Thermal degradation and flammability of TiO2–polyetherimide nanocomposite fibers

• Published in: Polymer bulletin (Berlin, Germany) Germany), 2020-09, Vol.77 (9), p.4937-4958
• Main Authors: Pasini, Sarah Mozzaquatro, Batistella, Marcos A., de Souza, Selene M. A. Guelli Ulson, Wang, Jingfeng, Hotza, Dachamir, de Souza, Antônio Augusto Ulson
• Format: Article
• Language: English
• Subjects: Adhesives; Bonding; Carbon; Characterization and Evaluation of Materials; Chemistry; Chemistry and Materials Science; Cold; Cold plasmas; Cold treatment; Complex Fluids and Microfluidics; Composite materials; Decomposition; Enthalpy; Flammability; Glass transition temperature; Heat release rate; Humidity; Infrared analysis; Infrared spectroscopy; Low pressure; Nanocomposites; Nanofibers; Nanoparticles; Organic Chemistry; Original Paper; Phenols; Photocatalysis; Photoelectrons; Physical Chemistry; Plasma; Polyetherimides; Polymer Sciences; Polymers; Polyvinyl alcohol; Pressure effects; Pyrolysis; Reduction; Scanning electron microscopy; Soft and Granular Matter; Surface treatment; Temperature; Thermal degradation; Thermal stability; Thermodynamic properties; Thermogravimetric analysis; Thin films; Ultraviolet radiation
• ISSN: 0170-0839; 1436-2449
• DOI: 10.1007/s00289-019-02970-1

In this work, the effect of low-pressure cold plasma treatment, UV and the incorporation of TiO 2 nanoparticles on thermal degradation and flammability of titanium dioxide (TiO 2 )/polyetherimide (PEI) nanofibers was evaluated. The morphology of nanocomposite fibers was studied using scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscope (XPS), thermogravimetric analysis (TGA) and differential scanning calorimetry. SEM images of plasma- and UV-treated nanocomposites show that some samples, e.g., those treated at 248 W and 4 min of exposition, seem more brittle compared with other samples. XPS of treated PEI nanocomposite showed that cold plasma treatment breaks C–C/C–H, C–N and C–O bonds at the surface ether groups leading to an increase in carboxyl and O–C bonds. Moreover, UV treatment breaks C–C/C–H and C–N bonds. Surface modification leads also to changes in thermal stability of PEI nanofibers with a decrease of ~ 4 °C in glass transition temperature ( T g ) and a reduction of ~ 200 °C in onset temperature under air compared to pristine PEI nanocomposite. Flammability results measured by pyrolysis-combustion flow calorimeter also showed a decrease in initial degradation temperature and a small increase in total heat released. Furthermore, incorporation of TiO 2 nanoparticles leads, as expected, to an improved flame retardancy with a reduction of ~ 40% in peak heat release rate as a function of TiO 2 content, but no significant difference was observed in onset degradation temperature observed by TGA. These results show that surface treatments do not significantly change thermal behavior of PEI nanocomposites and could be used for applications that require materials with improved characteristics.