Nanotechnology for Paper Recycling, 2006 International Conference on Nanotechnology
The extent and success of paper recycling depends on the quality of the recovered fibers from used paper. We modified short broken fibers by PSS/PAH layer-by-layer (LbL) nano-assemblies, first to smoothen out fiber wall damages and second to change fiber surface potentials for selective distribution of virgin and recycled fibers in the paper structure.
We substituted positively charged PSS/PAH electrolyte coated broken fibers for untreated broken fibers. At 10 % broken fiber addition to virgin fiber, the PSS/PAH nano-coating increased handsheet tensile properties by 24 %. When both fiber fractions; the virgin fibers were nanocoated to negative surface charge and the broken fibers were nanocoated to positive surface charge, the paper strength increased 45 %. The positively charged fines and broken short fibers readily adhered to the negatively charged virgin fibers. The positive, small fiber segments became an integral part of the paper structure and provided a tighter paper. Such repairs to damaged recovered fibers and surface modifications can restore fiber qualities and improve recycled paper quality.