In situ investigation of the effect of stretching speed and annealing conditions on the crazing of as-spun IPP fibres using Pluta polarizing interference microscope

The effect of annealing conditions and stretching speed on the crazing and fracture behaviour of thermally treated as-spun IPP fibres during stretching with constant strain rate was investigated. The study includes observations and quantifying the crazing that occurs on stretched fibres via the estimation of the areal craze density as a function of annealing duration and stretching speed. An automated two-beam polarizing light interference Pluta microscope with the aid of modified mechanical stretching device are used for this investigation. Increasing the strain rate for thermally treated samples tends to delay the craze initiation and lowers the amount of areal craze density. A technique based on microscopic image analysis system(MIAS) with suitable designed software were used to observe the general feature of a single craze and calculate its wide and length. The value of strain rate is more effective than thermal history (annealing temperature and duration) on the crazing process of IPP fibres.