Fibres from a bleached kraft pulp grafted with polystyrene by means of radiation initiation were studied. The purpose of grafting was to incorporate a polymer with a defined rheological behaviour, thereby changing the composition of the cell wall. The grafts had a polystyrene content ranging from 6 to 35 per cent by weight.
In order to decrease the crystallinity of the cellulose, the fibres were treated with aqueous zinc solutions of 65 and 70 per cent concentration. In addition to decrystallisation effects these treatments caused chemical degradation and dissolution of the cellulose.
Mechanical spectroscopy of the grafted fibres revealed an intense interaction between the polystyrene and the carbohydrate macromolecules. Apparently the treatment with zinc chloride causes degradation and structural breakdown of the grafted fibre which results in a less intense interaction between the cellulose and polystyrene phases.
The results of creep measurements in water and toluene indicate that the polystyrene can control the properties of the matrix while the amorphous cellulose still governs the stress transfer between the reinforcing microfibrils.