Exceptionally flame-retardant flexible polyurethane foam composites:synergistic effect of the silicone resin/graphene oxide coating

A facile strategy was developed to fabricate flexible polyurethane(PU)foam composites with exceptional flame retardancy.The approach involves the incorporation of graphene oxide(GO)into a silicone resin(SiR)solution,which is then deposited onto a PU foam surface via the dip-coating technique and cured.Fourier-transform infrared spectroscopy,scanning electron microscopy,and Raman spectroscopy measurements demonstrated that the SiR and GO were successfully coated onto the PU skeleton and the intrinsic porous structure of the PU foam remained intact.The effects of SiR and GO on the mechanical and thermal stability and flame retardancy of PU composites were evaluated through compression tests,thermogravimetric analysis,vertical combustion tests,and the limiting oxygen index.The measurement results revealed that the composites(PU@SiR-GO)showed superior flame retardancy and thermal and mechanical stability compared to pristine PU or PU coated with SiR alone.The mechanical and thermal stability and the flame-retardant properties of the PU composites were enhanced significantly with increasing GO content.Based on the composition,microstructure,and surface morphology of PU@SiR-GO composites before and after combustion tests,a possible flame-retardance mechanism is proposed.This work provides a simple and effective strategy for fabricating flame retardant composites with improved mechanical performance.

Improving the Sound Absorption Properties of Flexible Polyurethane (PU) Foam using Nanofibers and Nanoparticles

Polyurethane foam as the most well-known absorbent materials has a suitable absorption coefficient only within a limited frequency range.The aim of this study was to improve the sound absorption coefficient of flexible polyurethane(PU)foam within the range of various frequencies using clay nanoparticles,polyacrylonitrile nanofibers,and polyvinylidene fluoride nanofibers.The response surface method was used to determine the effect of addition of nanofibers of PAN and PVDF,addition of clay nanoparticles,absorbent thickness,and air gap on the sound absorption coefficient of flexible polyurethane foam(PU)across different frequency ranges.The absorption coefficient of the samples was measured using Impedance Tubes device.Nano clay at low thicknesses as well as polyacrylonitrile nanofibers and polyvinyl fluoride nanofibers at higher thicknesses had a greater positive effect on absorption coefficient.The mean sound absorption coefficient in the composite with the highest absorption coefficient at middle and high frequencies was 0.798 and 0.75,respectively.In comparison with pure polyurethane foam with the same thickness and air gap,these values were 2.22 times at the middle frequencies and 1.47 times at high frequencies,respectively.Surface porosity rose with increasing nano clay,but decreased with increasing polyacrylonitrile nanofibers and polyvinyl fluoride nanofibers.The results indicated that the absorption coefficient was elevated with increasing the thickness and air gap.This study suggests that the use of a combination of nanoparticles and nanofibers can enhance the acoustic properties of flexible polyurethane foam.