| Author | Lin, Tao |
| Call Number | AIT Diss. no.PP-07-01 |
| Subject(s) | Papermaking--Chemistry
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| Note | A dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Engineering in Pulp and Paper Technology |
| Publisher | Asian Institute of Technology |
| Abstract | The objective of this study was to evaluate the effect of chemical pulp fines addition on filler retention and paper properties, and then find a simple and effective process to improve filler's share in fine paper through fines without loss of paper strength properties. The fines or fillers added to furnish separately without using any retention aid. It was found that filler retention was marginal compared to the retention of fines as no retention aids was added. The filler retention sharply increased with addition of fines in furnish. The drainability reduced with increasing the dosage of fines, especially secondary fines from the refined pulp. The drainability reduced more if fines from the heavily refined pulps were added. On the contrary; fillers had no effect on drainage. Fillers have the ability to improve surface smoothness, optical properties, and printing properties while the fines of chemical pulps strongly influence the paper strength. The results show that the processing parameters and the paper properties both could be improved by addition of fines-fillers composite. Fines-fillers composite indicates premixing of fillers and fines prior to their addition to papermaking furnish. The negative effect of fillers on strength was well prevented by coupling fines with fillers. The effects of different type of fines, such as primary fines, secondary fines, fines from different beating degree, fines from different pulps, and fines from different refining equipment were also evaluated for filler retention and paper properties. Fibrils content of fines, ray-cell content of fines, viscosity, dewatering rate, hydrodynamic specific volume and surface charge were measured to understand the role of different fines on retention and paper properties. It was found that highly refined pine pulp fines have the highest fibrillar content and strongest bonding potential. The size and shape of fillers and fines influenced process parameters and paper properties. Bigger size fines were captured by the fiber net work, but they prolonged drainage time and resulted in poor formation. The smaller size fines poorly retained on the screen, thus the fines effects on paper strength or optical properties were marginal. Bigger size fillers retained well, improved air permeability and had less impact on paper strength, but smaller size filler improved optical properties. The three different processes: 1) Co-flocculation process (Co-flocculation of fines and fillers with CPAM); 2) Pre-flocculation process; and 3) Semi-conventional process were compared for processing parameters and paper properties. Co-flocculation process was the best compared to the other two processes. Co-flocculation process was also examined for different retention aids (i.e., CPAM, starches, etc.). CPAM was more effective in retention than starch, thus CPAM was recommended. PERCOL 182 retained more fillers and kept good formation at low polymer dosage. Therefore it was selected for co-flocculation of fines and fillers. Nano-particles (silica) and micro-particles (bentonite) were also examined for co-flocculation process. Both were found beneficial for filler retention. Colloidal silica improved paper strength but the formation slightly suffered. Bentonite had no negative impact on paper properties. Compared to conventional process at 15% ash content, FFPB co-flocculation process (co-flocculation of pine fines and filler with CPAM and bentonite) at 25% ash content saved 80% CPAM dosage, increased strength and optical properties (TEA, tensile index, and light scattering coefficient 107%, 10% and 21% respectively). It was concluded that FFPB co-flocculation process improved the processing parameters and paper properties without deteriorating other properties except for drainage. Drainability was slightly lower than the conventional process. |
| Year | 2007 |
| Type | Dissertation |
| School | School of Environment, Resources, and Development (SERD) |
| Department | Department of Food, Agriculture and Natural Resources (Former title: Department of Food Agriculture, and BioResources (DFAB)) |
| Academic Program/FoS | Pulp and Paper Technology (PP) |
| Chairperson(s) | Nazhad, Mousa M.; |
| Examination Committee(s) | Hubbe, Martin A. ;Lehtinen, Esa ;Retulainen, Elias ;Malinen, Raimo ;Dutta, Joydeep; |
| Scholarship Donor(s) | Finland ;Asian Institute of Technology Fellowship; |
| Degree | Thesis (Ph.D.) - Asian Institute of Technology, 2007 |