**2. Effect of incorporating filler materials on polymer-based composite materials**

Several efforts have been explored toward solving the challenges mentioned above—loading several reinforcements or nanofiller into polymetric material to produce a polymer-based composite with improved properties [4–11]. Dittanet and Pearson confirmed that incorporating filler is a viable way to improve the thermal, physical, and chemical of polymer-based composite or hybrid. Furthermore, adding filler/s has been adopted to reduce the cost of the expensive polymetric matrix for composite material development [4–8].

Several materials with required reinforcement have been manufactured into different sizes and used as fillers in polymer composites material with improved properties [9, 12–15]. Fillers and reinforcement produced from SiO2, TiO2, and carbonbased materials have been widely explored [8, 12, 14, 16–18]. Among the material used for reinforcement or fillers, carbon-based materials and nanoclay are commonly used. Nanoclay is commonly used as filler or reinforcement in pulp and papers, paints, and polymer-based composite industries. Over many decades, montmorillonite (MMT) and kaolinite with a high concentration of CaCO3, commonly referred to as nanoclay, have been obtained from rock and synthesized using either gas pressure blasting or explosion method [19–21]. This filler is widely accepted and used for its reinforcement potential, availability, and low cost [11, 22, 23]. Furthermore, the development and application of nanoparticle-reinforced polymer-based composite have significantly increased over the decades. This increase in usage could be attributed to their availability, cost-effectiveness, easy processability, improved strength, stiffness, and lightweight [24, 25].

Yao and You [26] classified nanoclay-layered mineral silicate as montmorillonite, bentonite, and kaolinite in agreement with their chemical composition and morphology. They confirmed that montmorillonite is mostly used in industry and research. Mohan and Kanny confirmed the extended use of montmorillonite [14] as they confirmed that montmorillonite nanoparticle loading is a viable way of improving the composite mechanical, thermal, and tribological properties. However, the concentration and particle sizes of nanoclay have been explored, and it has been confirmed that these two factors substantially affect the inclusion of nanoclay in polymer composite properties.
