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

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Chapter 7 replace carbon black partly in tyres to reduce the rolling resistance of tyres and hence to bring down the fuel consumption. 4 120 However, the silica surface has a tendency to absorb moisture due to its hydrophilic character. This adversely influences the curing reaction and hence the properties of the final product. The hydroxyl groups on the surface of the silica control surface acidity. This intrinsic acidity can influence vulcanization. 5 The higher moisture content increases the dispersion time of silica into the rubber. Absorbed water can decrease cure time, tensile strength, bound rubber content 6 and also abrasion resistance. 7 Rubber articles under severe service conditions undergo different types of degradations like ozone, oxidation etc. Although ozone is present in the atmosphere at concentration normally in the range 0-7pphm 8, it can severely attack unsaturated rubber products under stress. The general subject of protection of rubber against ozone attack has been reviewed by a number of authors. 9-11 Several theories have appeared in the literature regarding the mechanism of antiozonant protection. The “scavenger” model states that the antiozonant blooms to the surface and preferentially reacts with ozone so that the rubber is not attacked until the antioxidant is exhausted. 11-12 The protective film theory is similar except that the ozone– antiozonant reaction products form a film on the rubber surface that prevent ozone attack. 13 A third “relinking” theory states that the antiozonant prevents scission of the ozonised rubber recombines several double bonds. 14 During recent years there has been a gradually increasing demand for antidegradants to give optimum protection of rubber goods. Derivatives of p-phenylenediamine (PPD) offer excellent protection to rubber vulcanizates as antioxidants, antiozonants and antiflex cracking agent. P-phenylenediamine antidegradants function as primary antioxidants and are recognized as the most powerful class of chemical antiozonants, antiflex cracking agents and
Use of antioxidant modified precipitated silica in natural rubber, chloroprene rubber and styrene butadiene rubber antioxidants. PPD′s are extensively used in tyres belting and molded and extruded rubber products as antiozonants and antiflex cracking agent. PPD′s are also used as polymer stabilizer. Derivatives of p-phenylenediamine fall into three classes: 1) N,N'-dialkyl PPD′s 2) N-alkyl-N'-aryl PPD′s 3) N,N'-diaryl PPD′s Even though N,N'-dialkyl p-phenylenediamines offer excellent static ozone resistance, they are not very effective under dynamic conditions. They are more sensitive to oxygen and hence suffer from lack of persistency and poor shelf life, where as alkyl–aryl PPD′s and diaryl PPD′s are less volatile than dialkyl PPD′s. They are stable and have good shelf life. To overcome the difficulty in dispersing silica in rubber matrix and also to protect the rubber from deterioration due to heat, light, oxygen and ozone, precipitated silica is modified by antioxidant. This chapter explains the modification of silica with antioxidant and their use as filler in natural rubber and in synthetic rubbers. The mechanical properties and ozone resistance are measured and compared with that containing equivalent amount of antioxidant and silica. Part@ A USE OF ANTIOXIDANT MODIFIED SILICA IN 7.2 Experimental Materials NATURAL RUBBER Natural rubber of grade ISNR-5, conventional zinc oxide, stearic acid, precipitated silica, antioxidants IPPD [N-isopropyl-N′-phenyl-p- 121
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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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Chapter 2 were carried out at a cro
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Chapter 2 2.2.4 Strain-sweep studie
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Chapter 2 2.2.6 Bound rubber conten
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Chapter 2 Surface area 59 Surface a
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Preparation and characterization of
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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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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
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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
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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: Use of antioxidant modified precipi
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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
Page 167 and 168: Rubber compounding Products from ri
Page 169 and 170: Soxhlet extraction Products from ri
Page 173 and 174: 8.3.4 Bound rubber content Products
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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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