See discussions, stats, and author profiles for this publication at: https://www.researchgate.net/publication/275208472
Structural Study of Plasticized Carboxy Methylcellulose Based Solid Biopolymer Electrolyte
Article in Advanced Materials Research · June 2015
DOI: 10.4028/www.scientific.net/AMR.1107.242
CITATIONS
7
READS
178 2 authors:
Some of the authors of this publication are also working on these related projects:
biopolymer electrolyteView project
Development of Novel Hydron Battery based on Enhanced Cellulose Solid Biopolymer Electrolytes.View project Chai Mui Nyuk (M.N. Chai)
Universiti Teknologi PETRONAS 17PUBLICATIONS 342CITATIONS
SEE PROFILE
Mohd Ikmar Nizam Mohamad Isa USIM | Universiti Sains Islam Malaysia 153PUBLICATIONS 2,531CITATIONS
SEE PROFILE
All content following this page was uploaded by Mohd Ikmar Nizam Mohamad Isa on 20 April 2015.
The user has requested enhancement of the downloaded file.
Structural Study of Plasticized Carboxy Methylcellulose Based Solid Biopolymer Electrolyte
M.N. Chai
1,a& M.I.N. Isa
1,2,b1School of Fundamental Sciences, University Malaysia Terengganu, 21030 Kuala Terengganu, Terengganu, Malaysia
2Center of Corporate Communication and Image Development, Chancellery, Universiti Malaysia Terengganu, 21030 Kuala Terengganu, Terengganu, Malaysia.
a[email protected], b[email protected]
Keywords: Solid biopolymer electrolyte, carboxyl methylcellulose, ionic conductivity, dissociation
Abstract. Carboxyl methylcellulose (CMC) doped with oleic acid (OA) and plasticized with glycerol was able to be produced into solid biopolymer electrolytes using the solution cast technique. The CMC-OA-glycerol solid biopolymer electrolyte obtained the highest conductivity of 1.64 x 10-4 S cm-1 at room temperature for sample Gly 40 wt. %. Within the temperature range investigated, the conductivity– temperature relationship of the biopolymer electrolytes is characteristically Arrhenius behaviour, suggesting that the conductivity is thermally assisted.
Fourier Transform Infrared studies was carried out to determine the dissociation of free protons (H+) from the carboxyl group (–COOH) of glycerol.
Introduction
In the world of modern technologies, commercial batteries represent a large number of toxic and hazardous materials which brings harm to the environment and human health. Over the past year, the electrochemical power was obtained by using liquid electrolyte due to its conductivity.
Unfortunately, this liquid electrolyte gives a lot of disadvantages such as leakage, reaction with electrode, and poor electrochemical stability, which makes it unsuitable for use in electro-chemical devices.
Since Wright discovered ionic conductivity in a PEO/ Na+ complex in 1975, researchers started to be more concern on solid polymer electrolytes (SPE), in particular for improvement of the ionic conductivity [1]. The advantages of SPE are due to their desirable characteristics that show good compatibility with electrodes; no leakage, low self-discharge in batteries, elasticity and easy to process [2].
In this study, a solid biopolymer electrolyte is presented to overcome this problem. Thus, fabricating cellulose or cellulose derivative based electrolyte is an evolutional research where the well-known insulator material (cellulose is the wall cell of plant – wood) is manipulated to be an ionic conducting materials. Carboxyl methylcellulose (CMC) is a naturally occurring polysaccharide and the most abundant organic substance on the earth. Due to the abundance, low cost and easier process ability, cellulose based electrolytes is expected to bring better future of green nations than non- biodegradable, toxic and harmful materials used in the commercial batteries today. To enhance the conductivity of SPEs, the contribution of mixing polymer and ionic dopant based on the modified double lattice (MDL) is necessary thus oleic acid (OA) was chosen to be used as the ionic dopant. In addition, the findings in this research offer the possibility to provide educators and researchers on the significant effects of diverse concentrations of glycerol (Gly) on CMC and OA SBE’s conductivity by EIS study.
Experimental method
The CMC based SBEs were prepared by using the solution casting technique. 1 g of CMC (weighted by a digital mass balance) was mixed with 33 ml distilled water and stirred continuously until the CMC dissolved. 20 wt. % (0.25g) of OA was dissolved in the CMC solution. The CMC- OA composition is following our previous research [3] of the highest ionic conductivity SBE. In
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 TTP, www.ttp.net. (ID: 103.255.170.2-29/03/15,08:19:18)
addition to the previous work, the CMC-OA solution was added with different composition of glycerol (0 – 50 wt. %) as plasticizer for each sample respectively. The mixture of CMC-OA- glycerol was poured into Petri dishes and dried in an oven at 60 °C. The samples were then kept in desiccators for further drying process. SBEs were characterized by several techniques in order to determine the characteristics of the CMC based biopolymer electrolytes. Infrared measurement were performed by Thermo Nicolet Avatar 380 FT-IR spectrometer equipped with an attenuated total reflection (ATR) accessory with a germanium crystal in the frequency ranging from 4000 to 675 cm-1 with spectra resolution of 4 cm-1. Impedance measurement of the CMC-OA biopolymer electrolytes were measured by using the HIOKI 3532-50 LCR Hi-Tester that was interfaced to a computer in frequency range 50 Hz to 1 MHz. The films was cut into a fitting size and placed between the stainless steel blocking electrodes of the sample holder which connected with the LCR tester. The software controlling the measurement also calculates the real and imaginary impedance.
The bulk impedance, Rb value was obtained from the plot of negative imaginary impedance; -Zi
versus real part, Zr of impedance and the conductivity of the sample was calculated as follow:
(1) where = area of film–electrode contact and =thickness of the film.
Result and discussion
Conductivity study. The ionic conductivity is depending of various factors, such as cation and anion types, salt concentration and temperature. The ionic conductivity, σ,of CMC-OA-glycerol was depicted in Fig. 1.
Fig. 1. The conductivity of CMC-OA-glycerol SBEs at room temperature.
From Fig. 1, it is noted that by the addition of plasticizer affected the conductivity of the CMC-OA- glycerol SBEs. It can be observed that the ionic conductivity in this system increases until 40 wt. % of glycerol and decreases with the addition of higher than 40 wt. % of glycerol. The dependence of ionic conductivity on the plasticizers concentration provides more information on the specific interaction among ionic dopant, polymer matrix and plasticizer. The initial increase of ionic conductivity can be explained by association of ions at higher plasticizer concentration, which leads to the formation of ion clusters and the number of charge carriers and their mobility. When the amount of plasticizer is increased, the ions would transport mainly in the plasticizer-rich phase [4].
According to [5], by postulating the existence of separate ionic pathways for the migration of free ions through the plasticizer, it is possible to explain the enhancement of ionic conductivity when plasticizer is introduced. In the other hand, the decrement of conductivity is mainly due to the higher amount of glycerol which contributed to the overcrowd of ions thus reduces the number of charge carriers further gives limitation on the mobility of ions [6,7]. For further understanding on Advanced Materials Research Vol. 1107 243
the ionic conductivity mechanism, the ionic conductivity of SBEs were tested at elevated temperature ranges from 313 K to 393 K.
From Figure 2, the relationship between conductivity and temperature of the SBEs are naturally Arrhenius behaviour. The regression values, R2, obtained for the temperature dependence is R2~1.
Hence, proven the samples obey the Arrhenius law and it is thermally activated similar to the work done by previous researchers [7,8,9,10].
Fig. 2. The Arrhenius plot of plasticized SPEs with different wt% of plasticizer.
FTIR study. Fig. 3 highlight the FTIR spectrum between 1200 and 1800 cm-1. The same behaviour was also observed for COO− stretching of the carboxyl group of CMC at 1590 cm-1. The peak intensity was decreased from Gly-0 until Gly-40 and the peak increases upon addition of higher wt.
% of glycerol (>40 wt. %). This shows that the H+ of COOH in OA has protonated and becomes free ions. Besides that, from Fig. 3, it can be observed that a small twin peaks at 1418 cm-1 (OH stretching of CMC) and 1370 cm-1 (C-H stretching of CMC) were clearly seen for Gly-0. The peak intensity was start decreased after Gly-0 until Gly-40 and the peak increases after Gly-40. This again proved the occurrence of complexation between OA and CMC. In the other hand, a sharp peak at 1710 cm-1 (C=O stretch) as shown in Fig. 3 was clearly seen at Gly-40. This sharp peak was not appearing for sample Gly-0 and Gly-5. The peak was found at Gly-10 and started to increase until the addition of 40 wt. % of glycerol and decreased upon addition of higher wt. % of glycerol (>40 wt. %). This supported the conductivity values as discuss in previous section. This is due to the protonation of CMC and OA had occurred since glycerol was added to increase the ionic mobility of OA and become free ions [11] .
Figure 3: FTIR spectrum between 1200 and 1800 cm-1
Figure 4: FTIR spectrum between 2700 and 3100 cm-1.
Fig. 4 depicts the FTIR spectrum of CMC-OA-glycerol SBEs between 2700 and 3100 cm-1. From the figure, the twin peaks at 2920 and 2850 cm-1 (C-H stretching of OA) was found to be increased until the addition of 40 wt. % of glycerol and decreases at higher concentration of glycerol. Thus support the conductivity values where it is increases until the addition of 40 wt. % of glycerol and decreases at higher concentration of glycerol. Further addition of plasticizers caused the peak intensity of samples increased and accommodating to the values of the conductivity obtained for the samples [12].
Based on Fig. 3 and 4, it can be concluded that from the increases and decreases of peak intensity, CMC-OA-glycerol SBEs had interacted resulted in the movement of ions in the system and protonation is occurred which support the electrical study done in the previous section.
Conclusion
Solid biopolymer electrolytes based on CMC-OA plasticized with glycerol were prepared. Sample with 40 wt. % of glycerol was found to have the highest ionic conductivity at room temperature (303 K) of 1.64 x 10-4 S cm-1. The ionic conductivity results as a function of temperature exhibited Arrhenius rule and the value of activation energy is capsized of conductivity. FTIR studies was carried out to determine the dissociation of free protons (H+) from the carboxyl group (-COOH) of glycerol.
Acknowledgment
The authors would like to thank FRGS and ERGS grants for the financial supports given for this work.
Advanced Materials Research Vol. 1107 245
References
[1] M. Kazuo, I. Shuichi, & Y. Youetsu: Electrochimica Acta. Vol. 45(2000), p. 1501-1508.
[2] M.Z.A. Yahya, M.K. Harun, A.M.M. Ali, M.F. Mohamad, M.A.K.M. Hanafiah, S.C. Ibrahim, et al.: Journal of applied sciences, Vol. 6 (2006), p. 3150-3154.
[3] M.N. Chai & M.I.N. Isa: International Journal of Polymer Analysis and Characterization, Vol.
18 (2013), p. 280-286.
[4] S. Ibrahim, M.Y.S. Mariah, N.N. Meng, N. Roslina, & J.M. Rafie: Journal of Non-Crystalline Solids. Vol. 358 (2012), p. 210–216.
[5] L.R.A.K. Bandara, M.A.K.L. Dissanayake, & B.E. Mellander: Electrochimica Acta. Vol. 43 (1998), p. 1447 – 1451.
[6] S. Selvasekarapandian, G. Hirankumar, J. Kawamura, N. Kuwata, & T. Hattori: Materials Letters. Vol. 59 (2005), p. 2741-2745.
[7] M.N. Chai, & M.I.N. Isa: Journal of current engineering research, Vol. 1 (2011), p. 23-27.
[8] A.S.A. Khiar, R. Puteh, & A.K. Arof: Physica B. Vol. 373 (2006), p. 23-27.
[9] N.A. Nik Aziz, N.K. Idris, & M.I.N. Isa: International Journal of Polymer Analysis and Characterization. Vol. 15 (2010), p. 319-327.
[10] M.N. Chai, & M.I.N. Isa: Int. Journal of Advanced Technology & Engineering Research.
Vol. 2 (2012), p. 36-39.
[11] M.N. Chai, & M.I.N. Isa: Journal of Crystallization Process and Tech. Vol. 3 (2013), p. 1-4.
[12] S.R. Majid, & A.K.Arof: Physica B. Vol. 355 (2005), p. 78–82.
View publication stats View publication stats
