With the insurgence in the usage of PPA during the past few years for various applications, the need to ameliorate the transient properties and enhance the mechanical features of this polymer has come to surface. PPA is known to be brittle; it possesses a large storage modulus, and a glass transition temperature that is above its thermal degradation point, which renders the polymer unsuitable for a broad range of applications. One way to ameliorate its intrinsic properties is via the addition of a plasticizing agent that can disrupt the polymer's intermolecular packing, and thus making it more flexible, decreasing its storage modulus, depressing its glass transition temperature, and increasing its shear strength. A few examples of plasticizers that have been used with PPA include dimethyl phthalate, bis(2-ethylhexyl) phthalate, diethyl adipate, and tri-isononyl trimellitate (TINTM). In a recent study, the effect of two ether-ester plasticizers on the mechanical flexibility and photo-transience speed of cyclic PPA was investigated. The authors were able to show that the addition of these additives broadened the storage modulus range and decreased it from 2300 MPa in the case of pure PPA down to 19 MPa in the PPA/plasticizer mixture, hence making the polymer more flexible and in need of less energy to be distorted. In another study published by the same research group, the effect of diethyl adipate (DEA) plasticizer on the glass transition temperature of cyclic PPA was investigated. After determining the glass transition temperature of pure PPA to be 187 °C, PPA films with various DEA concentrations were prepared. By varying DEA concentration, the authors were able depress T to 12.5 °C demonstrating the importance of plasticizers in enhancing the mechanical flexibility and thermal properties of PPA. Similar results were previously observed where the thermal transitions were depressed from 95 °C for cPPA to 24 °C for diethyl phthalate (DEP)-plasticized cPPA. Among the few studies that have been reported on the usage of plasticizers with PPA, it has been noted that the usage of plasticizers results in a decrease in the tensile stress of the polymers which indicate that PPA is becoming more flexible and hence the film can fold more easily. Nevertheless, a control on the amount of plasticizer used is important. For instance, in the study discussed above, it has been reported that the usage of a large amount of plasticizer (more than 50% w/w in comparison with PPA polymer) results in phase segregation and a decrease in the flexibility of the PPA film. Furthermore, the nature of the used solvent can highly affect the mechanical properties of PPA as well. In particular, in another study published in 2019, both the elastic modulus and tensile strength increase when dichloromethane was used as a solvent to drop-cast PPA in comparison to dioxane and chloroform.