Research Article
SN Applied Sciences (2020) 2:1577 | https://doi.org/10.1007/s42452-020-03313-w
Fig. 6 FE-SEM images of unmodified PCC magnified A at 25 kx, B at 5 kx and C at 2 kx. Chitosan-modified PCC magnified D at 25 kx E at 5 kx and F at 2 kx, D – F represent chitosan dissolved in acetic acid. Chitosan-modified PCC magnified G at 25 kx, H at 5 kx and I at 2 kx, G – I represent chitosan dissolved in HCl
handsheets fabricated with chitosan-induced aggregated fillers are seen to improve tensile strength by 8.2% com- pared to native ones. Enhancement or negative impact of paper strength with different pre-flocs or bio-based composite mineral fillers is well verified by many authors [4, 8, 60]. According to our proposed mechanism instead of depositing on one single particle, chitosan seems to encapsulate several particles bounded to one another and enmeshed within the polymer chains. When mixed with pulp, amine groups (NH 2 ) of chitosan protruding from the surface of modified PCC establish hydrogen bonds with the cellulose fibers, thereby increasing in paper strength when dried. A similar trend for bursting strength of hand- sheets can be observed in the case of modified filler as evident in Fig. 10A. Higher improvement in tensile and burst with their corresponding correlation was reported by many while applying functionalized polymers in filler modification technology to achieve higher ash content [14, 60, 62]. Therefore, it is expected that the bonding potential of chitosan may be superior when it is anchored on the surface of PCC fillers rather than stochastically distributed between fibers and fillers. However, papers containing
Fig. 7 Particle size distribution of A unmodified PCC, B Chitosan- modified PCC. B Represents chitosan dissolved in HCl
individual fiber strength, inter-fiber contact area as well as bonding strength. Figure 9A reveals that at 15% filler dose, the tensile strength of paper decreases by 21% in the case of unmodi- fied fillers compared to unfilled paper. This finding is in consistent with the reported works [4]. Interestingly,
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