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Kraft method, the most widely used method in pulp production, causes to various environmental problems. Therefore, environmentally friendly pulp production methods have been investigated. In recent years, environmentally friendly deep eutectic solvents (DESs) as cooking liquor have been investigated. In this study, the possibilities of using a ternary DES (TDES) in pulp production from Scots pine (Pinus sylvestris L.) chips were investigated. TDES constituents were choline chloride (ChCl), lactic acid (LA), and glycerol (G). The effects of cooking temperature (145 °C and 155 °C) and cooking time (3 h, 3.5 h, and 4 h) on pulp and paper properties in TDES pulping were investigated. For comparison, kraft pulp from Scots pine was produced with conditions of 18% active alkali, 25% sulfidity, 155 °C cooking temperature, and 3.5 h cooking time. The highest lignin removal was obtained from TDES3 pulping conditions (155 °C and 4 h) with 76.0%. Lignin removal in the kraft pulp was 67.8%. TDES pulps were more quickly beaten to the target freeness level of 25°SR (the times for TDES3 and kraft pulps were 90 sec and 1350 sec, respectively.). Crystallinity index (CrI) values of kraft pulp and TDES3 pulp were 70.7% and 68.0%, respectively. TDES6 pulp had the highest pulp strength. But, the strength properties of all TDES pulps had lower than kraft pulp. TDES pulping can be a greener alternative to kraft pulping. • The pulp production using TDES from Scots pine was accomplished successfully. • The longer cooking time at 155 °C caused significant changes in fiber morphology. • Some properties of TDES pulps were comparable to those of the kraft pulps. • TDES pulping conditions had a significant effect on the pulp and paper properties. • TDES pulps more quickly reached to target freeness level. [ABSTRACT FROM AUTHOR]

Rice straw pulps produced under different conditions were subject to near infrared (NIR) spectroscopy. At the same time, samples from those pulps were used to make handsheets, whose mechanical properties were measured. These values and those of brightness were successfully fitted to the pulping variables. Relating them to the NIR spectra, we found valid correlations for all parameters except the burst index, concluding that NIR spectroscopy could be used as an economical, timesaving and non-intrusive way to predict the mechanical strength of pulps before the paper sheet is made. [ABSTRACT FROM AUTHOR]

• Multidisciplinary evaluation of three novel perennial crops as feedstock for the pulp and paper industry. • Meadow hay blends generated higher tensile indices compared to the pure birch control. • Fibre lengths of 0.5 (meadow hay), 1.3 (Virginia mallow), and 0.9 mm (cup plant) were measured. • The fibre widths of cup plant and Virginia mallow are broader compared to hardwoods. • These promising raw materials will be valueable in cardboard production for sustainable packaging. While the demand for paper and packaging material is increasing, industry and consumers are searching for more sustainable raw materials. This study evaluates three non-wood perennials to find alternative raw materials for the paper and pulp industry. Meadow hay, cup plant (Silphium perfoliatum L.) and Virginia mallow (Sida hermaphrodita (L.) Rusby) are attracting attention as potential raw materials for the bioeconomy due to biodiversity benefits, low fertilizer requirements as well as high yields. For the first time a detailed view on their fibre morphology and use as paper feedstock is given. After three different mechanical grinding methods, the plant material was screened, pulped in NaOH and beaten in a PFI mill. Birch fibre has been chosen as short-fibre control and blend base. Hand-sheets with different pulp blends of birch and one of the three raw materials were made, and paper properties were measured. For meadow hay, Virginia mallow and cup plant fibre lengths of 0.5, 1.3, and 0.9 mm were measured. Therefore, all perennial plant materials have comparable fibre lengths to hardwoods. Meadow hay blends with birch pulp percentages of 50 % and 75 % generated higher paper strength compared to the pure birch paper at a beating intensity of 5000 revolutions (PFI). The paper strength of cup plant and Virginia mallow blends is comparable to the strength of the birch control. Due to these promising results, all analyzed raw materials could find their application, especially in the growing area of sustainable packaging materials. [ABSTRACT FROM AUTHOR]

Abstract: In this work, we characterized various unconventional pulping raw materials in terms of their contents in hollocelulose, α-cellulose, lignin, ethanol–benzene extractables, ash, and hot water and 1% soda solubles. Also, we characterized pulp obtained from each material by using an ethyleneglycol concentration of 65% at 180°C for 75min, followed by beating at 1500 revolutions in a PFI refiner—all of which are compatible with existing facilities for Kraft and soda pulping processes. We characterized vine shoots, cotton stalks, Leucaena leucocephala and Chamaecytisus proliferus as pulping raw materials and found Ch. proliferus and cotton stalks to be the best for the intended purpose on the grounds of their increased contents in holocellulose (79.73 and 72.86%) and α-cellulose (45.37 and 58.48%), and their decreased contents in ethanol–benzene extractables (2.64 and 1.42%), hot water solubles (2.79 and 3.33%) and 1% soda solubles (16.67 and 20.34%). These properties resulted in increased pulp yields and hence in efficient use of these two types of raw material. The paper sheets obtained of different pulps were characterized and those from Ch. proliferus found to be the best overall as they exhibited an increased breaking length (4644m), stretch (2.87%), burst index (2.46kN/g) tear index (0.33mNm2/g) and brightness (49.92% ISO); in addition Ch. proliferus pulp was obtained with a high yield (62.88%). On the other hand, vine shoots provided the poorest results among the studied raw materials. [Copyright &y& Elsevier]

Abstract: The results of characterization for four different vine shoot varieties, grown using two different methods, revealed no significant differences in composition among vine varieties or between growing methods. The holocellulose content of vine shoots (67.14%) is lower than those of other non-wood raw materials (e.g. wheat straw, sunflower stalks, cotton stalks, etc.), but similar to those of pine and higher to those of olive trimmings. On the other hand, their lignin content (20.27%) is similar to those of eucalyptus and the non-wood raw materials. Also, their contents in cold-water, hot-water and 1% soda solubles, and ethanol–benzene extractables, are higher than for pine and eucalyptus. Soda, kraft, ethanol and ethylene–glycol pulping processes have low yields (29–47%) relative to the pulping processes applied to olive trimmings and wheat straw. Kraft pulp is that exhibiting the best properties, including a higher α-cellulose content (73.74%) than pulp from wheat straw or olive trimmings, but a higher lignin content (17.18%). Also, kraft pulp provides paper with the highest breaking length, burst index and tear index (viz. 1316m, 1.63kN/g and 1.59mNm2/g, respectively); these values, which are intermediate among those for olive trimmings, wheat straw and sunflower seeds, are low and can be substantially improved by appropriate refining of the pulp. [Copyright &y& Elsevier]