PAPERmaking! Vol3 Nr2 2017

making! PAPER

The e-magazine for the Fibrous Forest Products Sector

Produced by: The Paper Industry Technical Association

Volume 3 / Number 2 / 2017

PAPERmaking! FROM THE PUBLISHERS OF PAPER TECHNOLOGY Volume 3, Number 2, 2017

CONTENTS:

FEATURE ARTICLES: 1. Corrugated : Modelling corrugated board strength 2. Filler : Understanding the dispersion chemistry of talc

3. Hygiene : The issue of non-biodegradability of personal hygiene products 4. Bacterial Contamination : Characterizing bacterial communities in papermaking 5. Nanocellulose : Multi-layer nanopaper based composites 6. Wood Panel : Utilization of Waste Polyethylene in OSB 7. Environment : Life Cycle Paper Flows, Recycling Metrics, and Material Efficiency 8. Nonwovens : An engineered textile product 9. L&W Board Testing : Introducing the L&W range of board testing instruments 10. Pilz on Safety Controls : Update on BS EN ISO 13849-1 Third Ed. 2015 11. Stress Management : How to control and reduce stress

12. Note-Taking : Tips for improving note-taking skills 13. Effective Listening : Tips for improving listening skills 14. Change Leadership : Taking control of change

SUPPLIERS NEWS SECTION: Products & Services : Extended information on the latest products and services from: ABB Hyster Spray Nozzle Company Archroma Midland Pallet Trucks Turbex Bell Flow System Parker Hannifin Valmet CEA Sensonics Versaperm Fortress Interlocks SKF Gespasa Spirax Sarco DATA COMPILATION: Installations : Overview of equipment orders and installations since April 2017 Research Articles : Recent peer-reviewed articles from the technical paper press Technical Abstracts : Recent peer-reviewed articles from the general scientific press Events : Information on forthcoming national and international events The Paper Industry Technical Association (PITA) is an independent organisation which operates for the general benefit of its members – both individual and corporate – dedicated to promoting and improving the technical and scientific knowledge of those working in the UK pulp and paper industry. Formed in 1960, it serves the Industry, both manufacturers and suppliers, by providing a forum for members to meet and network; it organises visits, conferences and training seminars that cover all aspects of papermaking science. It also publishes the prestigious journal Paper Technology and the PITA Annual Review , both sent free to members, and a range of other technical publications which include conference proceedings and the acclaimed Essential Guide to Aqueous Coating .

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Contents

PAPERmaking! FROM THE PUBLISHERS OF PAPER TECHNOLOGY Volume 3, Number 2, 2017

Nonlinear Finite Element Analysis of the Fluted Corrugated Sheet in the Corrugated Cardboard Zhiguo Zhang (a,b,c), Tao Qiu (b), Riheng Song (b), and Yaoyu Sun (b) (a) Department of Polymer Science and Engineering, Zhejiang University, Hangzhou, Zhejiang 310027, China (b) School of Light Industry, Zhejiang University of Science and Technology, Hangzhou, Zhejiang 310023, China (c) Shengda Group Co., Ltd, Hangzhou, Zhejiang 311264, China The choice of corrugated medium, flute size, combining adhesive, and linerboards can be varied to design a corrugated board with specific properties. In this paper, the nonlinear finite element analysis of the fluted corrugated sheet in the corrugated cardboard based on software SolidWorks2008 was investigated. The model of corrugated board with three or more flutes is reliable for stress and displacement measurement to eliminate the influence of the number of flutes in models. According to the static pressure test, with the increase of flute height ܪ or arc radius of flute, the maximum stress in the models decreased and the maximum displacement increased. However the maximum stress and maximum displacement in the models increase nonlinearly in the static pressure test with the increase of the flute angle ߠ . According to the drop test, with the increase of flute height ܪ , the maximum stress of goods on the upper board in the drop test decreased. The maximum stress of the model in the drop test decreases firstly and then increases with the increase of flute angle, and the optimal flute angle ߠ could be 60° for corrugated board. All the conclusions are consistent with experimental data or product standards. Advances in Materials Science and Engineering, Volume 2014, Article ID 654012 http://dx.doi.org/10.1155/2014/654012

The Paper Industry Technical Association (PITA) is an independent organisation which operates for the general benefit of its members – both individual and corporate – dedicated to promoting and improving the technical and scientific knowledge of those working in the UK pulp and paper industry. Formed in 1960, it serves the Industry, both manufacturers and suppliers, by providing a forum for members to meet and network; it organises visits, conferences and training seminars that cover all aspects of papermaking science. It also publishes the prestigious journal Paper Technology and the PITA Annual Review , both sent free to members, and a range of other technical publications which include conference proceedings and the acclaimed Essential Guide to Aqueous Coating .

Page 1 of 9

Article 1 – Corrugated Strength

Hindawi Publishing Corporation Advances in Materials Science and Engineering Volume 2014, Article ID 654012, 8 pages http://dx.doi.org/10.1155/2014/654012

Research Article Nonlinear Finite Element Analysis of the Fluted Corrugated Sheet in the Corrugated Cardboard

Zhiguo Zhang, 1,2,3 TaoQiu, 2 Riheng Song, 2 and Yaoyu Sun 2 1 Department of Polymer Science and Engineering, Zhejiang University, Hangzhou, Zhejiang 310027, China 2 School of Light Industry, Zhejiang University of Science and Technology, Hangzhou, Zhejiang 310023, China 3 Shengda Group Co., Ltd, Hangzhou, Zhejiang 311264, China Correspondence should be addressed to Zhiguo Zhang; 107023@zust.edu.cn Received 3 February 2014; Revised 20 May 2014; Accepted 21 May 2014; Published 23 July 2014 Academic Editor: Jun Zhang

Copyright © 2014 Zhiguo Zhang et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The choice of corrugated medium, flute size, combining adhesive, and linerboards can be varied to design a corrugated board with specific properties. In this paper, the nonlinear finite element analysis of the fluted corrugated sheet in the corrugated cardboard based on software SolidWorks2008 was investigated. The model of corrugated board with three or more flutes is reliable for stress and displacement measurement to eliminate the influence of the number of flutes in models. According to the static pressure test, with the increase of flute height 𝐻 or arc radius of flute, the maximum stress in the models decreased and the maximum displacement increased. However the maximum stress and maximum displacement in the models increase nonlinearly in the static pressure test with the increase of the flute angle 𝜃 . According to the drop test, with the increase of flute height 𝐻 , the maximum stress of goods on the upper board in the drop test decreased. The maximum stress of the model in the drop test decreases firstly and then increases with the increase of flute angle, and the optimal flute angle 𝜃 couldbe60 ∘ for corrugated board. All the conclusions are consistent with experimental data or product standards.

1. Introduction Corrugated containers are the most important structural application of paperboard. Corrugated cardboard is a paper- based material consisting of a fluted corrugated sheet and one or two flat linerboards. It is widely used in the manufacture of corrugated cardboard boxes and shipping containers. The corrugated medium is often 0.026 pounds per square foot (0.13kg/m 2 ) basis weight in the USA; in the UK, a 90 grams per square metre (0.018 lb/sq ft) fluting paper is common. At the single-facer, it is heated, moistened, and formed into a fluted pattern on geared wheels. This is joined to a flat linerboard with a starch based adhesive to form single face board. At the double-backer, a second flat linerboard is adhered to the other side of the fluted medium to form single wall corrugated board. Linerboards are test liners (recycled paper) or kraft paperboard (of various grades). The liner may be bleached white, mottled white, colored, or preprinted [1–3]. The basic geometry of typical twin corrugated wall board is illustrated in Figure 1.

Common flute sizes are “A,” “B,” “C,” “E,” and “F.” The letter designation relates to the order that the flutes were invent- ed, not the relative sizes. Flute size refers to the number of flutes per linear foot, although the actual flute dimensions for different corrugator manufacturers may vary slightly. Measuring the number of flutes per linear foot is a more reliable method of identifying flute size than measuring board thickness, which can vary due to manufacturing conditions. The most common flute size in corrugated cardboard boxes is “C” flute. The choice of corrugated medium, flute size, com- bining adhesive, and linerboards can be varied to engineer a corrugated board with specific properties to match a wide variety of potential uses. The structural performance of a corrugated container is a function of numerous factors including the quality of the input cellulose fibers, the mechanical properties of the liner and medium, and the structural properties of the combined board. The complicated nonlinear behavior or paper makes modeling of the mechanical response of corrugated board

Advances in Materials Science and Engineering

Table 1: Parameters of linear elastic material [18].

Numerical value

Unit MPa MPa MPa MPa MPa MPa

Name

Twin wall corrugated board

7600 4020

𝐸 𝑥 𝐸 𝑦 𝐸 𝑧

Elastic modulus

2140

𝐺 𝑥𝑦 𝐺 𝑥𝑧 𝐺 𝑦𝑧 𝑉 𝑥𝑦 𝑉 𝑥𝑧 𝑉 𝑦𝑧

Shear modulus

20 70

Figure 1: Twin corrugated wall board structure.

— — —

0.34 0.01 0.01

Poisson’s ratio

and structures composed of corrugated board a difficult task [4]. Numerous studies have been focused on the properties of corrugated cardboard and external environment’s effects on the performance of corrugated carton [5–10]. Gilchrist et al. [4] have developed nonlinear finite element mod- els for corrugated board configurations. Results from the finite element simulations correlated reasonably well with the analogous experimental measurements performed using actual corrugated board specimens. Biancolini and Brutti [11] have developed a finite element “corrugated board” by means of a dedicated homogenization procedure in order to investigate the buckling of a complete package. The FEM model of the package, assembled with this new element, can accurately predict the experimental data of incipient buckling observed during the standard box compression test, despite the few degrees of freedom and the minimal computational effort. Biancolini [12] also presented a numerical approach to evaluating the stiffness parameters for corrugated board. The method is based on a detailed micromechanical rep- resentation of a region of corrugated board modelled by means of finite elements. Conde et al. [13] have developed a methodology for modelling corrugated board adhesive joints subjected to shear, considered to be the main load in most of these joints. The corrugated board adhesive joint model reproduced quite well the stiffness obtained in the test samples, as well as the failure load with a deviation of less than 14%. Biancolini et al. [1] compared results obtained from the simplified formula, an extended formula, and two numerical models developed by authors using finite elements (FE): an FE model realised with homogenised elements and an FE model representing the entire corrugation geometry. Numer- ical results of the capability to resist stacking loads obtained with FE models were consistent with experimental results. Haj-Ali et al. [14] presented a refined nonlinear finite ele- ment modeling approach for analyzing corrugated cardboard material and structural systems. This method can accurately predict overall mechanical behavior and ultimate failure for wide range corrugated systems. Talbi et al. [15] presented an analytical homogenization model for corrugated cardboard and its numerical implementation in a shell element. The shape and size of flute have an important effect on the performance of corrugated cardboard. However, there are no strict standards of flute size parameter to achieve the best elasticity and compressive strength of corrugated cardboard. There is also little literature regarding the finite element

kg/m 3

Density

404.5

Table 2: Parameters of rigid plate material.

Name

Numerical value

Unit

N/m 2 kg/m 3

Elastic modulus

1.0 × 10

1.0 × 10 − 8

Density

Poisson’s ratio

0.3

—

analysis of flute size. Yuan et al. [16, 17] have developed a model of UV-shaped corrugated cardboard by ANSYS. The results show that the closer the model to the U-shaped flute, the larger the corrugated board strain becomes. It is consistent with the empirical data, which prove the feasibility of finite element analysis method. In this paper, we focus on the investigation of nonlinear finite element analysis of the fluted corrugated sheet in the corrugated cardboard based on software SolidWorks2008. The shape and size of flute will be discussed with the help of SolidWorks and compared with the empirical data. 2. Modeling SolidWorks2008 has powerful structural modeling functions, among which Cosmos/Works is a function module which is specially used to make finite element analysis on structure. The model of common UV-shaped corrugated board is shown in Figure 2. In Figure 2, 𝐿 is flute length, 𝐻 is flute height, ℎ is facing paper thickness, 𝛿 is fluting paper thickness, 𝜃 is flute angle, and 𝑟 is arc radius. The principal aim of this work is to study the fluted corru- gated sheet. So we added a piece of rigid plate with large elastic modulus on upper facing paper (as shown in Figure 3) to eliminate the influence of the facing paper deformation. The maximum stress and strain of the improved model occur in the point in which flute contact with the upper facing paper in all cases. The material parameters of corrugated board model are given in Table 1 [18]. The material parameters of rigid plate model are given in Table 2 from the SolidWorks material library. 3. Results and Discussion 3.1. The Numbers of Flutes in Models. In order to eliminate the influence of the number of flutes in models, a series

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R 0.25

R 0.55

𝛿

0.30

𝜃

60 ∘

Figure 2: Model of UV-shaped corrugated board.

Figure 4: Model of corrugated board with two flutes.

From Figure 8, we can see that, with the flute height 𝐻 increased, the maximum stress in the models decreased and the maximum displacement increased. Therefore, with the flute height 𝐻 increased, the flat compression strength of corrugated board decreased and cushioning properties of corrugated board increased. As is well known, the cushioning properties of different shapes of corrugated cardboard have the sequence A > C > B > E, and the flat compression strength of corrugated board has the sequence A < C < B < E. Our simulation results are consistent with these conclusions. 3.3. Arc Radius 𝑟 . Effects of arc radius 𝑟 on the mechanical properties of corrugated cardboard model were investigated in this section. A series of models with different arc radius of flute were built and shown in Figure 9. The arc radius 𝑟 in models are 0, 0.1, 0.2, 0.25, 0.3, 0.35, and 0.4 mm. Fixing the bottom of models and then a static pressure test were made with a pressure of 150 Pa on the top floor. Then the maximum displacement and maximum stress of the models with different arc radius were obtained and the results are shown in Figure 10. From Figure 10, we can see that, with the arc radius of flute increased, the maximum stress in the models decreased and the maximum displacement increased. It means that when the arc radius 𝑟 increases the flat compression properties get worse and the cushioning properties get better. In fact, the smaller the arc radius, the closer the model to the V-shaped flute; the larger the arc radius, the closer the model to U- shaped flute. The simulation result also verified that the flat compression properties of V-shaped flute corrugated board are better than that of the U-shaped flute corrugated board and its cushioning properties are worse than that of the U- shaped flute. Actually, the triangle is the most stable structure. It is difficult to deform when a force was applied at the vertex of a triangle. But this structure is not suitable for the cushioning design. As the arc radius 𝑟 increases, the maximum displace- ments of the structure increase. So the stress can be dispersed to other parts rather than concentrating on one point. In this situation the cushioning properties of corrugated board get better to protect goods. In order to meet the needs of

Figure 3: Improved model of UV-shaped corrugated board with rigid plate.

of models with different number of flutes were built and shown in Figure 4. The numbers of flutes in models are 2, 3, 4, and 5. Fixing the bottom of models and then a static pressure test were made with a pressure of 150 Pa on the top floor. Then the stress and displacement contours of models of corrugated board were obtained as shown in Figure 5 (model with three flutes as example). From above calculation, the maximum displacement and maximum stress of the models with different number of flutes were obtained and the results are shown in Figure 6. From Figure 6, we can see that, with the number of flutes increased, the maximum stress in the models increased and the maximum displacement decreased. While the number of flutes increased to 3 or more, the maximum stress and displacement changed slightly. Therefore, the model of cor- rugated board with three or more flutes is reliable for stress and displacement measurement. In the coming simulation, the numbers of flutes in the models are all greater than 2. 3.2. Flute Height 𝐻 . Effects of flute height 𝐻 on the mechan- ical properties of corrugated cardboard model were investi- gated. A series of models with different flute height 𝐻 were built and shown in Figure 7. The flute heights 𝐻 inmodels are 2, 3, 4, and 5 mm. These models can be roughly classified as A flute (5 mm), C flute (4 mm), B flute (3 mm), and E flute (2 mm). Fixing the bottom of models and then a static pres- sure test were made with a pressure of 150 Pa on the top floor. Then the maximum displacement and maximum stress of the models with different flute height 𝐻 were obtained and the results are shown in Figure 8.

Advances in Materials Science and Engineering

7.300e + 003 6.692e + 003 6.084e + 003 5.475e + 003 4.867e + 003 4.259e + 003 3.650e + 003 3.042e + 003 2.434e + 003 1.825e + 003 1.217e + 002 6.087e + 002 3.235e − 001 1.270e − 012 1.164e − 012 1.058e − 012 9.522e − 013 8.464e − 013 7.406e − 013 6.348e − 013 5.290e − 013 4.232e − 013 3.174e − 013 2.116e − 013 1.058e − 013 1.000e − 033

(a) Stress contours

(b) Displacement contours Figure 5: The stress and displacement contours of models of corrugated board with three flutes.

900

0 1 2 3 4 5 6 7 8 9 10

1.5

2500

800

1.4

2000

700

1.3

1500

1.2

600

1000

1.1

500

e number of flutes Figure 6: Maximum stresses and maximum displacements of corrugated board models with different number of flutes.

Flute height (mm) Figure 8: Maximum stresses and maximum displacements of corrugated board models with different flute height.

0.30

Figure 7: Model of corrugated board with flute height 𝐻 of 5mm.

9.69

packaging cushioning design, we should determine the arc radius 𝑟 according to the actual packaging requirements.

Figure 9: Model of corrugated board with arc radius of 0.35 mm.

Advances in Materials Science and Engineering

1000

2.5

2500

10 12 14

900

2000

2.0

800

1500

0 2 4 6 8

1.5

700

1000

600

500

1.0

− 0.1 0.0 0.1 0.2 0.3 0.4 0.5 500

20 30 40 50 60 70 80 90 100 110 120 130 140 150 0

Arc radius (mm) Figure 10: Maximum stresses and maximum displacements of corrugated board models with different arc radius of flute.

Flute angle ( ∘ ) Figure 12: Maximum stresses and maximum displacements of corrugated board models with different flute angle 𝜃 .

𝜙1.10

R 0.25

0.30

20 ∘

Figure 13: The drop test model with different flute height.

R 0.25

Figure 11: Model of corrugated board with flute angle of 40 ∘ .

3.5. Drop Test 3.5.1. Flute Height 𝐻 . Both primary (consumer) packages and shipping containers have a risk of being dropped or being impacted by other items. Package integrity and product protection are important packaging functions. Drop tests are conducted to measure the resistance of packages and prod- ucts to controlled laboratory shock and impact. Drop testing also determines the effectiveness of package cushioning to isolate fragile products from shock. Effects of flute height 𝐻 on the dynamic mechanical properties of corrugated cardboard model in the drop test based on Cosmos/Works were investigated. A series of models with different flute height 𝐻 were built and shown in Figure 7. The flute heights 𝐻 in models are 2, 3, 4, and 5 mm. The drop test model was shown in Figure 13. A simplified model of corrugated board and goods on the upper board were investigated. Drop height is 0.3 m, initial velocity is 0 m/s, acceleration of gravity is 9.81 m/s 2 , and impact time is 600 𝜇 s. The material of the object on the upper board is Acry- lonitrile Butadiene Styrene (ABS) and the mass is 1.224 × 10 −4 kg. Then the stress and displacement contours of models of corrugated board were obtained and shown in Figure 14 (model with flute height 𝐻 of 5 mm). In order to investigate the stress of goods on the upper board in the drop test, we selected 2 points (A and B point as shown in Figure 13) from the model as the object of study. Then the time-dependent

3.4. Flute Angle 𝜃 . Effects of flute angle 𝜃 on the mechanical properties of corrugated cardboard model were investigated in this section. A series of models with different flute angle 𝜃 were built and shown in Figure 11. The flute angles 𝜃 in models are 40, 50, 60, 70, 80, 90, 100, 110, and 120 ∘ . Fixing the bottom of models and then a static pressure test were made with a pressure of 150 Pa on the top floor. Then the maxi- mum displacement and maximum stress of the models with different flute angle 𝜃 were obtained and the results are shown in Figure 12. From Figure 12, we can see that, with the increase of the flute angle 𝜃 , the maximum stress and maximum displace- ment in the models increase nonlinearly. The maximum stress and maximum displacement change slowly when 𝜃 is less than60 ∘ and then increase sharply when 𝜃 is larger than 60 ∘ . In addition, the number of flute per unit length increases as the 𝜃 decreases, and it means that the corrugated board needs more materials. Therefore, the optimal flute angle 𝜃 couldbe 60 ∘ for corrugated board. According to the Chinese national standards “Corrugated board and standard test method” (GB6544 ∼ 6548-86), the UV-shaped flute corrugated board should be 60 ∘ in the manufacture process. The simulation result is consistent with the standards of corrugated board.

Advances in Materials Science and Engineering

4.682e + 005 4.294e + 005 3.905e + 005 3.517e + 005 3.129e + 005 2.741e + 005 2.353e + 005 1.965e + 005 1.577e + 005 1.188e + 005 8.003e + 004 4.122e + 004 2.405e + 003 1.605e − 003 1.474e − 003 1.343e − 003 1.211e − 003 1.080e − 003 9.489e − 004 8.176e − 004 6.864e − 004 5.551e − 004 4.239e − 004 2.926e − 004 1.614e − 004 3.015e − 005

(a) Stress contours

(b) Displacement contours Figure 14: The stress and displacement contours of model with flute height 𝐻 of 5 mm in drop test.

2.0

1.20

1.8

1.00

1.6

8.00

1.4

1.2

6.00

1.0

4.00

0.8

0.6

2.00

Flute height (mm)

0.00 0.97 100.77 200.58 300.38 400.18 499.79 599.79 Time ( 𝜇 s) A B Figure 15: Time-dependent stress of A, B point in drop test (model with flute height 𝐻 of 5mm). stress of A, B point in the drop test was obtained and shown in Figure 15 (model with flute height 𝐻 of 5 mm). From above simulation, the maximum stresses of A, B point in the models with different flute height 𝐻 in the drop test were obtained and the results are shown in Figure 16.

A B Figure 16: Maximum stress of A, B point in the models with different flute height 𝐻 in the drop test.

From Figure 16, we can see that, with the increase of flute height 𝐻 , the maximum stress of goods on the upper board in the drop test decreased. Therefore, with the increase of flute height 𝐻 , the cushioning properties of corrugated board increased. This conclusion is consistent with the conclusions of Section 3.2.

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3.0

Drop direction

2.5

2.0

1.5

1.0

B Figure 17: The drop test model with different flute angle 𝜃 .

0.5

30 40 50 60 70 80 90 100 110 120

Flute angle ( ∘ )

A B

2.50

Figure 19: Maximum stress of A, B point in the models with different flute angle in the drop test.

2.00

point in the models with different flute angle 𝜃 in the drop test were obtained and the results are shown in Figure 19. From Figure 19, we can see, that with the increase of flute angle, the maximum stress of the model in the drop test decreases firstly and then increases. The maximum stress of the corrugated board bears is smallest when the flute angle 𝜃 reaches 60 ∘ . The reason is that the stress of the corrugated board could be dispersed to the flute structure efficiently and then reduces the maximum stress of the corrugated board in drop test. Therefore, the optimal flute angle 𝜃 could be 60 ∘ for corrugated board. This conclusion is consistent with the conclusions of Section 3.4. 4. Conclusions The shape and size of flute have an important effect on the performance of corrugated cardboard. In this paper, the non- linear finite element analysis of the fluted corrugated sheet in the corrugated cardboard based on software SolidWorks2008 was investigated. The obtained conclusions are as follow. (1) According to the static pressure test, with the flute height 𝐻 increased, the maximum stress in the models decreased and the maximum displacement increased. (2) According to the static pressure test, with the arc radius of flute increased, the maximum stress in the models decreased and the maximum displacement increased. (3) According to the static pressure test, with the increase of the flute angle 𝜃 , the maximum stress and max- imum displacement in the models increase nonlin- early. The optimal flute angle 𝜃 couldbe60 ∘ forcorru- gated board.

1.50

1.00

5.00

0.00 1.18 124.94 240.70 360.46 480.22 599.98 Time ( 𝜇 s) A B Figure 18: Time-dependent stress of A, B point in drop test (model with flute angle 𝜃 of 40 ∘ ). 3.5.2. Flute Angle 𝜃 . Effects of flute angle 𝜃 on the dynamic mechanical properties of corrugated cardboard model in the drop test based on Cosmos/Works were investigated. A series of models with different flute angle 𝜃 were built and shown in Figure 11. The flute angles 𝜃 in models are 40, 50, 60, 80, and 100 ∘ . The drop test model was shown in Figure 17. Drop height is 0.3 m, initial velocity is 0 m/s, acceleration of gravity is9.81m/s 2 , and impact time is 600 𝜇 s. The stress distribution of corrugated cardboard was obtained and we have found that the maximum stress occurs in the point which fluted corrugated sheet contact with the ground in all cases. So we selected 2 points (A and B point as shown in Figure 17) from the model as the object of study in the drop test. Then the time-dependent stress of A, B point in the drop test was obtained and shown in Figure 18 (model with flute angle 𝜃 of 40 ∘ ). From above simulation, the maximum stresses of A, B

Advances in Materials Science and Engineering

(4) According to the drop test, with the increase of flute height 𝐻 , the maximum stress of goods on the upper board in the drop test decreased. (5) According to the drop test, with the increase of flute angle, the maximum stress of the model decreases firstly and then increases. The maximum stress of the corrugated board bears is smallest when the flute angle 𝜃 reaches60 ∘ . Therefore, the optimal flute angle 𝜃 couldbe60 ∘ for corrugated board. All the conclusions are consistent with experimental data or product standards. Conflict of Interests The authors declare that there is no conflict of interests regarding the publication of this paper. Acknowledgments This work was financially supported by the National Natural Science Foundation of China (51206148, 51106140), Major Programs of Sci & Tech, Department of Science and Tech- nology of Zhejiang Province (2008C12062, 2013C03017-4), and Zhejiang Provincial Natural Science Foundation of China (Y1110642, Y407311). The authors are thankful for the finan- cial support of Zhejiang Provincial Key Disciplines “Pulp and Paper Engineering.” References [1] M. E. Biancolini, C. Brutti, and S. Porziani, “Corrugated board containers design methods,” International Journal of Computa- tional Materials Science and Surface Engineering , vol. 3, no. 2-3, pp. 143–163, 2010. [2] http://en.wikipedia.org/wiki/Corrugated fiberboard. [3] M. Tuomela, M. Vikman, A. Hatakka, and M. Ita¨vaara, “Biodeg- radation of lignin in a compost environment: a review,” Biore- source Technology , vol. 72, no. 2, pp. 169–183, 2000. [4] A. C. Gilchrist, J. C. Suhling, and T. J. Urbanik, “Nonlinear finite element modeling of corrugated board,” in ASME Joint Applied Mechanicals and Materials Division Meeting , pp. 101–106, 1998. [5] D. Twede and S. E. M. Selke, Cartons, Crates and Corrugated Board: Handbook of Paper and Wood Packaging Technology , DEStech, 2005. [6] T. J. Lu, C. Chen, and G. Zhu, “Compressive behaviour of corru- gated board panels,” Journal of Composite Materials , vol. 35, no. 23, pp. 2098–2126, 2001. [7] T. Nordstrand, “Analysis and testing of corrugated board panels into the post-buckling regime,” Composite Structures , vol. 63, no. 2, pp. 189–199, 2004. [8] U. Nyman and P. J. Gustafsson, “Material and structural failure criterion of corrugated board facings,” Composite Structures , vol. 50, no. 1, pp. 79–83, 2000. [9] M. Daum, D. Darby, G. Batt, and L. Campbell, “Application of the stress-energy method for generating corrugated board cushion curves,” Journal of Testing and Evaluation , vol. 41, no. 4, pp. 590–601, 2013. [10] J. Viguie´, P. J. J. Dumont, L. Orge´as, P. Vacher, I. Desloges, and E. Mauret, “Surface stress and strain fields on compressed panels

of corrugated board boxes: an experimental analysis by using digital image stereocorrelation,” Composite Structures , vol. 93, no. 11, pp. 2861–2873, 2011. [11] M. E. Biancolini and C. Brutti, “Numerical and experimental investigation of the strength of corrugated board packages,” Packaging Technology and Science , vol. 16, no. 2, pp. 47–60, 2003. [12] M. E. Biancolini, “Evaluation of equivalent stiffness properties of corrugated board,” Composite Structures , vol. 69, no. 3, pp. 322–328, 2005. [13] I. Conde, B. Garc´ıa, E. Liarte, and M. A. Jime´nez, “Analysis of adhesive joints in corrugated board under shear loading,” International Journal of Adhesion and Adhesives , vol. 38, pp. 50– 57, 2012. [14] R. Haj-Ali, J. Choi, B.-S. Wei, R. Popil, and M. Schaepe, “Refined nonlinear finite element models for corrugated fiberboards,” Composite Structures , vol. 87, no. 4, pp. 321–333, 2009. [15] N. Talbi, A. Batti, R. Ayad, and Y. Q. Guo, “An analytical homog- enization model for finite element modelling of corrugated cardboard,” Composite Structures , vol. 88, no. 2, pp. 280–289, 2009. [16] W. Yuan, M. G. Zhang, Z. D. Liao et al., “Corrugated board flute-shaped finite element analysis and optimization,” Applied Mechanics and Materials , vol. 477-478, pp. 1205–1209, 2014. [17] W. Yuan, J. X. Sun, G. M. Zhang et al., “Corrugated board UV flute-shaped structure size optimization design based on the finite element,” Applied Mechanics and Materials , vol. 469, pp. 213–216, 2014. [18] H. Guang-jun, H. Xiang, and F. Wei, “Finite element modeling and buckling analysis of corrugated box,” Packaging Engineer- ing , vol. 30, no. 3, pp. 34–35, 2009.

PAPERmaking! FROM THE PUBLISHERS OF PAPER TECHNOLOGY Volume 3, Number 2, 2017

Efficacy of dispersion of magnesium silicate (talc) in papermaking Vipul Singh Chauhan (a) Nishi Kant Bhardwaj (b) (a) Department of Paper Technology, Indian Institute of Technology Roorkee – Saharanpur Campus, Saharanpur 247 001, India (b) Thapar Centre for Industrial Research & Development, Yamuna Nagar 135 001, India The understanding of the dispersion chemistry of papermaking grade fillers is as important as their effect on paper. Magnesium silicate (talc) is one of the major fillers used for papermaking. It is hydrophobic and chemically inert. The dispersion chemistry of talc of different particle sizes was studied with wetting agent (non-ionic triblock copolymer) and anionic dispersant (sodium salt of polyacrylic acid). Both wetting agent and dispersant were added in talc slurry separately and in combination. The dispersion behavior was studied through measuring the Brookfield viscosity. The wetted and dispersed talc was also added to paper to understand its effect on papermaking process and paper properties. Wetting and dispersion changed the colloidal charge chemistry of talc making it more anionic which reduced the talc retention in paper. Lowering the particle size of talc significantly improved the light scattering coefficient (LSC) of paper and decreased its retention. Controlling colloidal charge of papermaking suspension with cationic polyacrylamide polymer helped in protecting the retention of talc without affecting the LSC of both filler and paper.

Arabian Journal of Chemistry (2017) 10, S1059 – S1066 http://dx.doi.org/10.1016/j.arabjc.2013.01.012

Page 1 of 9

Article 2 – Talc in Papermaking

Arabian Journal of Chemistry (2017) 10 , S1059–S1066

King Saud University

Arabian Journal of Chemistry

www.ksu.edu.sa www.sciencedirect.com

ORIGINAL ARTICLE

Efficacy of dispersion of magnesium silicate (talc) in papermaking

Vipul Singh Chauhan a , Nishi Kant Bhardwaj b, *

a Department of Paper Technology, Indian Institute of Technology Roorkee – Saharanpur Campus, Saharanpur 247 001, India b Thapar Centre for Industrial Research & Development, Yamuna Nagar 135 001, India

Received 23 August 2012; accepted 15 January 2013 Available online 4 February 2013

KEYWORDS

Abstract The understanding of the dispersion chemistry of papermaking grade fillers is as impor- tant as their effect on paper. Magnesium silicate (talc) is one of the major fillers used for papermak- ing. It is hydrophobic and chemically inert. The dispersion chemistry of talc of different particle sizes was studied with wetting agent (non-ionic triblock copolymer) and anionic dispersant (sodium salt of polyacrylic acid). Both wetting agent and dispersant were added in talc slurry separately and in combination. The dispersion behavior was studied through measuring the Brookfield viscosity. The wetted and dispersed talc was also added to paper to understand its effect on papermaking pro- cess and paper properties. Wetting and dispersion changed the colloidal charge chemistry of talc making it more anionic which reduced the talc retention in paper. Lowering the particle size of talc significantly improved the light scattering coefficient (LSC) of paper and decreased its retention. Controlling colloidal charge of papermaking suspension with cationic polyacrylamide polymer helped in protecting the retention of talc without affecting the LSC of both filler and paper. ª 2013 Production and hosting by Elsevier B.V. on behalf of King Saud University. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/3.0/).

Dispersion; Magnesium silicate; Polyacrylic acid; Non-ionic triblock copoly- mer; Paper; Scattering coefficient; Retention

1. Introduction

ing papers because they increase the light scattering, opacity and brightness, and generally improve printing properties. The mineral fillers for acid papers are talc, hydrous kaolin, cal- cined kaolin, precipitated silica and silicates, and titanium diox- ide. For neutral and alkaline papers, layered magnesium silicate (talc), hydrous kaolin, calcined kaolin, ground calcium carbon- ate (GCC), precipitated calcium carbonate (PCC), silica and sil- icates, and titanium dioxide are used. The use of filler is important when opacity is needed at a low-basis weight; they are invaluable in packaging grades where low permeability is combined with opacity to protect food from light. The presence of fillers, however, affects fiber-to-fiber contact and reduces the paper strength (Wilson, 2006; Chauhan et al., 2012a). Other properties are improved rendering the paper useful for special

Paper consists of not only cellulosic fibers but also considerable amounts of mineral fillers. Fillers are highly desirable in print-

* Corresponding author. Tel.: +91 1732 292703; fax: +91 1732 292748. E-mail addresses: nishikant_bhardwaj@rediffmail.com, dydirector@ thaparpaperresearch.org (N.K. Bhardwaj). Peer review under responsibility of King Saud University.

Production and hosting by Elsevier

http://dx.doi.org/10.1016/j.arabjc.2013.01.012 1878-5352 ª 2013 Production and hosting by Elsevier B.V. on behalf of King Saud University. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/3.0/).

S1060

V.S. Chauhan, N.K. Bhardwaj

cally hydrophobic, generally inert and the softest mineral on earth. Because both sides of this structure expose an oxide surface, individual talc platelets are held together only by weak van der Walls forces (Fig. 1) (Trivedi, 1997). Compared to other silicates, talc is relatively hydrophobic due to the oxide surfaces (Trivedi, 1997; Ciullo and Robinson, 2003). The edge face is, however, hydrophilic as a result of the –SiOH and –MgOH groups where the surface potential is pH dependent (Ma¨ lhammar, 1990; Fuerstenau et al., 1988). Being hydropho- bic in nature, proper dispersion of talc might be required before its addition in papermaking slurry. This may affect the light scattering and opacity of paper through properly dis- persed particles. These considerations are used in the present study. Five samples of talc with different particle size distribution have been chosen in order to understand their dispersion chemistry and the role of dispersed talc in papermaking.

purposes. Filler also decreases the energy demand in pulp and papermaking process due to lesser usage of fibrous mass (Dong et al., 2008; Chauhan et al., 2011). Loading of higher filler con- tent in paper is always desirous by the papermaker due to decreasing cost and increasing optical properties. The filler particles added to fibers suspended in water are not easily retained in the forming sheet, as they are too small to be entrapped mechanically. Additionally both filler and fibers are negatively charged, so they repel each other (Al-Mehbad, 2004). The properties of filler are linked with the ability of the same to refract and backscatter light through the surface of the sheet. If the filler is not evenly dispersed and flocculates in small clumps, then the optical efficiency of the fil- ler is reduced. No filler is capable of yielding high light scatter- ing for the development of brightness and opacity without having any detrimental impact on wet-web strength and phys- ical properties of paper. The filler used for the development of brightness and opacity debonds fibers because of its inherent high surface area (Wilson, 2006). Filler is supposed to be well dispersed prior to its addition to papermaking slurry in order to get its impact on light scat- tering power of both filler and paper. The light scattering pri- marily depends upon the particle size and shape of filler. For the particles of same shape, the higher the particle size the low- er is the scattering coefficient. The good dispersion of filler may help in increasing the light scattering for the same type of filler. The dispersion behavior of talc powders has been reported in few literatures (Charnay and Lagerge, 2003; Goalard et al., 2006; Chauhan et al., 2012b). The role of dispersion science in pulp and papermaking process was reviewed by Rojas and Hubbe (2005). They explored the scientific principles that underlie the art of papermaking, emphasizing the state of dis- persion of the fibrous slurries during various stages of the pa- per manufacturing process. The literature on dispersion of talc filler for use in papermaking is scarce. The filler/pigment used in paper coating are dispersed well with suitable dispersing agents prior to their application on the paper surface, however they are added as such in paper. The effect of wetting and dispersion of filler in papermaking is not, so far, available in detail. The most suitable wetting agent suggested in the literature is nonionic triblock copolymer. The triblock copolymer is having a central hydrophobic chain of poly(propylene oxide) flanked by two hydrophilic chains of poly(ethylene oxide) (Lee et al., 2010). It results in a complete removal of the bubble-induced attractive forces (Wallqvist et al., 2009). The widely used dispersing agent is sodium salt of anionic poly(acrylic acid) i.e. sodium polyacrylate. Sodium polyacrylate is a polymer with the chemical formula [ CH 2 CH(COONa) ] n . It has the ability to absorb as much as 200–300 times its mass in water. Acrylate polymers gener- ally are considered to possess an anionic charge. It does not adsorb to the basal plane of talc and affects the measured forces (Wallqvist et al., 2009). Now-a-days calcium carbonate based fillers (GCC and PCC) are manufactured in situ and available in the pre-dis- persed slurry form. They are mixed with some amount of dis- persant to avoid the agglomeration of particles. This practice is not yet commercialized for talc (Mg 3 Si 4 O 10 (OH) 2 ). This may be because of a comparatively higher particle size of talc fillers which is less favorable to particle agglomeration than the lower particle size calcium carbonate fillers. It is characteristi-

2. Experimental

2.1. Materials

The bleached mixed hardwood chemical pulp was collected from an integrated pulp and paper mill in north India. The pulp furnish was 50% eucalyptus, 35% poplar and 15% bam- boo. The initial freeness of the pulp measured on Canadian Standard Freeness (CSF) tester (Tappi test method T 227 om-09) was 620 ml which was decreased to 430 ml through refining in the PFI mill following the Tappi test method T 248 sp-00. Dry powders of talc filler with five different particle sizes were sourced from a talc manufacturer in north India. The talc fillers were designated as Talc-1, Talc-2, Talc-3, Talc-4, and Talc-5 based on the decreasing particle size. The nonionic triblock copolymer having a central hydrophobic chain of poly(propylene oxide) flanked by two hydrophilic chains of poly(ethylene oxide) and nominal molecular weight of 6300 Da was used as a wetting agent to wet the surface and remove the air from the surface of talc particles. The so- dium salt of poly(acrylic acid) based anionic polymer (sodium polyacrylate) having a nominal molecular weight of 5100 Da was used as a dispersant. Both wetting and dispersing agents were procured from a chemical supplier in north India. The commercial grade medium to high molecular weight cationic polyacrylamide (CPAM) was procured from a chemical man- ufacturer in India, and used for the retention of filler and fiber fines.

Figure 1

Molecular structure of pure talc mineral.

Efficacy of dispersion of magnesium silicate (talc) in papermaking

S1061

Table 1

Physico-chemical and optical properties of talc fillers of different particle size distribution.

Particular

Talc-1

Talc-2

Talc-3

Talc-4

Talc-5

ISO brightness, %

92.5

92.7

93.7

94.1

93.2

Ionic nature

Anionic

Colloidal charge demand, l eq/g

+1.1 501 9.0

+1.6 373 9.2

+2.0 455 9.3

+2.1 410 9.1

+2.1 492 9.1

Zeta potential, mV

Particle shape

Lamellar

2.4. Handsheet preparation and testing

2.2. Characteristics of talc fillers

The fillers were dispersed in water to 10% (w/v) slurry prior to the addition in the refined pulp stock of 1% consistency (w/v). The paper handsheets of 60 g/m 2 with target ash content of around 15% were prepared as per the Tappi test method T 205 sp-02. The ash content in paper was determined at 525 C as per the Tappi test method T 211 om-93. The ash con- tent and first pass ash retention (FPAR) were calculated with the following formula: Ash content in paper ; % ¼

The fillers were characterized for optical and physico-chemical characteristics; brightness, colloidal and surface charge, parti- cle size distribution (PSD), and shape. The moisture free fillers were compacted in the dice with the help of arbor press. The filler dice was then used to measure the optical properties in brightness tester (Datacolor Spectraflash 300). Filler suspen- sion (10% w/v) was filtered through a 300 l m screen and the pH of the filtrate was measured with the help of a pH meter. The colloidal charge or ionic behavior of 10% (w/v) slurry of fillers was examined on Mutek particle charge detector (PCD 03 pH). The surface charge on fillers was determined in the form of zeta potential on Mutek system zeta potential meter (SZP 06). About 500 ml filler sample (10% w/v) was ta- ken and mixed thoroughly before measurement. The PSD of the fillers was measured using Laser scattering particle size dis- tribution analyzer (Horiba LA950S2). The talc fillers were wet- ted with ethanol and then dispersed in deionized water to make 10% (w/v) slurry. In the case of Talc-3 filler, the particle size of filler was also measured after dispersing it in different manners i.e. in water only, with wetting agent, with dispersing agent, and with both wetting and dispersing agent. The measurement conditions in the analyzer were kept constant for all talc fillers. The particle shape of the fillers was determined by X-ray dif- fraction (Bruker AXS, D8 Advance, Switzerland) using Cu K a radiation. The micrographs of fillers were taken on Field emission scanning electron microscope (Quanta, FEI, Czech Republic).

o : d : weight of ash in paper ð g Þ o : d : weight of handsheet ð g Þ 100

ð 1 Þ

Ash in paper ð % Þ Filler added based on pulp and filler ð % Þ 100

FPAR ; % ¼

ð 2 Þ The light scattering coefficient of paper was measured on brightness tester (Datacolor Spectraflash 300) as per the Tappi test method T 519 om-02. The scattering coefficient of filler was calculated from the following formula: S sheet ¼ S unfilled sheet ð 1 L Þþ LS filler ð 3 Þ where S is the light scattering coefficient and L is the filler loading amount.

3. Results and discussion

2.3. Wetting and dispersion of talc filler

3.1. Physico-chemical and optical properties of talc fillers

Initially, the effect of agitation time on dispersion of talc fil- ler was studied. The talc filler was dispersed in deionized water (no wetting agent and dispersant) for different time periods of 30, 60, 90 and 120 min in an emulsifier at 2000 rpm speed. Secondly, the dosage of wetting agent and dispersant were optimized based upon the viscosity behavior of talc slurry. The talc filler was first diluted with deionized water at 50% solids (w/v). The slurry was agitated in high speed emulsifier for around 30 min. The wetting agent was added to the diluted filler slurry, agitated for around 5 min and the rheology of talc slurry was measured in terms of Brookfield viscosity. A graph between dosage of wetting agent/dispersant and viscosity of talc slurry was plotted to get the minima of viscosity. The dosage was selected based upon the lowest viscosity of talc slurry. The optimized dos- age of wetting agent and dispersant were then used together to completely disperse the talc filler.

The filler characteristics are important for the optical and structural developments in the paper matrix. All talc fillers were having almost comparable optical properties. They were anionic in nature which was indicated by their cationic colloi- dal charge demand and anionic zeta potential. The cationic charge demand was indirectly proportional to the particle size of talc filler. It was increased on decreasing the particle size, due to exposure of more oxide surfaces. All mineral fillers were alkaline in nature with a pH of around 9.0–9.2 (Table 1).

3.2. Particle size distribution and shape of talc fillers

The particle size distribution (PSD) and shape of fillers are the important factors responsible for the retention of filler and light scattering in paper. The PSD of Talc-1 was the broadest among all talc fillers followed by Talc-2, Talc-3, Talc-4 and

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