GÜLSOY and KILIÇ PEKGÖZLÜ / Turk J Agric For
digester of 15 L. Chips (750 g, oven-dried basis) for each cooking experiment were cooked in the digester. After cooking, pulps were washed with tap water to remove residual liquor. After washing, pulps were disintegrated, washed with tap water, and screened on a slot screen of 0.15 mm (TAPPI T 275). The Bauer McNett classifier (model with 4 classifier chambers) was used for fiber fractionation of kraft pulps according to TAPPI T 233 cm-06. In fiber fractionation of European black pine pulp, R16 (1.190 mm, retained fibers of a 16-mesh screen), P16/R30 (0.595 mm, i.e. passed 16 mesh, retained 30 mesh), P30/R50 (0.297 mm), and P50/ R100 (0.149 mm) classifier screens were used. In fiber fractionation of European aspen pulp, R30, P30/R50, P50/ R100, and P100/R200 classifier screens were used. Fiber morphology of each fiber fraction was determined with a light microscope. Fiber dimensions of each fractions were measured (n: 100). The aspect ratio (fiber length/fiber width) and flexibility ratio [(lumen width/fiber width) × 100] were calculated using the measured fiber dimensions. Handsheets of 75 g/m 2 from each fiber fraction, made with a Rapid-Kothen Sheet Former (ISO 5269-2), were conditioned (TAPPI T 402). Tensile index, tear index,
burst index, and apparent density of the handsheets were measured according to the T494, T414, T403, and T220 TAPPI standards, respectively. Also, roughness of the handsheets was determined according to the ISO 8971-2 standard method. The handsheets of each fiber fraction were coated with gold (80%) and palladium (20%) using a sputter coater (Quorum Q150 T) and were observed by field emission scanning electron microscopy (FE-SEM) (Tescan MAIA3 XMU) operating at 10 kV. The coating thickness was approximately 10 nm. The data of handsheet properties for each fiber fraction were subjected to analysis of variance (ANOVA) and Duncan test at 0.05 probability level. Different lowercase letters used in figures denotes that the difference in the average values of properties among the compared groups
was statistically significant. 3. Results and discussion
The results of Bauer McNett and fiber morphology for European black pine and European aspen are shown in Table 2. It can be seen that the fiber length and fiber width of both species decreased with increasing screen mesh.
Table 1. Kraft pulping conditions of European black pine and European aspen.
Conditions
European black pine
European aspen
Active alkali (%)
20 25
16 20
Sulfidity (%)
Temperature (°C)
170
Time to max. temperature (min) Time at max. temperature (min)
90 60
Total cooking time (min)
150 4/1
Liquor/chip ratio
Table 2. The results of fiber fractionation of European black pine and European aspen.
Wood species
Fiber fractions
Fiber ratio (%)
Fiber length (mm)
Fiber width (μm)
Double wall thickness (μm)
Lumen width (μm)
Aspect ratio
Flexibility ratio
R16 R30 R50
65.8 17.2
3.32 ± 0.02 40.40 ± 0.1 21.20 ± 0.3 2.75 ± 0.04 39.00 ± 0.1 18.25 ± 0.2 2.13 ± 0.04 37.10 ± 0.5 20.35 ± 0.1 1.33 ± 0.02 35.10 ± 0.2 19.25 ± 0.3
19.20 ± 0.2 79.70 47.52 20.75 ± 0.3 72.56 53.21 16.75 ± 0.1 62.26 44.15 15.85 ± 0.2 38.46 44.16
European black pine
7.6 3.9
R100
R200 + fines 5.5
-
-
-
-
-
-
R30 R50
38.1 30.6 25.9
1.27 ± 0.01 25.0 ± 0.1 11.35 ± 0.1 1.09 ± 0.01 24.5 ± 0.1 11.50 ± 0.1 0.89 ± 0.02 23.7 ± 0.1 11.80 ± 0.2 0.60 ± 0.01 21.4 ± 0.1 12.20 ± 0.1
13.65 ± 0.2 50.40 54.60 13.00 ± 0.1 45.31 53.06 11.90 ± 0.1 38.40 50.21
European aspen
R100 R200 Fines
2.1 3.3
9.20 ± 0.2
32.24 42.99
-
-
-
-
-
-
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