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

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Use of nano zinc oxide in styrene butadiene rubber VÉÇàxÇàá 6.1 Introduction 6.1 Introduction 6.2 Experimental 6.3 Results and discussion 6.4 Conclusions 6.5 References As described in previous chapters, zinc content in rubber products has come under increased scrutiny due to environmental concerns. The trend in rubber industry is therefore to reduce or even completely eliminate the zinc content, although to date no viable alternative for ZnO and zinc containing species for vulcanization purpose has been found. 1 There is general agreement that zinc cations from ZnO and/or zinc compounds react with organic accelerators to give active zinc–accelerator complexes, which is one of the main step in the vulcanization scheme. 2 It has been suggested in many different studies that these active complexes of Zn 2+ ions with accelerators are more reactive than the free accelerator 3,4 This active sulphurating agent reacts at the allylic sites of the rubber polymer unsaturations to form a rubber bound intermediate, which reacts with another rubber bound intermediate or with another polymer chain to generate a crosslink. The exact activator role of ZnO is highly dependent on the type of accelerator present in the initial vulcanization system.
Chapter 6 105 Fatty acids as co–activators in rubber vulcanization increase the crosslink yield. 5 It is assumed that stearic acid reacts with ZnO to form zinc stearate, which is an essential cure activator. Its function has been the subject of extensive research by Kruger and McGill. 6 Morrison and Porter reported that zinc stearate inhibits zinc promoted decomposition of mono sulphide cross links, though the mechanism is unclear. 7 It was observed that addition of nano zinc oxide (from precipitation and solid–state pyrolytic method) in polar synthetic rubber has improved the mechanical properties and so the same method was studied in non-polar synthetic rubber, styrene butadiene rubber (SBR). SBR is the most commonly used general purpose synthetic rubber which is a copolymer of styrene and butadiene and the butadiene unit is composed of cis-1,4-, trans-1,4- and vinyl components. They are produced by the copolymerization of styrene and butadiene under controlled conditions of reaction using different techniques of polymerization and the polymer properties vary with the method of polymerization. The unsaturation in SBR is less than that in NR and the double bonds are chemically less active than the double bonds of the isoprenoid unit in NR. The compounding of SBR is done in a way more or less similar to that of NR and other unsaturated hydrocarbon rubbers. 8 All types of SBR require less sulphur than NR for curing. On the other hand SBR requires more accelerators, because of lower unsaturation. This chapter explains the use of low dosage of ZnO(p) and ZnO(s) as activator in SBR and compares the mechanical properties of the vulcanizates with reference to the vulcanizates prepared from SBR and conventional zinc oxide (ZnO(c)).
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Studies on the use
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WxvÄtÜtà|ÉÇ I hereby declare t
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My heartfelt thanks are also due to
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The use of prepared zinc oxides as
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2.2.10 Characterization techniques
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Part@ B 7.3.1 Characterization - su
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Introduction 1.1 Composites 1.1 Com
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Introduction of reinforcement and m
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Nanophase material: They are same a
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Introduction developed at Oxford Un
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Introduction Rubbers are broadly cl
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Introduction The polymers are prepa
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1.4.1 Zinc oxide Introduction Zinc
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Introduction and tinted rubber comp
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Pharmaceutical industry Introductio
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Introduction textiles contain ZnO,
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1.4.2a. Carbon blacks Introduction
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Introduction especially glass and c
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Introduction properties, filler cha
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Introduction coupling agent in sili
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Introduction amphiphilic di and tri
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Introduction It has been reported t
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Introduction The external manifesta
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Introduction concern for a clean en
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12. C.R.Martin, Chem. Mater, 1996,
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41. E.J.Stewart, J.Elastomers plast
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Introduction 69. J.B. Donnet (Ed),
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Introduction 100. C.T.Kresge, M.E.L
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Introduction 129. E.R.Ericsson, R.A
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Chapter 2 47 In a particular experi
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Chapter 2 Stearic acid (co-activato
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Chapter 2 roll with mill opening at
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Page 69 and 70: Chapter 2 2.2.4 Strain-sweep studie
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Page 73 and 74: Chapter 2 Surface area 59 Surface a
Page 75 and 76: Preparation and characterization of
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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
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Page 101 and 102: Tear Strength (N/mm) 120 100 80 60
Page 103 and 104: 4.5 References Use of nano zinc oxi
Page 105 and 106: Chapter 5 oil resistance to oil swe
Page 107 and 108: Chapter 5 93 Ingredient phr Table 5
Page 109 and 110: Chapter 5 95 Torque (dNm) 6.5 6.0 5
Page 111 and 112: Chapter 5 97 Other technological pr
Page 113 and 114: Chapter 5 99 Table 5.8 Reinforcing
Page 115 and 116: Chapter 5 101 Hours Table 5.11 Agei
Page 117: Chapter 5 5.5 References 103 1. D.C
Page 121 and 122: Chapter 6 107 Physical properties s
Page 123 and 124: Chapter 6 The cure rate index of gu
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Page 127 and 128: Chapter 6 113 Table 6.6 Reinforcing
Page 129 and 130: Chapter 6 115 Tensile modulus (Mpa)
Page 131 and 132: Chapter 6 6.4 Conclusions 117 1. Gu
Page 133 and 134: Use of antioxidant modified precipi
Page 139 and 140: Mix Use of antioxidant modified pre
Page 143 and 144: Crosslink density Use of antioxidan
Page 151 and 152: Part@ B Use of antioxidant modified
Page 157 and 158: Thermal ageing studies Use of antio
Page 161 and 162: 7.9 References Use of antioxidant m
Page 163 and 164: Products from rice husk as filler i
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Page 167 and 168: Rubber compounding Products from ri
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Soxhlet extraction Products from ri
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Products from rice husk as filler i
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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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