Tensile Strength of Handsheets from Recovered Fibers Treated with N-Methylol Melamine and 1,3-Dimethylol-4,5-dihydroxyethyleneurea

The main objective of this study was to assess the effect of two amino resins, N-methylol melamine (NMM) and 1,3-dimethylol-4,5-dihydroxyethyleneurea (DMDHEU), on the intrafiber and interfiber strengths and water absorption of two types of waste paper categories, office paper (OP), and old corrugated containers (OCCs). The tensile strength of individual fibers measured at zero span was reduced by increases in the resin concentrations. The dry tensile strengths of the recovered handsheets measured at a finite span were enhanced with increases in the weight percentage gain of the resins. The increasing of the resin concentration also significantly improved the intrabonding of the OP and OCCs in moist measuring conditions. The water absorption of the handsheets considerably decreased at the higher concentration of the thermosetting resins, especially with NMM. The results are promising for the use of NMM- and DMDHEU-treated recovered fibers as an alternative fiber resource for the production of laminated paper and also for the use of DMDHEU as a new N-methylol compound for laminated paper. (c) 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41290.