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Direct electrostatic coating of paper Robert H. Marchessault, Patrice Rioux and Ilie Saracovan, Keywords: Coated papers, Polyolefins, Poly-P-hydroxyal- kanoates, Electrostatic coating, Corona discharge, Xerogra- phy, Toners, Adhesive strength, Barrier properties, Moisture transmission. SUMMARY: Direct Electrostatic Coating (DEC) of paper uses "as polymerized" reactor polyolefin and an electrostatic spraying applicator. A glossyltransparent polymer coat was obtained after hot-pressing the electrostatically deposited pow- der layer on the paper surface

regenerated cellulose films immersed in water (Yang et al. 2012). Most biopolymers and especially cellulosic materials are very poor moisture barrier materials. Water molecules diffuse easily into the structure and break the hydrogen bonds that hold the chains together. At high humidity conditions, the films tend to swell as a result of moisture absorption. Cellophane and CNF films had relatively high water permeability, which correlates well with the moisture absorption measurements. Walnut oil impregnation and further crosslinking decreased the moisture

%) -- -- -- Crystalline remains from MCC (dissolution time 14h) 56 10.5 200 8.5 21°C, 55% RH, 0.01mm/s Gindl et al. 2006 Water Vapour Barrier Properties Highly crystalline cellulose nanocrystals generally have the capacity to enhance the moisture barrier properties and decrease water vapor permeability (George, Siddaramaiah 2011, Bilbao-Sáinz et al. 2011, Saxena et al. 2011, Sanchez-Garcia, Lagaron 2010 and others). This enhancement is based on the dense film formed by the nanocrystals and the matrix, which has low moisture transmission properties. Most studies show

humidity atmosphere by placing in the bottom of the test cup a saturated salt solution or deionized water (wet side) to create a partial water vapor pressure difference, ΔP, across the specimen. The cup is weighted for different exposure times, Δt, to determine the mass increase of the desic- cant Δm. WVTR is the standard measurement by which films are compared for their WVP = m · eA · t · P 378       10 Swelling and barrier properties ability to resist moisture transmission. Lower values indicate better moisture protec- tion. Only values reported at the same

containing a desiccant. The tests are then performed in a controlled temperature and humidity atmosphere by placing in the bottom of the test cup a saturated salt solution or deionized water (wet side) to create a partial water vapor pressure difference, ΔP, across the specimen. The cup is weighted for different exposure times, Δt, to determine the mass increase of the desic- cant Δm. WVTR is the standard measurement by which films are compared for their ability to resist moisture transmission. Lower values indicate better moisture protec- tion. Only values reported

, Lappeenranta University of Technology, Finland. Lee, W.H., T. Okano and M. Ohta. 1991. Moisture transmission in wood. Moisture transfer and velocity of moisture transmis- sion in a steady state. Mokuzai Gakkaishi 37(2): 101-108. Liu, J.Y. 1989. A new method for separating diffusion coefficient and surface emission coefficient. Wood and Fiber Science 21: 133-141. McAdams, W.H. 1954. Heat transmission. 3rd ed. McGraw-Hill, Tokyo. Mounji, H., M. El Kouali, J. Bouzon and J.M. Vergnaud 1991 a. Modelling of the drying process of wood in three dimensions. Drying Technology 9: 1295