Method for the investigation of the dynamic compressibility of wet fibre networks

A method for measuring the dynamic compressibility of the fibre network inside a wet fibre web was developed. The web was compressed between two solid plates. The lower plate had a corrugated pattern of 1 mm thick parallel bars separated by 1 mm wide grooves while the upper plate was smooth. During a compression, water was expelled from the web into the grooves. The influence of the initial web saturation, stress pulse length and consecutive stress pulses on the compressibility was investigated. It was found that an increase in pulse length resulted in a decrease in the minimum strain measured, delta (m.min). During consecutive pulses, delta (m,min) remained approximately constant while the strain measured 300 s after the end of the stress pulse, delta (m,300), decreased. Initial web saturation conditions affected mainly delta (m,300).