5 results on '"Bongiorno, F"'
Search Results
2. Environmental aging effects on high-performance biocomposites reinforced by sisal fibers
- Author
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Bernardo Zuccarello, Carmelo Militello, Francesco Bongiorno, Zuccarello B., Militello C., and Bongiorno F.
- Subjects
Settore ING-IND/14 - Progettazione Meccanica E Costruzione Di Macchine ,Polymers and Plastics ,Mechanics of Materials ,Materials Chemistry ,Mechanical properties ,Condensed Matter Physics ,Biocomposite ,Sisal fiber ,Environmental degradation - Abstract
Among the innovative materials, an important role is played by the so-called biocomposites, generally made by an eco-friendly matrix reinforced with natural fibers. Unfortunately, due to the degradability of the green matrixes as well as to hydrophilicity of the natural fibers, the resistance of such innovative materials to the environmental agents is, in general, relativity low, and it can significantly limit their use in outdoor conditions. To contribute to the knowledge of the effects of the leading environmental agents on the mechanical properties of highperformance biocomposites made of a green epoxy matrix reinforced by agave fibers, a systematic experimental testing campaign has been carried out by considering three types of biocomposite laminates (unidirectional, cross-ply and quasi-isotropic with a Vf = 70%). In detail, the different effects of aging on matrix and reinforcement have been highlighted by also considering samples consisting of simple epoxy matrix alone. The usual outdoor operating conditions associated with frequent exposure to sunlight (temperature and UV cycles) and humidity have been reproduced by subjecting the biocomposites to an accelerated aging process. Successive tensile and delamination tests have shown that aging leads to significant mechanical properties reductions, ranging from about 40% (tensile) to about 70% (delamination). A systematic analysis of the experimental results has allowed to develop reliable models that can be used to predict the degradation affecting the mechanical properties when these biocomposites are subjected to the actual aging related to the outdoor service conditions.
- Published
- 2023
3. Enhancement of Static and Fatigue Strength of Short Sisal Fiber Biocomposites by Low Fraction Nanotubes
- Author
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F Bongiorno, Bernardo Zuccarello, Giuseppe Vincenzo Marannano, Antonio Pantano, Pantano, A., Bongiorno, F., Marannano, G., and Zuccarello, B.
- Subjects
Toughness ,Materials science ,Compression molding ,02 engineering and technology ,Carbon nanotube ,Polymer composite ,021001 nanoscience & nanotechnology ,Fatigue limit ,Sisal ,law.invention ,Settore ING-IND/14 - Progettazione Meccanica E Costruzione Di Macchine ,020303 mechanical engineering & transports ,Brittleness ,0203 mechanical engineering ,law ,Ultimate tensile strength ,Ceramics and Composites ,Fatigue ,Fiber ,Biocomposite ,Composite material ,0210 nano-technology - Abstract
Thanks to good mechanical performances, high availability, low cost and low weight, the agave sisalana fiber allows to obtain biocomposites characterised by high specific properties, potentially very attractive for the replacement of synthetic materials in various industrial fields. Unfortunately, due to the low strength versus transversal damage processes mainly related to the matrix brittleness and/or to the low fiber/matrix adhesion, the tensile performance of random short fiber biocomposites are quite low, and to date most of the fiber treatments proposed in literature to improve the fiber-matrix adhesion, have not led to very satisfactory results. In order to overcome such a drawback, this work in turn proposes the proper introduction of low fractions carbon nanotubes to activate advantageous improvements in matrix toughness as well as fiber-matrix bridging effects, that can both lead to appreciable increments of the tensile strength.Systematic experimental static and fatigue tests performed on high quality biocomposites obtained by an optimized compression molding process, have shown that the introduction of 1% of carbon nanotubes is sufficient to gives significant improvement in both stiffness and static tensile strength, respectively by approximately 28% and 30%. Furthermore, toughening the biocomposite with 1% of nanotubes results in an appreciable enhancement in lifetime of at least 3 orders of magnitude. Biocomposites with 2% of CNTs show instead more limited improvement of 13% in stiffness, 6% in strength and 150% in lifetime. Also, a thorough analysis of the damage processes by SEM micrographs, as well as of the main fatigue data, has allowed to determine the model that can be used to predict the fatigue performance of such biocomposites.
- Published
- 2021
4. New concept in bioderived composites: Biochar as toughening agent for improving performances and durability of agave-based epoxy biocomposites
- Author
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Antonio Pantano, Mattia Bartoli, F Bongiorno, Carmelo Militello, Alberto Tagliaferro, Bernardo Zuccarello, Zuccarello B., Bartoli M., Bongiorno F., Militello C., Tagliaferro A., and Pantano A.
- Subjects
Materials science ,Polymers and Plastics ,Compression molding ,02 engineering and technology ,engineering.material ,010402 general chemistry ,01 natural sciences ,Article ,lcsh:QD241-441 ,Settore ING-IND/14 - Progettazione Meccanica E Costruzione Di Macchine ,lcsh:Organic chemistry ,Agave ,Thermoset composites ,Filler (materials) ,Ultimate tensile strength ,Biochar ,Fiber ,Composite material ,Fatigue ,agave ,biochar ,thermoset composites ,fatigue ,General Chemistry ,Epoxy ,021001 nanoscience & nanotechnology ,Durability ,0104 chemical sciences ,visual_art ,engineering ,visual_art.visual_art_medium ,Biocomposite ,0210 nano-technology - Abstract
Biocomposites are increasingly used in the industry for the replacement of synthetic materials, thanks to their good mechanical properties, being lightweight, and having low cost. Unfortunately, in several potential fields of structural application their static strength and fatigue life are not high enough. For this reason, several chemical treatments on the fibers have been proposed in literature, although still without fully satisfactory results. To overcome this drawback, in this study we present a procedure based on the addition of a carbonaceous filler to a green epoxy matrix reinforced by Agave sisalana fibers. Among all carbon-based materials, biochar was selected for its environmental friendliness, along with its ability to improve the mechanical properties of polymers. Different percentages of biochar, 1, 2, and 4 wt %, were finely dispersed into the resin using a mixer and a sonicator, then a compression molding process coupled with an optimized thermomechanical cure process was used to produce a short fiber biocomposite with Vf = 35%. Systematic experimental tests have shown that the presence of biochar, in the amount 2 wt %, has significant effects on the matrix and fiber interphase, and leads to an increase of up to three orders of magnitude in the fatigue life, together with an appreciable improvement in static tensile strength.
- Published
- 2021
5. Low-velocity impact behaviour of green epoxy biocomposite laminates reinforced by sisal fibers
- Author
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Bernardo Zuccarello, F Bongiorno, Gabriella Epasto, Carmelo Militello, Militello C., Bongiorno F., Epasto G., and Zuccarello B.
- Subjects
Materials science ,Biocomposites, Natural fibers, Sisal, Impact strength, Computed tomography ,02 engineering and technology ,Impact test ,Impact strength ,Sisal ,Settore ING-IND/14 - Progettazione Meccanica E Costruzione Di Macchine ,0203 mechanical engineering ,Fiber ,Composite material ,Computed tomography ,SISAL ,Civil and Structural Engineering ,computer.programming_language ,Biocomposites ,Biocomposites, Computed tomography, Impact strength, Natural fibers, Sisal ,Izod impact strength test ,Epoxy ,021001 nanoscience & nanotechnology ,Aramid ,020303 mechanical engineering & transports ,visual_art ,Volume fraction ,Ceramics and Composites ,visual_art.visual_art_medium ,Natural fibers ,Biocomposite ,0210 nano-technology ,computer - Abstract
Due to its good mechanical characteristics, low cost and high availability in the current market, sisal fiber is one of the most used for the manufacturing of biocomposites in various industrial fields (automotive, marine, civil construction etc.). The particular sub-fibrillar structure of the sisal fiber (similar to aramid fibers) and the corresponding anisotropic behavior detected by recent research activities, suggest that such biocomposites should exhibit also high impact strength, in such a way to permit their advantageously use also for the manufacturing of crashworthy components (bumpers, helmets, protection systems etc.), that are at the same time also eco-friendly, lightweight and cheap. Through a low-velocity impact tests campaign, integrated by computer tomography (CT) and carried out on various “green epoxy”/sisal laminates, by varying the main influence parameters such as reinforcement distribution, fiber volume fraction and lay-up, it has been detected that angle-ply laminates exhibits specific impact performances superior to those of biocomposites reinforced by other natural fibers (flax, hemp, jute, etc.), and comparable with those of the best composites specially reported in literature, so that they can be actually used to substitute the synthetic materials for the manufacture of interesting eco-friendly energy absorbing devices, that are also lighter and cheaper.
- Published
- 2020
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