Evaluation of Different Additives in a Polyolefin System and Their Impact on the Polymer Properties

Abstract

The effect of various liquid and solid additives on the physical properties of a heterophasic PP copolymer were studied. Two sample preparation methods, compression molding and tape extrusion were used to study the mechanical and thermal properties of the polymer. To investigate the material properties, Wide Angle X-ray Scattering (WAXS), Small Angle X-ray Scattering (SAXS), Dynamic Mechanical Thermal Analysis (DMTA), Tensile test, Transient Plane Source (TPS) were performed. The incorporation of additives in polymer samples did not exhibit a considerable influence on the thermal properties of blends; however it affected the mechanical properties. The presence of liquid additives in the interlamellar distance may result in an increase in the interlamellar distance without a notable impact on lamellar thickness, as laterally investigated and confirmed by SAXS results. The liquid in amorphous phase decreases the modulus of the sample. Increasing interlamellar distance influenced the plastic deformation mechanism by decreasing yield stress. The additives exhibited a plasticizing effect on the polymer, reducing modulus in the testing temperature range, leading to an improvement in mechanical properties without compromising the thermal stability of the polymer blend. The additives did not affect the degree of crystallinity, despite the changes in kinetics of crystallization. The introduction of additives to the polymer did not cause a significant change in the degree of crystallinity; however, a higher cooling rate in the Tape extrusion sample preparation method led to crystallographic variations and a reduction in the content of γ- form.