effect-of-reclaim-rubber-loading-on-the-mechanical-properties-of-sbr-c

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________________________________________ Author for correspondence E-mail: samiralnesrawyyahoo.com Mo.: 009647801889584 Int. J. Chem. Sci.: 144 2016 2439-2449 ISSN 0972-768X www.sadgurupublications.com EFFECT OF RECLAIM RUBBER LOADING ON THE MECHANICAL PROPERTIES OF SBR COMPOSITES AHMED M. AJAM SAMEER HASSAN AL-NESRAWY and MOHAMMED AL-MAAMORI a College of Education for Pure Science University of Babylon HILLA IRAQ a College of Materials Engineering University of Babylon HILLA IRAQ ABSTRACT This article explores the possibility of using mix of reclaim rubber as reinforcement in styrene- butadiene rubber SBR. Mix of reclaim rubber used in this research to enhancement some of the mechanical properties of SBR as additives or fillers. Six different compound was prepared from SBR 100 pphr and loading level from Reclaim rubber 0 50 100 150 200 250 pphr in series while the hardness tensile strength tear résistance elongation elastic modulus and specific gravity have been studied in this research. We found that some of these properties are increasing with the increment of mix of reclaim rubber loading such as tensile strength elongation tear resistance specific gravity from other hand hardness elastic modulus were decreased with increment reclaim rubber loading . Key words: Composite materials Mechanical properties Waste of rubber R. R. INTRODUCTION The blending of two or more types of rubber is a useful technique for preparing materials with superior properties which are absent in the component rubbers 1-4 . The mechanical behavior of a polymer is strongly dependent on its morphology which in turn is influenced by the thermo-mechanical history during processing. Molecular orientation affects the crystallization behavior in two different aspects: Thermodynamics and hydrodynamic. The thermodynamic effect involves the reduction of entropy in extended chains and this will increase the opportunity of crystal formation by increasing the melting point while kinetically the extended chain is closer to a crystal state than a random chain. The hydrodynamic effect is a phase transformation which is responsible for the resultant morphology 5 . The present authors 6 have dealt with the various reclaiming processes of vulcanized rubber in the presence of different chemicals. Mechanochemical reclaiming of

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A. M. Ajam et al.: Effect of Reclaim Rubber Loading on…. 2440 ground vulcanized rubber was reclaimed by diaryl disulfide and process oil at 110 o C for 10 min in an open cracker cum two roll mixing mill 7 . The mechanical reclaiming of ground rubber tire GRT by tetramethylthiuram disulfide TMTD as reclaiming agent the extent of reclaiming and the performance evaluation of NR/RR blend were studied by the authors 89 . Styrene-Butadiene Rubber SBR: Is synthetic copolymer chemically SBR is a copolymer of styrene and butadiene typically containing about 23 styrene and 77 polybutadiene with a glass temperature T g is about -55 o C see Fig. 1 1011 . CH CH 2 CH 2 CH CH CH 2 CH 3 CH 3 H 2 C CH 3 CH 3 CH 2 CH 3 CH 3 Butadiene Styrene Fig. 1: Compositional formula of SBR Rubber Reclaim rubber is a rubber-compounding ingredient. Scrap rubber unlike scrap steel undergoes a special process before it can be reused and the obtained rubber at the end of this process is known as reclaimed rubber 12 . Reclaim is in fact a mixture of rubber carbon black oil zinc oxide stearic acid and other compounding ingredients used in the original compounds. It is lowers the green strength and tensile strength of the compounds in which it is used. Reclaim can be used in many tire applications such as internal casings components and inner liner compounds sidewalls chafers and rubber used in bead components 13 . Vulcanizing Agents: Sulfur is the most well-known vulcanizing agent. It is easily available in powder and prilled form packed in polyethylene bags. Sulfur vastly improves the properties of raw rubber which is sticky and soluble in solvents. With the addition of sulfur rubber is converted into a nontacky tough and elastic product 14 . This article study some of the mechanical properties such as tensile set and specific gravity and hardness specific gravity tests were carried out by Densitron according to Archimedes principle it was weighed in air and in water. The specific gravity is calculated by the following equation: Specific gravity in water Weight air in Weight air in Weight − × Specific gravity of water …1

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Int. J. Chem. Sci.: 144 2016 2441 So we can calculate the tensile strength T.S. by the equation T.S. F/A …2 where F is the observed force required to break the specimen and A is the cross sectional area. Youngs modulus was reported as the slope of the initial linear region of the stress– strain. Actual experimental values were reported as stress–strain curves. The stress σ and strain ε are described by the following expression 15 σ Force or load F/Cross sectional area A …3 Strain ε L-L o /L o …4 Thus Youngs modulus in a tensile test is given by E Δσ/ Δε …5 Therefore the ultimate elongation is mathematically calculated by the relation E L-L o /L o 100 …6 where L o Initial thickness and L Final thickness. with respect to the tear strength or the tear resistance in rubber it may be described as the resistance for growing a neck or cut when the tension is applied on the specimen and it depends upon the width and thickness of the test piece and the test results as the load necessary to tear specimen of standard width and thickness. Tear strength Ft 1 /t 2 …7 where F Maximum force t 1 Thickness of standard piece and t 2 The measured thickness of the specimen tested. Hardness may be defined as resistance to indentation under specific conditions. This test is conducted on rubbers in accordance with ASTM D2240-75 ASTM D1415-68 and ASTM D531-78.

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A. M. Ajam et al.: Effect of Reclaim Rubber Loading on…. 2442 EXPERIMENTAL Materials The SBR used is SBR–1502 with 23.5 styrene content made by the emulsion process Supplied by the Petkim Turkey. The Properties of SBR are listed in Table 1. The properties of reclaim rubber are listed in Table 2. Table 1: Properties SBR 1502 Properties Density g/cm 3 0.95 Bound styrene 23.5 ± max Volatile matter 0.75 max Ash 1.5 max Soap 0.5 max Organic acid 4.7-7.2 Zinc oxide 97 and stearic acid 99.4 were supplied by Durham U.K. MBS N- oxydiethylenebenzothiazole 2-sulfonamide 98.2 is supplied by ITT India. Paraphenic oil was supplied by the South Patrol Company. Sulfur was supplied by the Durham U.K. Table 2: Properties of reclaimed rubber products Type of reclaim Hardness shore A Resilience Tensile strength Mpa Elongation at break Mechanical waste NR/SBR 1:1 61 22 6.6 270 Mechanical waste NBR 63 5 6.8 220 Mechanical waste CR 64 12 4.6 230 Truck tires 80-100 NR 58 35 4.4 200 Passenger car tires 80–100 SBR 60 22 7.4 200 Equipments Laboratory mill: Baby mill was used the two roll mills having provisions for passing cold water. These rolls are cylindrical in shape and of 150 mm diameter and 300 mm length. The roll speed is 20 r.p.m. The hydraulic press is equipped with thermocouple and

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Int. J. Chem. Sci.: 144 2016 2443 maximum temperature is equal to 300°C and vulcanization process done at 20 min. Ingredients of SBR composite are listed in Table 3. Table 3: Ingredients of SBR composite Compounding ingredients Ratio pphr SBR Styrene-butadiene rubber 100 R. R. Reclaim rubber 0 50 100 150 200 250 Zinc oxide 3.5 Stearic acid 1.25 TMTD 1.75 Sulfur 1.75 Equipment for the measurement of tensile strength tear resistance elongation and modulus of elasticity Tests are carried out on samples which were prepared mill laboratory according to ASTM D412. Monsanto T10 tensometer was used. The test sample which is movable at speed of 200 mm/min for all except tear resistance at 50 mm/min. Equipment for hardness The International Hardness test is used in measurement of the penetration of rigid ball according to Brinall method into the rubber specimen. The measured penetration is converted to the international rubber hardness degrees. The scale of degrees is so chosen that zero represents a material having elastic modulus equal to zero and 100 represents a material of infinite elastic modulus. The scale covers all the normal range of hardness. Test was carried out according to ASTM D1415 specifications. Equipment for specific gravity measurement Mansanto-Densitron equipment was used to measure the specific gravity. The operating of equipment according to Archimedes principle the sample prepared was weighed in air then in water the resulting data were given to the compile which was linked to the equipment. Moulds preparation The necessary moulds were manufactured for test samples to study their mechanical properties according to British standard BS.

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A. M. Ajam et al.: Effect of Reclaim Rubber Loading on…. 2444 Table 4: The dimensions of the samples and forms Standard Samples and dimensions Test ASTM D 3182 ASTM D 13192 Tensile Modulus Elongation ASTM D 624-54 Tear Resistance ASTM D 1415 Hardness Specific Gravity Mould for preparing samples for tensile tear elongation and modulus tests For preparing samples for the above tests the sheet sample from each recipe with a dimension of 1501502.5 mm was prepared by using mould which consists of three parts the middle one in a dimension of 395 mm158 mm2.5 mm contains six sections with 1501502.5 mm dimension fixed on base of 39516010 mm and covered with a cover of the same dimension as that of the base for regulation of thickness.

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Int. J. Chem. Sci.: 144 2016 2445 Mould for testing hardness and specific gravity For preparing samples for hardness impact and water absorption the mould in the laboratories of Tyre Company was used the mould consists of three parts the middle part in a dimension of 2001806.5 mm which contains nine circular equivolume open with 65 mm diameter and 5 mm thickness while one of other two parts is bottom base and the other is a cover for the purpose of samples thickness regulation. They have a dimension of 15015010 mm. Samples preparation Hand-made wooden molds has been used with measurements and dimensions according to the American Society for testing and Materials ASTM. Table 4 shows the dimensions of the samples and forms. RESULTS AND DISCUSSION Tensile elongation modulusm and tear resistance Figs. 2-5 show that the increasing of loading ratio of reclaim rubber causes increasing in tensile strength elongation and tear resistance because of increasing cross-link between rubber and filler and this result due to sulfur presence in reclaim rubber which leads to increased cross-link density between the rubber chains as well as the existence of the proportion of carbon black and thus the cross-link density increase gradually and this go along with 1516 while the elastic modulus inversely proportional to the increase in elongation in the rubber chains lead to reduced elastic modulus of material and give a spongy elastic property. Tensile Mpa Reclaim rubber loading pphr 4.5 4 3.5 3 2.5 2 1.5 1 0.5 0 0 50 100 150 200 250 300 Fig. 2: Effect of adding reclaim rubber on tensile strength

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A. M. Ajam et al.: Effect of Reclaim Rubber Loading on…. 2446 Elastic modulus M a P Reclaim rubber loading pphr 0.09 0.08 0.07 0.06 0.05 0 50 100 150 200 250 300 Fig. 3: Effect of adding reclaim rubber on elastic modulus Elongation Reclaim rubber loading pphr 700 600 500 400 300 200 100 0 50 100 150 200 250 300 Fig. 4: Effect of adding reclaim rubber on elongation Tear resistance Mpa Reclaim rubber loading pphr 1.6 1.4 1.2 1 0.8 0.6 0.4 0 50 100 150 200 250 300 Fig. 5: Effect of addingreclaim rubber on tear resistance

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Int. J. Chem. Sci.: 144 2016 2447 Hardness Fig. 6 show that the increasing of loading ratio of reclaim rubber causes decreasing in hardness and this result due to reclaim rubber contain proportion of processing oil which in turn leads to sliding and divergence of rubber chains that lead to decreasing ability to resist penetration surface and this go along with 17 . Hardness shore A Reclaim rubber loading pphr 60 55 50 45 40 0 50 100 150 200 250 300 Fig. 6: Effect of adding reclaim rubber on hardness Specific gravity Fig. 7 show that the increasing of loading ratio of reclaim rubber causes increasing in specific gravity because of increasing cross-link between rubber and filler and thus material is more stacked lead to decrease formed pores within the sample and converge the molecules of material from each other. Specific gravity g/cm 3 Reclaim rubber loading pphr 1.07 1.05 1.03 1.01 0.99 0.97 0.95 0 50 100 150 200 250 300 Fig. 7: Effect of adding reclaim rubber on specific gravity

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A. M. Ajam et al.: Effect of Reclaim Rubber Loading on…. 2448 Therefore it works reducing of weight for unit size due to sulfur presence in reclaim rubber which leads to increased cross-link density between the rubber chains as well as the existence of the proportion of carbon black and thus the cross-link density increase gradually and this go along with 15 . CONCLUSION i The increasing of additives ratios of reclaim rubber due to increase the tensile strength elongation and tear resistance. ii The increasing of additives ratio of reclaim rubber causes decreasing in elastic modulus. iii The increasing of additives ratios of reclaim rubber causes decreasing in hardness. iv The increasing of additives ratios of reclaim rubber due to increase the specific gravity. REFERENCES 1. S. H. Al-Nesrawy M. H. Al-Maamori and H. R. Jappor Effect of Temperature on Rheological Properties of SBR Compounds Reinforced by some Industrial Scraps as a Filler Int. J. Chem. Sci. 14 1285-1295 2016. 2. J. B. Gardiner Curative Diffusion Between Dissimilar Elastomers and its Influence on Adhesion Rubber Chem. Technol. 41 1312-1328 1968. 3. M. E. Woods and J. A. Davidson Fundamental Considerations for the Covulcanization of Elastomer Blends II. Lead Oxide-Activated Cures of NBR–EPDM Blends Rubber Chem. Technol. 49 112-117 1976. 4. V. A. Shershnev Vulcanization of Polydiene and other Hydrocarbon Elastomers Rubber Chem. Technol. 55 537-574 1982. 5. A. H. Al-Noumannee Effect of Carbon Black and Silica on Physical and Mechanical Properties of NR and SBR Blends and Composites Ph.D. Thesis University of Baghdad Iraq 2010. 6. B. Adhikari D. De and S. Maiti Reclaim and Recycle of Waste Rubber Prog. Polym. Sci. 25 909-948 2000. 7. G. K. Jana and C. K. Das Devulcanization of Natural Rubber Vulcanizates by Mechanochemical Process Polym. Plast. Technol. Eng. 44 1399-1412 2005.

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Int. J. Chem. Sci.: 144 2016 2449 8. D. De A. Das B. Dey S. C. Debnath and B. Roy Reclaiming of Ground Rubber Tire GRT by a Novel Reclaiming Agent Eur. Polym. J. 42 917-927 2006. 9. D. De and G. M. Singharoy Reclaiming of Ground Rubber Tire GRT by a Novel Reclaiming Agent Part 1: Virgin Natural Rubber NR/Reclaimed GRT Vulcanizates Polym. Eng. Sci. 47 1091-1100 2007. 10. R. H. Gray Materials and Compounds Akron University Ohio USA 1986. 11. Y. S. Kitagawa A. Nakafutami Y. Yamada H. Karouji and T. Aoyagi New Technology Polymer for Tyres Journal Rubber World 214 38 1996. 12. V. C. Chandrasecaran Essential Rubber Formulary: Formulas for Practitioners William Andrew Inc USA 2007. 13. S. H. Al-Nesrawy M. H. Al-Maamori and Hamad Rahman Jappor Effect of Mixed of Industrial Scraps and Lamp Black Percent on the Mechanical Properties of NR70/SBR30 Composite Int. J. PharmTech Res. 9 207-217 2016. 14. M. Leny Development of Elastomeric Hybrid Composite Based on Synthesised NanoSilica and Short Nylon Fiber Ph.D. Thesis Cochin University of Science and Technology India 2009. 15. S. H.AL-Nesrawy Effect of Mixture of Reclaimed Tire and Carbon Black Percent on the Mechanical Properties of SBR/NR Blends Int. J. Adv. Res. 2 234-243 2014. 16. D. Debapriya K. P. Prabir R. Madhusudan and B. Satyaban Reinforcing Effect of Reclaim Rubber on Natural Rubber/Poly Butadiene Rubber Blends Materials and Design 46 142-150 2013. 17. R. Israa Design of Rubber Humbs from Pollutant Materials and Study their Mechanical Properties M.Sc. Thesis University of Babylon Iraq 2012. Accepted : 23.09.2016

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