Preparation of Cationic CMP and Softwood Long Fibers as Strength-Enhancing Additive to CMP Pulp
Compared to chemical pulp, mechanical and chemi-mechanical pulps (CMP) are limited in regards to the manufacturing of high quality paper. Chemical additives are an effective way to enhance the properties of paper; however, the effectiveness depends on the additive type and dosage. The utilization of cationized natural polymers has been shown to offer a promising solution. In this study, softwood long fiber (SLF) and CMP were cationized by 3-chloro-2-hydroxypropyl-trimethylammonium-chloride (CHPTAC), and the effects of cationization on the properties of CMP pulp were studied. Cationization was characterized by FTIR and the nitrogen content, and its effect on the CMP properties was evaluated through mechanical tests and fines retention. Cationization at low and moderate levels and in higher mixing rates improved the mechanical properties of CMP. Compared to cationized CMP, the addition of cationized SLF (CLF) improved the strength and fines retention properties. The CLF application to CMP at a CHPTAC dosage of 5% increased the tensile, burst, and tear strengths by 66.4%, 100%, and 3.6%, respectively. The cationized SLF increased the fines retention by 12.7%.
Interaction of cationic modified poly vinyl alcohol with high yield pulp
The influence of polymer characteristics on paper properties has not been well understood. In this work, we aimed at analyzing the performance of various cationic-modified poly vinyl alcohols (CPVA), as dry strength additives, on the properties of high-yield pulp (HYP). Various dosages of CPVA having different molecular weights (MW) and charge densities were applied on HYPs, and the resulting paper properties were evaluated. Also, an atomic force microscope (AFM) was employed to evaluate the attraction/repulsion force developed between modified fibers and AFM probes. Our results showed that the hydrophilicity and contact area of fibers were increased via CPVA application. High MW CPVA with the charge density of 0.7 meq/g was the most effective one in improving the properties of the fiber networks made from HYPs. The changes in the fiber morphology and chemistry played roles in improving the properties of fiber networks. The introduction of similar charges on HYPs via applying various dosages of different CPVAs confirmed that the changes in the fiber chemistry were not the only dominant factor in improving the properties. Additionally, the significance of polymer bridging (polymer characteristics) on the network properties was hindered due to the presence of fines in the HYP.
Thermodynamics on the Carbochlorination of Titanium-bearing Ores
The equilibrium compositions of the multi-component, multi-phase and multi-reaction system of carbochlorination of titanium-bearing ores are calculated with HSC, a computational chemistry software. The thermodynamic equilibrium calculation of the reaction system shows that a complete conversion of titanium-bearing ores is feasible at a temperature near 200oC. At temperatures ranging from 800 to 1600oC, the products of the reaction system are all in gaseous phase. Thermodynamic analysis accords with the industrial practice. The simulated results provide reasonable scientific basis for improving suitable technological conditions of the carbochlorination reduction.