High-power ultrasonication

For general aspects on sonochemistry the reader is referred to references [174,180], and for cavitation to references [175,186]. Cordemans [187] has briefly reviewed the use of (ultra)sound in the chemical industry. Typical applications include thermally induced polymer cross-linking, dispersion of Ti02 pigments in paints, and stabilisation of emulsions. High power ultrasonic waves allow rapid in situ copolymerisation and compatibilisation of immiscible polymer melt blends. Roberts [170] has reviewed high-intensity ultrasonics, cavitation and relevant parameters (frequency, intensity,... 

The vibrating faces are opposite each other in the rectangular cross-section geometry and so the possibility exists for the severe erosion of these faces. For this reason the design of such apparently simple flow reactors must be handled with care. Unless the pipe is seamless then high-powered ultrasonic vibration is also likely to find any weaknesses in the welded construction, particularly at corner joints. 

Dillon et al. [14] measured with TDS a reversible hydrogen uptake of 0.01 wt% for sonicated SWGNTs at room temperature. The sample contained only 0.1 wt% of nanotubes, therefore they estimated for pure nanotube samples a hydrogen storage capacity of approximately 5 to 10 wt%. A high-power ultrasonic treatment was applied to open the caps of the closed nanotubes, and cut the bundles in shorter... 

In this chapter, we present mainly our group s recent research and development in TC. For the first time, it has been found that the pitch of the lyotropic N -LCs of T-CNs can be tuned by high-power ultrasonic radiation. And after evaporation of the lyotropic N -LCs of T-CNs, some transparent films that could selectively reflect near-infrared light were prepared. Flexible paper-like materials of T-CN nanocomposites with high electrical conductivity were also prepared via in situ polymerization. 

Ultrasound technology is now being implemented in recycling used tyres and crosslinked plastics. The ultrasound energy is used to break up the three-dimensional network in the crosslinked rubbers and plastics [58]. The process consists essentially of screw extruding the heated crosslinked material onto a powerful sonicator. It was shown that high power ultrasonic waves are capable of rapidly breaking down the three-dimensional network present in crosslinked elastomers and plastics. 

The cup-hom (Fig. 7) can be considered as a probe system operated upside down, transforming it into a very high-power ultrasonic bath with the emitter surface in... 

GaUego-Juarez, J.A. 2010. High-power ultrasonic processing Recent developments and prospective advances. Physics Procedia. 3 35—47. 

A high-powered ultrasonic generator and transducer are included in the technology. 

Bates D, Patist A. 2009. Industrial applications of high power ultrasonics in the food, beverage and wine industry. Institute of Food Technology (IFT), Nonthermal Processing Division Newsletter, 11 2—15. 

It should be pointed out that high-power ultrasonication for a long time usually shortens the length of CNTs and reduces the aspect ratio, which is adverse to the properties of composites. Additionally, this method depends on the efficient dispersion of CNTs in the relevant solvent, and the choice of solvent is usually made based on the solubility of the polymer. However, in most cases, CNTs without functionalization cannot be well dispersed in most solvents. In order to overcome this problem, numerous research groups have used additives such as surfactants to disperse CNTs before mixing with the polymer solution. The most commonly used surfactants are derivatives of SDS. ... 

Sulphur cured SBR elastomers devulcanised by high power ultrasonic irradiation, were revulcanised using the same curing conditions as for virgin SBR. Crosslink density and gel fraction of virgin, devulcanised, and revulcanised SBR were investigated. 21 refs. 

Carbon nanotubes tend to agglomerate in the polymer matrix, and it is difficult to separate individual nanombes, even when surfactants are used during the mixing. To overcome the problems associated with agglomeration of nanofillers, various methods have been used in the preparation of the nanocomposites, including the use of high power ultrasonic mixers (1), surfactants in solution mixing (2) and in situ polymerization (3). 

While high power ultrasonic mixers (5), surfactants, solution mixing (6) and in situ polymerization have all been used to produce carbon nanotube-reinforced polymer composites with apparent homogeneous dispersion of the fillers, these techniques have many limitations, including... 

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