4
M. N. A. MOHAMMAD TAIB ET AL.
Processing methods for incorporating nano additives Wet-end addition
Wet-end addition involves the incorporation of nanofillers directly into the pulp slurry prior to sheet formation. This method allows intimate contact between nanofillers and fibers, enhancing interfacial bonding and reinforcing strength. However, issues like filler retention, agglomeration, and interference with flocculants and retention aids are common. Optimization of dispersants and coagulants is often necessary. Surface coating and Layer-by-Layer assembly Surface coating techniques involve the application of nanofillers onto the paper surface after sheet forma- tion. Methods include bar coating, spray coating, and roll coating. Layer-by-layer (LbL) deposition allows precise construction of multi-layered films using oppositely charged nanofillers, offering control over barrier and functional properties. These approaches are especially effective for applications in packaging and printed electronics. In situ formation or hybridization In situ formation involves generating nanostructures (e.g., metal nanoparticles) directly within the paper matrix or during pulp treatment. This technique can improve uniformity and functional integration. Hybridization, such as decorating nanocellulose with silver nanoparticles or embedding GO in polymer matrices, can produce multifunctional materials with enhanced antimicrobial, mechanical, or thermal properties. Characterization and application of nano additives in papermaking Nano additives are a type of nanomaterial with diverse chemical properties that possess at least one dimension in the nanoscale range (1–100 nm), including 0D, 1D, 2D, and 3D nanomaterials. Nano additives in pulp and paper can take the form of nanoparticles, nanosheets, and nanofibers (Frigione and Lettieri 2020). The nano additives have the potential to enhance and optimize the unique properties of paper and have emerged as a promising innovation in the field of papermaking. To improve the properties and performance, nano additives are often added to paper matrices. The introduction of nano additives offers numerous benefits, including improved paper strength, enhanced optical properties, increased resistance to moisture, and better printability. The use of nanofillers also allows for the reduction of raw material consumption and energy requirements, making it an eco-friendly approach. In this section, it highlights the current technology of nanofillers in papermaking, paving the way for advanced and sustainable paper products in various applications. The sub-chapters below list the applications of nanofillers based on improved properties.
Mechanical and barrier properties improvement Nanosilica
Silica is a chemical compound that is typically used in paper coatings, such as matte papers for inkjet printing (Shah et al. 2021). Silica can exist in amorphous, crystalline, and gel forms. It is used as a precursor for various materials, like optical coatings, or thin films in electronics. It is also commonly used in other fields such as catalysts, anticorrosion agents, chromatography, and ceramics. Conventional silica extraction and production from sand or quartz have several disadvantages, like high energy consumption and environmental pollution (Singh and Endley 2020). Silica can also be synthesized using the sol-gel method (Gamelas, Lourenco, and Ferreira 2011). Silica can be synthesized with micrometric and nanometric properties by various procedures using various chemically modified surfactants. The commercially available silica precursors are tetra ethoxy silane, tetra methoxy silane (TMOS), and sodium silicate (water glass). However, TMOS is highly toxic and harmful. As well, these precursors are costly starting materials, and
Made with FlippingBook interactive PDF creator