Search

Acute wound dressings can be based on PVA hydrogels, which present many characteristics of an ideal dressing, e.g., fluid uptake, a moisturized environment, etc. The lack of antimicrobial properties leads to the addition of natural active agents. The present work aims to manufacture and compare PVA gels loaded with Barbatimão bark extract, Leucaena bark extract, Aloe vera, and Lavender essential oil. They were characterized by FTIR, swelling tests, SEM, actives release. There were interactions between PVA and the active agents. The addition of Leucaena and Barbatimão increased the PVA ability to swell, but the opposite was found for Aloe vera and Lavender essential oil. PVA-Lavender essential oil samples presented interconnected pores, while samples with essential oil or extracts presented high crystallinity. Lavender essential oil and Aloe vera presented the highest release. The Barbatimão and Leucaena samples’ release may be related to the samples’ swelling, but the initial release of Aloe vera and Lavender samples was diffusion controlled by swelling. Their long-term release was dose-dependent for Aloe vera, while it was a non-Fickian diffusion for Lavender essential oil related to the hydrogel’s relaxation step. There is a synergistic effect when Aloe vera and Lavender essential oil are loaded in PVA hydrogels.

Submitted by Boris Flegr (boris@uerj.br) on 2021-01-07T19:04:14Z No. of bitstreams: 1 Thiago Ramos Correia.pdf: 2012687 bytes, checksum: 2d2bcb2b9c731c1cb7a1c2a73e58f13b (MD5) Made available in DSpace on 2021-01-07T19:04:14Z (GMT). No. of bitstreams: 1 Thiago Ramos Correia.pdf: 2012687 bytes, checksum: 2d2bcb2b9c731c1cb7a1c2a73e58f13b (MD5) Previous issue date: 2016-03-11 So much has been discussed about the problem of irregular disposal of plastic materials. As alternatives to decrease these problems, the study of biodegradable polymers has intensified every year. The poly (lactic acid) (PLA) is a biodegradable polymer which has a great versatility and the study of their crystallinity aims to find better properties to increase the number of its possible applications. In this work, the crystallinity of the poly (lactic acid) was induced by adding nucleating agent and annealing. Was verified and the influence of the crystallinity content at their biodegradability. Biodegradability tests were conducted in simulated soil following the ASTM G160-03 and G160-12 ASTM and were evaluated the loss of mass, surface morphology of the samples by techniques of optical microscopy (OM) and scanning electron microscopy (SEM) , their thermal stability by thermogravimetric analysis (TGA) and changes in crystallinity by differential scanning calorimetry (DSC), the chemical modification in structure of the compound by infrared spectroscopy (FT-IR) and monitoring the molar mass change of the polymer by gel permeation chromatography (GPC) over time subject to soil burial. Was observed that treatments for crystallinity induction on PLA were effective. The polymer suffers from microbial attack in simulated soil as evidenced by the appearance of surface erosion and microorganisms adhesion by OM and SEM techniques, the appearance of the carboxylic acid carbonyl bands by FTIR technique, and by changes in the thermal properties by DSC and TGA after the biodegradation test O problema ambiental causado pelo descarte irregular de materiais plásticos tem sido muito discutido. Como alternativas para minimizar estes problemas, o estudo de polímeros biodegradáveis tem se intensificado a cada ano. O poli(ácido lático) (PLA) é um polímero biodegradável e de grande versatilidade e o estudo da sua cristalinidade visa buscar melhores propriedades para aumentar o número de suas possíveis aplicações. Neste estudo, a cristalinidade do poli(ácido lático) comercial foi induzida por adição de agente nucleante e por tratamento térmico (annealing) e foi verificada a influência do teor de cristalinidade na sua biodegradabilidade. Os testes de biodegradabilidade foram realizados em solo simulado seguindo a norma ASTM G160-12 com avaliação de perda de massa, morfologia da superfície das amostras por técnicas de microscopia óptica (OM) e microscopia eletrônica de varredura (SEM), resistência térmica por análise termogravimétrica (TGA), variação da cristalinidade por calorimetria diferencial de varredura (DSC), modificação química na estrutura do composto por espectroscopia na região do infravermelho (FT-IR) e acompanhamento da variação da massa molar do polímero por cromatografia de permeação em gel (GPC) ao longo do teste de biodegradação. Foi observado que os tratamentos para indução da cristalinidade do PLA foram efetivos e que o PLA sofre ataque microbiano em solo simulado, comprovado pelo aparecimento de erosão superficial e adesão de microrganismos pelas técnicas de OM e SEM, pelo surgimento de bandas de carbonilas de ácido carboxílico por técnica de FTIR, e por modificações nas propriedades térmicas por DSC e TGA após o ensaio de biodegradabilidade