Study on thermal properties of poly( vinyl alcohol) and polyurethane composites with multiwalled carbon nanotubes/silica nanohybrids

Two kinds of multiwalled carbon nanotubes/silica nanohybrids (CNTs/SiO2) were synthesized via a sol-gel method by coating SiO2 on the surfaces of CNTs that had been functionalized with poly(sodium-p-styrenesulfonate) (PSS). The influence of the nanohybrids on the thermal properties of poly(vinyl alcohol) (PVA) and polyurethane (PU) composites was investigated. Characterization of CNTs/SiO2 nanohybrids, elucidated with scanning electron microscopy and X-ray diffraction, showed that PSS played a key role in the final morphology and resulted in a "core/shell'' and "candied haws on a stick'' like structure. The thermal degradation and thermo-oxidation of PVA and PU composites evaluated by thermogravimetic analyses suggested that the thermal properties of PVA/(CNTs/SiO2) composites were improved at relative high temperature range when compared with pure PVA, and the improvement mainly depended on the loading fraction of the nanohybrids, while for PU/(CNTs/SiO2) composites, a small fraction of the nanohybrids increased the materials thermal properties, but the improvements were influenced by the type of CNTs/SiO2 nanohybrids.