Influence of Temperature and Dose Rate of E‐Beam Modification on Electron‐Induced Changes in Polyacrylonitrile Fibers

Abstract

The present study investigates the influence of modification temperature and the dose rate of electron modification on the progress of these and the three important thermal induced reactions namely: cyclization, dehydrogenation, and oxidation. Since electron induced chemical reactions strongly depend on the polymer chain segment mobility, temperatures below the glass transition temperature (T g ) and above T g are tested. Electron paramagnetic resonance (EPR) spectroscopy measurements show the presence of alkyl-, peroxy-, and polyimineradicals alongside each other. Gel measurements identified a temperature dependent crosslinking behavior at doses ⩽ 150 kGy, but no dose rate depending on crosslinking. Changes in chemical structure are investigated using Fourier transform infrared spectroscopy (FT-IR), showing a dependency of stabilization behavior depending on dose and temperate more than on dose rate. Thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC) measurements complete the analyses by describing the behavior during further thermal treatments and measuring the residual mass at 800 °C.

Sensitivity of Offline and Inline Indicators for Fiber Stretching in Continuous Polyacrylonitrile Stabilization

“…According to this, the best tensile properties are obtained in the density range of 1.34-1.39 g/cm 3 and, in terms of energy usage, an SF with a lower density was favored [19]. There exists a considerable amount of literature on the impact of different processing parameters such as the residence time [20][21][22], temperature profile [17,[22][23][24], and steam ratio of the pretreatment step [25] on SF density. Qin et al [25] investigated the effect of stretching the PF on the preferred orientation and ladder molecules.…”