Plasticizers are additives that enhance the processability, flexibility, and ductility of plastics, resins, or elastomers without altering their chemical structure. They are categorized into internal and external plasticizers. Dioctyl phthalate (DOP), an external plasticizer, achieves its plasticizing effect through dipole interactions and steric shielding with PVC molecules.
2. Effects of Plasticizer DOP on PVC Performance
2.1 Shore Hardness
As shown in Fig. 1, the Shore hardness of soft PVC decreases with increasing DOP content. This is attributed to DOP molecules inserting between PVC chains, weakening intermolecular forces and reducing the energy required for chain segment movement.
2.2 Tensile Strength
Fig. 2 illustrates that tensile strength declines as DOP concentration rises. Excess DOP disrupts phase compatibility at the PVC matrix interface, compromising interfacial bonding and mechanical integrity.
2.3 Elongation at Break
Fig. 3 demonstrates that elongation at break significantly improves with higher DOP levels. DOP enhances polymer chain mobility and reduces crystallinity, promoting plastic deformation under stress.
3. Conclusion
This study confirms that DOP content inversely affects key mechanical properties of soft PVC:
Shore hardness and tensile strength decrease with rising DOP levels.
Elongation at break increases due to enhanced chain mobility.
These insights guide the optimization of PVC formulations for specific applications requiring flexibility or durability.
