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

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Chapter 1 30 Defect free siliceous mesoporous molecular sieve with composition of SiO2 are electrically neutral and this leads to a lack of strong intrinsic surface acidity. Numerous attempts were made to incorporate transition metal atoms as well as main group elements into mesoporous silica. Substitution of trivalent cations such as B +3, Ga +3, Al +3 and Fe +3 90-96 for silica in the wall of mesoporous silica, results a negative frame work charge, which can be compensated by protons providing catalytically active acid sites. The number of acid sites and strength is related to the amount and nature of the incorporated metal. These materials are used in acid catalyzed reaction and the main applications are in petroleum refining process. 97-98 The Ti, V and Cr containing MCM-48 molecular sieves are active catalysts for oxidative double bond cleavage of methyl methacrylate pyruvate and benzaldehyde as the dominant respective products. 99-101 Zr MCM-41 has been found to be active towards the dehydration of isopropyl alcohol. 102 A few reports describe the synthesis and characterization of mesoporous silica modified by metals like Mn 103 or Mo 104, which have been found to be catalytically active in the hydroxylation of phenol, 1-naphthol and oxidation of aniline with aqueous H2O2. Besides variable pore diameters and large surface areas, mesoporous materials contain different types of silanol groups, i.e., external surface, internal surface and interstitial silanol groups. The interstitial silanol groups are not accessible in chemistry, but the other two groups can be functionalized by introducing functional organic groups. The silanol groups present at the surface of the walls are suitable for chemical bonding of organic ligands or anchoring inorganic species. 105-106 For example Ti, V, Zr or Mo grafted MCM-48 were used as a catalyst for the oxidation of bulky 2,6-di- tertbutyl phenol (2,6-DTBP) using hydrogen peroxide. 107 Mesoporous materials anchored with AlCl3, SnCl2, Zn(O2CMe) 2 or Mn(O2CMe) 2 have high stability and catalytic activity along with ion-exchange capacity. 108
Introduction It has been reported that Co and Mo incorporated Al-MCM-41 shows higher hydrogenation and hydrocracking activities than Co-Mo/Al2O3 catalysts. 109 Mesoporous silica particles exhibits certain specific properties as very fine size and good dispersion of the particles besides of its high surface area and porosity can give rise to strong interaction with styrene butadiene rubber as long as their degree of hydration before been processed is low. 110 1.4.4 Rice husk silica Rice has been one of the most important agricultural products of India since ancient time. It was cultivated not only for domestic consumption but also for export. Consequently several million tons of rice husks, which can be considered as agricultural waste, are obtained every year. It was found that when rice husk is burnt, the resulting black ash contains silica. However, this silica from rice husk carries too many impurities and exhibits some inferior properties. As a result, researches have been carried out to convert this rice husk into high purity amorphous silica. 111-112 It is common to use silica as reinforcing filler owing to the fact that silica is non-black filler, that has the highest reinforcing capacity. The presence of silica in rice husk has been known since 1938. 113 Silica is in hydrated amorphous form, either opal or silica gel. Rice husk on burning gives ash containing 90% silica, which is highly reactive due to its ultra fine size and high surface area. 114-116 Silica in these cases is at a nanoscale and scientists in India and abroad has been successful in harnessing this nanosized silica to manufacture silicon carbide that has hardness next only to diamond. 117 Silica is widely used in electronics, ceramics, and polymer material industries. Because the silicon atoms in the rice husk have been naturally and uniformly dispersed by molecular units, silica powder with very fine particle size and very high purity and surface area can be prepared under controlled conditions. The ash contains >90% 31
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: Introduction amphiphilic di and tri
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 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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