Computational modelling of void growth in Phenolic Molding Compounds filled PolyPropylene from optical measurements

Abstract

Phenolic molding compounds (PMC), also known as Bakelite TM , are the first synthetic plastics ever produced. They are still in use today in electrical, household and automotive applications. However, one major drawback of PMC is their lack of recycling option. Indeed, landfilling is still the main route of disposal, which constitutes a serious environmental burden. A new alternative recycling method is the use of comminuted PMC as filler in a thermoplastic matrix, in order to improve its mechanical and thermal properties. Several key parameters of the manufactured composite structure are the fillers size distributions, their loading percentage, and the adhesion at the filler/matrix interface. These parameters are related to mechanical properties of the composites, such as tensile strength. In this work, a polypropylene matrix is filled with 20% by weight of comminuted PMC (d 50 = 24μm) functionalized with 3% by weight of PP-g-MA to improve matrix/fillers compatibility. A FE model was developed from the mechanical behavior of each component. PP matrix and PMC fillers are individually characterized from tensile tests instrumented with photomechanics for the matrix characterization and their behaviors were modelled through a set of numerical parameters (elasto-visco-plasticity with a Gurson criterion behavior for the matrix and damage elasticity for the fillers). Numerical simulations at several strain rates were conducted on representative volume element with various microstructures. Comparison between the determinist model results and the experimental data (strength, volumetric variation) shows that this type of modelling could be a predictive tool in order to design particulate composites with optimized mechanical properties. Hence, it is an adequate way to understand micromechanisms of deformation (damage, cavitation).

Impact of PP Impurities on ABS Tensile Properties: Computational Mechanical Modelling Aspects

“…In the early eighties, Tvergaard and Needleman [ 28 , 36 ] extended the Gurson approach, namely GTN model, including material hardening, multiple voids, and void coalescence. This GTN model, available in numerous finite elements software, has been already used by authors to describe the micromechanisms of deformation of a PP/Bakelite blend [ 37 ] for which the PP matrix exhibits porosity following a Gurson-type model.…”

Hierarchical thermoplastic biocomposites reinforced with flax fibres modified by xyloglucan and cellulose nanocrystals

“…These experiments were performed to better depict the effect of CNC and XG/CNC treatments on interfacial adhesion of flax / PP at the microscale. First, the PP_MAPP_flax composites break at average 233 ± 2 N, while PP_MAPP_flax_CNC and PP_MAPP_flax_XG/CNC break at higher tensile forces, respectively 262 ± 15 N and 260 ± 3 N. The strength improvement related to interfacial adhesion is thus more pronounced with the micro-mechanical tensile test, which is conducted at low tensile speed (0.1 mm/min), especially for matrices showing a strong strain rate dependency as PP (Caro et al, 2018). Besides, the quality of interfacial adhesion and its role on composite failure could also be strain rate dependent.…”