PAPERmaking! g FROM THE PUBLISHERS OF PAPER TECHNOLOGY Volume 2, Number 1, 2016
where A is the weight of the original sample, W is the weight of the solids (fines) in the filtrate, U is the weight of the filtrate, and T is total amount of fines in the sample. Preparation of handsheets with white ledger stock and the measurement of their physical properties White ledger stock was diluted using tap water to a consistency of 0.5% to prepare the handsheets. Handsheets with grammages of 100 ± 4g/m 2 were produced according to TAPPI T205 sp-06 (2006), after the C-PAMs were added to the pulp and mixed for 30 sec at 600 rpm. The addition levels of C-PAMs were 0.03, 0.05, and 0.07% of oven-dried fibers. The handsheets were wet-pressed at 3.5kgf/cm 2 for 5 min using a laboratory wet- press and were dried at 120°C for 4 min using a cylinder dryer. The dried handsheets were conditioned at 23°C and 50% RH to control the moisture content of the handsheets at 8%. The physical properties, including the bulk (TAPPI T411 om-10 2010), breaking length (TAPPI T494 om-06 2006), burst index (TAPPI T403 om-10 2010), compressive strength (TAPPI T818 cm-07 2007), and ash content (TAPPI T244 cm-99 1999) of the handsheets were measured.
Fig. 2. Flow diagram of the experimental process RESULTS AND DISCUSSION Pulp Properties of Recycled and Virgin Pulp
The pulp properties of recycled and virgin pulp are shown in Figs. 3 and 4. The Canadian standard freeness of white ledger was lower than that of OCC and that of virgin pulp, but the freeness of white ledger was higher than that of ONP. The fines content of white ledger was higher than that of virgin pulp but lower than that of ONP and OCC. The average fibre length of white ledger was the lowest of the six types of pulp, and its ash content was the second lowest among the five types of pulp. White ledger contains more fine particles (such as fibre fines and filler fines) than BKP. This indicates that
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Article 1 – Improving Retention and Strength
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