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%.
Treatment of Fractionated Fibers with Various Cationic-Modified Poly(vinyl alcohols) and Its Impact on Paper Properties
In this work, the effects of various high molecular weight cationic poly(vinyl alcohols), CPVAs, on the fiber morphology and the properties of papers made from fractionated refined fibers were investigated. At first, bleached sulfite fibers were refined under various revolutions and then refined fibers were fractionated under various time intervals to obtain refined fibers with a similar fiber length and fines content. Then, 20 mg/g CPVAs with various charge densities was adsorbed on the fractionated refined fibers prior to making hand sheets. The results showed that the lower the charge density of CPVA, the higher the effectiveness of CPVA in improving the paper strength at any refining revolution. The reasons for such a phenomenon were perhaps the different configurations of CPVAs on the surface of the fibers and the different adhesion/repulsion forces developed between CPVA-modified fibers in hand sheets. Also, by reducing the freeness of the fractionated fibers (increasing the refining revolutions), t...
Is there a future for chemically modified pulp
Technical properties of pulp fibers may be adapted to various kinds of requirements by chemical modification. Especially paper making properties can be improved substantially. Surface features like hydrophilicity and ionic charge may be changed by direct derivatisation, by grafting and by adsorptive polymer fixation. Thus web formation and retention can be improved effectively. Inherent characteristics like swellability and beatability may be enhanced by spacering reactions. Examples are given for cationic fiber modification and for spacering. A promising future may be forecast for chemical pulp modification, starting with highly specialized products and spreading slowly to commodities.