Introduction
Materials and methods
Pulp preparation through low consistency refining
Furnish | SPF |
---|---|
Net LC SRE (kWh/t) | 0 |
Freeness (mL, CSF) | 645 |
Mean fibre length (mm, LW) | 2.04 |
Tensile index (Nm/g) | 13.3 |
Bulk (cm3/g) | 4.94 |
Tear Index (mNm2/g) | 6.70 |
Baseline LC refining of high freeness TMP
Production of LC refined microfibres
Sample preparation
Specific energy target (kWh/t) | LCR-TMP | HC + TMPMF (1567) | HC + TMPMF (2242) | HC + KMF (2430) | ||||
---|---|---|---|---|---|---|---|---|
LCR-TMP | HC-TMP | TMPMF (1567) | HC-TMP | TMPMF (2242) | HC-TMP | KMF (2430) | HC-TMP | |
(wt%) | (wt%) | (wt%) | (wt%) | (wt%) | (wt%) | (wt%) | (wt%) | |
0 | 0 | 100a | – | – | – | – | – | – |
113 | 100 | 0 | 7 | 93 | 5 | 95 | 5 | 95 |
228 | 100 | 0 | – | – | 10 | 90 | – | – |
315 | 100 | 0 | 20 | 80 | 14 | 86 | 13 | 87 |
387 | 100 | 0 | – | – | 17 | 83 | – | – |
493 | 100 | 0 | 31 | 69 | 22 | 78 | 20 | 80 |
Characterization and testing
Results and discussions
Tensile development
Pulp freeness
Bulk preservation
Improved tear strength
Tensile energy absorption
Light scattering
Fibre length distribution
SEM characterization
Conclusion
- Both mechanical and kraft microfibre types produced in a pilot-scale LC refiner improved mechanical properties of TMP-based handsheets.
- The addition of TMP microfibre to primary pulp resulted in tensile development almost identical to that of the conventionally refined LCR-TMP at equivalent specific energies. Additionally, TMP microfibre additions increased tear strength, preserved bulk and exhibited improved freeness when compared with conventional LC refined samples. Light scattering coefficient for these microfibre composites were lower than LCR-TMP at a given tensile but higher at a given bulk.
- Kraft microfibre additions to primary pulp produced composites with the highest tensile and tear strength in the course of this study. At a given tensile index, bulk and freeness were notably higher for KMF composites than conventional LC refined samples. The addition of KMF to primary pulp resulted in the lowest improvement in light scattering among the different categories of pulp tested.