Daisy A Sriwendari, Edwin K Sijabat / JBAT 9 (2) (2020) 126-134
additives (PAC and cationic retention) in the blanko. The values of bursting index and ply bonding with surface sizing coating are better, compared to those without surface sizing coating, both in the blanko which uses surface sizing agent and in the trial which uses BNC to replace the surface sizing agent. The increase in bursting index and ply bonding is also affected by coat weight of the sizing. The heavier the coat weight will increase the ring crush index and concora index, and vice versa.
stock with low consistency. Thus BNC does not bind with AKD, because it is already bound to water. The cobb size result with surface sizing coating decreases compared to that of without surface sizing, both in the blanko, using surface sizing agent and in the trial using BNC to replace surface sizing agent, because the function of adhesive material (sizing) is to make the paper more water resistant, to increase paper strength and its folding power (Fitriani et al., 2016). In the handsheet trial with surface sizing coating, using BNC to replace the surface sizing agent can keep the liquid from penetrating because the starch added also functions as sizing agent that can block access to free OH groups in BNC (Syamsu et al., 2012). Also the BNC composition used on surface sizing is less than in raw materials, namely 5.56% of surface sizing solution. Figure 8 shows that the porosity value is increasing from the hand sheet blanko to the hand sheet trial 6, both in the experiment without the surface sizing coating, and in the experiment with surface sizing coating. The increase in the paper porosity value is caused by the increasing BNC composition used from the hand sheet blanko (0% BNC) to the hand sheet trial 6 (30% BNC).
Cobb Size Test Results
Figure 7 shows that the cobb size value is increasing, from the hand sheet blanko to the hand sheet trial 6, both in the experiment without the surface sizing coating, and in the experiment with surface sizing coating. The increase in the paper cobb size value is caused by the increasing BNC composition used from the hand sheet blanko (0% BNC) to the hand sheet trial 6 (30% BNC).
Figure 7. Cobb size test result.
According to Windarti & Siahaan (2008), one of the BNC unique characteristics is that its cellulose membrane is very strong and can bind water to more than 100 times of its own weight, thus forming a hydrogel. The ability of cellulose to bind large amounts of water is because the number of - OH groups possessed by cellulose, causes cellulose to be hydrophilic. The cellulose ability to bind large amounts of water is due to the numerous -OH groups possessed by cellulose, thus making it to be hydrophilic. As the BNC composition increases in the handsheet trial, it will increase the cobb size value. Because the higher the BNC, the more water can be binded. Whereas using internal sizing (AKD) as penetration barrier in the trial is less effective because the AKD dosing point is carried out on
Figure 8. Porosity test result.
According to Mahmudah et al. (2014), paper making can use BNC as an additive and retention material because it’s a large molecule with 4000-6000 in polymerization degree. The non- branched glucose chain makes a long fibrillar structure, because of the high number of free hydroxyl groups that produce extensive intra and intermolecular hydrogen bonds between adjacent chains (Brown, 1985). These fibres are very small and made of nano-sized fibers thus making the braid really strong and tight that even water will struggle to penetrate it. According to Sijabat et al. (2017), the addition of nanocellulose can reduce porosity
131
Made with FlippingBook Ebook Creator