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Nordic Pulp and Paper Research Journal Vol 21 no. 2/2006 245 KEYWORDS: Alkylketene dimer (AKD), AKD oligomers, Dispersion stability, Sizing degree, Pyrolysis-gas chromato- graphy, PCC-filled paper, Sizing performance SUMMARY: AKD oligomers are the major components occur- ring as impurities or by-products in AKD waxes produced at industrial level. In this study, a model of AKD oligomers was prepared from a mixture of stearic and palmitic acid chlorides, and converted to dispersions containing a standard AKD wax and the AKD oligomers in various weight ratios

340 Nordic Pulp and Paper Research Journal Vol 17 no. 3/2002 Keywords: Sizing, Alkyl ketene dimer, Oligomer, Analytical pyrolysis SUMMARY: For the first time, a total mass balance of AKD products, including AKD oligomers, is reported. Methods cur- rently in use for the analysis of AKD products in paper measure cellulose bound and hydrolysed AKD. Pyrolysis gas chromato- graphy mass spectrometry provides a way to quantify these pro- ducts and also the oligomers formed when AKD reacts with itself. Half of the AKD retained during papermaking was found to form

New insights into the AKD sizing mechanism Kyle J. Bottorff and Mark J. Sullivan, Hercules Incorporated, Wilmington, Delaware, USA Keywords: Alkylketene dimers, AKD, Reaction mechanisms, Solid State "C NMR, Sizing, P-Keto acid, P-Keto calcium salt, P-Keto ester, AKD oligomers. SUMMARY: Paper samples sized with 13C labeled alkylketene dimer (AKD) dispersions were characterized by solid state carbon NMR resulting in direct evidence supporting the forma- tion of AKD-cellulose P-keto esters on AKD sized paper. A series of AKD reaction products that may

sizing. The mostly used AKD-products are produced from fatty acids with 16 to 18 carbons. In paper AKD is partly reacted with the cel- lulose, but is also to some extent hydrolysed to form alkyl ketones. Commercial AKD-products may also contain a high molecular mass fraction called AKD-oligomers (Bot- torff 1994). The oligomers may also be formed during the sizing. A sample of AKD oligomers has been analysed with the SEC-system, as shown in Fig. 2. The peak at 20.7 min contains the alkyl ketone. Isooctane extraction of paper samples Total immersion The total amount

used formulations. The efficiency increases with carbon chain length from C-8 and levels off at C-20 (Brungardt and Varnell 2005). It is also known that small amounts (usually less than 10% (Hardell and Woodbury 2002) of AKD-oligomers are present in AKD (Bottorff 1993; Bottorff 1994; Asakura et al. 2006a) and that these oligomers give relatively poor sizing. Alkenylsubstituted AKDs (emulsions = liquid in liquid phase) are also commercially available and they have been found to give better runnability on high speed handling equipment than paper sized with suspensions

the harmonization of static 1:79 Mari-Ann Norborg headspace GC methods for analyzing Henry Lindell volatile organic compounds originating Tiina Räsänen from paperboard products Håkan Frisell Hanne-Lise Hardell A new method for the analysis 3:340 Simon Edward of AKD oligomers in Woodbury papermaking systems Pedro Fardim Critical comparison and validation 3:346 Bjarne Holmbom of methods for determination of Ari Ivaska anionic groups in pulp fibers Jouni Karhu Gerard Mortha Janne Laine Jiebing Li Oxymercuration-demercuration 4:410 Göran Gellerstedt kappa number: An

, AKD oligomers and AKD/cellulose β-ketoesters, can be detected and determined as dialkylketones (Isogai 1999; Asakura et al. 2006). Since no retention aid of AKD was used also in this experiment, the AKD and either DOFAS or DSFAS addition levels were set to be 0.5% and 2%, respectively. The 0.5% AKD-sized handsheets prepared without DOFAS or DSFAS gave a result similar to those reported previously (Lindström, Söderberg 1986a, 1986b, 1986c); approximately 29% of the total AKD remained as the non-extractable fraction in the CHCl3-extracted handsheets, and a

on cellulosic model surfaces Langmuir 15 22 7863 7869 Girardi, F. (1989) In: Proc. Tappi papermakers conference. Tappi Press, Atanta. pp. 205. Girardi F. 1989 Proc. Tappi papermakers conference Tappi Press Atanta 205 Hardell, H. L., Woodbury, S. E. (2002) A new method for the analysis of AKD oligomers in papermaking systems. Nord. Pulp Pap. Res. J. 17(3):340–345. 10.3183/npprj-2002-17-03-p340-345 Hardell H. L. Woodbury S. E. 2002 A new method for the analysis of AKD oligomers in papermaking systems Nord. Pulp Pap. Res. J. 17 3 340 345 Isogai, A., Taniguchi, R

deposits on paper machines – A review 2:154 Martin A. Hubbe, Orlando J. Rojas and Richard A. Venditti AKD sizing of TCF and ECF bleached birch pulp 2:237 characterized by peroxide edge wicking index Grete A. Åvitsland, Mirjam Sterner, Lars Wågberg and Lars Ödberg The effects of AKD oligomers present in AKD wax on 2:245 dispersion stability and paper sizing performance Kazumichi Asakura, Masao Iwamoto and Akira Isogai The effect of lignin on calcium carbonate scaling 3:286 Kjell Wikander, Per Kjellin and Krister Holmberg Tailoring of fibre/fibre joints in order to avoid

angle measurements are a useful tool for studying sizing efficiency and for appreciating differences neglected by other more conventional tests, such as Cobb. Acknowledgement The authors wish to thank CTP and CTPi members for their financial support. Many thanks are due to D. Beneventi for valuable discussion on surface and interface chemistry, to R. Bernet for assistance with some experiments and to J.Thomas for linguistic revision. Literature Asakura, K. and Isogai, A. (2003): Effects of fatty acids, fatty acid anhydrides and AKD-oligomers present in AKD wax on