1971 Volume 44 Issue 12 Pages 1015-1019
Polyester tire cords and filaments were steam (188°C) -or dry (220°C) -heat treated under tensionstates for 1 hour.
Tensile strength, wide and small angle X-ray diffraction etc. were measured at elevated temperature (dry-heat).
Following results were obtained.
(1) Tensile strength decreased with increasing temperature.
The decrease in tensile strength of polyester tire cord of higher specific gravity (steam-heat treated) with increasing temperature was smaller than that of lower specific gravity (dry-heat treated).
(2) (100), (T10), (010) spacing of crystal increased with increasing temperature.
(3) Electron density differences increased with increasing temperature.
(4) The degree of orientation under tension indicated no changes with increasing temperature.
(5) Intrinsic viscosity indicated no changes at the treating temperature from 70°C to 220°C (dry-heat).
It was concluded from these results that the decrease of tensile strength of polyester tire cords at elevated temperature depended on the slippage of the chain molecules in crystal lattice and amorphous region.
