Abstract
The sol-gel technique was used to prepare epoxy/silica nano-hybrids. The thermal characteristics, curing kinetics and structure of epoxy/silica nano-hybrids were studied using differential scanning calorimetry (DSC), 29Si nuclear magnetic resonance (NMR) and transmission electron microscopy (TEM). To improve the compatibility between the organic and inorganic phases, a coupling agent was used to modify the diglycidyl ether of bisphenol A (DGEBA) epoxy. The sol-gel technique enables the silica to be successfully incorporated into the network of the hybrids, increasing the thermal stability and improving the mechanical properties of the prepared epoxy/silica nano-hybrids. An autocatalytic mechanism of the epoxy/SiO2 nanocomposites was observed. The low reaction rate of epoxy in the nanocomposites is caused by the steric hindrance in the network of hybrids that arises from the consuming of epoxide group in the network of hybrids by the silica. In the nanocomposites, the nano-scale silica particles had an average size of approximately 35 nm, and the particles were well dispersed in the epoxy matrix, according to the TEM images.
Highlights
IntroductionEpoxies have many favorable properties such as high tensile strength and modulus, excellent chemical resistance, and high thermal stability
Epoxies have many favorable properties such as high tensile strength and modulus, excellent chemical resistance, and high thermal stability. These characteristics make them ideal matrices for many applications, such as epoxy molding compounds (EMCs) [1], printed circuit boards (PCBs) [2], adhesives [3], paints [4], and high-performance composites [5]
transmission electron microscopy (TEM) data reveal that the sizes of the nano-scale silica particles that were synthesized by the sol-gel method varied in the range 15–60 nm and the average size was 35 nm
Summary
Epoxies have many favorable properties such as high tensile strength and modulus, excellent chemical resistance, and high thermal stability. FFiigguurree 22 pplloottss tthhee rraattee ccuurrvveess tthhaatt wweerree oobbttaaiinneedd aatt tthhee ffiivvee iissootthheerrmmaall tteemmppeerraattuurreess. Varied coincided with the formation of the gel point, at which the curing reaction of the gelled epoxy network began to slow down. TEM data reveal that the sizes of the Figure 5 shows a TEM image of the silica/epoxy hybrid with 10 phr silica and the histogram of the particle sizes of silica that was cured at 1407°0C637for 60 min.
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