Effects of silica-coated carbon nanotubes on the curing behavior and properties of epoxy composites

Abstract

Carbon nanotubes coated with silica and resultant effects on epoxy composites.

Accelerated microwave curing of fibre-reinforced thermoset polymer composites for structural applications: A review of scientific challenges

“…Such determination can be the indication of solidification (rigidity) state of the cured material, and as such can correlate uneven structural scale polymer curing during microwave to the phenomenons occurring in microscale. Epoxy microwave curing in particular can be measured using thermoanalytical techniques such as DSC, dynamic mechanical thermal analysis (DMTA), field emission gun scanning electron microscopy (FE-SEM), Fourier transform infra-red (FTIR) spectroscopy and Raman spectroscopy [39,[59][60][61][62][63][64][65][66]. This paper does not intend to turn its focus on introduction of these methods however it should be noted that the methods are used to characterise material properties and cure characteristics in laboratory coupon level, and not used for in-situ structural measurements.…”

“…Microwave and radiofrequency heating (medium energy, frequency at order of >1GHz, wavelength of <10 3 mm): Microwave heating is known as the most efficient volume-heating process due to its excellent depth of penetration in polymers [29]. Its process can be tuned with the use of high efficient dielectric nanomaterials in polymers in order to boost microlevel heating at molecular scale [31,65,86,87]. Dielectric nanomaterials can efficiently absorb radiation and convert it to molecular vibrations/rotations via dipole moments, mainly as a result of dipolar polarisation ( Figure 6).…”

“…However, recent studies reveal that the dielectric properties of polymers can efficiently be enhanced by dielectric additives such as dielectric nanomaterials [102,103]. These polymers have been used in several tailored applications such as medical devices, aerospace, high voltage applications and microelectronics [29,65,104]. Conventional polymers usually have low dielectric constants requiring an activation field (e.g.…”

“…In another study [65] on use of silica-coated carbon nanotubes (CNTs) in epoxy for microwave curing rate enhancement, it was found that the amount of pores and void content in samples cured by microwave were higher than those cured from thermal heating that has not fully been justified what has caused the pores and voids. This phenomenon is not only specific to curing epoxies but also evident from the research in [86] carried out on post-cured epoxy exposure, while localised microwave heating was boosted by inclusion of dielectric nanoparticles (observed by 3D X-ray computed tomography as shown in Figure 8).…”

“…However it was reported that the excessive exposure has had adverse effect on the compressive strength of the material post-microwave as the exposure introduced porosity and degraded the epoxy matrix [86,90,91]. Note that no dielectric nanomaterial was used in [94], neither in [65,86] but the epoxy was still degraded via porosities induced by excessive microwave heating power.…”