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Cellulose (2019) 26:3473–3487
Fig. 5 Tensile stiffness (kNm/g) versus strain at break (%) of handsheets sprayed with the different polysaccharide solutions. The paper properties were measured after restrained (R) and unrestrained (UR) drying. The average values with their standard deviations are shown
Table 4 The mechanical properties of handsheets after unrestrained drying
Density kg/m 3 Tensile index
Unrestrained drying
Tensile stiffness
Strain at break
1D shrinkage Air permeabi lity
Nm/ g
s kNm/gs % s %
mL/min s
Reference
398.6
50.6 2.4 2.2
0.1 9.2 0.3 4.3
2394 398
Reference-sprayed
368.4
50.2 1.1 2.4
0.2 9.1 0.3 4.3
2380 129
2% Alginate ( ? 20% sorbitol) 2% Alginate ( ? 30 % sorbitol) 4 % Alginate ( ? 20% sorbitol)
431.7
69.1 2.5 2.2
0.2 11.3 0.4 5.4
556
54
382.8
69.0 2.9 2.1
0.2 11.3 0.3 5.3
187
76
419.2
65.0 3.2 1.9
0.2 10.5 0.3 4.8
377 113
4% Alginate ( ? 30% sorbitol)
404.0
67.9 2.5 2.2
0.1 10.7 0.2 4.8
316
96
2% Cationic guar gum ( ? 20% sorbitol) 416.9
56.7 3.5 2.2
0.2 9.9 0.5 4.0
2272 319
2% Cationic guar gum ( ? 30% sorbitol) 432.3
62.3 3.3 2.4
0.2 9.5 0.3 4.0
2356 128
4% Cationic guar gum ( ? 20% sorbitol) 411.6
56.9 3.2 2.4
0.2 9.4 0.6 3.9
2083 169
4% Cationic guar gum ( ? 30% sorbitol) 382.2
60.3 2.3 2.4
0.3 9.4 0.4 4.0
2218 427
2% Chitosan ( ? 20% sorbitol)
413.2
65.4 4.2 2.4
0.2 8.5 0.5 4.0
3010 283
2% Chitosan ( ? 30% sorbitol)
389.2
63.5 3.9 2.5
0.3 8.7 0.7 4.0
3528 194
4% Chitosan ( ? 20% sorbitol)
396.8
60.5 3.0 2.4
0.2 9.7 0.4 3.4
2774 390
4% Chitosan ( ? 30% sorbitol)
376.2
56.9 4.0 2.3
0.2 9.3 0.5 3.6
2724 274
The average values, as well as their standard deviations (s) are reported. The additions were calculated as wt% of o.d. pulp
that the base paper in the current study had a lower extensibility compared to in previous studies, i.e. 10% compared to 12–13% (Vishtal and Retulainen 2014a; Khakalo et al. 2014; Vishtal et al. 2015). In the current study, only low-consistency (LC) pulp refining had been used, while a combination of high-consistency (HC) and LC refining had been used in the other studies. It is known that combination of HC and LC
refining is a good strategy to produce paper with high elongation potential and with high tensile strength simultaneously (Zeng et al. 2013). Addition of cationic guar gum or chitosan resulted in very slight increases in 2D formability. Alginate, however, resulted in significant increases in 2D formability, with values between 12.3 and 13.1%, i.e. increases of 2.2–3%, at room temperature.
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