Evaluating the performance of hemp bast fibres in the production of packaging paper using different …
is one of the lowest quality and abundant wastepaper grades. This choice supports this study’s aim of compensating for the diminishing strength properties of wastepaper, which is typically observed when using lower-grade wastepaper. During the wastepaper pulp preparation step, some impurities/contaminants were observed on the wastepaper. Since the wastepaper was in a corrugated box, there were rusty staples and adhered box sealing tapes. The box was also mouldy and contained some nits inside of the corrugated part. To obtain real-condition results, the wastepaper pieces were torn from these contaminated parts of the box by way of sampling. After the wastepaper ply-pieces had been soaked in water for 10 min, it was observed that the corrugated medium plies did not absorb water as much as the liner plies, as shown in Fig. 5.
Fig. 5. The water absorption difference between a) corrugated medium ply and b) face ply Sizing chemicals are used to reduce the water permeability of paper. This corrugated medium might have been highly sized, so the rewetting for 10 min was insufficient for this paper ply compared to face paper. Figure 6 depicts the physical characteristics of handsheets with different hemp bast fibre percentages. There are some brown speckles on the handsheets shown in Fig. 6, particularly on the handsheets with 40%, 60% and 80% hemp bast fibre. These speckles are the paper clumps that were not disintegrated during wastepaper preparation and handsheet formation steps. The disintegration problem of the wastepaper was due to the low water absorption of the corrugated medium plies that did not dissociate completely during disintegration. In addition, few white speckles were smaller than the aforementioned brown speckles. These white speckles must have originated from the white top face ply of the corrugated wastepaper. The white top face ply differs from the brown ply in nature of the fibre (the white fibres are bleached) and may also contain fillers such as calcium carbonate [Eroğlu and Usta 2004] . These differences could be the cause of this slight disintegration problem of the white top face ply of the wastepaper corrugated box. The handsheet with 0% hemp bast fibre (100% wastepaper) had the same colour as wastepaper pulp. Since the hemp bast fibre pulp has white
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