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had better retention ability of PCC in paper rather than PEI. The lowest value in bursting strength and
folding endurance was in sample 7. This result is consistant with the reading of loading degree where
this sample had the highest percent of loading degree. The existence of PCC in large amounts had interfered
greatly in interibre bonding. This situation can be clearly seen in Figure 7. The bursting strength and the
number of folding endurance starts decreasing when the loading degree increases. PCC had interfered the
pulp ibre surfaces and ibre web in the sheet.
Figure 7: The Effect of Percent Loading Degree on Burst Index and Folding Endurance of The Paper
Figure 8: Percent of Brightness and Opacity of The Paper
The results of brightness and opacity of the paper are portrayed in Figure 8. It can be seen that
the brightness of the paper increased from sample 1 to 5. However, it dropped signiicantly for sample 6
and then increased slightly for sample 7. This can be concluded that the addition of PEI for the sample 6 and
7 had decreased the brightness of the paper. According to De la Orden [17,18], the photoyellowing effect can
occur due to the condensation of the primary groups of PEIs which react with cellulose carbonyl groups
to form coloured imines. This condition happens due to the paper is heated in air or dried at moderate
temperature. Meanwhile the results of opacity of the paper show the different pattern. The presence of the
PEI had increased the loading degree of PCC in paper and thus increased the opacity of the paper. This can
be concluded that the PEI had improved the opacity of the paper. This condition can also be related to the
loading degree of PCC in the paper as shown in Figure 9. It can be seen that the opacity had increased when
the percent of loading degree of PCC had increased. However the brightness of the paper increased at 20 to
30 of loading degree, and dropped when the loading degree increased more than 40.
Figure 9: The Effect of Percent Loading Degree on Brightness and Opacity of The Paper
3.3 Scanning Electron Microscopy SEM Analysis
Figure 10 shows the SEM micrographs of PCC used in this study. The shape of PCC from MRC was
perforated cubical and shape of commercial PCC was cubical. Koetz Kosmella [19] stated that the SEM
and TEM micrographs are able to determine the shape and size of individual nanoparticles directly.
Figure 11 shows the SEM micrograph of the paper surfaces for the sample with addition of laboratory PCC
and PEI. It can be seen that the PCC had locculated, deposited on the ibre surfaces and entrapped in the
ibre web. The used of retention aid had locculated the PCC and increased the retention of deposition
in the sheet. According to Schwartz [20], the use of polyelectrolytes as retention aid in papermaking
offers several possibilities for the modiication of particles, polymer surfaces and also able to control the
colloidal stability. In this study, the laboratory PCC is negatively charged. The presence of polyelectrolyes
had absorbed the negatively charged PCC, and in turn the retention aids tend to reverse the negative charge
of particles and encourage them to be deposited onto
the ibre surfaces [21]. Meanwhile Figure 12 shows the SEM micrograph of cross-section of paper for the
sample with addition of PCC and PEI. It can be clearly seen that PCC are entrapped in the ibre web. Figure
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Figure 10: SEM Micrographs of a PCC from PPM and b Commercial PCC
Figure 11: SEM Micrograph of The Paper Surfaces for The Sample with Addition of Laboratory PCC and
PEI Figure 12: SEM Micrograph of Cross-Section of
Paper for The Sample with Addition of Laboratory PCC and PEI
Figure 11: SEM Micrograph of The Paper Surfaces for The Sample with Addition of Laboratory PCC and
PEI Figure 12: SEM Micrograph of Cross-Section of
Paper for The Sample with Addition of Laboratory PCC and PEI
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13 shows the SEM micrograph of the paper surfaces for the sample with addition of commercial PCC and
PEI. Based on the results of the percent of loading degree of PCC, this sample had the highest loading
degree. This can be clearly illustrated in the Figure 13 where a large amounts of the PCC particle had been
deposited on the ibre surfaces and almost all of the ibre surfaces were covered by PCC. Kamiti and van
de Ven [22] stated that the use of polyelectrolytes can improves the retention of iller. Meanwhile, Figure 14
shows the SEM micrograph of cross-section of paper for the sample with addition of PCC and PEI.
4. Conclusions
