Silvia Luciana Fávaro

Bio: Silvia Luciana Fávaro is an academic researcher from Universidade Estadual de Maringá. The author has contributed to research in topics: Fiber & Bagasse. The author has an hindex of 14, co-authored 49 publications receiving 847 citations.

Chemical, morphological and mechanical analysis of sisal fiber-reinforced recycled high-density polyethylene composites

Abstract: Natural fibers are widely used as plastic composite material reinforcements. In this work, composites of post- consumer high-density polyethylene (HDPE) reinforced with sisal fibers were prepared. PE and sisal fibers were chemi- cally modified to improve their compatibilities, try to increase the hydrophobic character of the sisal fiber and hydrophilic character HDPE. Sisal was mercerized with a NaOH solution and acetylated and the PE was oxidized with KMnO4 solu- tion. The chemically modified fibers were characterized by Fourier Transformed Infrared Spectroscopy (FTIR) and 13 C Nuclear Magnetic Resonance Spectroscopy ( 13 C NMR). The composites were prepared by extrusion of modified and unmodified materials containing either 5 or 10 wt% fibers. The morphology of the obtained materials was evaluated by SEM. The fiber chemical modification improves it adhesion with matrix, but not benefit were obtained with HDPE oxida- tion. Flexural and impact tests demonstrated that the composites prepared with modified sisal fibers and unmodified PE present improved mechanical performance compared to pure PE.

Chemical, morphological, and mechanical analysis of rice husk/post-consumer polyethylene composites

Abstract: Composites were obtained from post-consumer high-density polyethylene (PE) reinforced with different concentrations of rice husk. PE and rice husk were chemically modified to improve their compatibility in composite preparation. Rice husk was mercerized with a NaOH solution and acetylated. The chemically modified fibers were characterized by FTIR and 13C NMR spectroscopy. The composites were prepared by extrusion of modified and unmodified materials containing either 5 or 10 wt.% fibers. The morphology of the obtained materials was analyzed by SEM. The chemical modification of the fiber surface was found to improve its adhesion with matrix. Flexural and impact tests demonstrated that PE/rice husk composites present improved mechanical performance comparatively to the pure polymer matrix, on the contrary no benefit is observed in the tensile strength over the pure PE.

Preparation and characterization of Zein and Zein-Chitosan microspheres with great prospective of application in controlled drug release

Abstract: Biomaterials applied as carriers for controlled drug delivery offer many advantages over the conventional systems. Among them, the increase of treatment effectiveness and also a significant reduction of toxicity, due to their biodegradability property, are some special features. In this work, microspheres based on the protein Zein (ZN) and ZN associated to the natural polymer Chitosan (CHI) were prepared and characterized. The microspheres of ZN and ZN/CHI were characterized by FT-IR spectroscopy and thermal analysis, and the morphology was analyzed by SEM images. The results confirmed the incorporation of CHI within the ZN-based microspheres. The morphological analysis showed that the CHI added increased the microspheres porosity when compared to the ZN microspheres. The chemical and physical characterization and the morphological analysis allow inferring that ZN/CHI microspheres are good candidates to act as a carrier for controlled drug release.

Mechanical properties of a polyurethane hybrid composite with natural lignocellulosic fibers

Abstract: Several low-cost hybrid composites composed of polyurethane and renewable natural fibers were developed and analyzed for their mechanical and physical properties. Composites were fabricated by replacing up to 20% w/w of the polyethylene glycol present in conventional polyurethane foams with one and the mixture of three natural fibers: sugarcane bagasse, sisal or rice husk. Prior to composite production, fibers were mercerized with sodium hydroxide and hydrogen peroxide to remove lignin and hemicellulose. A simplex-centroid mixture design model was used to evaluate the effects of the added fibers on composite properties such as resilience, elastic modulus and deformation under permanent compression. Obtained hybrid composites demonstrated up to 32% of resilience, 0.1 GPa of elastic modulus, and 7.32% of permanent deformation. In order to optimize these properties, fiber amounts were adjusted using a quadratic mathematical model, indicating that formulations containing only the rice husk or an 82/18 (% w/w) rice husk/sugarcane bagasse mixture will perform best. The obtained composite is a unique low cost material because is environmentally friendly and has a high potential for applications in shock absorption and padding materials, due its proven good resilience and elastic modulus.

Green composites: An overview

Abstract: The use of natural fibers to reinforce polymers is a well-established practice, and biocomposites are increasingly used in sectors such as automotive and construction. Green composites are a specific class of biocomposites, where a bio-based polymer matrix is reinforced by natural fibers, and they represent an emerging area in polymer science. This work discusses the environmental benefits deriving from the use of natural fibers in polymer composites and from substitution of oil-derived polymers by bio-based polymers as matrix material. New trends in the selection of natural fibers, that is, from waste rather than from valuable crops are described. Recently developed thermoplastic and thermosetting bio-based polymers are reviewed, and commercially available green composites obtained thereof are discussed. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers