The present research focuses on the synthesis, processing, and characterization of polyolefin-based nanocomposites reinforced with graphene nanofillers. The investigated materials are low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), and a LDPE/LLDPE blend, all of which were modified through the incorporation of graphene-containing masterbatches. The resulting nanocomposites exhibit filler concentrations varying from 0.35 to 1.25 wt%, enabling evaluation of the influence of graphene content on the morphological, mechanical, and rheological behavior of the matrix systems.
A comprehensive approach was employed to provide an integrated understanding of structure and property relationships. Rheological measurements were carried out under both shear and extensional flow regimes, using an Anton Paar MCR 502 rotational rheometer, alongside a special Sentmanat Extensional Rheometer (SER) attachment.
Uniaxial tensile testing results indicate that graphene incorporation led to notable improvements in stiffness, tensile strength, and thermal stability of the polyolefin matrices, especially at intermediate loading levels, where a balance between reinforcement and processability is achieved. At higher concentrations, however, signs of aggregation and heterogeneous distribution were observed, which may compromise the effectiveness of stress transfer and result in variability of extensional properties.
From a rheological standpoint, the presence of graphene induced clear modifications in the flow and viscoelastic behavior of the systems. Both shear viscosity and elastic modulus (G’) increase with filler addition, pointing to restricted molecular mobility and the onset of particle–matrix interactions. The evolution of the viscous modulus (G”) and the frequency-dependent behavior further suggest the development of a weakly percolated network structure at relatively low graphene contents, consistent with physical entanglements and van der Waals interactions among graphene sheets. These phenomena not only alter viscoelastic response but can also influence processing behavior, particularly in operations involving large deformations or extensional flow.
Extensional rheometry provided valuable insight into the nanofiller influence under elongational conditions relevant to typical polymer processing methods such as film blowing and extrusion molding. The SER measurements revealed significant changes in extensional viscosity and strain-hardening behavior, underscoring the importance of filler dispersion and interfacial adhesion in determining macroscopic flow performance. These observations support the premise that tailored incorporation of graphene into polyolefin matrices can enhance processability and mechanical integrity while maintaining desirable thermal characteristics.
Comissão Organizadora
Pedro Alves da Silva Autreto
Comissão Científica
Ferramenta completa de submissão, avaliação e publicação de anais para eventos científicos.
