Carolina Morelli - Academia.edu (original) (raw)

Papers by Carolina Morelli

Modo de acesso: World Wide Web Inclui bibliografia 1. Engenharia 2. Ensino. I. Título CDD-620 O c... more Modo de acesso: World Wide Web Inclui bibliografia 1. Engenharia 2. Ensino. I. Título CDD-620 O conteúdo dos artigos e seus dados em sua forma, correção e confiabilidade são de responsabilidade exclusiva dos seus respectivos autores.

Polymer Engineering and Science, Jun 12, 2023

Polymeric films are used in numerous applications in the biomedical area. The incorporation of an... more Polymeric films are used in numerous applications in the biomedical area. The incorporation of antimicrobial agents into these materials can prevent their surface from acting as a source of contamination of viruses and bacteria. In the present work, cinnamon and eucalyptus essential oils were incorporated into low‐density polyethylene (LDPE) by melt extrusion, as confirmed by Fourier transform infrared spectroscopy. For the success of incorporation, talc was used as an oil carrier and fixer. Despite high processing temperatures used (up to 175°C), the oleophilic character of talc was able to minimize oil losses, as proven by thermogravimetry. Good thermal and mechanical properties evaluated by differential scanning calorimetry and tensile tests were confirmed. In addition, antimicrobial tests confirmed film activity against virus SARS‐CoV‐2 and bacteria Staphylococcus aureus and Escherichia coli. LDPE films incorporated with both oils showed significant antiviral properties against SARS‐CoV‐2, with viral titers reduction between 95.89% and 100%. Cinnamon oil showed more efficient antibacterial properties than eucalyptus oil, with relative bacterial growths of films next to zero (0.37% for E. coli and 2.07% for S. aureus). To the best of our knowledge, no previous work has developed plastic films incorporated with essential oils with confirmed antiviral properties against SARS‐CoV‐2.

Journal of Applied Polymer Science, May 31, 2016

ABSTRACTTraditional commodity polymers are widely used in several disposable or short‐life items ... more ABSTRACTTraditional commodity polymers are widely used in several disposable or short‐life items and take hundreds of years to decompose in nature. These polymers could be replaced in several uses by biodegradable polymers, like polybutylene adipate‐co‐terephthalate (PBAT) studied in this work. For this, nonetheless, it is necessary to improve some of the PBAT properties, like mechanical resistance and barrier properties. In this work, cellulose nanocrystals (CNC) were incorporated in PBAT with this intention, through melt extrusion. Aiming to avoid CNC aggregation during the drying and extrusion process, a CNC chemical modification with phenylbutyl isocyanate was done. It was possible to obtain PBAT‐CNC melt extruded composites with an elastic modulus 55% higher and water vapor permeability 63% lower than the values of the pure polymer, without compromising PBAT biodegradation. Therefore, the composites prepared with these enhanced properties have great potential as substitutes for traditional commodity polymers. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43678.

Composites Part A-applied Science and Manufacturing, Apr 1, 2016

Abstract Cellulose nanocrystals (CNC) were grafted with an aliphatic and an aromatic isocyanate (... more Abstract Cellulose nanocrystals (CNC) were grafted with an aliphatic and an aromatic isocyanate (octadecyl and 4-phenylbutyl isocyanate) and composites of poly(butyleneadipate-co-terephthalate) – PBAT – with 5 and 10 wt% of modified and non-modified CNC were prepared through solvent casting. Rheological analysis confirmed that the degree of grafting contributed to CNC dispersion and allowed the formation of a percolated structure. The treated-CNC reinforced composites displayed improved mechanical properties, namely: an increase by 120% and 40% in the elastic modulus and the tensile strength, respectively. The best results were obtained with 4-phenylbutyl isocyanate-modified CNC, due to the π – π interactions between the phenyl rings grafted onto the CNC molecules and the aromatic rings of the polymeric chain, as indicated by Raman spectroscopy. To the best of our knowledge, it is the first time that the CNC incorporation is studied in a PBAT pure matrix.

Polymer Engineering and Science, Jun 4, 2016

Cellulose nanocrystals (CNC) were successfully grafted with a low molecular weight poly(butylene ... more Cellulose nanocrystals (CNC) were successfully grafted with a low molecular weight poly(butylene glutarate) through an “in situ” polymerization procedure. The grafting treatment decreased the CNC hydrophilic character and increased the onset of their thermal degradation by approximately 20°C, thus increasing the possibilities of CNC application. Composites of grafted and nongrafted CNC with a poly(butylene-adipate-co-terephthalate) (PBAT) matrix were prepared by melt extrusion. The CNC addition led to an increase of 50% of the tensile elastic modulus of the PBAT. In addition, dynamic mechanical thermal analysis showed that the composite with CNC retained its high modulus even at temperatures far above the glass transition temperature of PBAT. At 60°C the storage modulus of the composite with CNC was approximately 200% higher than that of the pure PBAT. Thus, in this work, nanocomposites of improved properties were obtained through a combination of “in situ” polymerization and melt extrusion. POLYM. ENG. SCI., 2016. © 2016 Society of Plastics Engineers

Macromolecular Symposia, Sep 1, 2012

ABSTRACT In this study cellulose nanowhiskers were obtained from balsa wood. For this purpose, fi... more ABSTRACT In this study cellulose nanowhiskers were obtained from balsa wood. For this purpose, fibers of balsa wood were exposed to hydrolysis reactions for lignin and hemicellulose digestion and acquisition of nano-scale cellulose. Transmission electron microscopy (TEM) results demonstrated that the obtained cellulose nanocrystals had average length and thickness of 176 (± 68 nm) and 7.5 (± 2.9 nm), respectively. Infrared spectroscopy (FTIR) and wide angle x-ray diffraction (WAXD) showed that the process for extracting the nanowhiskers digested nearly all the lignin and hemicellulose from the balsa fiber and still preserved the aspect ratio and crystallinity satisfactory enough for future application as nanofillers in polymer nanocomposites. The thermogravimetric analysis (TGA) showed that the onset temperature of thermal degradation of the cellulose nanocrystals (226 °C) was higher than the onset temperature of the balsa fiber (215 °C), allowing its use in molding processes with polymers melts.

OBSERVATÓRIO DE LA ECONOMÍA LATINOAMERICANA

No mercado automotivo atual existe uma busca constante pela redução das taxas de emissão de gases... more No mercado automotivo atual existe uma busca constante pela redução das taxas de emissão de gases poluentes e o aumento da segurança veicular. Para atender a essas demandas o mercado tem investido constantemente no desenvolvimento de novos materiais. O aumento de 10% na massa do veículo resulta em uma redução de eficiência de 4,6% no consumo de combustível, o que, por sua vez, aumenta as emissões de gases poluentes. Nesse contexto, os materiais poliméricos se tornaram uma opção amplamente utilizada na construção de veículos últimos anos. No entanto, a degradação e a durabilidade são as principais limitações na aplicação de polímeros na indústria automotiva. Este trabalho tem como objetivo estudar o processo de degradação termo-oxidativa da blenda de PEAD, EVOH e PE-g-AM. Nesse estudo foram realizadas seis condições experimentais, totalizando 48 amostras, que por sua vez foram analisadas por meio das técnicas de caracterização: Calorimetria Exploratória Diferencial (DSC), Espectrosco...

Polymer Engineering & Science

Materials Research

We discuss the preparation of Polypyrrole and Polylactic Polyacid (PPy/PLA) based blends and the ... more We discuss the preparation of Polypyrrole and Polylactic Polyacid (PPy/PLA) based blends and the subsequent investigation of their antibacterial properties. After being molded through injection processing, the blends were characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), Impedance Spectroscopy (IS), contact angle, thermogravimetry (TGA), and dynamic mechanical analysis (DMA). FTIR analysis confirmed the presence of PPy chains and the IS results indicated that the blends prepared with a 50% mass fraction of PPy have a conductive character. While the SEM images reveal the presence of small cracks on the surface of the samples, DMA analyses show that a decrease in their mechanical strength occurs in the 50°C-60°C range, with the blend with a 50% PPy load exhibiting the greater resistance and being able to withstand temperatures of the order of 120°C. The TGA degradation profile varies according to the amount of polypyrrole present in the blends, with those containing 50% PPy being able to retain about 32% of the polypyrrole mass at 600°C. The antibacterial activity tests done with the injected blends reveal that while no inhibition halo was formed for the Escherichia coli bacterium, the growth of Staphylococcus aureus is inhibited in the 50% PPy blend.

Notre travail a pour objectif l'étude de l'influence de l'ajout de nanocristaux de ce... more Notre travail a pour objectif l'étude de l'influence de l'ajout de nanocristaux de cellulose dans des matrices biodégradables sur leurs propriétés. Des films composites et des pièces injectées ont été préparés et caractérisés. Dans ce but, ont été choisis comme matrices le poly(acide lactique), PLA, et le poly (butylène adipate-co-téréphtalate)), PBAT. Deux matières première d'où des nanocristaux de celulose ont été extraites ont été sélectionnées : le bois balse et la cellulose microcrystalline (CMC). En raison du caractère fortement polaire des nanocristaux de cellulose différentes voies de modifications chimiques de la surface de ces particules ont été testées afin d'assurer une bonne dispersion de ceux-ci lorsqu'ils sont ajoutés à des matrices polymères de polarité inférieure. En effet, les approches testées étaient: (a) le greffage de deux types d'isocyanates, dont l'un aliphatique et l'autre aromatique: l'octadécyl isocyanate (NCC_oct) e...

Research, Society and Development, 2020

Os poliuretanos são polímeros preparados a partir da reação entre isocianatos polifuncionais e po... more Os poliuretanos são polímeros preparados a partir da reação entre isocianatos polifuncionais e polióis, contendo ligações uretano intramoleculares. O poliuretano termorrígido (PUR) é um polímero não biodegradável e não reprocessável por fusão, de modo que o seu resíduo se torna um problema ambiental. O objetivo desse trabalho foi produzir e caracterizar compósitos de poliuretano termoplástico (TPU) incorporados com partículas de resíduo de poliuretano termorrígido através do processo de extrusão, como uma alternativa para o reaproveitamento do resíduo de PUR e melhoria das propriedades do TPU. Os compósitos extrudados com teores de PUR de 10%, 20% e 30% em massa tiveram suas propriedades morfológicas, térmicas e mecânicas analisadas. O compósito com teor de 20% de carga (TPU/PUR20%) apresentou os melhores resultados, com um aumento de 117% no módulo elástico e de 79% na tensão de escoamento quando comparado à matriz pura (TPU/PUR0%). O não incremento adicional das propriedades mecân...

Ampliação e Aprofundamento de Conhecimentos nas Áreas das Engenharias 2, 2020

O presente estudo de doutorado teve como objetivo avaliar o potencial deaplicacao de nanocristais... more O presente estudo de doutorado teve como objetivo avaliar o potencial deaplicacao de nanocristais de celulose como reforco em matrizes polimericasbiodegradaveis, em aplicacoes de filmes ou em pecas moldadas por injecao.Duas matrizes polimericas de diferentes propriedades foram utilizadas paraestudo nessas aplicacoes, sendo elas: poli(butileno adipato-co-tereftalato),PBAT, e poli(acido lactico), PLA. Foram tambem selecionadas duas fontes paraextracao dos nanocristais de celulose (NCC): a celulose microcristalina (CMC)e a madeira balsa.Devido ao carater altamente polar dos nanocristais de celulose diferentesrotas de modificacoes quimicas superficiais dessas particulas foram testadas,visando garantir a boa dispersao dos mesmos quando adicionados as matrizespolimericas de menor polaridade. Foram elas: a) modificacao quimica com doistipos de isocianatos, sendo um de cadeia alifatica (octadecil isocianato) e outrode cadeia aromatica (fenilbutil isocianato); b) enxertia do poli(butileno gl...

Notre travail a pour objectif l'etude de l'influence de l'ajout de nanocristaux de ce... more Notre travail a pour objectif l'etude de l'influence de l'ajout de nanocristaux de cellulose dans des matrices biodegradables sur leurs proprietes. Des films composites et des pieces injectees ont ete prepares et caracterises. Dans ce but, ont ete choisis comme matrices le poly(acide lactique), PLA, et le poly (butylene adipate-co-terephtalate)), PBAT. Deux matieres premiere d'ou des nanocristaux de celulose ont ete extraites ont ete selectionnees : le bois balse et la cellulose microcrystalline (CMC). En raison du caractere fortement polaire des nanocristaux de cellulose differentes voies de modifications chimiques de la surface de ces particules ont ete testees afin d'assurer une bonne dispersion de ceux-ci lorsqu'ils sont ajoutes a des matrices polymeres de polarite inferieure. En effet, les approches testees etaient: (a) le greffage de deux types d'isocyanates, dont l'un aliphatique et l'autre aromatique: l'octadecyl isocyanate (NCC_oct) e...

Polymers from Renewable Resources, 2020

Plastic packagings are widely used for several food products. Considering the relatively short se... more Plastic packagings are widely used for several food products. Considering the relatively short service lifetime of this application, it is important to perceive in the search of eco-friendly alternatives to this market, such as polymers from renewable sources, as thermoplastic starch and “green” polyethylene. The incorporation of an antibacterial agent to the packaging can extend food shelf life. Camellia sinensis is a plant with known antibacterial properties used in the preparation of “green tea.” In the present work, green tea was incorporated to a blend of cassava thermoplastic starch and high-density polyethylene (HDPE) by melt extrusion, aiming application as active packaging. Films were obtained by thermopressing and characterized through infrared spectroscopy, thermogravimetric analysis, scanning electron microscopy and tensile tests. Their antibacterial properties were evaluated against Staphylococcus aureus and Escherichia coli. The results indicated that the material deve...

Polymers and Polymer Composites, 2019

Antistatic packagings are very important for proper transportation and storage of electronic comp... more Antistatic packagings are very important for proper transportation and storage of electronic components since these components can be damaged with electric overloads generated through rubbing. Therefore, the purpose of this study was to develop an innovative material for antistatic packaging with a sustainable character. For this, a blend of recycled poly(ethylene terephthalate) (PET), polycarbonate (PC), and polyaniline (PAni) was prepared by melt extrusion. Samples have a final content of 68 wt% of PET, 29 wt% of PC, and 3 wt% of PAni doped with cobalt (PAni-Co). The properties were determined by differential scanning calorimetry, thermogravimetric analysis, tensile testing, electrical resistivity analysis, and Fourier transform infrared spectroscopy. To the best of our knowledge, no previous work studied the incorporation of PAni-Co in PET/PC blend.

Journal of Renewable Materials, 2019

Although nanocomposites have recently attracted special interest in the tissue engineering area, ... more Although nanocomposites have recently attracted special interest in the tissue engineering area, due to their potential to reinforce scaffolds for hard tissues applications, a number of variables must be set prior to any clinical application. This manuscript addresses the evaluation of thermo-mechanical properties and of cell proliferation of cellulose nanocrystals (CNC), poly(butylene adipate-co-terephthalate) (PBAT), poly(ε-caprolactone) (PCL) films and their bionanocomposites with 2 wt% of CNC obtained by casting technique. Cellulose nanocrystals extracted from Balsa wood by acid hydrolysis were used as a reinforcing phase in PBAT and PCL matrix films. The films and pure CNC at different concentrations were cultured with osteoblasts MG-63 and the cell proliferation was assessed by AlamarBlue ® assay. The thermal-mechanical properties of the films were evaluated by dynamic-mechanical thermal analysis (DMTA). It was found by DMTA that the CNC acted as reinforcing agent. The addition of CNCs in the PBAT and PCL matrices induced higher storage moduli due to the reinforcement effects of CNCs. The cell viability results showed that neat CNC favored osteoblast proliferation and both PBAT and PCL films incorporated with CNC were biocompatible and supported cell proliferation along time. The nature of the polymeric matrix or the presence of CNC practically did not affect the cell proliferation, confirming they have no in vitro toxicity. Such features make cellulose nanocrystals a suitable candidate for the reinforcement of biodegradable scaffolds for tissue engineering and biomedical applications.