ELISABETH CARVALHO L. CARDOSO

ELISABETH CARVALHO L. CARDOSO

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Study of mechanical properties of inner tubes exposed to gamma radiation
2023 - SCAGLIUSI, SANDRA R.; CARDOSO, ELISABETH C.L.; ESPER, FABIO J.; LUGAO, ADEMAR B.; WIEBECK, HELIO
Due to the technical evolution of tires, currently most automotive tires do not have an inner tube. However, truck, motorcycle and bicycle tires still use tires with inner tubes, mostly made of synthetic elastomeric material, which guarantees good potential for air restriction or longer periods for tire pressure failure. This work aims to study changes in the mechanical properties of a truck inner tire, after its exposure to gamma rays, to promote the subsequent recycling of the material. The choice of ionizing radiation is due to its ability to modify the structure and properties of materials, in addition to its applicability in recycling/recovering rubber. For the characterization of the samples, doses of 5, 10, 15, 20, 25 and 30 kGy were applied, and after irradiation as a sample, they were tested using the following characterization methods: traction and elongation at break, hardness, thermal aging and elemental analysis. Observed that is a decrease in the values of the mechanical properties of the samples after irradiation, mainly at doses greater than 10 kGy.
Study of mechanical and chemical properties stability of inner tubes exposed to gamma radiation
2021 - SCAGLIUSI, SANDRA R.; CARDOSO, ELIZABETH L.C.; ESPER, FABIO J.; LUGAO, ADEMAR B.; WIEBECK, HELIO
Nowadays, car tires are not provided with inner air or tubeless, pointing toward a technical evolution. Nevertheless, trucks tires even use at present inner tires, composed almost fully by a synthetic material, which ensures either a good potential for air constraint or longer periods for inspection of tires pressure. Inner tire is located inside the tire, which does not have any extra sealing in the wheel to withstand compressed air. It is designed to resist to expansion of these elements, inside common tires. This rubbery and vulcanized coating has chemical and physical characteristics which enable it to bear a very high air pressurization, avoiding leakages while protects tire outer frame. Inner tires models are exposed to higher temperatures and pressures that contribute to accelerate abrasion. This work aims to the study of mechanical properties changes of an inner tire used in trucks, after gamma rays exposure, in order to promote further material recycling. Ionizing radiation choice was due to its capacity to modify materials structure and properties besides its applicability for rubbers recycling/recovery. For samples characterization, non-irradiated and irradiated at 5, 10, 15, 20, 25 and 30 kGy, there were accomplished following tests: tensile and elongation at break, hardness, and thermal ageing and CHN elementary analysis. It was observed a decrease in mechanical properties for irradiated samples at doses higher than 20 kGy.
Radiation effects on crosslinking of butyl rubber compounds
2019 - SCAGLIUSI, SANDRA R.; CARDOSO, ELISABETH C.L.; LUGAO, ADEMAR B.
When butyl rubbers are subjected to high energy radiation, they form easy free radicals that initiate various chemical reactions. These reactions alter the molecular distribution of irradiated rubbers by crosslinking or scission affect their physical and mechanical properties. This work aims to the analysis of effect induced by γ-exposure on the crosslinking density in butyl rubbers by swelling measurements accomplished before and after irradiation at 25, 50, 100 and 200 kGy, with further evaluation of crosslinking density accomplished by Flory-Rehner equation; this is a proper procedure for the qualification of radiation resistance. It can be noticed that changes in material structure was due to build-up of new three-dimensional network in studied rubbers. Changes in crosslinking density of butyl rubber compounds emphasize that degradation mechanism is strongly influenced by gamma-radiation doses higher than 50 kGy, since chain scission process predominates over crosslinking reaction.
Study of mechanical and chemical properties stability of inner tubes exposed to gamma radiation
2019 - SCAGLIUSI, SANDRA R.; CARDOSO, ELISABETH C.L.; CAVIQUIOLI, FERNANDO; SALES, RICARDO M.; LUGAO, ADEMAR B.
Nowadays, car tires are not provided with inner air or tubeless, pointing toward a technical evolution. Nevertheless, trucks tires even use at present inner tires, composed almost fully by a synthetic material, which ensures either a good potential for air constraint or longer periods for inspection of tires pressure. Inner tire is located inside the tire which does not have any extra sealing in the wheel to withstand compressed air. It is designed to resist to expansion of these elements, inside common tires. This rubbery and vulcanized coating has chemical and physical characteristics which enable it to bear a very high air pressurization, avoiding leakages while protects tire outer frame. Inner tires models are exposed to higher temperatures and pressures that contribute to accelerate abrasion. This work aims to the study of mechanical properties changes of an inner tire used in trucks, after gamma rays exposure, in order to promote further material recycling. Ionizing radiation choice was due to its capacity to modify materials structure and properties besides its applicability for rubbers recycling/recovery. For samples characterization, non-irradiated and irradiated at 5, 10, 15, 20, 25 and 30 kGy, there were accomplished following tests: tensile and elongation at break, hardness, thermal ageing and CHN elementary analysis. It was observed a decrease in mechanical properties for irradiated samples at doses higher than 20 kGy,.
Butyl rubber recycling by means of gamma radiation followed by mechanical shear
2018 - SCAGLIUSI, SANDRA R.; CARDOSO, ELIZABETH C.L.; LUGAO, ADEMAR B.
Polymeric materials (plastics and rubbers) cover a continuously raising proportion of urban and industrial solid wastes discarded in landfills and consequently their impact on environment are more and more concern. Rubbers exhibit a very slow natural decomposition due to their chemical structure weather resistant as well to enzymatic degradation and to microorganisms. Rubber recovering is hampered by its insolubility caused by crosslinked structures. Besides, this tridimensional structure causes various problems for material recovering and reprocessing. Just 8% to 12% of polymeric residues are thermoplastic polymers; remaining are elastomers especially post consumption tires. It is relevant to emphasize that the crosslinking is essential for practical use of rubber and this process is worldwide known as vulcanizing process, discovered by North American Charles Goodyear. The implementation of new technologies in order to reduce polymeric residues, acceptable from the environmental viewpoint and at an effective cost proved to be a great problem due to inherent complexities for polymers reuse. Ionizing radiation has capacity to change structure and properties of polymeric materials. Butyl rubbers have been used in wide scale within a variety of applications such as tires spare-parts and diverse artifacts. Major effect of high energy photon, such as gamma rays in butyl and halo-butyl rubbers is the creation of free radicals accompanied by changes in mechanical properties. This work aims to the development of processes of controlled degradation (de-vulcanizing) of butyl rubber in order to characterize their availability for modification and changes of their properties. Experimental results obtained showed that butyl rubbers irradiated at 25 kGy and further sheared can be used as the starting point for mixtures with pristine rubber.
Butyl rubber recycling via gamma radiation followed by mechanical shear
2018 - SCAGLIUSI, SANDRA R.; CARDOSO, ELIZABETH C.L.; ESPER, FABIO; LUGAO, ADEMAR B.
Polymeric materials (plastics and rubber) have been contributing in a continuously and raising way for the generation of litter and industrial wastes discarded in landfills. The implementation of new technologies for the reduction of polymeric materials, acceptable from the environmental viewpoint and at an effective cost, proved to be a great problem, due to complexities inherent for the re-use, especially of rubbers. Gamma ionizing radiation has capacity for changing structure and properties of polymeric materials and can be applied to almost all types of polymers; irradiation is an expectation for problem-solving of rubber wastes management that can be utilized as raw-materials or chemical additives. The relatively low degree of unsaturation presented by butyl rubber (IIR) is responsible for the great resistance of butyl rubber to oxygen, ozone and heat, as well as low gas and water vapor permeability. At the initial stage of irradiation, the degradation of bromobutyl rubber occurs predominantly via random chain-scission and chain-crosslinking may occur caused from the isoprene copolymerized units. This work aims to the introduction of a new recovery technique for bromobutyl rubber, by using processing via gamma rays followed by shear. Rubber was irradiated at 0 kGy, 5 kGy, 15 kGy, 25 kGy, 50 kGy, 100 KGy, 150 kGy and 200 KGy doses, in order to study the feasibility of bromobutyl rubber for recycling. 25 kGy doses, applied to butyl rubber further sheared, pointed toward a less degraded material, indicating that this type of elastomer is able to be incorporated to a new rubber compound and replacing some parts of pristine rubber in formulations without imparting great losses in physical-chemical properties.
Effect of gamma-radiation on thermal ageing of butyl rubber compounds
2018 - SCAGLIUSI, SANDRA R.; CARDOSO, ELIZABETH C.L.; LUGAO, ADEMAR B.
Butyl rubber has a comprehensive use in sealing systems, especially in tires inner tubes, due to their low permeability to gases. So, it is required that butyl rubber compounds show a better performance, more and more. Butyl rubber is provided with excellent mechanical properties and oxidation resistance. Besides showing these properties, radiation exposures impart modifications in physical-chemical and morphological properties on butyl rubber materials. When exposed to gamma-radiation, rubbers suffer changes in their mechanical and physical properties, caused by material degradation. The major radiation effect in butyl rubbers is chain- scission; besides, ageing promotes too the same effect with further build-up of free radicals. This work aims to the study of gamma-radiation in physical-chemical properties of butyl rubber subjected to thermal ageing. Doses used herein were: 25 kGy, 50 kGy, 100 kGy, 150 kGy and 200 KGy. Samples were evaluated before and after ageing according to traditional essays, such as: hardness, tensile strength and elongation at break. From accomplished assessments it is possible to affirm that at doses higher than 50 kGy it was observed a sharp decreasing in butyl rubber physical-chemical properties, before and after exposure to ageing.
Influence of gamma radiation on epdm compounds properties for use in nuclear plants
2016 - SCAGLIUSI, SANDRA R.; CARDOSO, ELISABETH C.L.; ZAHARESCU, TRAIAN; LUGAO, ADEMAR B.
Various types of EPDM rubbers are used in radiation areas such as coating materials for wire and electrical cables, due to their higher resistance to environmental effects when compared to other types of rubbers. Properties set for EPDM rubbers that include degradation and good chemical resistance, besides excellent electrical properties have been stimulating the application of this elastomer for low and medium voltage (up to 35 kV). EPDM rubber is classified as radiation-resistant, because EPDM structure includes in its principal chain totally saturated bonds, and consequently is able to absorb more energy without cracking polymeric chain. The purpose of this work was studying radiation influence on rubbers compounds used in wires and electrical cables installed in Nuclear Plants. There were prepared EPDM compounds samples, further subjected to gamma radiation at doses: 25 kGy, 50 kGy, 75 kGy, 100 kGy and 200 kGy. Mechanicals properties and swelling properties were assessed in non-irradiated and irradiated samples at different doses. It was observed a reduction in tensile at break values, proportional to the dose applied and pointing toward a raise in material fragility. This reduction is more severe for doses higher than 100 kGy, indicating the predominance of chain-scission with further polymer degradation.
A influência da incorporação de borracha irradiada em compostos de borracha clorobutílica
2015 - SCAGLIUSI, SANDRA R.; CARDOSO, ELIZABETH C.L.; LUGAO, ADEMAR B.
Study of recycling feasibility of bromobutyl rubber to gamma radiation
2015 - SCAGLIUSI, SANDRA R.; CARDOSO, ELISABETH C.L.; LUGAO, ADEMAR B.