## 3 Effect of Surfactants on Mechanico-Thermal Properties
### Effect of Cationic Surfactant  
Table 8 shows the mechanico-thermal properties of polymer nanocomposites modified by cationic surfactants. HTAB (chemical structure showed in Figure 4a) could modify inorganic nanofillers like MMT and modified MMTs have been used for the preparation of MMT/PBS nanocomposites [20]. The modification of MMT improved the mechanico-thermal properties of the nanocomposites. The mechanical properties, such as tensile strength, tensile modulus, elongation at break, flexural  
strength, flexural modulus, and impact strength, of the nanocomposites increased by up to 34%, 7.3%, 210%, 34%, 3.6%, and 66%, respectively, compared to the unmodified MMT/PBS nanocomposite. This is due to the presence of trimethyl groups in HTAB that eased the MMT dispersion and offered a better reinforcement effect. Additionally, the high aspect ratio of HTAB-modified MMTs provided a higher surface area to interact with the PBS matrix [20]. Furthermore, the melting temperature also improved by up to 2.3% because of the higher degree of crystallinity of the nanocomposites. In addition, the crystallization temperature also increased by up to 6.5% due to the improved modified MMTs and the PBS matrix interactions and better filler dispersion [20]. LAE (chemical structure showed in Figure 4b) could modify organic nanofillers such as CNCs and modified CNCs have been utilized for the preparation of CNC/PLA nanocomposites [29]. The modification of CNCs increased the tensile strength, Young's modulus, and strain at break by up to 91%, 78%, and 58%, respectively. This could probably be attributed to the result of improved crystallinity and the enhanced dispersion/interface compatibility of LAE-modified CNCs within the PLA matrix. Additionally, the storage modulus of the nanocomposites increased by up to 69%; this could be associated with the creation of a stiff continuous modified CNC percolation network and the modified CNCs, which prompted the limitation of the PLA chain movement [29]. Furthermore, the glass transition temperature and melting temperature also improved by up to 15%, and 1.4%, respectively, due to the increased modified CNC dispersion and interface compatibility, which efficiently restricted the movement of PLA chains. In contrast, the crystallization temperature of the nanocomposites decreased compared to the nanocomposite without LAE because of the strong nucleating effect of modified CNCs, which promoted crystallization [29]. On the other hand, HMAC (chemical structure showed in Figure 4c) could modify inorganic nanofillers like MMT and modified MMTs have been applied for the preparation of MMT/PEVA nanocomposites [9]. The modification of MMT improved the mechanical properties of the nanocomposites, such as storage modulus. The storage modulus of the nanocomposites increased by up to 340%, due to strong HMAC-modified MMT and PEVA interactions compared to the nanocomposite without HMAC [9]. However, the melting temperature of the nanocomposites decreased due to the presence of HMAC, which offered interactions between the modified MMTs and the PEVA matrix [9]. Moreover, the crystallization temperature of the nanocomposites also decreased because the crystallization kinetics were altered by modified MMTs, which diminished the crystal perfection of the PEVA matrix. HTAB could also modify inorganic nanofillers like G NPs and modified G NPs have been used for the preparation of G NPs/PUA nanocomposites [13]. The modification of G NPs improved the mechanico-thermal properties of the nanocomposites. The storage modulus of the nanocomposites increased by up to 104% compared to the neat PUA; this could be attributed to a high aspect ratio of HTAB-modified G NPs with high surface areas dispersed evenly in the PUA matrix and forming strong interfacial interactions with the matrix via hydrogen bonding [13].