Navegando por Autor "Costa, Anna Raffaela Matos"
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Artigo Degradation during processing of vegetable fiber compounds based on PBAT/PHB blends(Elsevier, 2018-08) Ito, Edson Noriyuki; Costa, Anna Raffaela Matos; Reul, Lízzia Tanira Albuquerque; Sousa, Fernanda M.; Carvalho, Laura Hecker de; Canedo, Eduardo LuísThe effect of the type of filler and concentration on the degradation rate of compounds based on a blend of poly (β-hydroxybutyrate) (PHB) and poly (butylene adipate-co-terephthalate) (PBAT) were studied using a fast and simple procedure of monitoring polymer degradation under processing conditions using torque rheometry. It was found that both the presence and level of two types of filler, taken from two different layers of the babassu palm fruit (mesocarp and epicarp), greatly increase incipient degradation of the blend when processed in an internal laboratory mixer. The qualitative trends and quantitative estimates may be explained by the chemical and morphological characteristics of the two fillers, as observed by optical microscopy. Fracture surface morphology was investigated by scanning electron microscopy (SEM) and indicated better filler-matrix adhesion in PHB-rich blends in epicarp compoundsArtigo Non-isothermal melt crystallization kinetics of poly(3-hydroxybutyrate), poly(butylene adipate-co-terephthalate) and its mixture(Associação Brasileira de Polímeros, 2019) Ito, Edson Noriyuki; Costa, Anna Raffaela Matos; Cavalho, Laura Hecker; Canedo, Eduardo LuísNonisothermal crystallization and melting of the biodegradable thermoplastics poly(3-hydroxybutyrate) (PHB), poly(butylene adipate-co-terephthalate) (PBAT), and a 1:1 PHB/PBAT blend were investigated by differential scanning calorimetry (DSC) over an extensive range of heating/cooling rates (2 to 64°C/min). The different phase transition behavior of the neat components was reflected in the mixture and suggest an immiscible blend. Pseudo-Avrami, Ozawa and Mo classical macrokinetic models were used to describe the evolution of the melt crystallization process. Results suggest that none of these models could be used to predict the experimental results of crystallization kinetics of the blend with sufficient precision for polymer processing applications. However, some methods may be of used for the neat resins over restricted ranges of cooling rate, temperature or conversion (e.g., Ozawa for PHB at low cooling rate, Mo for PBAT)