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Materials Letters 62 (20

Styrene–butadiene rubber electrolytes modifiedwith MgCl2, NiCl2, ZnCl2, and active carbon

Tomasz Borowski ⁎

Department of Chemistry and Water Environmental Protection, Natural Science Faculty, Szczecin University, 3 C Felczaka Street, 71-412 Szczecin, Poland

Received 11 May 2007; accepted 21 August 2007Available online 28 August 2007

Abstract

Styrene–butadiene rubber (SBR), as a solvent and repository of electric charges, starts to gain these properties after adding to SBR MgCl2 orNiCl2 or ZnCl2 in the form of methanol solution with addition of active carbon. Electrical conductivity of such an SBR-active carbon system withadded MgCl2 or NiCl2 or ZnCl2 equals from 10−5 to 10−4 S cm−1 at a room temperature of 293 K and a frequency of 10 kHz. The examinedelectrolytes were tested for the frequency range of 1 kHz–25 kHz. These polymer electrolyte systems may find their application as materials foranticorrosive and antielectrostatic protection of fuel or hazardous material tanks.© 2007 Elsevier B.V. All rights reserved.

Keywords: Polymer electrolytes; SBR; Active carbon (900 m2 g-1 type)

1. Introduction

At present, there are a lot of publications containing theexamples of conductive polymer application. Polymers modi-fied with lithium compounds [1–7], which are widely used aselectrolytes in the production of polymer batteries [8,9], can beincluded among one of the greatest achievements. Polymercomposites are also obtained with copper compounds [10],magnesium compounds [11], silver compounds [12] andsodium compounds [13–21], but to a lesser degree whencompared with lithium compounds.

In the present paper, a method is presented of obtainingpolymer electrolytes from styrene–butadiene rubber. As a factorinducing electrical conductivity of polymer systems, MgCl2,NiCl2 and ZnCl2 (manufactured by Chempur®, Poland) wereused as well as active carbon (also manufactured by Chempur®,Poland) with a 900 m2 active surface per 1 g of active carbon.

For research purposes, styrene–butadiene rubber as a 1,4-cisand -trans mixture composed of 77% butadiene and 23%styrene (these values being expressed as molar fractions) wasselected due to its good quality and low price, manufactured by

⁎ Tel.: +48 91 444 15 71; fax: +48 91 444 15 13.E-mail address: tomasz.borowski@poczta.onet.eu.

0167-577X/$ - see front matter © 2007 Elsevier B.V. All rights reserved.doi:10.1016/j.matlet.2007.08.060

the Dwory Chemical Plant S.A. near Oświęcim. This rubberwas obtained in the process of low-temperature emulsioncopolymerisation, No. KER® 1507.

2. Experimental procedure

2.1. Synthesis of the system: SBR+MgCl2, NiCl2 and ZnCl2+active carbon

2.1.1. Stage 1—dissolution of styrene–butadiene rubber withactive carbon addition

Styrene–butadiene rubber is well-soluble in toluene. Tolu-ene, in the amount of 40 cm3, is added to 3 g of fine-cut SBR.After three days of leaving it at room temperature, the polymerbecomes an oily substance. Such a dissolved rubber wassupplemented with active carbon (powdery form) in the amountof 0.5 g, 1 g, 1.5 g, 2 g, and 2.5 g.

2.1.2. Stage 2—synthesis of polymer electrolyteBefore obtaining a rubber electrolyte with active carbon

addition, a maximum amount of MgCl2 or NiCl2 or ZnCl2possible for adding was determined. This amount was assayedand it equaled to 5 g of MgCl2 or NiCl2 or ZnCl2. After adding alarger amount than 5 g of MgCl2 or NiCl2 or ZnCl2, problems

Table 1Electrical conductivity of rubber electrolyte in a temperature ranging from 273 Kto 313 K for SBR+MgCl2, NiCl2, ZnCl2+active carbon system

Temperature[K]

Substance Quantity of active carbon

0.5 g 1 g 1.5 g 2 g 2.5 g

273 MgCl2 [S cm−1] 10−6 10−6 10−5 10−5 8.0 ·10−5

NiCl2 [S cm−1] 10−7 10−6 10−6 10−6 1.1 ·10−5

ZnCl2 [S cm−1] 10−6 10−5 10−5 10−4 2.8 ·10−4

283 MgCl2 [S cm−1] 10−6 10−6 10−5 10−5 8.1 ·10−5

NiCl2 [S cm−1] 10−7 10−6 10−6 10−6 1.1 ·10−5

ZnCl2 [S cm−1] 10−6 10−5 10−5 10−4 2.8 ·10−4

293 MgCl2 [S cm−1] 10−6 10−6 10−5 10−5 8.1 ·10−5

NiCl2 [S cm−1] 10−7 10−6 10−6 10−6 1.2 ·10−5

ZnCl2 [S cm−1] 10−6 10−5 10−5 10−4 2.9 ·10−4

303 MgCl2 [S cm−1] 10−6 10−6 10−5 10−5 8.2 ·10−5

NiCl2 [S cm−1] 10−7 10−6 10−6 10−6 1.2 ·10−5

ZnCl2 [S cm−1] 10−6 10−5 10−5 10−4 3.0 ·10−4

313 MgCl2 [S cm−1] 10−6 10−6 10−5 10−5 8.3 ·10−5

NiCl2 [S cm−1] 10−7 10−6 10−6 10−6 1.2 ·10−5

ZnCl2 [S cm−1] 10−6 10−5 10−5 10−4 3.1 ·10−4

1383T. Borowski / Materials Letters 62 (2008) 1382–1384

related to precipitation of rubber electrolytes in the form of gelfrom this solution occurred in all systems. These problemsconsisted in a non-homogenous form of gel.

MgCl2 or NiCl2 or ZnCl2 in the amount of 5 g dissolved in40 cm3 methanol and added to the SBR solution prepared earlierwith addition of active carbon.

After stirring, rubber electrolyte precipitated from thesolution almost at once. Such a rubber electrolyte system isleft for one day after removal from the solution. After one day,the rubber system is subjected to electrical conductivity testing.

3. Methods for measurements of polymeric electrolytes

To determine the electrolytic conductivity, the systemobtained was subjected to testing using a variable current witha frequency varying between 1 Hz and 25 kHz. The followingtesting equipment was used for this purpose (Fig. 1)

➢ A Hewlett Packard's Alternator 33120A 15 MHz AFunction/Arbitrary Waveform Generator

➢ An Agilent 3458A 8 1/2 Digit Multimeter➢ A Hewlett Packard's Infinium Oscilloscope 500 MHz

1 Gsa/s

4. Summary findings

Table 1 presented the amounts of active carbon in methanol,which were added to the rubber for a constant concentration of3 g SBR per 40 cm3 toluene and a variable amount of activecarbon in a temperature ranging from 273 K to 313 K. For eachtemperature, electrical conductivity was determined of theobtained rubber electrolytes with addition of active carbon andof the added electrolytes in methanol: MgCl2 or NiCl2 or ZnCl2.

5. Discussion

Rubber electrolyte systems after adding MgCl2 or NiCl2 orZnCl2 causes the whole system to become a conductive system.After addingMgCl2 or NiCl2 or ZnCl2 to SBRwith active carbon,the electrical conductivity of such systems ranges from 10−5 to10−4 S cm−1. For these four systems of rubber electrolytes, anoptimum amount of the added equals to 5 g.

Fig. 1. Measuring diagram of the conductivity of the polymer system beingtested: 1—copper plates, 2—junction of a conductor with a copper plate, 3—multimeter, 4—alternator, 5—oscilloscope, 6—polymeric electrolyte.

It results for each rubber electrolyte system tested for itselectrical conductivity that such rubber systems have lowconductive properties. Such systems, however, show inconsid-erable changes of electrical conductivity in a temperatureranging from 273 K to 313 K. One may think thus that suchrubber systems are stabile in a variable temperature, althoughthey have low values of electrical conductivity.

6. Conclusions

Such systems can find their application as materials foranticorrosive and antielectrostatic protection of tanks with inflam-mable and hazardous materials, as electrical conductivity of thetested systems changes inconsiderably in a variable temperature.

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