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American-Eurasian Journal of Sustainable Agriculture ISSN: 1995-0748

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2014 Special; 8(4): pages 99-103.

Published Online 20 June 2014.

Research Article

White Fly Ash Filled Natural Rubber Compounds: Effect on Mooney Scorch Time, Swelling Behavior, Hardness and Resilience. 1

Hisyam Mokhtar, 1,2Razif Nordin, 3Saidatulakmar Shamsuddin, 3N.Z. Noriman

1

Department of Chemistry, Faculty Applied Sciences, Universiti Teknologi MARA, Shah Alam, Selangor Department of Chemistry, Faculty of Applied Sciences, Universiti Teknologi MARA Arau, Perlis. Department of Physics, Fculty of Applied Sciences, Universiti Teknologi MARA, Arau, Perlis.

2 3

Received: 28 February 2014; Revised: 25 May 2014; Accepted: 6 June 2014; Available online: 20 June 2014

© 2014

AENSI PUBLISHER All rights reserved ABSTRACT

The effects white fly ash (WFA) filled natural rubber compounds on mooney scorch time, swelling behavior, hardness and resilience of natural rubber compounds were investigated in the range 0 to 30 phr. The size of WFA that was used in this study was 4575 µm. The result indicated that Mooney scorch time of natural rubber compounds was decreased with the increasing of temperature. The increasing of WFA loading gave natural rubber compounds a better resistance towards swelling whereas crosslink density and hardness showed an increasing trend. However, the resilience of natural rubber compounds exhibit a decreasing trend. Keywords: White fly ash ; Natural rubber ; Mooney scorch time ; swelling behavior ; resilience

INTRODUCTION Malaysia is the world’s largest producer and exporter of palm oil, thus resulting in a millions of tonnes of oil palm waste annually. Presently, the solid waste could be used as alternative fuel for steam generation in oil palm mill plants. The byproduct known as white fly ash is obtained. Increasing awareness among the world population to protect our environment has promoted an intensive of biomass wastes. The agriculture industry in Malaysia, with its more 6 million hectares of plantation, produced over 100 million tons of biomass. Biomass residue from agricultural wastes are exploring the potential of using fillers such as sisal, jute, pineapple leaves, banana steam, oil palm, rice hulls and sugar palm are mostly available in abundance, can be found at no or low cost and renewable throughout the whole year in countries like Malaysia. In this study, WFA was used because Malaysia is the second largest product of palm oil after Indonesia. Along with increasing demand for palm oil, WFA has also become highly abundant and

is usually dumped in open fields, leading to severe environmental problems. 2. Objectives: The objective of this article is to study the potential of WFA filled natural rubber (NR) compounds at various filler loading. In this present work, the effect of WFA loading on mooney scorch time, swelling behavior, hardness and resilience of natural rubber is reported. Materials and Methods Natural rubber (SMR 10) was purchased from Hock Soon Rubber Sdn Bhd, Penang, Malaysia. WFA is by-product of the process of palm oil was collected from United Oil Palm Mill, Penang, Malaysia. Then, WFA was grind with pulveriser and sieve to 45-75 µm. The formulation is natural rubber, 100 phr, zinc oxide, 5 phr, stearic acid, 2.5 phr, sulphur, 2.5 phr, CBS, 0.5 phr, BKF, 1.0 phr and WFA is 5, 10, 20 and 30 phr.

Corresponding Author: Razif Nordin, Department of Chemsitry, Faculty Applied Sciences, Universiti Teknologi MARA, Shah Alam, Selangor. Tel: +90-195665348 E-mail: [email protected]

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Testing: 3.1 FTIR analysis: The spectrum was obtained using Perkin-Elmer Spectrum One Series equipment and the attenuated total reflection (ATR) technique was adopted. About 10 mg of sample is distributed in a liquid paraffin of approximately equal refractive index in a mortar and pestle. Analytical measurement program was set up according to the scanning range with 4 cm-1 and 600 to 4000 cm-1, respectively. For each spectrum, 32 scans were co-added. 3.2 Mooney scorch time: The mooney scorch time was determined by using a Monsanto automatic Mooney Viscometer (MV 2000) at five different temperature, ranging from 120 0C-180 0C. The curing characteristics t5 (time taken to achieve five Mooney unit above the minimum viscosity), t35 (time taken to achieve 35 Mooney units above the minimum viscosity) and the cure index was calculated by using the following equation [8];

cm3/mol), is the volume fraction of the polymer in the swollen specimen, is the weight increase of the blends in toluene and is the interaction parameter of the rubber network-solvent ( of NR = 0.393). The crosslink density is given by: (5) 3.4 Hardness: The hardness measurement of sample was done according to ASTM D 1415-88 using a Wallace dead load, with the hardness ranging from 30 to 85 IRHD (International Rubber Hardness Degree). 3.5 Resilience: While Resilience was studied using a Wallace Dunlop Tripsometer according to ASTM D 1054-91. Rebound resilience was calculated according to the following equation[11]: (6)

(1) 3.3 Swelling behaviour: Swelling was studied in toluene according to ASTM D 471-79. Cures test pieces of dimensions 30 x 5 x 2 mm were weighed using an electrical balance, and each test piece was immersed in a glass vessel containing toluene (30 mL) at 25 °C. The vessel was kept in the dark to prevent oxidation. The sample was removed from the glass vessels and excess toluene was removed by lens blotting paper. The samples were then kept 48 hours in a closed vessel to prevent toluene evaporation and the weights of the swollen samples were determined. The sample was then re-immersed in the toluene and the process was repeated until a constant swollen weight could be obtained. Calculation of the change in mass was as follows[9]: (2) where M1 is the initial mass of specimen (g) and M2 is the mass of specimen (g) after immersion. The swelling result were also used to calculate the molecular weight between crosslinks (Mc) by apply the Flory-Rehner Equation[10]:

(3)

(4) where is the rubber density ( NR = 0.92 g/cm3 ), is the molar volume of the toluene ( = 106.4

Where θ1 is the initial angle (450) and θ2 is the maximum rebound angle. Result and Discussion 4.1 Fourier Transform Infra-red (FT-IR): Figure 1 show the FTIR spectra of WFA. The peak at 2352.70 cm-1 and 2336.63 cm-1 (1) due to CH stretching. Also the intensity of the absorption at 1060.42 cm-1 (2) assigned to Si-O-C stretching is decreasing and at 794.31 cm-1 (3) due to Si-O-Si symmetric vibrations is increasing, are associated of silica particles into WFA [12]. Figure 2 shows the exponential dependence of the Mooney scorch time with temperature at fixed concentration of 5 phr filler loading. It is observed that the scorch time for WFA loading show the decreasing trend when increase the temperature. At lower temperature, the difference in scorch time is much greater compared to that at higher temperature. According to Lee and Poh [13], the exponential decrease of scorch time with increasing temperature can be expressed mathematically as: (7) where t and T are the scorch time and temperature, respectively. The shorter scorch time observed as the temperature increases can be accounted for by availability of sufficient thermal energy to effect faster curing at higher temperatures. Also the mobility of the rubber chain is increased thus increasing the probability for crosslinking occur [14]. Figure 3 show the effect of filler loading on swelling percentage of natural rubber compounds in toulene (after 24 hr) respectively. This figures

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indicate that swelling percentage decreasing with increase in filler loading. This observation is attributed to the increasing rubber-filler interaction. A different study in swelling behavior that used silica as a filler gives same orservation with WFA[15]. Besides, the decrease in filler-rubber interaction is

thought to be another cause for the reduction in swelling resistance as WFA loading increases. Therefore, the increase in WFA loading should lead to an increases in the WFA-WFA interaction and, hence, a decrease in filler-rubber interaction.

Fig. 1: FTIR spectra of WFA. 20 18 16

t 5 (min)

14

12 10 8 6

4 2 0 120

130

140

150 Temperature (˚C)

Fig. 2: Variation of Mooney scorch time of WFA.

Fig. 3: Equilibrium swelling of WFA filled NR compounds.

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170

180

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Fig. 4: Crosslink density of WFA filled NR compounds.

Fig. 5: The effect of different fillers on hardness and resilience of natural rubber compounds at different loadings. The hardness will increase when increase the WFA loading in natural rubber. The increase in hardness is related to tensile modulus (M100) and increasing filler loading in NR compounds. On the contrary, as can be observed from the resillience test, the elastic behavior of the rubber compounds inversely proprotional to filler loading. As the loading of filler increases, the ability of NR compounds to dispersed to dispersed impact energy decreases since there are less ratio of rubber matrix to fillers. Conclusion: A potential application of WFA as filler for NR is reported in this study. The Mooney scorch time decreased when increase the temperature. The swelling behaviour of the natural rubber compounds in toluene was studied as well. It was also found that the solvent uptake decrease linearly with increasing white fly ash loading whereas crosslink density and hardness showed an increasing trend. However, the resilience of natural rubber compounds exhibit a decreasing trend

Acknowledgement Special thanks is dedicated to Universiti Teknologi Mara; Fundamental Research Grant Scheme (600-RMI/FRGS 5/3 (17/2012) and Faculty of Applied Sciences for supporting the funds for the research References 1.

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