Teses em Engenharia de Recursos Naturais da Amazônia (Doutorado) - PRODERNA/ITEC

URI Permanente para esta coleçãohttps://repositorio.ufpa.br/handle/2011/4045

O Doutorado Acadêmico inicou-se em 2006 e pertence ao Programa de Pós-Graduação em Engenharia de Recursos Naturais da Amazônia (PRODERNA) do Instituto de Tecnologia da UFPA (ITEC) da Universidade Federal do Pará (UFPA).

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Biocompósito a partir de PLA, Biovidro e Nanotubos de Carbono por Impressão 3D visando Regeneração Óssea
(Universidade Federal do Pará, 2023-03-31) VASCONCELOS, Esleane Vilela; REIS, Marcos Allan Leite; http://lattes.cnpq.br/8252507933374637; https://orcid.org/0000-0003-2226-2653; CANDIDO, Verônica Scarpini; http://lattes.cnpq.br/8274665115727809; https://orcid.org/0000-0002-3926-0403
Bone involvement promoted by aging and accidents has aroused interest in biomaterials and technologies for bone regeneration purposes. Thus, 3D printing technology gained prominence in the production of scaffolds due to its versatility in the production of complex geometries with interconnected pores. In this work, scaffolds composed of poly (lactic acid) (PLA), bioglass (BV) and carbon nanotubes (NTC) were produced by 3D printing, using hexagonal geometry, similar to honeycomb, interleaved. Poly (lactic acid) is a biopolymer already used in biomaterials, while bioglass has proven to be an excellent strategy for use in bone regeneration due to its excellent properties of biocompatibility, bioactivity and osteointegration, however they have low mechanical resistance and carbon nanotubes have shown excellent mechanical reinforcement in composite biomaterials. Thus, the main objective of this study was to produce and characterize a biocomposite of PLA, bioglass and carbon nanotubes by 3D printing and to study its chemical structure, crystallineity and morphology, using fourier transform infrared spectroscopy, Raman spectroscopy, X-ray diffraction and scanning electron microscope. The thermal stability of the composite was evaluated by thermogravimetry, mechanical properties by compression tests and cell viability was determined by the Alamar Blue test. The bioglass was synthesized by sol-gel method presenting bioactive phases of silicate. The scaffolds were produced by 3D printing with hexagonal structures in honeycomb in PLA, PLA/BV and PLA/NTC that were impregnated with bioglass on its surface. The results of the scaffolds demonstratedinterconnected and well-defined pores, ranging from 130 μm to 800 μm. Raman spectroscopy confirmed the interaction of BV in the polymer matrix through new peaks in the spectrum between 1400 and 2600 cm-1 and the presence of the D, G and 2D bands of NTC. In the compression assay, PLA scaffolds with 2 mm diameter showed higher compression stress of 14.88 ± 2.35 MPa, while PLA/NTC higher modulus of apparent compression, 0.58 ± 0.36 GPa. In cell viability, statistical tests showed that there was no significant difference between scaffolds with 2 and 4 mm diameter. The results reveal promising results for the use of 3D printed composites in bone repair sponges. Thus, we suggest the composite of PLA/NTC of 4mm impregnated with BV on the surface as the best bone substitute, however, the application in implants remains limited in relation to osteogenic integration.
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Compósitos híbridos reforçados com tecidos de curauá, carnaúba e aramida com aplicações em blindagem balística
(Universidade Federal do Pará, 2023-01-31) OLIVEIRA FILHO, Edwillson Gonçalves de; CANDIDO, Verônica Scarpini; http://lattes.cnpq.br/8274665115727809
The development of effective ballistic armor systems is essential to ensure human and vehicle protection. These shields are usually made up of different materials, such as fiber-reinforced polymeric composites, which are used when a good weight/ballistic protection ratio is desired. In addition, the search for ecologically correct materials, which associate good mechanical performance with sustainability, has been very frequent nowadays. The present work was directed to the study of the mechanical and ballistic properties presented by composites reinforced with lignocellulosic fibers, intended for armoring applications. An investigation was carried out regarding the characteristics of curaua (Ananas erectifolium) and carnauba (Copernicia prunifera) fibers, examining the average diameter, morphological and chemical analyses. The mechanical characterization of the composites was carried out using curaua and carnauba fibers in continuous and aligned distributions through manual production of polyester-fiber composites with 10, 20 and 30%v/v, through tensile, flexural and Charpy impact. From these results, laminated polyester composites were produced for the first time, using hybrid systems with layers of Aramid-Curaua, Aramid-Carnauba and Curaua-Carnauba fabrics, adopting the molding process by cold pressing. All proposed hybrid composites have 30%v/v of fibers and were produced in non-alternating configuration, being submitted to ballistic impact tests considering the level of protection and residual velocity. The ballistic results showed that the Curaua-Carnauba systems were perforated, unlike the Aramid-Curaua and Aramid-Carnauba systems, which were not pierced, which obtained a level I of ballistic protection. In addition, through the residual velocity results, it confirmed the need for fabrics, not blankets, to be used for ballistic applications of these composites. The results are a strong indication of the possible potential of similar hybrid composite solutions.
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Estudo da incorporação de resíduos industriais, lama vermelha e caulim, nas propriedades de compósitos de matriz poliéster reforçados com fibras de juta e malva
(Universidade Federal do Pará, 2022-07-18) RIBEIRO, Maurício Maia; SILVA, Alisson Clay Rios da; http://lattes.cnpq.br/7389345867032737; https://orcid.org/0000-0001-9186-2287; CANDIDO, Verônica Scarpini; http://lattes.cnpq.br/8274665115727809; https://orcid.org/0000-0002-3926-0403
The Amazon region of Brazil is a major producer of bauxite and kaolin, with the state of Pará accounting for a large national share of the production of these materials. The processing of these raw materials generates considerable amounts of waste that is then stored in sedimentation ponds which can cause serious environmental damage, therefore it is very important to explore reasonable methods of utilizing the red mud and kaolin waste, and thus reduce their landfill volumes. Many recent studies have been conducted and presented various ways of comprehensive utilization of these wastes. Natural fiber reinforced composites with insertion of these industrial wastes have received increasing attention in recent decades, as good specific mechanical properties can be achieved and industrial wastes can be reduced and used in a useful form. In this work, polyester matrix composite materials reinforced by jute and mallow fibers in continuous configuration and aligned at 0° and 90° in the loading direction, and composite materials with insertion of industrial waste were manufactured. The polyester matrix used was a pre-accelerated orthophytalic and cured at room temperature with methyl ethyl ketone peroxide 1.0% by mass. The Jute and mallow fibers were manually cut in length of 300 mm and manually arranged in a continuous manner and aligned and without surface treatment. Fiber composites were produced by vacuum-assisted hand lay-up/vaccum-bagging procedure. The proportions of the fiber volume fraction have varied by 5, 15 e 25 %. The composites with kaolin and red mud residues were manufactured by a manual process in the form of silicone and pressed mold. The proportions of the mass fractions of waste have varied by 5, 10, 15, 20, 25 e 30 %. The residues were characterized in terms of their physical, morphological and chemical aspects and the fibers in terms of their physical and mechanical aspects and the experimental values are similar to that presented from old newspaper. Just as the composites manufactured had their specific mass determined, which resulted in an increase in the average value of the specific mass of the composites with insertion of red mud and kaolin residues. In the case of composites reinforced with fibers of jute and mallow, there was a reduction in the average value when compared to the matrix. Tensile and shear properties were observed for the composites with industrial waste, red mud and kaolin. The composite 5RC exhibited tensile strength value closer to the matrix, as well as for 5RLV, 10RLV and 15 RLV which exhibited the same behavior. For shear strength the composites 10RLV and 15 RLV were closer to the matrix. As well as the composites reinforced with jute fibers 0° presented the highest tensile strength were 0J5, 0J15 and 0J25, exceeding in 2%, 150% and 166% the tensile strength of polyester. For the composites reinforced with mallow fibers 0° showed the highest tensile strength were 0M15 and 0M25, exceeding in 67% and 96% the tensile strength of polyester. For shear strength the composites reinforced with jute (0J15 and 0J25) and mallow (0M15 and 0M25) fibers exceeded the matrix in 201%, 206%, 71% and 144%, respectively. The tensile strength of the three-phase composites (0JRLV, 0JRC, 0MRLV and 0MRC) exceeded the matrix by 129|%, 100%, 54% and 21%, respectively. For shear strength they exceeded the matrix by 49%, 47%, 63% and 52%. Composites with 0-aligned fibers showed satisfactory mechanical behavior for application in composite materials presenting reinforcement characteristics.
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Manufatura aditiva de biocompósitos a partir de ácido poliláctico reforçado por hidroxiapatita e nanotubos de carbono para regeneração de tecido ósseo
(Universidade Federal do Pará, 2024-01-22) BELO, Francilene da Luz; REIS, Marcos Allan Leite dos; http://lattes.cnpq.br/8252507933374637; CANDIDO, Verônica Scarpini; http://lattes.cnpq.br/8274665115727809
Bone tissue is one of the most important tissues in the human body. Unfortunately, some traumatic events can cause fractures that can lead to temporary or permanent disability. Scaffolds are some of the materials that help in the treatment of these fractures, as they play an important role in the bone repair process and can be manufactured by 3D printing. Polylactic acid (PLA), as it is biodegradable, is one of the materials used in the production of scaffolds. Furthermore, the association of PLA and hydroxyapatite (HA) in its manufacture has shown excellent results, accelerating bone regeneration and reducing healing time. Another promising material for making scaffolds are carbon nanotubes (CNT), which have excellent mechanical properties and also accelerate bone growth. Thus, the main objective of this study was to produce scaffolds by additive manufacturing from polylactic acid (PLA) reinforced with hydroxyapatite (HA) and carbon nanotubes (CNT), to be applied in the regeneration of bone tissue and characterized through mechanical and biological. Hydroxyapatite was synthesized by wet means and characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM), presenting phases characteristic of HA, characteristic groups and a morphology with a porous surface with varying particle sizes, important characteristics for a biomaterial. The pure PLA, PLA/HA and PLA/NTC scaffolds were produced by additive manufacturing with an opening between the walls of 1 mm and 2 mm and characterized through mechanical tests and biological tests. Furthermore, PLA/NTC scaffold samples were impregnated with HA on the surface by thermal and chemical treatment to evaluate the influence of ceramics on the composite surface. The micrograph of the scaffolds showed that the addition of CNT made the PLA surface rougher compared to the sample containing HA; The TGA curves suggested that temperature may favor the thermal stability of PLA/NTC scaffolds impregnated with HA on the surface; Ramam showed an interaction between hydroxyapatite on the CNT surface and a possible structural transformation of PLA/CNT; In compression tests, PLA/NTC scaffolds with an opening between the walls of 1 mm showed better compression resistance; In cell viability assays, fibroblasts incubated with pure PLA, PLA/HA and PLA/NTC scaffolds showed high viability after evaluation by the MTT assay for the two forms of preparation (heat treatment impregnation and chemical treatment impregnation and for the two openings between the walls. More than 85% of the cells remained viable after 48h of incubation with all scaffolds tested, with the groups that had NTC in their composition showing the best results, both for heat treatment (more than 95% of cell viability) as well as chemical treatment (acetone). Given the results presented, it is concluded that PLA scaffold reinforced with HA and CNT may be promising as a biomaterial used to aid in the regeneration of bone tissue, contributing to the reduction of time hospitalization of patients suffering from bone fractures.
Acesso aberto (Open Access)
Métodos de obtenção e caracterização de biomembrana de quitosana e copaíba para potencial uso em feridas
(Universidade Federal do Pará, 2022-06-14) PARANHOS, Sheila Barbosa; PASSOS, Marcele Fonseca; http://lattes.cnpq.br/0588450144351187; https://orcid.org/0000-0002-5616-2127; CANDIDO, Verônica Scarpini; http://lattes.cnpq.br/8274665115727809; https://orcid.org/0000-0002-3926-0403
Health professionals deal directly with several complex situations in the care of sick people. Among these, there are skin wounds that can harm the patient's clinical condition, in addition to costly treatment for healing. Skin wounds require dressings to protect against pathogenic microorganisms and to accelerate the healing process. With the emergence of biomaterials available for use in wound treatment, chitosan has become an effective choice, easily found in a natural and renewable form with healing potential. The chitosan membrane presents ideal conditions in the treatment of wounds, such as absorption, protection, biocompatibility and antimicrobial potential. To increase its healing effects, natural oils have been incorporated into the polymer matrix, such as copaiba, which has a high anti-inflammatory action. In this context, the work aimed to obtain and characterize chitosan membranes by emulsion and nanoemulsion of copaiba oil to treat skin wounds. The chitosan membranes with oil addition by emulsion and nanoemulsion were synthesized by the solvent evaporation technique. They were evaluated by macroscopic analysis and characterized by scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, differential scanning calorimetry, swelling percentage, humidity, contact angle. An in vitro assay of antibacterial activity against the bacterium S.aureus was carried out. The membranes had an apparently thin appearance, little malleability, relative opacity, continuous and good handling. He observed more porosity on the surfaces of membranes synthesized by nanoemulsion of copaiba oil, in addition to a more amorphous behavior. He noticed a better interaction between chitosan and oil constituents when the oil synthesis was prepared by nanoemulsion, resulting in improved stability of the material produced. The swelling percentages were higher in the MQCoN-0.1 (214±3.22%) compositions when immersed in water and the MQCoN-5.0 composition (220±6.83%) in the PBS solution. The wetter behavior was significant in membranes composed of 0.1% (0.80±1.37%) and 0.5% (3.00 ±0.79%) copaiba oil nanoemulsions. There was no great influence on the contact angle between syntheses and compositions. The chitosan membrane with 1.0% (v/v) of emulsified oil and the chitosan membrane with 0.5% (v/v) of nanoemulsified oil were the most hydrophilic membranes. All membranes were able to inhibit bacterial growth, except the chitosan membrane with 1.0%(v/v) oil emulsion. Materials obtained by nanoemulsion have ideal attributes for application in the use of skin wounds.
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Síntese e Caracterização de Membrana de Quitosana com Extrato de Banana Verde e Andiroba para Cicatrização de Lesões Epiteliais
(Universidade Federal do Pará, 2022-03-21) FERREIRA, Elisângela da Silva; CANDIDO, Verônica Scarpini; http://lattes.cnpq.br/8274665115727809; https://orcid.org/0000-0002-3926-0403
Biomaterials must enable the surrounging healthy cells to grow and replace the matrix that constitutes the material. The application of other bioactives is being widely studied, as well as the incorporation of phytosan into chemical removal films in wound healing by different techniques. This study aimed to synthesize and characterize chitosan membranes, green banana peel extract and andiroba oil for application in epithelial devices. Membranes were made in different compositions and characterization tests were carried out on the synthesizer. Andiroba oil was added in pure form or oil-in-water (O/W) emulsion in the chitosan solution. Higher in chitosan membranes with emulsion O/W, being 978.79 % e 423.64 %, in Nano M6 and Nano M11, respectively, after 24 hours of life in water. The highest percentage of moisture was in M7 (24.9 ± 3.8 %) and the lowest in Nano M7 (13.46 ± 0.8 %). All samples are hydrophilic, with lower values with banana peel extracts from the first decoction, M1 (24.0° ± 1.9°) and Nano M6 (23.7° ± 4.3°). Diffractograms are mostly amorphous material, for the most part. Thermal analysis has greater stability of chitosan membranes synthesized with banana peel extract and addition of andiroba oil. Spectroscopy showed characteristic peaks and bands of sample components and interaction between these components, as well as suggestion or encapsulation of the oil. The material first presented characteristics of absorption of liquids and synthesized, in particular the membranes of banana extraction of the day of decoction interaction and with addition of O/W emulsions, with greater possibility of duration of its healing of composting epithelial deficiencies.

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