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

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Chapter 4 sulphur and fatty acids diffuse through the rubber matrix and are adsorbed onto ZnO with the formation of intermediate complexes. 5,6 Fatty acids are generally regarded as indispensable activators in conjunction with zinc oxide. The function of fatty acid activators such as stearic acid , is to solubilize the zinc oxide, a secondary effect is an increase in the amount of zinc sulphide produced. 7 The zinc salts of fatty acids, which are a type of surfactant , also solubilize insoluble accelerators to form the actual catalyst. A general scheme of accelerated sulfur vulcanization that demonstrates the role of zinc oxides in conjunction with fatty acids is shown in scheme I. 8,9 vulcanization 76 Scheme I: Role of ZnO and fatty acid in accelerated sulfur X= Accelerator residue. L = ligand Duchacek 10 noted that increasing zinc oxide concentration increased the rate and extent of cross linking up to a certain zinc oxide concentration, this concentration is believed to be the minimum level of zinc oxide needed for complete conversion of accelerator to the zinc-accelerator sulfur complex. It was also noted that the optimum zinc oxide content to minimize reversion was slightly greater than this minimum. Coran 11 also noted that the induction time had a dependence on the zinc oxide concentration in excess of that
Use of nano zinc oxide in natural rubber required for formation of the accelerator-zinc complex. This suggests that zinc oxide exerts an influence beyond inclusion in the accelerator complex. The efficiency of ZnO during vulcanization can be enhanced by the maximization of the contact between the ZnO particles and the accelerators in the compound. This contact is dependant on the size of the particle, their shape and the specific surface area. In some rubbers such as natural rubber (NR) and ethylene-propylene diene rubber (EPDM), there is evidence that a considerable amount of ZnO is consumed and transformed into ZnS. 12-14 The zinc content in rubber products has come under increased scrutiny due to environmental concerns. The trend in rubber industry is, therefore, to reduce the zinc content in rubber products. This chapter describes the use of nano ZnO samples prepared in the laboratory in dry NR and the mechanical properties of the vulcanizates are evaluated with reference to the vulcanizates prepared using conventional ZnO. 4.2 Experimental Materials: Natural rubber used in this study was ISNR- 5 of Mooney viscosity (ML 1+4,100 0C) 85. Conventional zinc oxide (ZnO(c)), zinc oxide samples prepared in the laboratory (ZnO(p), ZnO(s)), stearic acid, high abrasion furnace black, aromatic oil, antioxidantHS, N-cyclohexylbenzothiazyl sulphenamide (CBS), tetramethylthiuram disulphide (TMTD), sulphur were also used in this investigation. 77
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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
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 and 48: Introduction The external manifesta
Page 49 and 50: Introduction concern for a clean en
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: Use of nano zinc oxide in natural r
Page 93 and 94: Use of nano zinc oxide in natural r
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 and 118: Chapter 5 5.5 References 103 1. D.C
Page 119 and 120: Chapter 6 105 Fatty acids as co-act
Page 121 and 122: Chapter 6 107 Physical properties s
Page 123 and 124: Chapter 6 The cure rate index of gu
Page 125 and 126: Chapter 6 show better mechanical pr
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
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Use of antioxidant modified precipi
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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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