Studies on the use of nano zinc oxide and modified silica in NR, CR ...

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Chapter 1 34 Antiozonant efficiency should therefore be dependent on the rate of diffusion of fresh antiozonant to the surface, rate of reaction of antiozonant with O3 and the initial concentration of the antiozonant in the rubber phase. 129 Products of the ozonation of aromatic amines and diamines include oximes, hydroxylamines, nitroso and nitro compounds. 130-133 Service requirement placed on many finished rubber products demand improved polymer stabilization. The effectiveness of antioxidants depends on two factors. (a) Intrinsic activity of the antioxidant This is the fundamental ability of the antioxidant and its transformation products to interfere with and retard the radical chain oxidation process, which in turn depend on the chemical structure of the antioxidant. (b) Permanence of the antioxidant in the polymer The concentration of the antioxidant in a polymer decreases during long term use, as a consequence of two process (1) chemical loss of antioxidant, (2) physical loss of antioxidant from the polymer. 134-138 1.5 Scope and objectives of the work The main objective of this study has been to develop more environment friendly, coloured and cheaper rubber products: (i) by reducing the amount of zinc oxide and (ii) by making the incorporation of silica easier. Release of zinc from rubber products occurs during disposal, recycling and also during service life. In view of the upcoming legislations and ecolabelling requirements for vehicle tyres, for instance, it can be stated that it is desirable to keep the ZnO content in rubber compounds as low as possible, not only from environmental considerations but also from economical reasons. The
Introduction concern for a clean environment has gripped all development more than ever before. Rubber technology has also to adopt safer, cleaner and greener ways. Since silica is hydrophilic and rubber is hydrophobic, uniformly distributing silica in rubber is extremely difficult and poses problems like high initial viscosity. Silica has a number of hydroxyl groups, which results in filler-filler particle agglomeration and reagglomeration. Incorporation of silica in rubber is quite difficult compared to that of carbon black. Carbon black and hydrocarbon rubbers are hydrophobic materials and the incorporation of carbon black in rubber is easy. To overcome this difficulty, it is proposed to modify silica surface with antioxidants. The specific objectives of the work are 1. To prepare nano zinc oxide by precipitation method and by solid-state pyrolytic method [ZnO(p) and ZnO(s)]. 2. To characterize the prepared zinc oxides using X-ray diffraction (XRD), transmission electron microscopy (TEM), BET adsorption and infrared spectroscopy. 3. To use this nano zinc oxide in rubber compounding and to compare the cure characteristics and mechanical properties of three typical rubbers: natural rubber, polychloroprene, styrene butadiene rubber compounds using low dosage of zinc oxides [ZnO(p) and ZnO(s)] with those of compounds containing conventional zinc oxide. 4. To prepare modified precipitated silica and compare the properties of modified silica filled natural rubber, polychloroprene and styrene butadiene composites with those of unmodified silica filled natural rubber, polychloroprene and styrene butadiene composite. 5. To prepare mesoporous silica and rice husk silica from low cost silica source (rice husk) and to characterize these silica particles using X-ray 35
Page 2: Studies on the use
Page 5 and 6: WxvÄtÜtà|ÉÇ I hereby declare t
Page 7 and 8: My heartfelt thanks are also due to
Page 9 and 10: The use of prepared zinc oxides as
Page 11 and 12: 2.2.10 Characterization techniques
Page 13 and 14: Part@ B 7.3.1 Characterization - su
Page 15 and 16: Introduction 1.1 Composites 1.1 Com
Page 17 and 18: Introduction of reinforcement and m
Page 19 and 20: Nanophase material: They are same a
Page 21 and 22: Introduction developed at Oxford Un
Page 23 and 24: Introduction Rubbers are broadly cl
Page 25 and 26: Introduction The polymers are prepa
Page 27 and 28: 1.4.1 Zinc oxide Introduction Zinc
Page 29 and 30: Introduction and tinted rubber comp
Page 31 and 32: Pharmaceutical industry Introductio
Page 33 and 34: Introduction textiles contain ZnO,
Page 35 and 36: 1.4.2a. Carbon blacks Introduction
Page 37 and 38: Introduction especially glass and c
Page 39 and 40: Introduction properties, filler cha
Page 41 and 42: Introduction coupling agent in sili
Page 43 and 44: Introduction amphiphilic di and tri
Page 45 and 46: Introduction It has been reported t
Page 47: Introduction The external manifesta
Page 51 and 52: 12. C.R.Martin, Chem. Mater, 1996,
Page 53 and 54: 41. E.J.Stewart, J.Elastomers plast
Page 55 and 56: Introduction 69. J.B. Donnet (Ed),
Page 57 and 58: Introduction 100. C.T.Kresge, M.E.L
Page 59 and 60: Introduction 129. E.R.Ericsson, R.A
Page 61 and 62: Chapter 2 47 In a particular experi
Page 63 and 64: Chapter 2 Stearic acid (co-activato
Page 65 and 66: Chapter 2 roll with mill opening at
Page 67 and 68: Chapter 2 were carried out at a cro
Page 69 and 70: Chapter 2 2.2.4 Strain-sweep studie
Page 71 and 72: Chapter 2 2.2.6 Bound rubber conten
Page 73 and 74: Chapter 2 Surface area 59 Surface a
Page 75 and 76: Preparation and characterization of
Page 77 and 78: 3.2.2 Method I- Precipitation metho
Page 79 and 80: Energy dispersive X-ray spectrometr
Page 85 and 86: 3.4.9 Differential scanning calorim
Page 87 and 88: 3.6 References Preparation and char
Page 89 and 90: Use of nano zinc oxide in natural r
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Use of nano zinc oxide in natural r
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Tear Strength (N/mm) 120 100 80 60
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4.5 References Use of nano zinc oxi
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Chapter 5 oil resistance to oil swe
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Chapter 5 93 Ingredient phr Table 5
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Chapter 5 95 Torque (dNm) 6.5 6.0 5
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Chapter 5 97 Other technological pr
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Chapter 5 99 Table 5.8 Reinforcing
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Chapter 5 101 Hours Table 5.11 Agei
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Chapter 5 5.5 References 103 1. D.C
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Chapter 6 105 Fatty acids as co-act
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Chapter 6 107 Physical properties s
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Chapter 6 The cure rate index of gu
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Chapter 6 show better mechanical pr
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Chapter 6 113 Table 6.6 Reinforcing
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Chapter 6 115 Tensile modulus (Mpa)
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Chapter 6 6.4 Conclusions 117 1. Gu
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Use of antioxidant modified precipi
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Mix Use of antioxidant modified pre
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Crosslink density Use of antioxidan
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Part@ B Use of antioxidant modified
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Thermal ageing studies Use of antio
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7.9 References Use of antioxidant m
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Products from rice husk as filler i
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Rubber compounding Products from ri
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Soxhlet extraction Products from ri
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8.3.4 Bound rubber content Products
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. Hardness (Shore A ) 70 60 50 40 3
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8.8 References 1. V.M.H. Govindaro
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Summary and Conclusions Polymers ar
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Summary and Conclusion compounds an
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ASTM : American Society for Testing
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A. International/National journals
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P.M.SABURA BEGUM Senior Scale Lectu
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