Waste and Biomass Valorization
One of the major functions of a packaging material is the protection of its content during transportation. For this, the ability to endure compressive forces is especially important, as it is a measure of its stacking strength [69]. The stacking strength of a corrugated board box is greatly influenced by the edgewise compression strength (ECT) and the flexural stiffness [70]. As there is a direct relationship between the ECT of a corrugated board and the compression strength of the individual parts [71, 72], the compression strength of the liner and flute, measured either by the Ring-Crush- Test (RCT) or by the Short-Compression-Test (SCT), can be used to assess the suitability of a given paper substrate for corrugated boards. In this study the SCT was used to determine the compression strength, as the SCT is reported to show a better correlation to ECT than the RCT [73, 74]. In a field study, Adamopoulos et al. [75] have evaluated 16 different recycled liners and 7 different corrugating recycled- mediums and have found an average Compression Index (CI) in machine direction of 28.8 and 30.8 N m g −1 and an average CI in cross direction of 15.3 and 17.3 N m g −1 ,
significantly influence the beating degree resulting from the beating duration, except for the samples beaten for 20 min, in which a gap of 17 °SR between the samples treated at the highest and lowest severity was measured.
Paper Strength Properties
Hand sheet testing can be used to gain information about the potential contribution of a given pulp to the strength of the final paper product. In Table 4 the paper strength properties of the measured test sheets of SR-MDF (A) and (B) are pre- sented. In general, the paper strength properties of the steam refined waste MDF fibers were improved by intense beating and the highest strength properties could be realized at high beating degrees. However, as the beating degree is a meas- urement of the drainability of a fiber web, this reduction in dewatering capability leads to a reduction in paper machine speed [40]. In practice, a compromise between the drainabil- ity and the paper strength has to be found, and paper strength is usually compared at a similar beating degree.
Table 4 Paper strength properties of SR-MDF (A) and SR-MDF (B)
Treatment severity
SR-MDF (A)
SR-MDF (B)
Beating degree Compression- Index
Tensile-Index Tear-Index Beating degree Compression- Index
Tensile-Index Tear-Index
2 /g) (°SR)
(mN*m 2 /g)
(Log R 0 )
(°SR)
(Nm/g)
(Nm/g)
(mN*m
(Nm/g)
(Nm/g)
2.5
9.0
–
1.2 5.6 5.3 6.8 3.7 7.4
0.6 0.6 0.7 0.7 0.9 0.8 0.8 0.8 0.9 0.8 0.8 0.8 1.0 1.0 1.1 1.3 1.4 1.9 1.7 1.8 1.3 1.7 1.8 1.7
11.0 25.0 46.5 59.0 10.5 24.5 50.5 63.0 10.0 35.0 48.0 59.0
– – –
2.5 6.4 6.0
0.7 0.8 0.7 1.0 0.7 0.8 0.8 0.8 0.9 0.8 0.8 0.8 0.8 0.9 0.8 0.9 0.7 0.9 0.9 0.8 0.7 0.8 1.0 0.9
16.5 32.0 41.5 11.0 29.5 41.0 51.5 11.5 32.0 44.5 54.5 14.5 33.5 62.5 66.5 16.0 47.5 62.5 66.5 17.0 48.5 63.5 71.0
10.6 11.3 14.0
17.5
11.3
2.8
–
– –
2.6 7.3 7.6
11.2 13.2 14.7
10.1 12.7
11.8 15.6
10.4
3.1
–
4.2 9.1
– –
2.2 3.7 6.4
12.3 15.5 17.8
11.6 13.0
12.3 15.2
10.2
3.4
9.7
4.5
9.5
–
2.7 6.5
17.3 20.4 22.4 11.2 20.6 25.1 27.7
11.8 18.0 22.2
36.0 50.0 60.0
11.7 14.3 16.1
10.0 11.4
3.7
8.8
9.0
–
1.2 7.1 9.5
22.8 29.2 32.8
39.0 51.0 62.5
15.0 16.9 16.0
10.9
4.0
9.9
7.6
9.0
–
1.6 6.2 9.9
19.4 24.2 26.1
21.3 26.3 31.8
42.0 56.0 64.0
11.3 13.1 15.9
11.3
Values marked as “–” were too low to be measurable
1 3
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