Polyurethane Sonication

Fischer et al. proposed a simple method for recovering analytes based on backflushing of the sampling cartridge (filled with Cl8) with 20 ml methanol or w-hexane. In their pioneer study on the presence of phthalate esters in the Swedish atmosphere, Thuren and Larsson used polyurethane filters connected in series.Compounds adsorbed to the PUF filters were extracted with acetone hexane in an ultrasonic bath. More recently, Otake et al. extracted the esters adsorbed in a charcoal tube by sonication with 1 ml of toluene for 10 min. These authors proved that longer sonication times did not improve the efficiency of the extraction (97.5 to 115%). Soxhlet can also be used to extract the analytes from the sorbent cartridges. Rudel et performed an extraction... 

Extraction aims to recover as much as possible of the pollutants from the sampling material. So it is a very fundamental aspect in the analytical process (Yusa et al. 2009). The extraction of POPs in air can be achieved through several established methods (Hawthorne et al. 1989 Chee et al. 1997 Lenicek et al. 2000 Yeo et al. 2003 Christensen et al. 2005). USEPA method 3542 (Soxhlet extraction) has been used to extract semi-volatile organic pollutants from air samples such as filters, XAD-2 resin or polyurethane foam (PUF). Sonication is also one of the extraction methods mostly used to prepare air samples for determination of POPs. All of these traditional procedures have some weaknesses of large volumes... 

In the ease of polyurethane elastomers, very interesting results have also been obtained in the case of other types of mechanical solicitation than traction, namely eompression, bending, sonic, etc [207, 919]. 

For example, Li et al. [153] used a simple solution-precipitation technique to improve the dispersion of CNTs in a polycarbonate solution by sonication at a frequency of 20 kHz for 10 min. They showed that the CNTs were uniformly dispersed in polycarbonate matrix on its consolidation. Safadi et al. [154] dispersed MWNTs in PS using ultrasonication and dismembrator at 300 W for 30 min. Uniform dispersions of CNTs in PS were achieved by using sonication. Recently, Cho and coworkers successfully prepared polyurethane (PU)/MWNT composites with better dispersion of CNTs up to 20 wt% in PU [155]. 

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