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Sizing mechanism of alkylketene dimers Part 1. Possibility for AKD to form P-ketoesters in papersheets Akira Isogai. Ryu Taniguchi, Fumihiko Onahe and Makoto U.suda, Department of Forest Products, Faculty of Agriculture, The University of Tokyo, Japan Keywords: Sizing, Alkylketene dimers, Cellulase. Extraction, Cellulose, Amorphous. P-Ketoesters, Retention. SUMMARY: The possibility for alkylketene dimer (AKD) to form P-ketoesters with hydroxyl groups of cellulose andlor hemicellulose in pulp fibers during papermaking and condition- ing processes was

On the mechanism of sizing with alkylketene dimers Part 4. The effects of HC03 ions and polymeric reaction accelerators on the rate of reaction between alkylketene dimers and cellulose Tom Lindstrom and Gunnel Soderberg, Swedish Forest Products Research Laboratory, Stockholm Keywords: Kraft pulps, Sizing, Accelerating agents, Alkyl- ketene dimers*, Reaction kinetics, Radioisotopes. SUMMARY: The effects of various additives on the rate of reaction between I4C-alkylketene dimer (AKD) and a de- crilled bleached kraft pulp have been investigated, particu

On the mechanism of sizing with alkylketene dimers Part 2. The kinetics of reaction between alkylketene dimers and cellulose Tom Lindstrom, The Swedish Forest Products Research Laboratory, Stockholm, and Hugh O'Brian, Pulp and Paper International, Brussels Keywords: Kraft pulps, Sizing, Alkylketene dimers*, Reac- tion kinetics, Activation energy, Radioisotopes. SUMMARY: The effects of temperature and curing time on the rate of reaction between an alkylketene dimer (AKD) and a decrilled bleached kraft pulp have been investigated. The AKD was added to the

On the mechanism of sizing with alkylketene dimers Part 1. Studies on the amount of alkylketene dimer required for sizing different pulps Tom Lindstrom and Gunnel Soderberg, Swedish Forest Products Research Laboratory, Stockholm Keywords: Kraft pulps, Mechanical pulps, Sizing, Alkylke- tene dimers*, Reaction mechanisms, Radioisotopes. SUMMARY: The amount of alkylketene dimer (AKD) required to size different pulps has been investigated. The quantities of AKD retained on the fibers and reacted with the fibers were determined using radioactive labelled (14C

On the mechanism of sizing with alkylketene dimers Part 3 . The role of pH, electrolytes, retention aids, extractives, Ca-lignosulfonates and mode of addition on alkylketene dimer retention Tom Lindstrom and Gunnel Soderberg, Swedish Forest Products Research Laboratory, Stockholm Keywords: Kraft pulps, Mechanical pulps, Sizing, Alkyl- ketene dimers*, PH, Electrolytes, Retention aids, Extrac- tive~, Lignosulfonates, Radioisotopes. SUMMARY: The effects of pH, electrolyte concentration (NaCI, Na,SO,, CaCI,), calcium-lignosulfonates, various retention aids

Sizing mechanism of alkylketene dimers Part 2. Deterioration of alkylketene dimer emulsion Akira Isogai, Ryu Taniguchi, Fumihiko Onclbe and Makoto Usuda, Department of Forest Products. Faculty of Agriculture, The University of Tokyo, Tokyo, Japan Keywords: Alkylketene dimer, Deterioration , Sizing, Emul- sion, (-Potential. Dispersibility, Ketones. NMR. SUMMARY: The mechanism of deterioration of alkylketene dimer (AKD) emulsions at 4OC was studied in terms of dispers- ibility of emulsions, deterioration of the emulsion stabilizer. formation of ketones

Sizing mechanism of alkylketene dimers Part 4. Effects of AKD and ketone in emulsions on sizing Akira Isogai, Ryu Taniguchi and Fumihiko Onabe, Department of Forest Products, Faculty of Agriculture, The University of Tokyo, Tokyo, Japan Keywords: Sizing, Alkylketene dimer, Ketone, Dispersibi- lity, Emulsions, Hydrolysis, Flocculation. SUMMARY: In order to elucidate the roles of AKD and hy- drolyzed AKD (i.e. ketone mixture) in emulsions for internal sizing, emulsions containing 1 % mixture of AKD and hydro- lyzed AKD with various ratios were prepared in

Sizing mechanism of alkylketene dimers Part 3. Appearance of sizing features of AKD-sized sheets Ryu Taniguchi, Akira Isogai, Fumihiko Onabe, and Makoto Usuda, Department of Forest Products, Faculty of Agriculture, The University of Tokyo, Tokyo, Japan Keywords: Sizing, Ketenes, Dimers, Distribution, Scanning electron microscopy, SEM-EDX, Heating, Emulsion, Coa- gulation. SUMMARY: Appearance of sizing features of AKD-sized sheets was examined in terms of the following three aspects; I ) impregnation of AKD and its related compounds into filter papers

164 Nordic Pulp and Paper Research Journal Vol 17 no. 2/2002 Keywords: Sizing, AKD, Deposit, Wood-free paper SUMMARY: This paper examines the tendency of alkylketene dimer (AKD) dispersions to form deposits on paper machines. The influence of AKD wax melting point, type of protective col- loid in the dispersion, furnish pH and temperature, on deposit for- mation was investigated. These factors are related strongly to each other in the formation of deposits. Firstly, in order to decrease deposit formation, the melting point of AKD, should not be close to the

240 Nordic Pulp and Paper Research Journal Vol 17 no. 3/2002 Keywords: Agglomeration, AKD, Alkylketene dimer, Disper- sion, Flocculation, Internal sizing, Retention. SUMMARY: Pre-flocculated AKD dispersions were used to size laboratory sheets. The cationic AKD dispersion was pre-floccula- ted in a Britt Dynamic Drainage Jar. Carboxymethylcellulose and white water from a linerboard mill were used as flocculating agents. The particle size distribution was determined to verify the flocculation. Laboratory sheets sized with pre-flocculated AKD disper- sions were