Coefficient of thermal expansion for Twaron® fibers using crystallographic data

The effect of in situ heating on the unit cell dimensions of crystalline aramid fiber (Twaron® fibers) has been studied in the temperature range 20–280°C. The changes in the unit cell dimensions have been used to estimate the coefficients of thermal expansion along the axial directions. On heating, the a and b axes expand, the coefficients of thermal expansion being α a = 35.84 × 10 −6 /°C and α b = 38 × 10 −6 /°C at room temperature. The c ‐axis contracts on heating, giving negative coefficient of thermal expansion α c = −5.38 × 10 −6 /°C at room temperature. Volume coefficient of thermal expansion α V however is positive, being 101.22 × 10 −6 /°C. POLYM. ENG. SCI., 2008. © 2007 Society of Plastics Engineers