A Facile Coating Method for Superhydrophobic Magnetic Composite Sheet from Biodegradable Durian Peel for Electromagnetic Wave Absorbance Application.
Key Engineering Materials
ISSN: 1662-9795, Vol. 694, pp 39-43
doi:10.4028/www.scientific.net/KEM.694.39
© 2016 Trans Tech Publications, Switzerland
Submitted: 2015-07-27
Revised: 2015-11-16
Accepted: 2016-02-07
Online: 2016-05-21
A Facile Coating Method for Superhydrophobic Magnetic Composite
Sheet from Biodegradable Durian Peel for Electromagnetic Wave
Absorbance Application
Rose Farahiyan Munawar1,a, Afraha Baiti Arif1,b,
Wan Nur Fateehah Wan Abdullah Shani1,c, Mohd Asyadi Azam1,d,
Mohd Edeerozey Abd Manaf1,e, Maisarah Abu2,f,
Muhammad Zaimi Zainal Abidin1,g and Syahriza Ismail1,h
1
Carbon Research Technology Research Group, Engineering Materials Department, Faculty of
Manufacturing Engineering, Universiti Teknikal Malaysia Melaka, Hang Tuah Jaya, 76100, Durian
Tunggal, Melaka, Malaysia
2
Faculty of Electronic and Computer Engineering, Universiti Teknikal Malaysia Melaka, Hang
Tuah Jaya, 76100, Durian Tunggal, Melaka, Malaysia
a
rosefarahiyan@utem.edu.my, brahaarif@gmail.com, cfateehah_shani@yahoo.com,
asyadi@utem.edu.my, eedee@utem.edu.my, fmaisarah@utem.edu.my, gmdzaimi@utem.edu.my,
h
syahriza@utem.edu.my
d
Keywords: Superhydrophobic, Durian peel, Stearic acid
Abstract. Most of the electromagnetic (EM) wave absorbers are commonly made from polymerbased materials. A large number of polymers are resistant to the environmental degradation and are
thus responsible for the buildup of polymeric solid waste materials. These solid wastes cause acute
environmental problems and remain undegraded for quite a long time. In a view of the awareness
and concern for the problems created by the polymeric solid wastes, new biodegradable cellulosic
composite with low cost and nontoxic materials, have been designed and developed. However, the
properties of natural fibers that tends to absorb water, thus limiting their application. In this study,
precipitated calcium carbonate (PCC) was added with stearic acid (SA) in order to generate a
hydrophobic coating formulation. PCC works as filler and SA acts as surface hydrophobic
modification agent. Polymer latex was then added to the coating compound as the binder. The
composite surface morphology was inspected using scanning electron microscope (SEM). Results
show that durian peel composite sheet had successfully achieved a superhydrophobic surface with a
water contact angle of 154.85° which exceed 150°.
Introduction
The quick-tempered growth of telecommunication application in industrial, medical and also
military field has led to the high frequency of electromagnetic (EM) wave [1]. This high frequency
generated electromagnetic interference (EMI) which may cause disruption in those applications.
Therefore, EM wave absorber with the capability of absorbing these unwanted EM signals is
invented.
Presently most of the EM wave absorbers are made from polymers due to the light weight and
flexibility. However, they are environmental degradation resistance and the accumulation of their
solid wastes may cause serious environmental problems. Due to that, a new EM wave absorber
from natural fiber is designed and produced in this research with the goal of overcoming the
problem. Furthermore, the selection of natural fiber as the absorber material is due to its sustainable
ability, low cost and renewability.
Due to the great prominence in research and real-life applications including the prospective in
industrial applications, superhydrophobic surfaces with a water contact angle higher than 150° have
attracted increasing interest [2-4]. The wettability characteristic of a solid surface is generally
driven by the chemical composition and the geometrical structure of the surface [5-7]. In fabricating
superhydrophobic surface, two techniques are adopted: (1) forming more rough structure on the
All rights reserved. No part of contents of this paper may be reproduced or transmitted in any form or by any means without the written permission of Trans
Tech Publications, www.ttp.net. (ID: 103.198.52.1-15/03/16,02:58:10)
40
Current Trends in Materials Engineering
hydrophobic material surface [8-10]; (2) modifying the rough surface to lower the surface energy
[9,10]. There were a lot of approaches to achieve superhydrophobic surface, such as multi-layer
deposition [11,12], sol–gel process [13-15], chemical vapor deposition [16] and solution-immersion
[17].
Although the selection of natural fiber as an alternative to polymer is perfect in terms of
availability, less cost and renewability, however, it is very hygroscopic. It tends to have high water
and moisture absorptions because of the presence of hydrophilic groups, mainly hydroxyl, carboxyl
or sulfonic groups [18]. The high hygroscopicity may cause the magnetic composite sheet to absorb
water vapor easily from the environment and loss its valuable mechanical properties. This is the
reason the coating method by using the hydrophobic stearic acid is applied in this study. This
method was selected based on the factors of simplicity, non-toxicity and cost efficiency.
Durian peel is a new material used in this study, selected for its properties such as hard shell
texture and high pore volumes [19]. The higher the pore distribution in the fiber, the higher the
degree of loading of the magnetic particles should be and the better the quality of the magnetic
sheet.
Experimental Method
Sample Preparation. Durian peels were cleaned up and repeatedly washed with tap water to
remove grime and unnecessary materials on the peel’s surface. Then, they were cut to about 2 to 3
cm in length and about 0.4 cm in thickness. Next, the durian chips were dried at 50 °C for 24 hours
in drying oven to remove the moisture content.
Pulping. After the drying process, dried durian peel underwent the process of pulping to remove
lignin from cellulose. The selected pulping process was soda pulping process and it was conducted
by using rotary digester machine. The use of sodium hydroxide (NaOH) in making wood pulp is
called as soda pulping process. The process was carried out with 17 % concentration of NaOH.
About 300 g (oven-dried) of durian chips was placed into the digester. The ratio of durian chips to
cooking liquor was 1:7. The cooking temperature was set at 170 °C for the period of 7200 sec. Once
cooked, the unbleached durian peel pulp was washed, screened and centrifuged.
Preparation of Magnetic Composite Sheet using Lumen Loading Method. The magnetic
composite sheets were produced through the lumen loading method. 15 g dry weight of unbleached
durian shell pulp was disintegrated in 1250 ml of distilled water containing 0.1 gL-1 aluminium
sulphate for 1800 sec in a mechanical stirrer at the rotor speed of 1000 rpm. Magnetic pigment,
iron (II, III) oxide Aldrich 637106 nanopowder with particle size less than 50 nm at the weight of
30 g was mixed in 250 ml distilled water which contained 0.1 gL-1 aluminium sulphate. Next, both
suspensions were mixed and mechanically stirred for 1800-3600 sec at the rotor speed of 1000 rpm.
This stage is called as impregnation stage, where particles are forced to embed in the lumen fibers.
Later, the suspension was slowly stirred to 400 rpm for 14,400 sec when polyethylenimine (PEI, 2
%, w/w polymer on pulp) was added in the mixture. PEI was added as retention aid to retain the
magnetic particles inside the lumen. The excess pigment that remained on surface of fiber and
suspension were removed by washing with tap water in a self-designed fiber classifier containing a
filter screen (45 µm) for period range of 1800-3600 sec. The clean pulp then proceeded to paper
making process [20].
Fabrication of Superhydrophobic Surface of Composite Sheet. 40 g of PCC (Albacar® HO) and
1.238 g of SA (Peter Greven Asia Sdn. Bhd.) were added into 90 ml of distilled water. Next, the
suspension were stirred at 75 °C for 1800 sec to allow fatty acid to form a thin layer of water
insoluble calcium salt on the PCC surface. The suspension was then mixed with 9.16 g of polymer
latex (Acronal NX 4787 X) after cooling down to room temperature and was stirred again for 1800
sec with agitator. Next, a roller was used for applying the coating suspension onto the surface of the
durian magnetic composite sheet. The coated paper was air-dried for 3600 sec before immersing
into a container of 0.0015 mol/L potassium stearate (PS) suspension for 180 sec. The immersion
Key Engineering Materials Vol. 694
41
process in the PS suspension is known as treatment stage to further improve the water resistance of
the coated paper. The coated paper was then rinsed with distilled water at 75 °C to remove the
excess stearate salt present on the paper surface. The coated paper was air-dried again for another
3600 sec prior to paper testing [2].
Characterization of Coated Magnetic Composite Sheet. The Carl Zeiss Model 1450VP variable
pressure scanning electron microscope (SEM) was used in characterizing the morphology of the
composite sheet surface. The water contact angle (WCA) of the samples was examined using FECA
Contact-Angle Meter. The mechanical properties; tensile strength and tear strength were measured
using a Büchel-Van Der Korput horizontol tensile tester Elmendorf tear tester, respectively. The test
was in accordance to TAPPI standard method T 949 om-01 and TAPPI Standard T414 om-88.
Result and Discussion
Surface Morphology of Coated Magnetic Composite Sheet. This method involved several
dipping process stages in order to form a superhydrophobic surface. The coating formulation in the
technique applied in this study contains both fatty acid modified PCC and polymer binder. Since the
acid group in a stearic acid molecule forms an insoluble calcium salt and leaves a hydrophobic tail
oriented to the air, therefore the fatty acid modified PCC is hydrophobic. The main function of
stearic acid (SA) in coating formulation is to reduce high surface energy and decrease the
agglomeration of particles such as precipitated calcium carbonate (PCC).
At the same time, PCC is widely used as fillers in this method that act as adhesives and sealants
when react with SA. By knowing the general properties of each material that are used, the formation
of the superhydrophobic surface can be performed effectively. To improve both WCA and water
resistance, the surface coated paper was treated further by dipping in potassium stearate aqueous
solution [21].
The surface morphology of coated durian peel magnetic composite sheet is given in Fig. 1(a)
and 1(b). It shows the distribution of PCC particles on the coated composite sheet. The surface
roughness can be seen from SEM image and this contributes to the superhydrophobicity properties
of the magnetic composite sheet [7].
Fig. 1 SEM images of surface coating using stearic acid at (a) low magnification, and (b) high
magnification.
Water Contact Angle of Magnetic Composite Sheet. The water contact angle measurement is one
of the important analyses in measuring superhydrophobic properties. Generally, material surface is
classified as hydrophilic if the contact angle is less than 90°. When the contact angle higher than
90°, the surface is called hydrophobic, and when the contact angle is greater than 150°, the surface
is called superhydrophobic [2].
42
Current Trends in Materials Engineering
Fig. 2(a) shows the image of a water droplet on the coated magnetic composite sheet surface
with a water contact angle of 154.85°, which indicates that the resulting coated surface achieves
superhydrophobicity. As compared to the uncoated magnetic composite sheet in Fig. 2(b), no water
contact angle was produced. The untreated magnetic composite sheet has zero water contact angle
due to the hydrophilic properties of natural fiber [18].
a
b
Water droplet fully absorbed onto the
uncoated surface (zero water contact
angle)
o
154.85
Fig. 2 (a) Image of a water droplet that formed WCA of 154.85° on the coated magnetic composite
sheet surface, (b) Image of water droplet being fully absorbed onto the surface of uncoated or
untreated magnetic composite sheet.
Summary
A superhydrophobic surface of magnetic composite sheet with a water contact angle 154.85° was
successfully fabricated by simple coating method in PCC, stearic acid and polymer latex. Dipping
the coated composite sheet into potassium stearate (PS) solution resulted in sheet with a higher
resistance to water penetration.
Acknowledgements
Authors would like to thank Universiti Teknikal Malaysia Melaka (UTeM) and Ministry of Higher
Education, Malaysia for supporting this research under Fundamental Research Grant Scheme
(FRGS): FRGS/2013/FKP/TK06/02/2/F00157. The Faculty of Manufacturing Engineering,
Universiti Teknikal Malaysia Melaka is gratefully acknowledged for providing the facilities.
References
[1] X. Tang, K.A. Hu, Preparation and electromagnetic wave absorption properties of Fe-doped zinc
oxide coated barium ferrite composites, Mater. Sci. Eng., B 139 (2007) 119-123.
[2] H. H. Abdullah, A. Z. M. Asa'ari, N. I. M. Zawawi, L. C. Abdullah, S. Zakaria, Effects of
physical treatments on the hydrophobicity of kenaf whole stem paper surface using stearic acid,
BioResources, 8(3) (2013) 4088-4100.
[3] J. Zhang, J. Li, Y. Han, Superhydrophobic PTFE surfaces by extension, Macromol. Rapid
Commun. 25 (2004) 1105–1108.
[4] L. Feng, Y. Song, J. Zhai, B. Liu, J. Xu, L. Jiang, D. Zhu, Creation of a superhydrophobic
surface from an amphiphilic polymer, Angew. Chem. Int. Ed. 42 (2003) 800–802.
[5] Z. Chen, F. Li, L.Hao, A. Chen, Y. Kong, One-step electrodeposition process to fabricate
cathodic superhydrophobic surface, Appl. Surf. Sci. 258 (2011) 1395–1398.
Key Engineering Materials Vol. 694
43
[6] L. Feng, Z. Zhang, Z. Mai, Y. Ma, B. Liu, L. Jiang, D. Zhu, A superhydrophobic and superoleophilic coating mesh film for the separation of oil and water, Angew. Chem. Int. Ed. 116 (2004)
2046–2048.
[7] N. Verplanck, Y. Coffinier, V. Thomy, R. Boukherroub, Wettability Switching Techniques on
Superhydrophobic Surfaces, Nanoscale Res. Lett. 2 (2007) 577-596.
[8] L. Cao, H. H. Hu, D. Gao, Design and fabrication of micro-textures for inducing a
superhydrophobic behavior on hydrophilic materials, Langmuir 23 (2007) 4310-4314.
[9] X. Zhang, X. Liu, J. Laakso, E. Levänen, T. Mäntylä, Easy-to-clean property and durability of
superhydrophobic flaky c-alumina coating on stainless steel in field test at a paper machine, Appl.
Surf. Sci. 258 (2012) 3102–3108.
[10] L. Feng, S. Li, H. Li, J. Zhai, Y. Song, L. Jiang, D. Zhu, Super-hydrophobic surface of aligned
polyacrylonitrile nanofibers, Angew. Chem. Int. Ed. 41 (2002) 1221–1223.
[11] H. Yang, Y. Deng, Preparation and physical properties of superhydrophobic papers, J. Colloid
Interface Sci. 325 (2008) 588-593.
[12] W. Wang, S. Ji, I. Lee, A facile method of nickel electroless deposition on various neutral
hydrophobic polymer surfaces, Appl. Surf. Sci. 283 (2013) 309-320.
[13] S.S. Latthe, S.L. Dhere, C. Kappenstein, H. Imai, V. Ganesan, A.V. Rao, P.B. Wagh, S.C.
Gupta, Sliding behavior of water drops on sol–gel derived hydrophobic silica films, Appl. Surf. Sci.
256 (2010) 3259–3264.
[14] A.V. Rao, S.S. Latthe, S.A. Mahadik, C. Kappenstein, Mechanically stable and corrosion
resistant superhydrophobic sol–gel coatings on copper substrate, Appl. Surf. Sci. 257 (2011) 5772–
5776.
[15] S.S. Latthe, H. Imai, V. Ganesan, A.V. Rao, Ultrahydrophobic silica films by sol–gel process,
J. Porous Mater. 17 (2010) 565–571.
[16] Z. Zheng, Z. Gu, R. Huo, Y. Ye, Superhydrophobicity of polyvinylidene fluoride membrane
fabricated by chemical vapor deposition from solution, Appl. Surf. Sci. 255 (2009) 7263–7267.
[17] S. Wang, L. Feng, L. Jiang, One-step solution-immersion process for the fabrication of stable
bionic superhydrophobic surfaces, Adv. Mater. 18 (2006) 767–770.
[18] J. Shen, X. Qian, Use of mineral pigments in fabrication of superhydrophobically engineered
cellulosic paper, Bioresources, 7 (2012) 4495-4498.
[19] T.C. Chandra, M.M. Mirna, J. Sunarso, Y. Sudaryanto, S. Ismadji, Activated carbon from
durian shell: Preparation and characterization, J. Taiwan Inst. Chem. Eng., 40 (2009) 457-462.
[20] R. Farahiyan, M. K. Shahril, M. Abu, A. Y. B. Hashim, Green magnetic wave absorber: The
potential of paddy straw and recycled paper, Mater. Res. Innovations 18 (2014) 21-25.
[21] Z. Hu, X. Zen, J. Gong, Y. Deng, Water resistance improvement of paper by superhydrophobic
modification with microsized CaCO3 and fatty acid coating, Colloids Surf., A. 351 (2009) 65-70.
ISSN: 1662-9795, Vol. 694, pp 39-43
doi:10.4028/www.scientific.net/KEM.694.39
© 2016 Trans Tech Publications, Switzerland
Submitted: 2015-07-27
Revised: 2015-11-16
Accepted: 2016-02-07
Online: 2016-05-21
A Facile Coating Method for Superhydrophobic Magnetic Composite
Sheet from Biodegradable Durian Peel for Electromagnetic Wave
Absorbance Application
Rose Farahiyan Munawar1,a, Afraha Baiti Arif1,b,
Wan Nur Fateehah Wan Abdullah Shani1,c, Mohd Asyadi Azam1,d,
Mohd Edeerozey Abd Manaf1,e, Maisarah Abu2,f,
Muhammad Zaimi Zainal Abidin1,g and Syahriza Ismail1,h
1
Carbon Research Technology Research Group, Engineering Materials Department, Faculty of
Manufacturing Engineering, Universiti Teknikal Malaysia Melaka, Hang Tuah Jaya, 76100, Durian
Tunggal, Melaka, Malaysia
2
Faculty of Electronic and Computer Engineering, Universiti Teknikal Malaysia Melaka, Hang
Tuah Jaya, 76100, Durian Tunggal, Melaka, Malaysia
a
rosefarahiyan@utem.edu.my, brahaarif@gmail.com, cfateehah_shani@yahoo.com,
asyadi@utem.edu.my, eedee@utem.edu.my, fmaisarah@utem.edu.my, gmdzaimi@utem.edu.my,
h
syahriza@utem.edu.my
d
Keywords: Superhydrophobic, Durian peel, Stearic acid
Abstract. Most of the electromagnetic (EM) wave absorbers are commonly made from polymerbased materials. A large number of polymers are resistant to the environmental degradation and are
thus responsible for the buildup of polymeric solid waste materials. These solid wastes cause acute
environmental problems and remain undegraded for quite a long time. In a view of the awareness
and concern for the problems created by the polymeric solid wastes, new biodegradable cellulosic
composite with low cost and nontoxic materials, have been designed and developed. However, the
properties of natural fibers that tends to absorb water, thus limiting their application. In this study,
precipitated calcium carbonate (PCC) was added with stearic acid (SA) in order to generate a
hydrophobic coating formulation. PCC works as filler and SA acts as surface hydrophobic
modification agent. Polymer latex was then added to the coating compound as the binder. The
composite surface morphology was inspected using scanning electron microscope (SEM). Results
show that durian peel composite sheet had successfully achieved a superhydrophobic surface with a
water contact angle of 154.85° which exceed 150°.
Introduction
The quick-tempered growth of telecommunication application in industrial, medical and also
military field has led to the high frequency of electromagnetic (EM) wave [1]. This high frequency
generated electromagnetic interference (EMI) which may cause disruption in those applications.
Therefore, EM wave absorber with the capability of absorbing these unwanted EM signals is
invented.
Presently most of the EM wave absorbers are made from polymers due to the light weight and
flexibility. However, they are environmental degradation resistance and the accumulation of their
solid wastes may cause serious environmental problems. Due to that, a new EM wave absorber
from natural fiber is designed and produced in this research with the goal of overcoming the
problem. Furthermore, the selection of natural fiber as the absorber material is due to its sustainable
ability, low cost and renewability.
Due to the great prominence in research and real-life applications including the prospective in
industrial applications, superhydrophobic surfaces with a water contact angle higher than 150° have
attracted increasing interest [2-4]. The wettability characteristic of a solid surface is generally
driven by the chemical composition and the geometrical structure of the surface [5-7]. In fabricating
superhydrophobic surface, two techniques are adopted: (1) forming more rough structure on the
All rights reserved. No part of contents of this paper may be reproduced or transmitted in any form or by any means without the written permission of Trans
Tech Publications, www.ttp.net. (ID: 103.198.52.1-15/03/16,02:58:10)
40
Current Trends in Materials Engineering
hydrophobic material surface [8-10]; (2) modifying the rough surface to lower the surface energy
[9,10]. There were a lot of approaches to achieve superhydrophobic surface, such as multi-layer
deposition [11,12], sol–gel process [13-15], chemical vapor deposition [16] and solution-immersion
[17].
Although the selection of natural fiber as an alternative to polymer is perfect in terms of
availability, less cost and renewability, however, it is very hygroscopic. It tends to have high water
and moisture absorptions because of the presence of hydrophilic groups, mainly hydroxyl, carboxyl
or sulfonic groups [18]. The high hygroscopicity may cause the magnetic composite sheet to absorb
water vapor easily from the environment and loss its valuable mechanical properties. This is the
reason the coating method by using the hydrophobic stearic acid is applied in this study. This
method was selected based on the factors of simplicity, non-toxicity and cost efficiency.
Durian peel is a new material used in this study, selected for its properties such as hard shell
texture and high pore volumes [19]. The higher the pore distribution in the fiber, the higher the
degree of loading of the magnetic particles should be and the better the quality of the magnetic
sheet.
Experimental Method
Sample Preparation. Durian peels were cleaned up and repeatedly washed with tap water to
remove grime and unnecessary materials on the peel’s surface. Then, they were cut to about 2 to 3
cm in length and about 0.4 cm in thickness. Next, the durian chips were dried at 50 °C for 24 hours
in drying oven to remove the moisture content.
Pulping. After the drying process, dried durian peel underwent the process of pulping to remove
lignin from cellulose. The selected pulping process was soda pulping process and it was conducted
by using rotary digester machine. The use of sodium hydroxide (NaOH) in making wood pulp is
called as soda pulping process. The process was carried out with 17 % concentration of NaOH.
About 300 g (oven-dried) of durian chips was placed into the digester. The ratio of durian chips to
cooking liquor was 1:7. The cooking temperature was set at 170 °C for the period of 7200 sec. Once
cooked, the unbleached durian peel pulp was washed, screened and centrifuged.
Preparation of Magnetic Composite Sheet using Lumen Loading Method. The magnetic
composite sheets were produced through the lumen loading method. 15 g dry weight of unbleached
durian shell pulp was disintegrated in 1250 ml of distilled water containing 0.1 gL-1 aluminium
sulphate for 1800 sec in a mechanical stirrer at the rotor speed of 1000 rpm. Magnetic pigment,
iron (II, III) oxide Aldrich 637106 nanopowder with particle size less than 50 nm at the weight of
30 g was mixed in 250 ml distilled water which contained 0.1 gL-1 aluminium sulphate. Next, both
suspensions were mixed and mechanically stirred for 1800-3600 sec at the rotor speed of 1000 rpm.
This stage is called as impregnation stage, where particles are forced to embed in the lumen fibers.
Later, the suspension was slowly stirred to 400 rpm for 14,400 sec when polyethylenimine (PEI, 2
%, w/w polymer on pulp) was added in the mixture. PEI was added as retention aid to retain the
magnetic particles inside the lumen. The excess pigment that remained on surface of fiber and
suspension were removed by washing with tap water in a self-designed fiber classifier containing a
filter screen (45 µm) for period range of 1800-3600 sec. The clean pulp then proceeded to paper
making process [20].
Fabrication of Superhydrophobic Surface of Composite Sheet. 40 g of PCC (Albacar® HO) and
1.238 g of SA (Peter Greven Asia Sdn. Bhd.) were added into 90 ml of distilled water. Next, the
suspension were stirred at 75 °C for 1800 sec to allow fatty acid to form a thin layer of water
insoluble calcium salt on the PCC surface. The suspension was then mixed with 9.16 g of polymer
latex (Acronal NX 4787 X) after cooling down to room temperature and was stirred again for 1800
sec with agitator. Next, a roller was used for applying the coating suspension onto the surface of the
durian magnetic composite sheet. The coated paper was air-dried for 3600 sec before immersing
into a container of 0.0015 mol/L potassium stearate (PS) suspension for 180 sec. The immersion
Key Engineering Materials Vol. 694
41
process in the PS suspension is known as treatment stage to further improve the water resistance of
the coated paper. The coated paper was then rinsed with distilled water at 75 °C to remove the
excess stearate salt present on the paper surface. The coated paper was air-dried again for another
3600 sec prior to paper testing [2].
Characterization of Coated Magnetic Composite Sheet. The Carl Zeiss Model 1450VP variable
pressure scanning electron microscope (SEM) was used in characterizing the morphology of the
composite sheet surface. The water contact angle (WCA) of the samples was examined using FECA
Contact-Angle Meter. The mechanical properties; tensile strength and tear strength were measured
using a Büchel-Van Der Korput horizontol tensile tester Elmendorf tear tester, respectively. The test
was in accordance to TAPPI standard method T 949 om-01 and TAPPI Standard T414 om-88.
Result and Discussion
Surface Morphology of Coated Magnetic Composite Sheet. This method involved several
dipping process stages in order to form a superhydrophobic surface. The coating formulation in the
technique applied in this study contains both fatty acid modified PCC and polymer binder. Since the
acid group in a stearic acid molecule forms an insoluble calcium salt and leaves a hydrophobic tail
oriented to the air, therefore the fatty acid modified PCC is hydrophobic. The main function of
stearic acid (SA) in coating formulation is to reduce high surface energy and decrease the
agglomeration of particles such as precipitated calcium carbonate (PCC).
At the same time, PCC is widely used as fillers in this method that act as adhesives and sealants
when react with SA. By knowing the general properties of each material that are used, the formation
of the superhydrophobic surface can be performed effectively. To improve both WCA and water
resistance, the surface coated paper was treated further by dipping in potassium stearate aqueous
solution [21].
The surface morphology of coated durian peel magnetic composite sheet is given in Fig. 1(a)
and 1(b). It shows the distribution of PCC particles on the coated composite sheet. The surface
roughness can be seen from SEM image and this contributes to the superhydrophobicity properties
of the magnetic composite sheet [7].
Fig. 1 SEM images of surface coating using stearic acid at (a) low magnification, and (b) high
magnification.
Water Contact Angle of Magnetic Composite Sheet. The water contact angle measurement is one
of the important analyses in measuring superhydrophobic properties. Generally, material surface is
classified as hydrophilic if the contact angle is less than 90°. When the contact angle higher than
90°, the surface is called hydrophobic, and when the contact angle is greater than 150°, the surface
is called superhydrophobic [2].
42
Current Trends in Materials Engineering
Fig. 2(a) shows the image of a water droplet on the coated magnetic composite sheet surface
with a water contact angle of 154.85°, which indicates that the resulting coated surface achieves
superhydrophobicity. As compared to the uncoated magnetic composite sheet in Fig. 2(b), no water
contact angle was produced. The untreated magnetic composite sheet has zero water contact angle
due to the hydrophilic properties of natural fiber [18].
a
b
Water droplet fully absorbed onto the
uncoated surface (zero water contact
angle)
o
154.85
Fig. 2 (a) Image of a water droplet that formed WCA of 154.85° on the coated magnetic composite
sheet surface, (b) Image of water droplet being fully absorbed onto the surface of uncoated or
untreated magnetic composite sheet.
Summary
A superhydrophobic surface of magnetic composite sheet with a water contact angle 154.85° was
successfully fabricated by simple coating method in PCC, stearic acid and polymer latex. Dipping
the coated composite sheet into potassium stearate (PS) solution resulted in sheet with a higher
resistance to water penetration.
Acknowledgements
Authors would like to thank Universiti Teknikal Malaysia Melaka (UTeM) and Ministry of Higher
Education, Malaysia for supporting this research under Fundamental Research Grant Scheme
(FRGS): FRGS/2013/FKP/TK06/02/2/F00157. The Faculty of Manufacturing Engineering,
Universiti Teknikal Malaysia Melaka is gratefully acknowledged for providing the facilities.
References
[1] X. Tang, K.A. Hu, Preparation and electromagnetic wave absorption properties of Fe-doped zinc
oxide coated barium ferrite composites, Mater. Sci. Eng., B 139 (2007) 119-123.
[2] H. H. Abdullah, A. Z. M. Asa'ari, N. I. M. Zawawi, L. C. Abdullah, S. Zakaria, Effects of
physical treatments on the hydrophobicity of kenaf whole stem paper surface using stearic acid,
BioResources, 8(3) (2013) 4088-4100.
[3] J. Zhang, J. Li, Y. Han, Superhydrophobic PTFE surfaces by extension, Macromol. Rapid
Commun. 25 (2004) 1105–1108.
[4] L. Feng, Y. Song, J. Zhai, B. Liu, J. Xu, L. Jiang, D. Zhu, Creation of a superhydrophobic
surface from an amphiphilic polymer, Angew. Chem. Int. Ed. 42 (2003) 800–802.
[5] Z. Chen, F. Li, L.Hao, A. Chen, Y. Kong, One-step electrodeposition process to fabricate
cathodic superhydrophobic surface, Appl. Surf. Sci. 258 (2011) 1395–1398.
Key Engineering Materials Vol. 694
43
[6] L. Feng, Z. Zhang, Z. Mai, Y. Ma, B. Liu, L. Jiang, D. Zhu, A superhydrophobic and superoleophilic coating mesh film for the separation of oil and water, Angew. Chem. Int. Ed. 116 (2004)
2046–2048.
[7] N. Verplanck, Y. Coffinier, V. Thomy, R. Boukherroub, Wettability Switching Techniques on
Superhydrophobic Surfaces, Nanoscale Res. Lett. 2 (2007) 577-596.
[8] L. Cao, H. H. Hu, D. Gao, Design and fabrication of micro-textures for inducing a
superhydrophobic behavior on hydrophilic materials, Langmuir 23 (2007) 4310-4314.
[9] X. Zhang, X. Liu, J. Laakso, E. Levänen, T. Mäntylä, Easy-to-clean property and durability of
superhydrophobic flaky c-alumina coating on stainless steel in field test at a paper machine, Appl.
Surf. Sci. 258 (2012) 3102–3108.
[10] L. Feng, S. Li, H. Li, J. Zhai, Y. Song, L. Jiang, D. Zhu, Super-hydrophobic surface of aligned
polyacrylonitrile nanofibers, Angew. Chem. Int. Ed. 41 (2002) 1221–1223.
[11] H. Yang, Y. Deng, Preparation and physical properties of superhydrophobic papers, J. Colloid
Interface Sci. 325 (2008) 588-593.
[12] W. Wang, S. Ji, I. Lee, A facile method of nickel electroless deposition on various neutral
hydrophobic polymer surfaces, Appl. Surf. Sci. 283 (2013) 309-320.
[13] S.S. Latthe, S.L. Dhere, C. Kappenstein, H. Imai, V. Ganesan, A.V. Rao, P.B. Wagh, S.C.
Gupta, Sliding behavior of water drops on sol–gel derived hydrophobic silica films, Appl. Surf. Sci.
256 (2010) 3259–3264.
[14] A.V. Rao, S.S. Latthe, S.A. Mahadik, C. Kappenstein, Mechanically stable and corrosion
resistant superhydrophobic sol–gel coatings on copper substrate, Appl. Surf. Sci. 257 (2011) 5772–
5776.
[15] S.S. Latthe, H. Imai, V. Ganesan, A.V. Rao, Ultrahydrophobic silica films by sol–gel process,
J. Porous Mater. 17 (2010) 565–571.
[16] Z. Zheng, Z. Gu, R. Huo, Y. Ye, Superhydrophobicity of polyvinylidene fluoride membrane
fabricated by chemical vapor deposition from solution, Appl. Surf. Sci. 255 (2009) 7263–7267.
[17] S. Wang, L. Feng, L. Jiang, One-step solution-immersion process for the fabrication of stable
bionic superhydrophobic surfaces, Adv. Mater. 18 (2006) 767–770.
[18] J. Shen, X. Qian, Use of mineral pigments in fabrication of superhydrophobically engineered
cellulosic paper, Bioresources, 7 (2012) 4495-4498.
[19] T.C. Chandra, M.M. Mirna, J. Sunarso, Y. Sudaryanto, S. Ismadji, Activated carbon from
durian shell: Preparation and characterization, J. Taiwan Inst. Chem. Eng., 40 (2009) 457-462.
[20] R. Farahiyan, M. K. Shahril, M. Abu, A. Y. B. Hashim, Green magnetic wave absorber: The
potential of paddy straw and recycled paper, Mater. Res. Innovations 18 (2014) 21-25.
[21] Z. Hu, X. Zen, J. Gong, Y. Deng, Water resistance improvement of paper by superhydrophobic
modification with microsized CaCO3 and fatty acid coating, Colloids Surf., A. 351 (2009) 65-70.