2002 Volume 56 Issue 8 Pages 1191-1196
In this paper, porous structures of the swollen hydrogels of the cross-linked CM-LBKP were examined by solute exclusion technique. Water absorbents prepared by cross-linking of CM-LBKP with different types of polyethylene glycol diglycidyl ethers (PEGDGEs) had very porous structures. The total pore volume of cross-linked CM-LBKP up to 560 Å in width was about 100 times of that of untreated pulps. Increased amount of cross-linking agent bound to CM-LBKP not only decreased the total pore volume, but also decreased the pore size with increased contribution of small pores up to 560 Å in width. Re-cross-linking of the water soluble fraction from the first cross-linking of CM-LBKP seemed to proceed more homogeneously and eventually to give more homogeneous distribution of cross-linkage. Thereby re-cross-linking products had higher water absorbency and lower water solubility.
