Synthesis and characterization of acrylic rubber/silica hybrid composites prepared by sol‐gel technique

Abstract

ABSTRACT:The organic-inorganic hybrid composites comprising acrylic rubber and silica were synthesized through sol-gel technique at ambient temperature. The composites were generated through the acid-catalyzed hydrolysis and subsequent condensations of inorganic tetraethoxysilane (TEOS) in the organic acrylic rubber (ACM), solvated in tetrahydrofuran. The morphology of the hybrid materials was investigated by using the transmission electron microscope (TEM) and scanning electron microscope (SEM). Transmission electron micrographs revealed that the silica particles, uniformly distributed over the rubber matrix, are of nanometer scale (20 -90 nm). The scanning electron micrographs demonstrated the existence of silica frameworks dispersed in the rubber matrix of the hybrid composites. The X-ray silicon mapping also supported that observation. There was no evidence of chemical interaction between the rubber phase and the dispersed inorganic phase, as confirmed from the infrared spectroscopic analysis and solubility measurements. Dynamic mechanical analysis indicated mechanical reinforcements within the hybrid composites. The composites containing in situ silica, formed by sol-gel technique, demonstrated superior tensile strengths and tensile modulus values at 300% elongations with increasing proportions of tetraethoxysilane. However, the improvements in physical properties with similar proportions of precipitated silica were not significant. Maximum tensile strength and tensile modulus were obtained when the rubber phase in the hybrid composites was cured with ammonium benzoate and hexamethylenediamine carbamate system, as compared with benzoyl peroxide cured system. Thermal stability of the hybrid composites was not improved appreciably with respect to the virgin rubber specimen. Residue analysis from thermogravimetric study together with infrared spectroscopic analysis indicated the presence of unhydrolyzed tetraethoxysilane in the hybrid composites.

P(EMA-co-HEA)/SiO2 hybrid nanocomposites for guided dentin tissue regeneration: structure, characterization and bioactivity.

“…The rubbery modulus increases, mainly from 10 wt% of silica content. This strong increase of the rubbery plateau modulus agrees well with the literature [91,111,117,131,148] and seems to be related with the percolation of the silica phase, forming a continuous network extended throughout the sample for silica contents higher than that threshold, which constrains the long distance cooperative motions of the copolymer chains. The fact that only for these silica contents a continuous densified silica structure was obtained after performing a pyrolysis and removal of the organic phase, is consistent with this observation.…”

“…The organic monomer polymerizes leaving an organic network that fills up both kinds of pores left by the silica structure (Figure 1.6 Although hydrolysis and condensations occur concurrently, the pH, but also the amount of added water, the hydrophilicity of the polymeric monomer [131] , and the sometimes necessary addition of an alcoholic common solvent (ethanol, isopropanol) to homogenize the solution [132] , all affect the relative rate and extent of these reactions and thus the final structures and properties of the materials [125] .…”

Water/Ethanol Selectivity of New Organic‐Inorganic Hybrid Membranes Fabricated from Poly(vinyl alcohol) and an Oligosilane

“…[10] In organic-inorganic hybridizations, the size of the dispersed phase can be controlled on a nanometer or molecular-size scale in multi-component systems. [11][12][13][14] Hybridizations from organic and inorganic compounds can be carried out by the sol-gel method, in which starting materials are in solution and synthesized at the lowest possible temperatures. [15][16][17] By using the sol-gel method, it is possible to homogeneously hybridize the organic and inorganic components.…”

Waterborne Acrylate-Based Hybrid Coatings with Enhanced Resistance Properties on Stone Surfaces

“…Conversely, in other cases, high amounts of nanosilica reduced the T g and the temperature for maximum mechanical damping. Furthermore, high amount of silica nanoparticles lead to a more brittle behavior [32][33][34][35][36].…”