Role of Inorganic Fillers on the Physical Aging and Toughness Loss of PLLA/BaSO4 Composites
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PROVIDER: S-EPMC10653123 | biostudies-literature | 2023 Nov
REPOSITORIES: biostudies-literature
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Project description:This review is dedicated to versatile silicone rubber composites based on carbon nanotube/graphene (CNT/G) hybrid fillers. Due to their unique mechanical, electrical, thermal, and biological properties, such composites have enormous potential for medical, environmental, and electronics applications. In the scope of this paper, we have explored CNT/graphene/silicone composites with a different morphology, analyzed the synergistic effect of hybrid fillers on various properties of silicone composites, and observed the existing approaches for the fabrication of hybrid composites with a seamless, assembled, and/or foamed structure. In conclusion, current challenges and future prospects for silicone composites based on CNTs and graphene have been thoroughly discussed.
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Project description:Brittleness is a major limitation of polymer-derived ceramics (PDCs). Different concentrations of three nanofillers (carbon nanotubes, Si3N4 and Al2O3 nanoparticles) were evaluated to improve both toughness and modulus of a commercial polysilazane (PSZ) PDC. The PSZs were thermally cross-linked and pyrolyzed under isostatic pressure in nitrogen. A combination of mechanical, chemical, density, and microscopy characterizations was used to determine the effects of these fillers. Si3N4 and Al2O3 nanoparticles (that were found to be active fillers) were more effective than nanotubes and improved the elastic modulus, hardness, and fracture toughness (JIC) of the PDC by ~ 1.5 ×, ~ 3 ×, and ~ 2.5 ×, respectively. Nanotubes were also effective in maintaining the integrity of the samples during pyrolysis. The modulus and hardness of PDCs correlated positively with their apparent density; this can provide a fast way to assess future PDCs. The improvement in fracture toughness was attributed to crack deflection and bridging observed in the micro-indentation cracks in the modified PDCs. The specific toughness of the modified PDCs was 4 × higher than that of high-purity alumina, and its specific modulus reached that of commercially available technical ceramics. These PDCs can also easily take different shapes and therefore are of interest in protective armor, propulsion, thermal protection, device packaging and biomaterial systems.
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Project description:Nature's wisdom resides in achieving a joint enhancement of strength and toughness by constructing intelligent, hierarchical architectures from extremely limited resources. A representative example is nacre, in which a brick-and-mortar structure enables a confluence of toughening mechanisms on multiple length scales. The result is an outstanding combination of strength and toughness which is hardly achieved by engineering materials. Here, a bioinspired Ni/Ni3C composite with nacre-like, brick-and-mortar structure was constructed from Ni powders and graphene sheets. This composite achieved a 73% increase in strength with only a 28% compromise on ductility, leading to a notable improvement in toughness. The graphene-derived Ni-Ti-Al/Ni3C composite retained high hardness up to 1000°C. The present study unveiled a method to smartly use 2D materials to fabricate high-performance metal matrix composites with brick-and-mortar structure through interfacial reactions and, furthermore, created an opportunity of developing advanced Ni-C-based alloys for high-temperature environments.
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Project description:The aim of the research was to study the effects of adding natural fillers to a polypropylene (PP) matrix on mechanical and physical properties of hybrid composites. The 10%, 15%, and 20% by weight basalt fibers (BF) and ground hazelnut shells (HS) were added to the PP matrix. Composites were produced by making use of an injection molding method. Tensile strength, tensile modulus, strain at break, Charpy impact strength, and the coefficient of thermal expansion were determined. The influence of temperature, thermal aging, and water absorption on mechanical properties was also investigated. In addition, short-time creep tests were carried out. To characterize the morphology and the filler distribution within the matrix, a scanning electron microscope (SEM) was used. The results showed that the addition of the two types of filler enhanced mechanical properties. Furthermore, improvements in thermal stability were monitored. After water absorption, the changes in the tensile properties of the tested composites were moderate. However, thermal aging caused a decrease in tensile strength and tensile modulus.
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