A novel non-aqueous sol–gel route for the in situ synthesis of high loaded silica–rubber nanocomposites (original) (raw)
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Natural rubber nanocomposite reinforced with nano silica
Polymer Engineering & Science, 2008
Inorganic nano fillers have demonstrated great potential to enhance the properties of natural rubber (NR). The present article reports the successful development of a NR nanocomposite reinforced with nano silica (SiO 2 ). Its dynamic mechanical properties, thermal aging resistance, and morphology are investigated. The results show that the SiO 2 nanoparticles are homogenously distributed throughout the NR matrix in a form of spherical nano-cluster with an average size of 80 nm when the SiO 2 content is 4 wt%. With the introduction of SiO 2 , the thermal resistance and the storage modulus of NR host significantly increase, and the activation energy of relaxation of the nanocomposite, compared to the raw NR, increases from 90.1 to 125.8 kJ/mol.
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The antagonistic effect of processing and thermal annealing on both the filler structure and the polymer matrix is explored in polymer nanocomposites based on natural rubber with precipitated silica incorporated by coagulation from aqueous suspension followed by roll-milling. Their structure and linear and non-linear rheology have been studied, with a particular emphasis on the effect of high temperature thermal treatment and the number of milling passes. Small-angle X-ray scattering intensities show that the silica is organized in small, unbreakable aggregates containing ca. 50 primary nanoparticles, which are reorganized on a larger scale in filler networks percolating at the highest silica contents. As expected, the filler network structure is found to be sensitive to milling, more milling inducing rupture, as evidenced by the decreasing Payne effect. After thermal treatment, the nanocomposite structure is found to be rejuvenated, erasing the effect of the previous milling on the low-strain modulus. In parallel, the dynamics of the samples described by the rheology or the calorimetric glass-transition temperature remain unchanged, whereas the natural latex polymer network structure is modified by milling towards a more fluid-like rheology, and cannot be recovered.
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Rubber Chemistry and Technology, 2005
The effect of a large amount of precipitated amorphous white silica nanofiller, pre-treated with bis[3-triethoxysilylpropyl-)tetrasulfide (TESPT), on the mechanical properties of a sulfur-cured natural rubber (NR) was studied. TESPT chemically adheres silica to rubber and also prevents silica from interfering with the reaction mechanism of sulfur-cure. The silica particles were fully dispersed in the rubber, which was cured primarily by using sulfur in TESPT, or, by adding a small amount of elemental sulfur to the cure system. The cure was also optimized by incorporating sulphenamide accelerator and zinc oxide into the rubber. The hardness, tear strength, tensile strength, and stored energy density at break of the vulcanizate were substantially improved when the filler was added. Interestingly, these properties were also enhanced when the rubber was cured primarily by using sulfur in TESPT.
Chemical Mapping of Silica Prepared via Sol–Gel Reaction in Rubber Nanocomposites
Macromolecules, 2015
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Controlled growth of in situ silica, into natural rubber (NR)/nitrile rubber (NBR) blend (40/60 composition by weight) following solution sol–gel method, results in a coherent blend morphology with enhanced composite properties. Similar composites, i.e., in situ silica-filled NR/ NBR blend (40/60 by weight), showed better mechanical properties than any other composition that were prepared by soaking sol–gel method in earlier study. However, silica content in the rubber blend was limited to 20 phr (parts per hundred parts of rubber) and could not be increased under experimental condition following soaking sol–gel method. In the present work, silica content is increased (up to 30 phr) beyond that limit for the same blend composition. Accordingly, mechanical properties of the NR/NBR composites are improved. Use of a silane coupling agent, viz., bis-(3-triethoxysilylpropyl)-tetra sulfide, in the reactive sol–gel system during in situ silica generation brings in remarkable effect in silica distribution, rubber–filler interaction and mechanical properties of the composites. TEM micrographs of the selected composites reveal that silica is mostly grown at the interfacial region, when silane is used in particular. This results in further enhancement in mechanical properties and compatibility of the blend at the same silica content as evident from stress–strain and dynamic mechanical analysis studies. The reinforcement of effect in situ silica is assessed by Guth–Gold equation and modified form of Guth equation (with shape factor f = 2.53). The results are supported by the detailed studies on rheological, morphological, mechanical and viscoelastic properties of the composites. Graphical Abstract Keywords Rubber blend Á Sol–gel method Á In situ silica Á Rubber–filler interaction Á Silane treatment Á Reinforcement
Novel functional silica nanoparticles for rubber vulcanization and reinforcement
Composites Science and Technology, 2017
A high reactive sulfocompound, sulfur monochloride, was chemically supported onto the surface of silica (silica-s-S 2 Cl 2) by the reaction between chloric atom and silanol hydroxyl to obtain a novel vulcanizing agent, silica supported sulfur monochloride (silica-s-S 2 Cl 2). Silica-s-S 2 Cl 2 can be homogeneously dispersed in SBR matrix as a modifier and cure the styrene-butadiene rubber (SBR) without sulfur as a novel high-efficiency vulcanizing agent. The sulfur and Bis[3-(triethoxysilyl)propyl] Tetrasulfide (TESPT) silane coupling agent vulcanized SBR composites were mainly polysulfide crosslinks, on the contrary, the vulcanization by silica-s-S 2 Cl 2 give priority to the mono-and disulfides crosslinks. The highlight of this work lies in the fact that apparent improvement has been achieved by novel and high efficient functional particles due to the silica surface supported with sulfur monochloride, which may open up new opportunities for the preparation of functional nano-fillers in rubber industry.
Journal of Nanomaterials, 2012
A highly performing natural rubber/silica (NR/SiO 2 ) nanocomposite with a SiO 2 loading of 2 wt% was prepared by combining similar dissolve mutually theory with latex compounding techniques. Before polymerization, double bonds were introduced onto the surface of the SiO 2 particles with the silane-coupling agent. The core-shell structure silica-poly(methyl methacrylate), SiO 2 -PMMA, nanoparticles were formed by grafting polymerization of MMA on the surface of the modified SiO 2 particles via in situ emulsion, and then NR/SiO 2 nanocomposite was prepared by blending SiO 2 -PMMA and PMMA-modified NR (NR-PMMA). The Fourier transform infrared spectroscopy results show that PMMA has been successfully introduced onto the surface of SiO 2 , which can be well dispersed in NR matrix and present good interfacial adhesion with NR phase. Compared with those of pure NR, the thermal resistance and tensile properties of NR/SiO 2 nanocomposite are significantly improved.
Journal of Applied Chemical …, 2010
Silane coupling agent has long been used to enhance degree of reinforcement of silica in rubber matrix. Recently various types of these coupling agents have been developed and commercialized. In the present study, two new silane coupling agents were introduced as decyloxytriethylsilane and 5,11,17-Tritertbutyl-23-trimethylsilylethynyl-25,26,27,28-tetrapropoxy calix(4)aren to compare the effect of generating Van der waals interaction between filler and polymer matrix that was originated by decyloxytriethylsilane in comparison with π-π interactions that was due to 5,11,17-Tritertbutyl-23-trimethylsilylethynyl-25,26,27,28tetrapropoxy calix(4)aren. Cure characteristics and physicomechanical properties of a nano-silica filled NR/ SBR polymer based compounds using these two agents were investigated and compared with commercialized Si69. Distribution of the filler in the rubber matrix was considered by scanning electron microscopy. These two suggestions were presented coupling agent effects. Decyloxytriethylsilane was shown better results due to the reduction of curative absorption and van der waals interactions between filler and polymer matrix in comparison with π-π interactions that was originated by the other coupling agent.
Journal of Applied Polymer Science, 2008
The effect of the same amount of precipitated silica nanofiller on the curing and mechanical properties of natural rubber and synthetic polyisoprene was investigated. The silica surfaces were pretreated with bis(3-triethoxysilylpropyl) tetrasulfide (TESPT) to chemically bond silica to rubber. The rubbers were primarily cured by using sulfur in TESPT, and the cure was optimized by the addition of accelerator and activator, which helped to form sulfur chemical bonds between the rubber and filler. Different amounts of accelerator and activator were needed to fully crosslink the filled rubbers. The hardness, tensile strength, elongation at break, stored energy density at break, tearing energy, and modulus of the vulcanizates improved substantially by the incorporation of the filler in the rubber. This was due to high level of rubber-filler adhesion and formation of chemical bonds between the rubber and TESPT. Interestingly, natural rubber benefited more from the filler than did synthetic polyisoprene. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008