Desenvolvimento de compósitos híbridos de polipropileno e grafeno com fibra de vidro para injeção

Abstract

This work presents the development and evaluation of hybrid composites based on Braskem H301 polypropylene homopolymer (PP), Owens Corning 405B glass fiber (GF), and UCSGRAPHENE UGZ 1004 graphene nanoplatelets (GNP) for the injection molding process. Formulations were produced varying the contents of GF and GNP, with and without the use of maleic anhydride-grafted polypropylene (PPMA) Polybond 3200 as a compatibilizing agent, aiming to optimize mechanical, thermal, and rheological properties, as well as to investigate the potential for improved processability. The methodology included raw material characterization, extrusion and injection processing, and sample evaluation by scanning electron microscopy (SEM), mechanical testing, dynamic mechanical thermal analysis (DMA), capillary rheology, specific heat measurement, differential scanning calorimetry (DSC), and creep analysis. As an innovative approach, Pressure-Volume-Temperature (PVT) data were obtained and fitted to the two-domain Tait model, enabling the correlation of volumetric parameters with mechanical and thermal properties. The addition of GF increased tensile strength by up to 22% compared to neat PP. Although graphene did not significantly affect tensile or flexural strength, it enhanced the material’s toughness in glass fiber-reinforced samples. Notably, when comparing the sample containing only PPMA (H1F) with the one containing GNP (H2F), both reinforced with GF, graphene yielded a 73% increase in toughness compared to the PPMA counterpart. The combined presence of GF and GNP resulted in specific gains in stiffness and thermal stability, while PPMA improved interfacial adhesion and fiber length preservation. PVT analysis revealed the influence of fillers on the volumetric transition temperature (b₅) and pressure sensitivity (b₃ and b₄). It was also observed that glass fiber reduces crystallization, while graphene mitigates this effect—a result consistent with the DSC findings, where the presence of GNP restored the crystallinity of the material to the level of neat PP. The evidence demonstrates that the Tait model can be employed as a complementary tool for the characterization and selection of composites for industrial applications. This research contributes to the understanding of interactions between nanofillers and conventional reinforcements in polymer matrices, providing data and methodology that can enhance the production of injection-molded components, with potential applications in the automotive sector and other areas that demand high strength-to-weight ratio and durability. [resumo fornecido pelo autor]