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

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Chapter 8 polar nature of silica surface adsorbs a part of the curative and or silica- zinc ion interaction leads to slowing down of the curing reaction. 22 This will result in an increased cure time and a reduced cure rate index. But the cure characteristics of antioxidant modified mesoporous silica composite indicate improvement in these values. 158 Scorch safety has increased and cure time was found to be lower for antioxidant modified mesoporous silica compound. This might have resulted from the improved rubber–filler interaction. 8.3.3 Thermal ageing studies Variation of tensile strength of vulcanizates of mix A and mix B before and after ageing at 100 °C for 96 hours are shown in Figure 8.4. Retention in property is slightly improved for IPPD bound mesoporous silica. Higher concentration of antioxidants may be incorporated in the pores of mesoporous silica which indicates slow leaching of antioxidant IPPD from the pores of mesoporous silica. Tensile strength (MPa) 30 28 26 24 22 20 18 16 Mesoporous silica Precipitated silica 0 20 40 60 80 100 Hours Figure 8.4 Variation of tensile strength of vulcanizates of mix A and mix B before and after ageing at 100°C for 96 hours
8.3.4 Bound rubber content Products from rice husk as filler in natural rubber Bound rubber content of samples I and II are shown in Table 8.3. This determination is based on the assumption that the fraction of polymer, which does not interact or is not bonded to the silica, is soluble in toluene. Bound rubber is the rubber that is trapped by the filler aggregates after mixing. The rubber chains are attracted either physically or chemically to form a rubber shell on the surface of the silica particles. The bound rubber fraction of an uncured compound is the amount of rubber that is not extracted when it is exposed to a good solvent. It is observed that BRC increases with increasing the BET surface area of the silica. 23. Table 8.3 Bound rubber content Mix Bound rubber content (%) Mesoporous silica + NR 21.05 Precipitated silica + NR 6.65 It can be concluded that sample I with mesoporous silica gives a higher percentage of bound rubber content compared to that containing precipitated silica (sample II). The high bound rubber content values show that there will be a higher rubber-filler interaction with the mesoporous silica compared to conventional precipitated silica. 8.3.5 Thermogravimetric analysis The thermograms of natural rubber with precipitated silica and mesoporous silica are recorded. Figure 8.5 shows the thermograms of NR with precipitated silica and mesoporous silica. It can be seen that initiation of degradation is found delayed for mesoporous silica composite. This indicates that NR is more stabilized by mesoporous silica. It is clear from the Table 8.4 that the temperature of complete degradation has improved with mesoporous silica. There is slight increase in maximum degradation temperature for 159
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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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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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Page 143 and 144: Crosslink density Use of antioxidan
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Page 161 and 162: 7.9 References Use of antioxidant m
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Page 167 and 168: Rubber compounding Products from ri
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