SLIDE 1
Fiber Modification Kraft-TMP Bonding
SLIDE 2 Fiber Modification: Fiber Bond Enhancement
Background: What is unknown
- Why tensile strength of TMP-made paper is weaker than
KP-made paper? Weaker bonding or something else?
- Structure of interfiber bonding has focused on chemical
pulp sheets. However, there are no comprehensive models for describing the structure of mechanical pulp bonds.
- Mechanism of bond enhancement by bonding agents was
studied for chemical pulp. Same study should be prosecuted to understand the mechanical pulp bonding for the development of bond enhancement strategy.
SLIDE 3 Fiber Modification: Fiber Bond Enhancement
Background: What needs to be understood
- Structure of mechanical pulp bond
– Surface of long fibers and fines (layer separation by pulping) – Contact between fines and long fibers – Chemical contamination on the surface (extractives) – TMP/TMP bond – TMP/KP bond – KP/KP bond
- Effect of bonding agent on the mode of bond breakage
SLIDE 4 Fiber Modification: Fiber Bond Enhancement
- How to approach to the mechanical pulp
sheet bonding
SLIDE 5
Fiber Modification: Fiber Bond Enhancement
SLIDE 6
Fiber Modification: Fiber Bond Enhancement
SLIDE 7
Fiber Modification: Fiber Bond Enhancement
SLIDE 8
Fiber Modification: Fiber Bond Enhancement
SLIDE 9
Fiber Modification: Fiber Bond Enhancement
SLIDE 10
Fiber Modification: Fiber Bond Enhancement
SLIDE 11
Fiber Modification: Fiber Bond Enhancement
SLIDE 12
Fiber Modification: Fiber Bond Enhancement
SLIDE 13
Fiber Modification: Fiber Bond Enhancement
SLIDE 14
Fiber Modification: Fiber Bond Enhancement
SLIDE 15
Fiber Modification: Fiber Bond Enhancement
SLIDE 16 Effect of bonding agent dosage on the mode of bond breakage
– It is believed that improvement of tensile strength of paper by addition of bonding agents is due to the increase of specific bond strength (bond strength/bonded area) not by the increase
– Observation of broken bond will provide insight into how bonding agents improve bond strength.
SLIDE 17 Visualization of broken bonds by vapor phase osmium coating of paper
Coating of internal surface of paper by osmium Sheet splitting
SLIDE 18 Handsheet used for sheet splitting
Cationic Potato Starch 50 55 60 65 70 75 0.5 1 1.5 2 Dosage, % Tensile, N m/g
Pulp: Southern Pine Bleached Kraft Freeness: 500 ml CSF Starch: cationic potato starch Dosage: 0.3, 0.5, 1.0, 2.0%
SLIDE 19
Bond breakage mode: type A Very smooth surface with no fibrils rising from it
SLIDE 20
Bond breakage mode: type B
Relatively smooth surface with some fibrils rising from it
SLIDE 21
Bond breakage mode: type C
The S1 layer is broken and partially peeled off from the S2
SLIDE 22
Bond breakage mode: type D
The S1 is peeled off and the S2 is exposed
SLIDE 23 Effect of C-starch dosage on the bond breakage mode
Dosage: 0%
32 58 6 4 20 40 60 80 A B C D
Dosage: 0.3%
4 38 54 4 20 40 60 80
A B C D
Dosage: 0.5%
33 44 23 20 40 60 80
A B C D Dosage: 1.0% 11 70 19 20 40 60 80 A B C D
Dosage: 2.0% 3 60 37 20 40 60 80 A B C D
SLIDE 24 Mechanism of Fiber-Fiber Bonding Conclusions
- The improvement of paper tensile
strength is not simply due to the increase of specific bond strength.
- The position of the bond breakage shifts
from the bonded surface to the S1, and to the S1/S2 border with the increase of dosage of the bonding agent.
