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.
PLA, PBAT, Cellulose Nanocrystals (CNCs), and their blends
2023 - COSTA, FERNANDA A.T. da; PARRA, DUCLERC F.; CARDOSO, ELISABETH C.L.; GUVEN, OLGUN
PLA/PBAT (Poly (lactic acid)/Poly (butylene adipate-co-terephthalate)) blend is a biodegradable material commonly considered a potential alternative to polymeric products from petroleum sources. PLA is intrinsically brittle, endowed with a low elongation at break and poor impact strength that restricts its use for some applications while PBAT has high ductility, heat resistance, and impact resistance. However, PLA associated with PBAT results in an incompatible blend, due to poor interfacial adhesion. The compatibilization of PLA/PBAT can be improved through physical and chemical interaction between the components, and with exposure to ionizing radiation. Cellulose is the most abundant biodegradable polymer available and is considered the potential material to be used as reinforcement in sustainable composite materials, as well as nanocellulose while an alternative to synthetic nanoparticles. This review describes the state of the art of polymer blends of PBAT and PLA, in terms of manufacturability, compatibilization, biodegradation, radiation processing, and cellulose nanocrystal reinforcement.
Introduction to foamability study of a LDPE subjected to gamma radiation
2022 - CARDOSO, ELIZABETH C.L.; SCAGLIUSI, SANDRA R.; PARRA, DUCLERC F.; LUGAO, ADEMAR B.
Nowadays, polymer foams have a wide application area due to their light weight, emphasizing resistance to impact, high thermal insulation and damping properties, among others. So, automotive, packing industry, electronic, aerospace, building construction, bedding and even medical applications are some of the fields where polymer foams are applied. Foams can be classified as open and closed: Closed-cell foam is provided with tiny and discrete pockets of gas, each one totally enclosed within polymer walls; open cell foam has tiny cells which are not completely closed. In this work, LDPE (low density polyethylene) resin foamability was investigated after exposure to ionizing radiation (gamma), at 5, 10 and 15 kGy. Characterizations included: melt flow index, melt strength and scanning electron microscopy.
Introduction to the study of mechanical properties of terpolymer PP/EPDM mixtures
2021 - SCAGLIUSI, SANDRA R.; CARVALHO, ELIZABETH C.L.; LUGAO, ADEMAR B.
Thermoplastic elastomers (TPEs), based in PP (Polypropylene) / EPDM (Ethylene Propylene Diene Monomer) have as purpose improving PP resistance and impact, aiming to a more comprehensive use in automotive market, among edifications, construction and packaging sectors, due to their recyclability properties. PP is a commodity, with a high melting point, high mechanical resistance and low density, posing a balance between physical and mechanical properties; in addition, it shows an easy processing, at low cost. In order to minimize this deficiency, EPDM, an impact modifier, can be used. Nevertheless, most of polymeric blends are incompatible and immiscible, i.e., show a mutual and limited solubility and in most of cases, a high interfacial tension. However, there is a relatively low interfacial tension (force which acts on transformation of a continuous structure in a dispersion) between PP and EPDM (approximately 0.3 mN.m-1), reducing the rate of breakup and facilitating the build-up of a continuous structure. This work aims to the study of compatibility of PP and EPDM blends and variation of mechanical properties, emphasizing that many properties of thermoplastic elastomers can be processed according with conventional thermoplastics methods: herein, PP/EPDM blends, 90/10, 80/20, 70/30 and 50/50 were characterized according to: Mechanical essays, Differential Scanning Calorimetry, Thermogravimetric Analyses, Melt Flow Index, Izod Impact Strength and Dynamic mechanical Analyses.
Effect of ionizing radiation applied to PLA used as compatibilizing agent in reinforced eGG shell PBAT/PLA bio-based composites
2021 - CARDOSO, ELIZABETH C.L.; PARRA, DUCLERC F.; SCAGLIUSI, SANDRA R.; KOMATSU, L.G.H.; LUGAO, ADEMAR B.
Bio-filler from eggshells as reinforcement of bio-based polymers are based on their benefits as adequate strength and stiffness, besides friendly, degradable and renewable environment. Eggshell is an agricultural waste considered as garbage, contributing to pollution; nevertheless, it can be transformed into bio-calcium carbonate, acquiring new values. As biodegradable polymers, there were chosen PLA (poly-lactic-acid) and PBAT (butylene adipate co-terephthalate), thermoplastics capable to be processed via conventional methods. PLA is a linear, aliphatic thermoplastic polyester, high in strength and modulus, but brittle. PBAT is a synthetic polymer, very flexible, based on fossil resources with high elongation at break, but low strength. It will be required the use of compatibilizers, for reducing interfacial tension exhibited by PLA/PBAT immiscible blend, considering their extreme glass transition temperatures: 62 ° C for PLA and – 30 ° C for PBAT. Herein it was used ionizing radiation for inducing compatibilization by free radicals, improving dispersion and adhesion of blend phases, without using chemical additives, at room temperature. PLA, acting as compatibilizer, was previously e-beam and gamma radiated, at 150 kGy. PBAT/PLA 50/50 blend with 15 phr of biofiller from avian eggs 125 μm particle size and both compatibilizers were homogeneized in a co-rotating twin-screw extruder, within a temperature profile 120 to 145 ° C, from hopper to die. Characterization involved: Differential Scanning Calorimeter, Thermogravimetric Analyses, Fourier Transform Infrared Spectroscopy, Wide Angle X-Ray Diffraction, Tensile Strength and Elongation at Break.
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.
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.
Gamma-radiation effect on mechanical properties of Pp/Epdm polymeric blends
2016 - CARDOSO, ELIZABETH C.L.; SCAGLIUSI, SANDRA R.; LUGAO, ADEMAR B.
Thermoplastic elastomers (TPEs) are provided with many properties of elastomeric or rubbery materials, but can be processed with the thermoplastic processing methods; they are one of the fastest growing polymers materials which combine the elastic and mechanical properties of crosslinked rubbers with the melt processability of thermoplastics. In addition, TPEs find a lot of applications in automotive, buildings and construction, wires and cables, etc.; besides their ability to reuse and recycle the production scrap and waste. Polypropylene (Pp) is a commodity, with high melting point, high chemical resistance, low density, with a balance between physical and mechanical properties and easy processing at low cost. Nevertheless, Pp shows limitations for some special applications, in terms of impact resistance; in order to minimize this characteristic, an impact modifier, as Ethylene Propylene Diene Terpolymer (Epdm) can be used. Due to different polarity and structure between the thermoplastic and elastomeric phases, most thermoplastic elastomers are incompatible. Poor interfacial adhesion and high interfacial tension between rubber and thermoplastic phases are main reasons for incompatibility of these systems; in case of Pp and Epdm, there is a relatively low interfacial tension (driving force for the transformation of a co-continuous structure into a dispersed one) between Pp and Epdm (approximately 0.3 mN/m), reducing the rate of breakup and facilitating the formation of a continuous structure. Pp/Epdm blends are completely recyclable and reusable, safe to the environment, thus improving the overall profitability of the process. Besides a higher impact resistance shown by Pp/Epdm blends, it is possible that Epdm incorporation in Pp causes a reduction in tensile resistance. In order to eliminate this interference and assuring a more comprehensive application in automotive, buildings and construction, Pp/Epdm blends, rubber contents ranging from zero to 30% (thirty percent), were subjected to gamma-irradiation, within doses from 5 to 20 kGy. Isotactic Pp was considered for this work. Characterization assessments included mechanical, thermal and rheological essays.
A influência da incorporação de borracha irradiada em compostos de borracha clorobutílica
2015 - SCAGLIUSI, SANDRA R.; CARDOSO, ELIZABETH C.L.; LUGAO, ADEMAR B.
Prevention of degradation of 'gamma'-irradiated EPDM using phenolic antioxidants
2016 - ZAHARESCU, TRAIAN; ZEN, HELOISA A.; MARINESCU, MADALINA; SCAGLIUSI, SANDRA R.; CARDOSO, ELISABETH C.L.; LUGAO, ADEMAR B.