Papers by Gisele Cristina Valle Iulianelli
Observatorio de la economía latinoamericana, Jan 25, 2024
Observatorio de la economía latinoamericana, Jan 25, 2024
Concilium, Sep 13, 2023
Currently, the use of biodegradable polymers for packaging application has been an imperative top... more Currently, the use of biodegradable polymers for packaging application has been an imperative topic due to the environmental damage caused by non-biodegradable materials. In the present study, PBAT/ZnO biodegradable nanocomposites were prepared by melt processing and characterized by FEG-SEM, DSC, XRD, TDNMR and water activity analysis. The main results showed an increase in the Tc values for all produced formulations, indicating a change in the crystalline profile of the PBAT, which was corroborated by XRD results. FEG-SEM showed that the systems containing up to 1 wt.% of ZnO showed better nanoparticles dispersion, while formulations containing 3 and 5 wt.% of ZnO presented large aggregates. TDNMR provided a more detailed assessment, showing that PBAT/ZnO systems containing 0.5 and 5 wt.% of ZnO presented a higher heterogeneity at molecular level. Finally, water activity analysis showed that ZnO addition promoted an increment in the biosafety levels compared to neat PBAT, making the PBAT/ZnO nanocomposites more promising for food packaging application.
Polymer Testing, Feb 1, 2018
PHB/TiO 2 nanocomposites were prepared and characterized in terms of thermal, morphological and m... more PHB/TiO 2 nanocomposites were prepared and characterized in terms of thermal, morphological and molecular dynamic characteristics. The TGA analysis revealed that all the PHB systems containing TiO 2 presented an increment in thermal stability. From XRD analysis, it was seen that between 30 and 90°C the systems did not present significant differences regarding their crystalline profiles. On the other hand, presence of TiO 2 nanoparticles promoted notable changes, revealing that they can act as nucleating agent for PHB. The systems were also investigated by T 1 H measurement, combining different experimental NMR techniques. The main NMR results showed that FFC-NMR provided more detailed information about molecular motion in different time and length scales. It was seen that TiO 2 addition changed the dynamic molecular behavior of the PHB matrix for chain segments containing more than fifty carbon atoms.
Brazilian Journal of Development, Jun 16, 2021
A sopa derivada dos alimentos funcionais e temperos funcionais têm como objetivo principal propor... more A sopa derivada dos alimentos funcionais e temperos funcionais têm como objetivo principal proporcionar a população uma alimentação funcional, saudável, saborosa e com alimentos de fácil acesso e baixo custo, visando aumentar a imunidade do organismo rapidamente, ajudado a combater as doenças do trato respiratórias, auxiliando na eliminação de secreção das vias respiratórias.
Journal of Food Composition and Analysis, May 1, 2016
Cassava is widely cultivated in tropical and subtropical regions of Africa, Asia and Latin Americ... more Cassava is widely cultivated in tropical and subtropical regions of Africa, Asia and Latin America and is the third most important source of calories in the tropics, after rice and maize. Cassava is mainly composed of starch, fibre, proteins, lipids and essential minerals. However, the nutrient composition differs according to the variety. Despite the large number of cassava genotypes, studies involving both chemical composition and structural aspects through molecular dynamic behaviour are scarce. The present study investigated six cassava genotypes with respect to chemical composition and molecular dynamic behaviour, employing nuclear magnetic resonance (NMR) spectroscopy. The samples were characterized by high-field NMR and low-field NMR techniques, namely cross-polarization magic-angle spinning, variable contact time, proton spin-lattice relaxation time in rotating frame, spin-spin relaxation time and NMR measurements of lipid fraction. The combined use of solid-state NMR techniques was shown to be a powerful tool for characterizing foods such as cassava. The main results revealed that the six cassava genotypes differ in the chemical composition of the starch, as well as the minor components, such as fibre and oil. These differences influence structural aspects; thus changes in the molecular dynamic behaviour can be observed. 2016 Published by Elsevier Inc.
Polymer Engineering and Science, Sep 23, 2016
The preparation and properties of hybrid materials based on poly(lactic acid)/poly(lactic acid-co... more The preparation and properties of hybrid materials based on poly(lactic acid)/poly(lactic acid-co-glycolic acid) (PLA/ PLGA) blends using microcrystalline cellulose (MCC) and organophilic silica (R972) as fillers have been investigated. Hybrid materials were manufactured by solution casting using chloroform as solvent to prepare films. R972 was incorporated in a ratio of 3 wt%, and MCC was added in ratios of 3, 5, or 7 wt% with respect to the weight of the polymeric matrix. Films were prepared with only MCC addition or with MCC and R972 combined. Properties of the films were evaluated by X-ray diffraction (XRD), nuclear magnetic resonance, differential scanning calorimetry (DSC) and mechanical property measurements. The results show that each filler, when added individually or in combination, affects the structure and final properties of the films differently. MCC acts as a nucleating agent for the crystallization of the polymeric matrix. An increase in the MCC content increased the crystallinity of the films. This effect became more pronounced with silica addition. The domain distribution curves showed PLA/PLGA blends to be homogeneous, which was further confirmed by DSC. An improvement in the mechanical performance was observed with MCC addition, especially when silica was added together with cellulose. POLYM. ENG. SCI.,
Chemistry and Chemical Technology, Sep 15, 2010
PVC/wood flour composites were prepared by compression molding using sapwood and heartwood from A... more PVC/wood flour composites were prepared by compression molding using sapwood and heartwood from Angelin Pedra as filler. The composites specimens were subjected to water immersion and impact tests. The results showed that the water absorption of all composites increased slightly with increasing immersion time and wood content. However, the values were considerably low compared with control sample, common solid woods and wood plastic composites reported in literature. PVC/sapwood composites showed slightly higher values for moisture absorption ability due to the difference in chemical constituents' ratio. PVC compound and PVC/sapwood composite containing 10 phr of wood flour exhibited maximum water absorption in 63 days and it corresponded to 0.25 % and 0.58 % weight gain, respectively. In relation to impact test, the results indicated that impact property was affected by wood content and less by wood type. Composites containing 10 phr of wood content showed greater impact strength (decreased by around 60 %) than those prepared with 25 and 40 phr of wood flour content (decreased approximately by 75 %). In general the composites prepared with 10 phr of wood flour content exhibited a better performance in both parameters measured in this study.
Polymer Testing, Aug 1, 2017
The aim of this work was to compare the effects of microcrystalline cellulose (MCC) and cellulose... more The aim of this work was to compare the effects of microcrystalline cellulose (MCC) and cellulose nanocrystals (CNC) addition on the properties of PLA matrix. The CNC were obtained by acid hydrolysis of the MCC. Both MCC and CNC were separately incorporated in PLA at ratios of 3, 5 and 7 wt%. In some compositions, organophilic silica (R972) was added to improve the cellulose-matrix compatibility. The properties of the materials were evaluated by FTIR, XRD, NMR and mechanical tests. Functional groups and crystalline structure of MCC and CNC were determined by FTIR and XRD, respectively. NMR T 1 H values showed that films containing CNC presented better interfacial interaction than those containing MCC, and indicated that R972 acts as compatibilizer. MCC and CNC acted as nucleating agents for PLA crystallization and there was an improvement in the mechanical performance of materials with the addition of CNC.
Materials Sciences and Applications, 2021
In recent years, there has been a growing discussion about the problems related to the massive us... more In recent years, there has been a growing discussion about the problems related to the massive use of many synthetic plastic materials, which inevitably leads to an increase in environmental pollution caused by the inappropriate disposal of these materials. In this sense, biodegradable materials have been a subject of great interest, as they are a real alternative to replace these materials and tackle this issue. In this work, fully biodegradable composites were prepared by solution casting method. Microcrystalline cellulose (MCC) and treated microcrystalline cellulose (TMCC) were separately incorporated into biodegradable PLA and PHB matrices at ratios of 3, 5 and 7 wt% and the properties of the obtained biocomposites were evaluated by TGA, DSC, XRD and TD-NMR. From thermal analyses, it was seen that TMCC resulted in better thermal stability and 3 wt% of filler, in general, promoted a more pronounced thermal improvement. Furthermore Tg, Tc and Tm remained practically unchanged after MCC and TMCC addition. From XRD it was seen that the cellulose fillers influence in different ways the matrices, promoting increase or decrease in the degree of crystallinity. Finally, the results obtained by TD-NMR showed a decrease in the T 1 H values for all prepared biocomposites, indicating a good dispersion of the cellulose fillers in the matrices and pointed that the systems containing 3 wt% of cellulose fillers were the most homogeneous formulations.
Materials Sciences and Applications, 2017
NMR relaxometry is one of the techniques that allow observing changes in the molecular mobility t... more NMR relaxometry is one of the techniques that allow observing changes in the molecular mobility that come from materials' morphology. T 1 H has been used to monitor food and polymer sciences. However, T 2 H, although being a revealing as T 1 H, is rarely used to analyze changes in thermoplastic systems it is more sensitive to the mobile region. High Impact Polystyrene nanomaterials were prepared through solution casting and were exposed for different times to UV light in the air. The samples, removed after each exposure interval, were characterized by T 2 H, focusing on the changes in the relaxation data. The results for this parameter showed that the changes in the relaxation data come from the competition of chain scission and chain recombination processes, which occurs due to the UV light influence with increased time. The T 2 H data indicated that the clay ratio can influence the chain degradation processes, acting to inhibit or accelerate the aging process [1] [2].
Materials Sciences and Applications, 2016
In recent years, several studies have been performed using nanocellulose as a component in polyme... more In recent years, several studies have been performed using nanocellulose as a component in polymeric nanocomposites. The interest in studying cellulose-based nanocomposite is due to the abundance, renewable nature, and outstanding mechanical properties of this nanoparticle. However, obtaining nanocomposites based on nanocellulose, with optimal properties, requires good nanoparticle dispersion in the polymeric matrix. The chemical compatibility between nanofiller and polymer plays a major role in both the dispersion of particles in the matrix and the adhesion between these phases. The aim of this review is to present the fundamental concepts about nanocellulose, such as its structural aspects, production methods and current trends in classification, and the main aspects about cellulose-based nanocomposites, including the progress that has been reached in relation to their compatibilization, production, final properties and potential applications.
Brazilian Journal of Development, 2020
Neste trabalho foi empregada a ressonância magnética nuclear para caracterizar os componentes/com... more Neste trabalho foi empregada a ressonância magnética nuclear para caracterizar os componentes/compostos obtidos dos extratos da canela obtidos pelo emprego de diferentes solventes visando detectar os bioativos que apresentam atividade bactericida, fungicida e antiviral. Foi detectado em todos os extratos a presença do cinamaldeído, que apresenta a característica bactericida e fungicida, além do eugenol em pequenas proporções que apresenta ação antiviral. Além desses componentes também foi observado os sinais referentes ao polímero poli(metil hidroxi calcona) que tem por característica mimetizar a ação da insulina; permitindo assim uma ação efetiva no controle da glicemia.
Macromolecular Symposia, 2011
The main purpose of the present work is to use a renewable material obtained from fruit seed to p... more The main purpose of the present work is to use a renewable material obtained from fruit seed to prepare a reinforced polymer composite with poly(vinyl chloride) (PVC). The characterization of the composites was based on the determination of the molecular motion and of mechanical and thermal properties. The thermal properties were characterized through thermogravimetric analysis (TG) and differential scanning calorimetry (DSC). The mechanical properties were characterized through tensile tests. The molecular dynamic behavior of the polymer matrix was studied by proton spin-lattice relaxation, using low field nuclear magnetic resonance (NMR). It is shown that the thermal properties do not depend on the filler content, although mechanical properties are improved with the addition of filler. Despite that, no strong interaction between the filler and the PVC matrix could be detected.
Materials Research-ibero-american Journal of Materials, 2023
In this work, biodegradable biocomposites were developed using PLA/PHB blend as matrix and two ty... more In this work, biodegradable biocomposites were developed using PLA/PHB blend as matrix and two types of microcrystalline cellulose as filler at three different contents. The biocomposites were evaluated regarding their thermal and morphological characteristics and molecular dynamic behavior. It was seen that cellulose addition did not promote significant changes in the Tm, Tc and Tcc in the matrix. On the other hand, XRD and TGA revealed that the addition of the highest content (7 wt%) of cellulose fillers resulted in a more significant decrease in crystallinity and thermal stability of the PLA/PHB matrix, suggesting a formation of filler aggregates. This indication was confirmed by TD-NMR, whose results pointed to a greater heterogeneity molecular in the samples containing higher cellulose contents. Therefore, this technique proved to be a relevant and complementary tool for the characterization of composites materials, contributing to determinate the most appropriate filler content introduced in a polymer matrix.
Seven Editora eBooks, May 12, 2023
A soup with functional foods and functional seasonings, which have bioactive substances that bene... more A soup with functional foods and functional seasonings, which have bioactive substances that benefit our body and bring greater protection against diseases. The following functional foods and seasonings were chosen for this soup: Yam; Green cabbage; Pumpkin, Sweet Potato, and Red Meat, in addition to functional seasonings such as garlic, tomato, and onion, topping up after ready, with chopped chives and others, such as pepper, for example. The ingredients described are fundamental to the composition of the soup; other seasonings can be added to taste. The main objective of this soup composition was to provide the population with a functional, healthy, tasty diet with easily accessible and low-cost foods, aiming to increase the body's immunity quickly, helping to combat respiratory tract diseases, and helping to eliminate secretions of the airways.
Materials Sciences and Applications, 2015
This article reports the preparation of a series of EVA nanocomposites employing solution casting... more This article reports the preparation of a series of EVA nanocomposites employing solution casting methods using different types of organo-modified montmorillonite clay. The effect of the organoclay type on the structural organization and thermal behavior of EVA nanostructured materials were systematically investigated. Regarding thermal behavior, the thermogravimetric analysis showed that the nanocomposites presented a slight decrease in thermal degradation temperature compared to EVA, while differential scanning calorimetry, in general, did not show a significant change in the thermal transition temperatures such as glass transition, melting temperature and crystallization temperature of the nanocomposites, regardless of the type and proportion of organoclay in the systems. With respect to structural aspect, the X-ray diffractograms showed that all systems presented a heterogeneous distribution of the nanoparticles, containing part intercalated. Nuclear magnetic resonance relaxometry data provided complementary information for the X-ray results, showing that the EVA systems containing 5 wt% of both studied organoclays presented a mixture of intercalated and exfoliated structures, evidencing that there was a surface interaction between polymer chains and clay lamellae.
Polymer Testing, Feb 1, 2016
Abstract Nanostructured materials based on PHB and different types of nanoclay were prepared and ... more Abstract Nanostructured materials based on PHB and different types of nanoclay were prepared and characterized as regards changes in the thermal behavior and morphological/structural characteristics. With respect to the thermal degradation profile, the addition of nanoclays to the PHB matrix did not, in general, cause loss of thermal stability. Regarding morphology/structure, X-ray diffraction revealed that the addition of the nanonoclays altered the crystallinity profile of some samples and suggested that the materials containing 1 wt% nanoclay have a predominantly exfoliated structure. In turn, the information obtained by NMR relaxometry provided a more precise and detailed understanding of the nanomaterials' structure, including the systems with 1 wt% nanoclay. The T 1 H values provided details on the degree of intercalation/exfoliation attained by the different systems, and the domain distribution curves allowed insight into the homogeneity of the systems. According to the NMR relaxometry data, the system formed by PHB/S7 presented the best exfoliated/intercalated relation.
Journal of Research Updates in Polymer Science
The purpose of this work was to study the molecular dynamics, morphology, mechanical and thermal ... more The purpose of this work was to study the molecular dynamics, morphology, mechanical and thermal performance of nanomaterials formed by poly(vinyl alcohol) and molybdenum trioxide (PVA/MoO3) obtained through solution casting method, focusing new materials with therapeutic applications since the molybdenum trioxide exhibit an excellent antibacterial activity and could be a pathway to prevent viruses. The obtaining materials were characterized by conventional techniques as X-ray diffraction, thermogravimetric and dynamical-mechanical analysis. The unconventional low-field NMR relaxometry was used to evaluate the molecular dynamic and morphology of these systems. The results obtained showed that the MoO3 addition into PVA matrix promote an increase on the thermal stability at higher temperatures and a progressive increase on the rigidity of the PVA systems. Also changes in the molecular mobility of nanomaterials determined through the proton spin-lattice relaxation time showed that low...
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Papers by Gisele Cristina Valle Iulianelli