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

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Chapter 1 a. Activation 14 In the curing process for natural rubber and most types of synthetic rubbers, the chemical reactivity of ZnO is utilized to activate the organic accelerator. The unreacted portion of the ZnO remains available as a basic reserve to neutralize the sulphur–bearing acidic decomposition products formed during vulcanization. Adequate level of ZnO contributes markedly to chemical reinforcement; scorch control, and resistance to heat ageing and compression fatigue. b. Acceleration Zinc oxide serves as the accelerator with some types of elastomer and the cross linking, which it induces, takes several forms. With some systems, ZnO is an effective co-accelerator in the vulcanization process. c. Biochemical activity ZnO is useful in the preservation of plantation latex as it reacts with the enzyme responsible for the decomposition. The oxide is also a fungistat, inhibiting the growth of such fungi as mold and mildew. d. Heat stabilization ZnO similarly retards devulcanization of many types of rubber compounds operating at elevated temperatures. e. Latex gelation In the production of latex foam rubber products, ZnO is particularly effective in gelation of the foam with sufficient stability. f. Light stabilization ZnO is outstanding among white pigments and extenders for its absorption of ultraviolet rays. Thus, it serves as an effective stabilizer of white
Introduction and tinted rubber compounds under prolonged exposure to the destructive rays of the sun. g. Pigmentation Through its high brightness, refractive index, and optimum particle size, ZnO provides a high degree of whiteness and tinting strength for such rubber products as tyre sidewalls, sheeting and surgical gloves. h. Reinforcement ZnO provides reinforcement in natural rubber, and in some synthetic elastomers such as polysulfides and chloroprene. The degree of reinforcement appears to depend upon the combination of the particle size of the oxide, the finest size being the most effective, and the reactivity of the oxide with the rubber. Under such service condition involving rapid flexing or compression, ZnO also provides heat conduction to more rapidly dissipate the heat and thereby provides lower operating temperatures. In addition, it imparts heat stabilization by reacting with acidic decomposition products. i. Rubber- metal bonding In the bonding of rubber to brass, ZnO reacts with copper oxide on the brass surface to form a tightly adhering zinc-copper salt. j. Tack retention One of the unique properties of ZnO is its ability to retain over many months of shelf-storage the tack of uncured rubber compounds for adhesive tapes. In plastics Zinc compounds can provide a variety of properties in the plastics field. Heat resistance and mechanical strength are imparted to acrylic 15
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: 1.4.1 Zinc oxide Introduction Zinc
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 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
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Energy dispersive X-ray spectrometr
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Preparation and characterization of
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Preparation and characterization of
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3.4.9 Differential scanning calorim
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3.6 References Preparation and char
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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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