Thermal, mechanical and thermomechanical properties of tough electrospun poly(imide-co-benzoxazole) nanofiber belts

Abstract

Electrospun PI-co-PBO nanofiber belts possessed superior thermal mechanical properties.Mechanically strong electrospun nanofibers at high temperature are highly desired in aerospace industry, high temperature filtration and fire protection clothing. In the present work, highly tough poly(imide-co-benzoxazole) (PI-co-PBO) nanofiber belts with excellent thermal stability, mechanical properties and thermal mechanical properties were produced from the high viscous methoxy-containing polyamic acid (MeO-PAA) solution by electrospinning followed with thermal rearrangement. The chemical structures of the polymer nanofibers and the corresponding thermal rearrangement were confirmed by 1H-NMR, FT-IR and TGA. The mechanical properties and thermal mechanical properties were characterized by tensile test and thermal mechanical analysis (TMA). The aligned nanofiber belt heat-treated at 450 °C (ANF-450) had the highest tensile strength of 559 MPa, modulus of 11.2 GPa and toughness of 12.0 J g-1, respectively, which were much higher than those of the pure PBO films made by thermal rearrangement. The TMA test showed that the ANF-450 exhibited high tensile strength retention of 90% and modulus retention of 94% at a high temperature of 200 °C. These excellent thermal mechanical properties make electrospun PI-co-PBO nanofibers promising candidates in high temperature areas.

Coaxial Electrospinning as a Process to Engineer Biodegradable Polymeric Scaffolds as Drug Delivery Systems for Anti-Inflammatory and Anti- Thrombotic Pharmaceutical Agents

“…A comparison with values from the literature is difficult because of the nature of the testing processes and the different protocols that can be followed. Furthermore, toughness is another important mechanical property for the fabricated materials opted for biomedical applications [37,38].…”

High‐performance polyimide nanofibers reinforced polyimide nanocomposite films fabricated by co‐electrospinning followed by hot‐pressing

“…The absorption bands from 2500 to 3600 cm −1 were attributed to the stretching vibrations of OH in the COOH groups of BP‐PAA and HO‐PAA, the band centered at 1654 cm −1 was originated from the stretching vibrations of the CONH groups in BP‐PAA and HO‐PAA. After the thermal imidization at 300 °C, these two absorption bands disappeared; and PAA precursor nanofibers were converted into PI nanofibers, as evidenced by characteristic absorption bands centered at 1771, 1704, 1375, and 729 cm −1 , which were, respectively, attributed to the asymmetric stretching variation of CO, symmetric stretching variation of CO, stretching variation of CN, and bending variation of CO in the resulting imide structures . The most obvious difference in FTIR spectra acquired from BP‐PI (P1 spectrum in Figure ) and HO‐PI (P7 spectrum in Figure ) was that the HO‐PI spectrum had an absorption band at 1238 cm −1 , which was attributed to the CO stretching variation of aromatic ether structure in HO‐PI macromolecules [see the chemical structure in Figure (b)].…”

Investigating the draw ratio and velocity of an electrically charged liquid jet during electrospinning

“…42 It is very important to investigate the draw ratio of the electrospinning charged jet because the draw ratio will signicantly affect the molecular orientation, and therefore inuence the physical properties, especially the mechanical properties. [43][44][45][46] There are some studies aimed at deducing the velocity of jet and the draw ratio. 38,[47][48][49][50][51][52][53] However, because of the complexity of the electrospinning process, too many electrospinning parameters, such as polymers, concentration, evaporation of solvent, ow rate, should be considered, which leads to the difficulties in proposing a universal model to deduce the draw ratio and velocity of the electrospinning jet.…”