Ultrasonic curing of one-part epoxy system

Abstract

Ultrasonic curing of one-part epoxy system was studied using differential scanning calorimetry (DSC) analysis. During both isothermal oven curing and ultrasonic curing of this system, an induction period was observed. For the rapid progression of polymerization reaction in ultrasonic curing, a preheating temperature of 100 C was found to be sufficient. However, degree of curing due to the nonthermal effect of ultrasonic curing was found to be maximal at a preheating temperature of 80 C. It was noticed that the ultrasonic curing reduced the time of curing by a factor of four, and the curing level from pure thermal effects could be determined by incorporating the curing temperature history into the autocatalytic chemical model. The degree of curing from the experimental results of isothermal heating in DSC and the one predicted by the autocatalytic chemical model exhibited a good agreement.

A novel powder-epoxy towpregging line for wind and tidal turbine blades

“…FreiLacke, DSM, AkzoNobel, 3M, etc.). These powders tend to have excellent storage stability due to a high initial glass transition temperature (around 40°C) [38] and the frequent use of heat-activated latent curing agents in their formulation [39]. This means they can be used to make VBO prepregs which do not require temperature-controlled storage and generate significantly less exotherm than conventional epoxy systems [30,32].…”

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“…The effect of temperature T on the mean dynamic viscosity η of the sonicated and non-sonicated epoxy resin ED-20 and compositions with nanodispersed soot disturbances caused by the collapse of rapidly growing vapour-gas bubbles in the epoxy oligomer volume. Apparently, the shock waves formed upon collapse at the stage of developed cavitation (Brennen 2013) are the main driving factor that leads to the destruction of hydrogen bonds of polymer macromolecules (Sharma, Luzinov 2011;Huang et al 2002). At the same time, the С-С, С=С, С=О bonds, as well as other types of bonds between individual segments and groups of the main chains of macromolecules, fragment hydrogen bonds while being destroyed themselves.…”

“…Another method for changing the viscosity of polymer systems is the targeted influence of energy fields during their formation. It is known that UltraSonic Treatment (UST) and heating of polymer mixtures leads to changes in a number of their properties, including viscosity (Ganiev 2007;Sharma, Luzinov 2011;Buketov et al 2014). UST does not impair the physicalmechanical and thermophysical properties of the compos-ites obtained.…”

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“…It is already applied for thermoplastic welding due to the extremely short welding times, ease of automation, excellent quality, etc. 48,49 Curing of pure thermoset epoxy resin by ultrasound was also investigated by Sharma et al 50 . However, the use of ultrasound for the consolidation of polymer matrix composites containing more than 35 to 40% by volume of reinforcing fibre was viewed as very challenging due to severe fibre disruption and damage 51 .…”