Comparison of different methods for determining the imidization degree of polyimide fibers

High energy density of polyimide films employing an imidization reaction kinetics strategy at elevated temperature

“…3a and b, the ID of ODPA-MPD-1–7 films can be accurately calculated according to the TGA results. 27–29 Taking the ODPA-MPD-1 film as an example, the total weight loss of the ODPA-MPD-1 film includes three steps when the DMAc solvent is completely evaporated: dehydration of water adsorbed on the film surface (the first step), cyclization dehydration of PAA chains (the second step, two H 2 O molecules per repeating unit) and thermal decomposition of PI (the third step). The ID can be obtained by using the following eqn (1) using the weight loss generated in the second step.where M (PAA) is the molecular weight of the PAA repeating unit and M (H 2 O) represents the molecular weight of H 2 O.…”

Influences of different imidization conditions on polyimide fiber properties and structure

“…It is noticed that imidization reaction was sensitive to temperature and could be completed in a very short time at high temperature. And the conversion ratio of PAA into PI would exert an important influence on the final properties of the PI fiber 31 . The imidization degree (ID) can be determined based on the area of the absorption bands at 1348 cm −1 on the FTIR spectra.…”

“…The broad peaks illustrated in Figure 4 indicated a typical amorphous structure in the co‐PI fibers. The order degree X, which is also listed in Table 1, can be measured by the following equation 31 : It was obvious that the fibers imidizied at 440°C possessed the highest order degree, suggesting that it was conductive to the formation of ordered structure when the fibers were imidized at appropriate temperature sense the flexibility of the molecular chains was significantly affected by temperature. Furthermore, the rapid evaporation of small molecular may also have some effect on molecular chain packing.…”

Decomposition and Flammability of Polyimide Graphene Composites

“…The second degradation stage occurs at temperatures of 210-330 °C. This is attributed to the evaporation of water resulting from the closure of uncyclized amic acids (imidization) [24]. Major weight loss occurs at 480-600 °C.…”

“…The first stage occurs at temperatures below 100 • C and it is attributed to evaporation of preabsorbed water and solvent from the films [23]. The second degradation stage occurs at temperatures of 210-330 • C. This is attributed to the evaporation of water resulting from the closure of uncyclized amic acids (imidization) [24]. Major weight loss occurs at 480-600 • C. The proposed reaction scheme of the major weight loss is as shown in Figure 5.…”