Adsorption of cationic starch on Eucalyptus pulp fibers in closed water systems | |
| Author | Zhang, Hongmin |
| Call Number | AIT Thesis no.PP-04-01 |
| Subject(s) | Paper--Dry strength Fibers Addition polymerization |
| Note | A thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering, School of Environment, Resources and Development |
| Publisher | Asian Institute of Technology |
| Series Statement | Thesis ; no. PP-04-01 |
| Abstract | The adsorption of cationic starch (CS) on pulp fibers is of great importance for the improvement of paper dry strength, especially in the white water cycling system where large amount of anionic trash and high conductivity deteriorate the performance of all the cationic additives. For this concern, the effect of conductivity, anionic trash and degree of substitution had been investigated and the suitable anionic trash catchers were determined for the benefit of dry strength. It was found that anionic trash consumed CS by charge neutralization and thus reduced the adsorption of CS on the fibers, especially in pulp filtrate. Compared with the situation in clean water, the increase in internal bond strength by 1.5% CS addition got a loss of 19% and 15% in pulp and broke filtrate respectively and the losses for tensile strength were 13% and 7%. High conductivity reduced the reactivity of fibers and thus affected the adsorption of CS. While high conductivity deteriorated the ability of CS in increasing internal bond strength both in pulp filtrate and broke filtrate, it showed complex effects for tensile strength by improving the ability of CS in pulp filtrate but destroying this ability in broke filtrate . Charge analysis showed that both PAC and PA are effective in reducing the anionic trash in pulp and broke filtrate, but PAC was better at protecting the fibers charges. For more adsorption of CS on fibers and less consumption of CS by anionic trash, charge analysis showed PAC is a more suitable A TC than PA in pulp filtrate, and its dosage was 6.4% at low and high conductivity. However, only P AC-6.4% showed some efficiency in broke filtrate. For the benefit of both tensile strength and internal bond strength, it was determined that in pulp filtrate the suitable ATC was PA-0.8% at low conductivity and P AC-6.4% at high conductivity, while in broke filtrate the suitable ATC was P AC-6.4% at either low or high conductivity. Last but not least, the cationic starch with higher degree of substitution was found to be more vulnerable to the interference of anionic trash, but not to the high conductivity. |
| Year | 2004 |
| Corresponding Series Added Entry | Asian Institute of Technology. Thesis ; no. PP-04-01 |
| Type | Thesis |
| School | School of Environment, Resources, and Development (SERD) |
| Department | Other Field of Studies (No Department) |
| Academic Program/FoS | Pulp and Paper Technology (PP) |
| Chairperson(s) | Malinen, Raimo; |
| Examination Committee(s) | Kolmodin, Hakan; Lehtinen, Esa; |
| Scholarship Donor(s) | Government of Finland;AIT Fellowship; |
| Degree | Thesis (M.Eng.) - Asian Institute of Technology, 2004 |