JOURNAL OF NATURAL FIBERS
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Table 5. Mechanical properties of unloaded with ZnO paper and paper loaded with nano Zinc Oxide (Chauhan and Chakrabarti 2012). Type of samples Tensile Index (N.m/g) Tearing Index (mN.m 2 /g) unloaded with ZnO paper 50.20 22.30 Paper with nano ZnO 39.04 11.99
for advancing the quality, functionality, and overall performance of paper materials. Recent research also indicates significant enhancements in the brightness, whiteness, smoothness, print density, print unifor- mity, picking velocity, and oil absorbency of paper coated with nano ZnO, and the presence of nano ZnO during coating on paper demonstrates remarkable antifungal and UV-protective properties, which play a crucial role in extending the lifespan of the paper.
Brightness and whiteness enhancement Nano Titanium Oxide
Nano titanium dioxide (TiO 2 ) has garnered significant attention recently due to its numerous advantages. Nano TiO 2 is a fine white powder that is unreactive or chemically inert (El-Sherbiny et al. 2014). These include high surface tension, specific surface area, magnetic properties, lower melting point, good thermal conductivity, and environmental friendliness (He et al. 2008). These properties make it suitable for a wide range of applications, such as cosmetics, coatings for paper and medical devices, and gas sensors (Deorsola and Dario 2008; Kobayashi et al. 2007). Nano TiO 2 is classified based on its crystalline arrangement. The crystalline arrangements are known as anatase or rutile (El-Sherbiny et al. 2014). The nano TiO 2 is also known to have a significant number of hydroxyl groups on its surface. The low light absorption, high light reflectivity, and nano-sized particles make this pigment ideal for obtaining better opacity (Pfaff 2021). Thus, it contributes to the good performance of paper sheets in terms of optical brightness and opacity (Zhang 2024). Moreover, it also has strong antimicrobial properties that are nontoxic and have potential bacter- icidal and fungicidal applications for packaging surfaces (Corrales, Avelina, and Jung 2014; Rezić, Haramina, and Rezić 2017). Another study also reported the use of nano TiO 2 as a retention agent for supporting materials on paper sheets (Adjimi et al. 2014; Senadeera et al. 2006). Nano TiO 2 is also typically used as a retention filter for wet-end papermaking. Nano TiO 2 has good retention and filter effects. The suspension from Nano TiO 2 can be coated on the paper sheet surface in wet-end papermaking. This process will have a bulking distribution of nano TiO 2 with a higher loading on the paper sheet. Another option is to deposit nano TiO 2 onto individual fibers before paper sheet formation. Furthermore, it effectively inhibits the pollution of white water by harmful substances (Taib 2023). The phases exhibit by TiO 2 are variations in synthesis and properties, with rutile and anatase being the most frequently synthesized phases due to their favorable thermodynamic characteristics and physical properties. Figure 8 shows the SEM image of TiO2 nanoparticles at two magnifications.
Figure 8. TiO 2 nanofiller at 120 C at high magnification (a) and at low magnification (b) (El-Sherbiny et al. 2014).
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