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Strength agent: PAE application in TMP rejects
thesisposted on 21.03.2017, 23:46 by Hu, Lei
In this paper cationic polymer Nopcobond 1213 as a class of polyamideamine epichorohydrin (PAE) resins were used to enhance the wet and the dry strength of paper at 5 different addition rate 0mg/g, 2mg/g, 5mg/g, 10mg/g and 20mg/g by mixing with two types of pulp with three different pressing level (0bar, 3.75 bar and 5.6 bar): (1) reject TMP radiate pine pulp taken from the feed stream of the rejected refiner (2.09% shive content); (2) fractionated shive-free of the first type of pulp. This study has found that Nopcobond 1213 significantly increases strength for handsheets made from both type of pulp and 5mg/g is the optimum addition rate. In addition, light basis weight, about 0.2-0.35 kg/m3 paper products are able to made from the TMP reject stream with desirable tensile strength (dry tensile index about 10-25 Nm/g, wet tensile index about 1-7 Nm/g). Handsheet were made and tested for physical properties and opacity properties including bulk, tensile strength, bending stiffness, fibre strength and formation, ring crush compressive strength, light scattering coefficient and opacity. Due to the long fibre and small amount of fines loss in the shive-free pulp, test samples showed relatively lower tensile strength compared to the whole pulp. Moreover, the shive-free handsheets did not completely dry in the drying process (due to wrinkles formation of high temperature), freely dried shive-free handsheets had worse formation than handsheets made from the whole pulp (as they are totally dried in drying section), therefore polymer in the shive-free handsheets reduced its performance in imparting paper strength. The whole pulp handsheets with better formation and more long fibres in the pulp showed good strength but relatively lower light scattering coefficient and opacity. The coarse and large fibres made handsheets from the whole pulp less sensitive to the different levels of pressing.