In situ Foaming Evolution of Flexible Polyurethane Foam Nanocomposites

Abstract

The effect of both as‐produced and functionalised CNTs on the polymerisation evolution of water‐blown PU foams containing up to 0.3 wt.‐% CNTs was studied by in situ FT‐IR spectroscopy. FT‐IR revealed a decrease on the rate of isocyanate conversion as a function of loading fraction for both as‐grown and oxidised CNTs. This dependency suggested that the isocyanate conversion at the early stages of the reaction was governed by the kinetic effects imposed by the presence of the CNTs. The onset of microphase separation was accelerated by the addition of functionalised CNTs (f‐CNTs) but not by as‐produced CNTs due to the different surface functionalities. Measurements of the foaming viscoelastic properties showed an increase on the storage modulus with the CNT content, which indicated the reinforcement of the foam.

Comparing the effect of carbon-based nanofillers on the physical properties of flexible polyurethane foams

“…The density value increased due to the inclusion of the carbon nanofillers [10]. The presence of f-MWCNTs and FGS on the foam density is greater and it could be ascribed to the slow down on the foaming evolution of these nanocomposite foams as has been described previously by the authors [19].…”

“…4 and Table 4. These two steps appear to be influenced not only by the functional groups present on the surface of the nanofillers but also by [19]. f-MWCNT ought to have improved heat dissipation and thermal stability compared to raw MWCNT/ PU sample, due to the direct covalent bonding with the matrix; but that was not the case.…”

“…Aligned MWCNTs were synthesized using the chemical vapor deposition (CVD) injection method based on the decomposition of a ferrocene toluene vapor (3 wt% ferrocene in toluene) as reported elsewhere [10,19,20]. The diameters of the MWCNTs vary around 40-60 nm with a length of around 160 lm.…”

“…Hence, the properties of PU foams depend not only on their final cellular structure but also on the phase-separated microstructure [15,17]. Recently, carbon nanofillers have been incorporated in PU foams showing that they did not only improve the physical properties [2,7,10,14,18] but also affected the kinetics of foaming polymerization [10,14,19].…”

Obtenção de espumas flexíveis de poliuretano com celulose de Pinus elliottii

“…Observando as células individualmente verifica-se que existe uma maior quantidade de poros nas células das espumas com cargas do que na amostra EPU. Segundo a literatura, cargas em espumas de PU afetam as paredes de suas células, contribuindo para ruptura de sua parede devido ao efeito desestabilizador da carga através de mecanismos de retração das arestas das células [11,[33][34][35] . Este fato justifica a morfologia encontrada para as amostras EPU0,5 e EPU1.…”