LbL Nanocoating for Fiber Recycling Improved Paper Recycling through Fiber Polycation/Polyanion Multilayer Nanocoating J. Y. Zhu 1 , M. Fleischmann 1 , Z. Zheng 2 , E. Lvov 3 , G. Grozdits 3, 4 , J. Chapman 5 and Y. Lvov 2, 3 1 USDA Forest Service, Forest Products Laboratory, Madison, WI, 2 Institute of Micromanufacturing at Louisiana Tech University, Ruston, LA, 3 Nano Pulp and Paper LLC, Ruston, LA , 4 School of Forestry at Louisiana Tech University, Ruston, LA, 5 Smurfit-Stone Paper Corp. Hodge, LA Tappi - 8th Research Forum on Recycling Niagara Falls, ON, Canada September 23-26, 2007 Niagara Falls, ON, Sept. 23-26, 2007
Paper Recycling is driven by economic incentives and societal pressures It requires modified/new fiber preparations and paper making Recycling in part requires used fiber rejuvenation But it allows creation and operation of small and specialty mills close to resources and market, Damaged Fibers (green positive), virgin fiber (red negative), they electrostatically attract each other Niagara Falls, ON, Sept. 23-26, 2007
In this paper we report on the rejuvenation of fibers from recycled paper by Layer-by-Layer Self Assemblies of polyelectrolytes onto fibers to create enhanced electrostatic bonding potentials Micro-Emulsion Technologies Layer-by-Layer Nanocoating •10 -6 m droplets •10 -9 m thick continuous coatings •spot-welding of fiber • fiber surface contact bonding Emulsified electrolytes Short fibers Whole fibers Niagara Falls, ON, Sept. 23-26, 2007
B asics of Layer-by-Layer Assembly by Alternate Adsorption of Oppositely Charged Linear Polyions and Nanoparticles Development of Nano-LbL-selfassemblies 1992-1999 G.Decher, H.Moehwald, Y.Lvov, M.Rubner, J.Fendler, J.Schlenoff, P.Hammond, N.Kotov, T.Kunitake, F.Caruso, G.Sukhorukov The LbL-assembly regimes for more than 50 compounds were established at IfM (using the “dipping automate” equipment). G. Decher Science , 1997, v.227, 1232 “Fuzzy nanoassemblies: Toward layered multicomposites” Y. Lvov, K. Ariga, T. Kunitake, J. Am. Chem. Soc ., 1995, v.117, 6117-6122 "Assembly of multicomponent protein films by means of electrostatic layer-by-layer adsorption" Niagara Falls, ON, Sept. 23-26, 2007
Nano assemblies change cellulose fibers properties Confocal images Zeta ( ξ ) potential approximation Presence of nano-layers Fiber surface properties, as well as, shown labeled electrolyte mechanical & physical properties Niagara Falls, ON, Sept. 23-26, 2007
History and Development of The Louisiana Tech Nano Pulp and Paper Initiative Established LbL nanocoating feasibility in clean-lab conditions 1. Used positive & negative LbL treated unbeaten bleached Kraft commercial pine pulp 2. Used unbeaten bleached Kraft commercial pine pulp with LbL treated broke and fines in clean lab conditions 3. Used machine stock with LbL treated mill broke, LbL treatment in DI water 4. Used machine stock with LbL treated mill broke, LbL treatment in mill process water This work report on the use of 100 % recycled linerboard pulps, in a limited pilot plant study can, done at USDA-FS-FPL at Madison, WI. To demonstrate how we move from clean lab conditions to practical paper recycling and linerboard production Niagara Falls, ON, Sept. 23-26, 2007
Positive+negative pulp 200 Orginal+positive Tensile Index N•m/g 160 pulp Orginal+negative pulp 120 Orginal pulp 80 40 0 1 2 3 4 Tensile strength (Tappi-T205 standard) of hand sheets made from LbL- treated (with {PAH/PSS} .5 electrolytes) softwood unbeaten commercial pulp. LbL nanocoating was done under “clean-lab” conditions. The commercial pulp was washed and treatments done in DI water. 100 % increase in paper tensile index Z. Zheng, J. McDonald, R. Khillan, T. Shutava,, G. Grozdits, Y. Lvov. J. Niagara Falls, ON, Sept. 23-26, 2007 Nanoscience and Nanotechnology, v.6, 1-9, 2006
1 6 0 1 4 0 co n t ro l (u n t re a t e d 1 2 0 w h o l e f i b e r 1 0 0 + u n t re a t e d b ro ke n f i b e r) 8 0 N e g a t i ve w h o l e 6 0 f i b e r + p o si t i ve b ro ke n f i b e r 4 0 2 0 0 1 0 % b ro ke n 3 0 % b ro ke n Tensile strength (Tappi-T205 standard) of hand sheets made from unbeaten softwood commercial pulp with the additions of 10% and 30% LbL-treated (with {PAH/PSS} 3.5 electrolytes) short fibers and fines (simulated broke). LbL nanocoating was done in “clean-lab” conditions. 50 % increase in tensile index Y.M. Lvov, G.A. Grozdits, S. Eadula, Z. Zheng Z. Lu. Northern Niagara Falls, ON, Sept. 23-26, 2007 Pulp & paper Research Journal v. 21, no 5: 552-557, 2006
100 Control: Handsheets prepared from untreated w hole fibers 90 Others: Handsheets prepared from LbL treated negative w hole fibers mixed w ith LbL treated positive Tensile Index (N•m/g) broken fibers 80 70 60 50 40 control (0%) 10% 20% 30% 40% Broken Fiber ratio (%) Tensile strength (Tappi 205 Standard) of handsheets made from southern pine virgin machine stock and paper mill broke from Hodge Paper mill, LA. The pulps were washed in DI water, then treated with {PAH/PSS} 3.5 electrolytes. Each electrolyte self- assembly was done in “clean lab” conditions (electrolyte in 0.5N NaCl DI water solution LbL nanocoated papermill stock increased tensile index by 50 to 15 % Niagara Falls, ON, Sept. 23-26, 2007
Effect of LbL Treatment of Mill Broke on Tensile index 90 Tensile Index - N m/g 100% UB 85 100% UM 80 30% UB/70% UM 30% TB/70% UM 75 40% TB/60% UM 70 UB-untreated broke 1 UM-untreated machine stock Pulp Compositions - see Legend TB-treated broke Tensile strength (Tappi 205 Standard) of handsheets made from Southern pine virgin machine stock and paper mill broke from Hodge Paper mill, LA. The pulps were not washed before treatment and LbL nanocoated with {PDDA/PSS} 3.5. LbL nanocoating was done in mill process waters (“dirty water”) with electrolyte concentration control. Nanocoating in unwashed pulps in mill process waters “dirty water” increased tensile index by 15 % Niagara Falls, ON, Sept. 23-26, 2007
Application OF LBL to 100% OCC The objectives: Effect of washing Effect of refining Partial coating Old corrugated cardboards (OCC) under close to practical paper recycling conditions were recycled with LbL treatment with (PAH/PSS) 1.5 electrolyte layers. 6-inch diameter handsheets were made from using 50 % untreated and 50 % LbL treated pulp with one or three self- assembled layers. Pulp and handsheet properties; Canadian standard freeness, sheet density, basis weight, paper thickness (caliper), stiffness, tensile index, bulk, tear index, stiffness index, and modulus, were measured or tested. This work was done at the USDA-FS-Forest Products Laboratory, Madison, WI Niagara Falls, ON, Sept. 23-26, 2007
70 60 Tensile index (N-m/g) 50 40 30 Control, 100% unrefined Control, 100% refined 20 50% refined + 50% refined and coated One layer coating 10 Three layer coating 0 Coating applied to 50% of the pulp not coated refined pulp, no washing Tensile index of handsheets made with refined (negative,) and with refined-LbL nanocoated (positive) recycled linerboard pulps from old container linerboards. Niagara Falls, ON, Sept. 23-26, 2007
70 60 Tensile index (N-m/g) 50 40 Control, 100% unrefined Control, 100% refined 30 50% refined + 50% refined and coated One layer coating, no washing 20 One layer coating, washing Three layer coating, no washig 10 Three layer coating, washing 0 pulp not coated Coating applied to 50% refined pulp Effect of pulp washing between and after LbL polyelectrolyte nanocoating on tensile index handsheets made from old container linerbboards . Niagara Falls, ON, Sept. 23-26, 2007
Unrefined control, uncoated 50% refined, uncaoted 80 100% refined, uncoated 50% refined uncoated+50% unrefined coated, washed one layer three layers 50% refined uncoated+50% refined coated 70 one layer, unwashed one layer, washed Tensile index (Nm/g) three layers, washed three layers, unwashed 60 50 40 30 600 620 640 660 680 700 720 3 ) Sheet density (kg/m Effect of LbL on sheet densification
Limited Pilot Scale Experiments -Conclusion 1. Refining (beating) itself can improve paper bonding significantly as it is known. 2. LbL nanocoating with PAH/PSS polyelectrolytes of recycled linerdboard pulps also improved paper strength. 3. Washing of the nanocoated pulps between and after polyelectrolyte applications has a negative effect because washing actually removes fines. 4. Multiple LbL nanolayering can improve paper strength, when using 50 : 50 mix of positive and negative surface potential pulps. Niagara Falls, ON, Sept. 23-26, 2007
Are the LbL molecular layers really separated in the LbL multilayer? Or we creating a composite layer with new “composite” properties? Niagara Falls, ON, Sept. 23-26, 2007
PSS Absortion PSS Concentration Chang 0.35 0.3 0.25 Mashine - mg/ml Stock 0.2 Recycled Stock 0.15 0.1 0.05 0 1st PSS 2nd PSS 3rd PSS Treatment Sequence Recycled fiber surfaces adsorbed different, smaller amounts of PSS electrolyte, than virgin pulp Niagara Falls, ON, Sept. 23-26, 2007
THANK YOU Louisiana Tech Nano Pulp and Paper Initiative in Cooperation with USDA-FS-Forest Products Laboratory, Madison, WI Niagara Falls, ON, Sept. 23-26, 2007
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