Search

This study investigates the mechanical properties and fracture behavior of polypropylene (PP)‐based blend‐nanocomposites comprising 30 wt.% ethylene–propylene–diene monomer (EPDM) and 5 wt.% SiO2 nanoparticles. Different mixing sequences were employed to prepare the nanocomposites, and the resulting morphology development and dispersion states of modifiers were analyzed. Mechanical performance of the nanocomposites was evaluated through quasi‐static and high‐speed dynamic fracture tests. The dispersion and distribution of SiO2 nanoparticles within the nanocomposites were significantly influenced by the mixing protocol. In impact fracture tests, the presence of nanoparticles exhibited a beneficial efffect on fracture energy, demonstrating a synergistic toughening effect of the soft EPDM and rigid SiO2 particles. Conversely, adverse effects were observed in quasi‐static tests. Essential work of fracture (EWF) parameters indicated an increase in the yielding component and a decrease in the necking‐to‐tearing component with SiO2 incorporation into the PP/EPDM blends. During impact loadings, the highest improvement in crack propagation resistance was observed in nanocomposites with nanoparticles localized around the rubbery domains forming a network‐like structure of EPDM/SiO2‐nanoparticles. Morphologies where rubber domains and nanoparticles were separately distributed in the PP matrix resulted in the lowest fracture parameters. Energy dissipation mechanisms were elucidated, revealing multiple void formation followed by matrix shear yielding as the primary source under both quasi‐static and impact fracture conditions. In the latter case, stress‐concentrating percolated structures in the PP matrix facilitated the nucleation of dilatational bands evolving into highly stretched void‐fibrillar structures upon further loading. These findings contribute valuable insights into tailoring nanocomposite morphologies for enhanced mechanical performance in different loading scenarios. Highlights: Fracture behavior of PP/EPDM/SiO2 ternary systems was evaluated by EWF methodology and Izod impact test.Rubber particles surrounded by silica nanoparticles led to a percolated morphology and as a result to superior impact resistance.EWF parameters were mostly controlled by the tearing‐related parts regardless of phase morphology.The impact toughness was mainly controlled by the dispersion and distribution characteristics of the SiO2 nanoparticles. [ABSTRACT FROM AUTHOR]

The main objective of this work was to study the effect of the controlling parameters on the morphology and mechanical properties of the peroxide crosslinked low-density polyethylene foams. The relationship between the morphology and mechanical properties was also considered. Using different Dicumyl peroxide (DCP) and azodicrbonamide (ADCA) concentrations, various foams with different cell structures were prepared. Gel content and density of the foams were measured according to the standard methods. The morphology was examined using SEM technique. The mechanical properties of the foams were evaluated by means of compression and creep recovery tests. The results showed that the gel content and the density are mainly controlled by DCP and ADCA concentration, respectively. The results also showed that the cell size distribution is mainly controlled by DCP concentration. Increasing of DCP increased the gel content and decreased the cell size and cell size distribution. Foam density was mainly controlled by ADCA concentration, whereas the morphology was less affected with ADCA concentration. The foams with small cell size and narrow cell size distribution showed higher mechanical strength and lower plastic strain. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012 [ABSTRACT FROM AUTHOR]

Thermal stability of acrylonitrile-butadiene-styrene (ABS) polymers is one of the most essential necessities for color and glossy durability of their surfaces. On the other hand, mechanical properties of ABS are significantly affected by its thermal degradation. One way to protect ABS against degradation is the addition of carbon black (CB) that can act as a stabilizer. In this work, CB was compounded with ABS via melt mixing and the effect of CB structures on the melt and final ABS/CB composites behavior were examined. Flow behavior of ABS/CB compounds was investigated by measurement of melt flow index (MFI). The variation of the MFI of the composites with CB content, particle size and the applied load was also investigated. The results showed that the effect of smaller particles in decreasing the MFI was pronounced than larger particles. The fracture surfaces of the impact tests were studied by scanning electron microscopy, and showed that a semi-brittle fracture surface appeared when CB was added to the ABS. The Young's modulus of ABS increased and the yield stress decreased by increasing the CB loading. [ABSTRACT FROM AUTHOR]