| Abstract: | Bleached sulfite softwood pulp and the corresponding paper have been grafted with acrylic and methacrylic acids and a number of other monomers. A practical, all aqueous, ceric ion method was used as described in Part I of this series. The water and saline retention values of the grafted pulps were determined. Super water sorbency, up to 48 g/g, were obtained after suitable post treatments. A number of variables were studied including the effects of pH, counterion, crosslinking, drying, and beating. It was gratifying that drying did not affect the effeciency of water or saline water retention. Useful linear functional relationships were found between the saline water retention values and the logarithm of the percent sodium chloride in the water. The two “model” parameters of the plots also correlated well with the water retention values and with the degree of grafting expressed as the ion exchange equivalents of the pulps. The osmotic pressure approach to the water sorption as developed by Grignon and Scallan5 coupled with the restraining forces of the grafted polymer itself is used to interpret the process. |
