GÜLSOY and KILIÇ PEKGÖZLÜ / Turk J Agric For
0.75
c
b
a
a
0.6
d
c
b
a
0.45
0.3
0.15
0
R16
R30 R50 European black pine
R100
R30
R50 R100 European aspen
R200
Figure 4. Effect of fiber fractionation on the apparent density of handsheets.
1000 1200 1400 1600 1800
a
a
b
c
b
d
0 200 400 600 800
c
d
R50 R100 European aspen
R16
R30 R50 European black pine
R100
R30
R200
Figure 5. Effect of fiber fractionation on the roughness of handsheets.
index increased. Apparent density of handsheets in both species was positively correlated with increasing screen mesh. Fiber fractionation may not be technically feasible for mill-scale paper production, but papermaking from unfractionated fibers ignores the opportunity to use the natural advantages of the individual fiber fractions. Also, selective refining of fractions results in paper quality improvements. More studies related to effects of fiber fractionation (especially the effect of vessel element-rich and element-poor fractions) on paper properties of other lignocellulosic materials have to be carried out. Acknowledgment This research was supported by the Scientific and Technological Research Council of Turkey (TÜBİTAK, Project Number: 113O146). The authors are thankful to TÜBİTAK for the financial support.
and finer fibers of high screen mesh fractions (Table 2; Figures 6 and 7). This result can also be attributed to the action of vessel elements in fractions of European aspen samples that are rich in vessel elements (Malik et al., 2004). Demuner (1999) reported that the smoothness of fine fractions was higher than that of coarse fractions. FE-SEM handsheet micrographs of each fractionation of European black pine and European aspen are shown in Figures 6 and 7, respectively. In conclusion, the results of this study have shown that the handsheet properties were statistically significantly affected by fiber fractionation. In European black pine samples, tensile index, tear index, burst index, and roughness of handsheets decreased with increasing screen mesh number. In European aspen samples, tear index and roughness of handsheets decreased with increasing screen mesh number, while tensile index and burst
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