 (1), 34. (26) Seth, R. S. The Measurement and Significance of Fines. Pulp Pap. Can. 2003, 104 (2), 41. (27) Seth, R. S. Understanding Sheet Extensibility. Pulp Pap. Can. 2005, 106 (2), 33. (28) Torgnysdotter, A.; Wagberg, L. Influence of Electrostatic Interactions on Fiber/fiber Joint and Paper Strength. Nord. Pulp Pap. Res. J. 2004, 19 (4), 440.
ReceiVed for reView June 12, 2008 ReVised manuscript receiVed October 7, 2008 Accepted October 26, 2008 IE800929P
