## 4 Influence of QACs on Thermo-Mechanical Properties of Polymer Blends and Polymer Composites
### Influence of QASs on Polymer Composites  
Table 8 shows the thermo-mechanical properties of polymer composites influenced by QASs. QAS like HTAB has been applied for compatibilization of HDPE/LDPE/Cellulose composites [16]. The application of HTAB has influenced the degradation temperature, melting temperature, tensile strength, tensile modulus, tensile extension, and impact strength of the composites. The degradation temperature of the composites decreased because of the lower initial degradation temperature of HTAB than other composite components, which affected the degradation temperature of the overall composites. Nevertheless, the melting temperature of the composites remains unchanged because of the presence of crystal lattice of HTAB in the composites [16]. Moreover, the mechanical properties, such as tensile strength and tensile modulus of the composites increased by up to 25% and 25%, respectively, compared to the neat HDPE/LDPE/Cellulose composite. This is attributed to the existence of HTAB, which enhanced the interfacial adhesion between HDPE/LDPE matrix and cellulose filler, as a result, improved the stress transfer from HDPE/LDPE to cellulose. However, the tensile extension and impact strength of the composites decreased caused by the excess of the crystal lattice of HTAB in the composites, which increased their brittleness [16]. This is related to the increase of the stiffness property of the composites. It is a well-known fact that the crystal lattice with higher content in the matrix can decrease the tensile extension and impact strength of the composites as a rule of mixture. QAS like OTAB (chemical structure is shown in Figure 5) has been applied for compatibilization of PBE/BN composites [18]. The application of OTAB has influenced the thermal conductivity, flexural strength, flexural modulus, and impact strength of the composites (Table 8). The thermal conductivity of the composites increased by up to 79%, compared to the neat PBE/BN composite. This is attributed to the improvement of interfacial adhesion between PBE matrix and BN filler, which induced heat transfer across the interface efficiently [18]. Moreover, the mechanical properties, such as flexural strength, flexural modulus, and impact strength of the composites increased by up to 38%, 8.5%, and 11%, respectively, in comparison with the neat composite. This is because of the long alkyl chain length of OTAB, which effectively adsorbed on the surface of the composites [18]. Therefore, the compatibilization by applying OTAB not only increased the thermal conductivity of the composites but also improved their flexural and impact properties as well. HTAB has also been applied for compatibilization of HDPE/Agar composites [22]. The application of HTAB has influenced the degradation temperature, melting temperature, tensile strength, tensile modulus, tensile extension, and impact strength of the composites (Table 8). The thermal properties, such as degradation temperature and melting temperature of the composites decreased compared to the neat HDPE/Agar composite. This is due to the presence of interactions between HDPE matrix and agar filler generated by HTAB [22]. Moreover, the mechanical properties, for instance, tensile strength and tensile modulus of the composites decreased because of their ductile behavior with the presence of HTAB. The existence of ductile behavior leads to the decrease of brittleness of the composites, which also reduced the stiffness property of the composites. This is induced by HTAB that improved the interfacial adhesion between HDPE and agar. Nevertheless, the tensile extension and impact strength of the composites increased by up to 72% and 24%, respectively, in comparison with the neat composite. This is attributed to the compatibilization effect of HTAB, which improved the compatibility between the composite components, as a result, increased the ductility of the HDPE/Agar composites [22].