Maurício Alves Ramos

Silica-rich rice husk ash (RHA) was upcycled as an inorganic filler to engineer cellulose acetate (CA) films with tunable properties for higher-value sustainable packaging. Composite films were produced by solvent casting, varying RHA loading with and without glycerol plasticization. FTIRconfirmed the chemical integrity of CA and indicated an increase in hydroxyl interactions in glycerol-plasticized films. Optical microscopy showed that RHA progressively induces particle domains and aggregation, while glycerol improves dispersion and surface uniformity. These microstructural effects translated into controllable optical–mechanical trade-offs: neat CA remained highly transparent, whereas RHA reduced transmittance. Glycerol had a minor effect effect on transmittance, indicating that shielding is primarily governed by the ash-derived inorganic domains and tensile testing highlighted an optimal low-filler regime. A small RHA addition maximized strength and stiffness in non-plasticized films. Contact-angle measurements in neutral and alkaline media indicated pH-sensitive wetting, with faster deterioration under alkaline conditions. Thermogravimetric analysis confirmed increased char residue with RHA addition and that glycerol introduces an early mass-loss stage. Overall, the CA/RHA platform offers a simple and potentially scalable route to upcycled, silica-reinforced films, and the formulation of CA and 1.33 wt% RHA (without glycerol) stands out as a robust secondary layer with low transmittance in the UV-Vis range, making it suitable for high-value light-sensitive flexible healthcare packaging, such as protective overwraps or translucent pouches.

A proliferação de espécies exóticas invasoras (EEIs) como o Pittosporum undulatum representa um grande desafio para a estabilidade dos ecossistemas naturais. Sua rápida disseminação torna a erradicação e restauração de áreas afetadas inviáveis devido aos altos custos de manejo. Este estudo avalia o potencial de agregar valor à madeira de P. undulatum, buscando formas de transformá-la em um recurso valioso para comunidades locais. Para isso, cinco árvores adultas foram analisadas quanto a suas propriedades químicas, térmicas, caloríficas, físicas e mecânicas. A análise revelou 2,35% de extrativos, 25,56% de lignina e 0,92% de cinzas, com valor calorífico de 4561,2 kcal/kg. Com densidade específica aparente de 0,655 g/cm³, as propriedades mecânicas incluem módulo de ruptura (MOR) de 58,27 MPa. A dureza Janka perpendicular foi de 1841 kgf/cm². A madeira do P. undulatum mostrou propriedades comparáveis a madeiras comercialmente disponíveis, sugerindo viabilidade para aplicações energéticas e na indústria moveleira, com algumas limitações. Os resultados indicam a possibilidade de integrar seu manejo com retornos financeiros.