PAPERmaking! FROM THE PUBLISHERS OF PAPER TECHNOLOGY Volume 5, Number 2, 2019
With the purpose of setting a step towards in the standardization of design and testing practices of eco Ǧ friendly packaging, this work focused on the characterization of the thermoforming process of moulded pulp products and their characteristics. Three different analyses were carried out for this purpose, covering the dewatering efficiency of the process, a quantification of the moulding geometrical accuracy, and an analysis of the internal microstructure of the parts. Experimental results and statistical analysis show that the dewatering efficiency is mainly governed by the mould's temperature while the duration of the contact time is not influential. In the second investigation, the geometrical accuracy of the mouldability of microfeatures was assessed. The process appeared to be dependently related to the pulp type employed. Finally, the internal microstructure was documented using X Ǧ ray computed tomography. The analysis shows an increase in the internal void fraction linked with an increase in the mould's temperature. The role of the water change of phase in the thermoforming process is also discussed by reference to the work conducted on impulse drying. NANO-SCIENCE Cellulose nanofiber (CNF) as a versatile filler for the preparation of bamboo pulp based tissue paper handsheets, Min Guan et al, Cellulose , 26 (4), pp.2613 – 2624 . Tissue paper that is prepared from bamboo has a very promising future in the world, especially in China, thanks to the various merits of bamboo fibers. However, the water absorption behavior and mechanical properties of bamboo pulp based tissue paper need to be improved due to the inherent drawbacks of bamboo fiber, such as high stiffness, weak interaction between bamboo fibers etc. Hence, cellulose nanofibers (CNFs) were combined with bamboo fibers before the tissue paper-making process, to improve the water absorption behavior and mechanical properties of tissue paper. The hypotheses are that: (1) CNFs themselves possess large specific surface area and abundant hydroxyl groups as well, thus enhancing the hydrophilicity of tissue paper; and (2) the added CNFs can form 3D structures in tissue paper, thus providing abundant pores with uniform small size, which would facilitate the capillary effect for water absorption; and (3) more hydrogen bonds will be formed between CNF and bamboo fibers, thus improving the strength properties of tissue paper, thanks to the excellent mechanical and physical properties of CNF. The results from water absorption and tensile strength tests of bamboo handsheets indicated that the addition of CNFs can increase the water absorption capacity from 6.6 to 8.7 g/g when the CNF dosage was 10 wt% (based on the dried pulp). The water retention value of prepared bamboo fibers increased from 163 to 190% at the same CNF dosage, the tensile index increased from 18.5 to 24.5 N m/g as well. The results from the bulk and pore size analyses, FTIR, as well as SEM images of tissue paper also evidenced the conclusions above. Carboxymethylated cellulose nanofibrils in papermaking: influence on filler retention and paper properties, Ana F. Lourenço et al, Cellulose , 26 (5), pp.3489 – 3502. The papermaking industry competitiveness has been exponentially increasing. In order to improve the paper properties, processes have to be optimized in such a way that new horizons, such as the synthesis of new materials, are in sight. The present paper deals with the production of cellulose nanofibrils (CNF) from bleached Eucalyptus kraft pulp by carboxymethylation and TEMPO-mediated oxidation, followed by high pressure homogenisation. The main purpose of the work was to increase the filler retention and mechanical strength of printing and writing paper grades. Mineral fillers are of utmost importance in papermaking and therefore a thorough study of the CNF influence in filler- containing handsheets is mandatory. In this sense, flocculation studies revealed the extraordinary ability of CNF to flocculate calcium carbonate, which was translated into high
Technical Abstracts
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