PAPER making! FROM THE PUBLISHERS OF PAPER TECHNOLOGY INTERNATIONAL Volume 7, Number 3, 2021
“ Experimental quantification of differences in damage due to in-plane tensile test and bending of paperboard ”, Gustav Marin, Mikael Nygårds & Sören Östlund. Packaging Technology and Science , published online (2021). Creasing is an essential process to convert paperboards into packages since it enables folding along well-defined lines. The creasing process relies on purpose-made damage that is initiated in the paperboard structure: delamination. However, creasing might also cause in-plane cracks, which must be avoided. In this laboratory study, three paperboards were creased at six different depths, respectively. Two mechanical tests were performed to characterize the creases at standard climate (23°C and 50% RH): 2-point folding, to examine the bending force and short-span in-plane tensile test to evaluate the strength. The results were normalized with the values for the uncreased boards, which gave the relative strength ratios: relative creasing strength (RCS) and relative tensile strength (RTS). When the relative strengths were evaluated against the normative shear strains, a creasing window was formed. This window has an upper limit given by the RTS values, corresponding to the in-plane cracks, and a lower limit given by the RCS values, corresponding to the delamination damage initiated in the paperboard during creasing. It was observed that both the RCS and RTS values exhibit a linear relation against normative shear strain. From this, it was concluded that performing tests at two creasing depths might be sufficient to estimate the lower, and upper, limits for the creasing window in future studies. Finally, the effect of moisture was investigated by creasing, folding and tensile testing at 23°C and 90% RH, which showed that moisture had no clear effect on the RCS or the RTS values. TISSUE “ Dust Exposures in Swedish Soft Tissue Paper Mills ”, Richard L Neitzel, Marianne Andersson, Susanna Lohman, Gerd Sällsten, Kjell Torén & Eva Andersson, Annals of Work Exposures and Health , 2021, https://doi.org/10.1093/annweh/wxab063. Paper dust has previously been linked to adverse health effects. However, a comprehensive dataset of paper dust exposures does not appear to have been published previously. Our study was intended to address this need by describing a large dataset of measurements made in Swedish soft tissue paper mills. Our analysis of measured paper dust exposures may be useful for historical and contemporary exposure assessment in our own and other epidemiological studies. We have identified specific characteristics (i.e. papermaking operations and mill) and time trends that are important data features to consider, and documented continuing overexposure situations. Our results highlight the ongoing need for application of exposure controls to reduce paper dust exposures in the soft tissue paper industry. WASTE TREATMENT “A review of process and wastewater reuse in the recycled paper industry”, Ngoc Han, Jianhua Zhang & Manh Hoang, Environmental Technology & Innovation , Vol.24, November 2021, 101860. Water plays several essential roles in paper manufacturing. It serves as a suspending medium and a swelling agent for the fibres, dispersing and forming them into a uniform sheet during the initial stage of the papermaking process. It also serves as the solvent for a variety of chemicals and additives to adjust product quality. Water reclamation has always been a momentous task in the pulp and paper (P&P) industry. The main driving forces for the adoption of process water and wastewater treatment technologies are environmental regulations, costs of wastewater discharge and the high cost of freshwater. Recent developments have made it possible to not only reduce water consumption and environmental impacts, but also to recover treated water and valuable compounds such as fibres, making water recycling technologies cost-efficient. Thus, the economic viability of these technologies has played
Technical Abstracts
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