Alberto Gonçalves Vieira de Carvalho Neto

Bio: Alberto Gonçalves Vieira de Carvalho Neto is an academic researcher from Universidade Estadual de Maringá. The author has contributed to research in topics: Polyethylene & Fiber. The author has an hindex of 3, co-authored 3 publications receiving 220 citations.

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.

Development of composites based on recycled polyethylene/sugarcane bagasse fibers

Abstract: In this work, sugarcane bagasse fibers were used as filler in composites having recycled high-density polyethylene (PEr) as matrix. Because of the poor interaction between fibers surface and the PEr, the surface of bagasse was chemically modified. This modification consists of washing with water at 80°C, a mercerization process using sodium hydroxide and acetylation reaction with acetic anhydride. The chemical modification was characterized by Fourier transform infrared–horizontal attenuated total reflectance (FTIR-HATR) and 13C nuclear magnetic resonance spectroscopies (NMR), thermogravimetric analysis (TGA), and scanning electronic microscopy (SEM). The composites were prepared from modified and unmodified fibers into PEr matrix, containing 5, 10, and 20% (w/w) of fiber. The samples were processed by extrusion and molds were prepared by injection process in order to perform mechanical tests. These materials were analyzed by SEM, TGA, and the water uptake was evaluated. Also, their mechanical properties were analyzed. Morphological analysis indicated that the chemical modification of sugarcane bagasse increased the compatibility between matrix and reinforcement. Tensile, flexural, and impact tests showed that the mechanical properties of the composite were improved compared to PEr due to the presence of the fibers. POLYM. COMPOS., 35:768–774, 2014. © 2013 Society of Plastics Engineers

Review of Hydrogels and Aerogels Containing Nanocellulose

Abstract: Naturally derived cellulose nanocrystals (CNCs) and cellulose nanofibrils (CNFs) are emerging nanomaterials that display high strength, high surface area, and tunable surface chemistry, allowing for controlled interactions with polymers, nanoparticles, small molecules, and biological materials. Industrial production of nanocelluloses is increasing rapidly with several companies already producing on the tons-per-day scale, intensifying the quest for viable products across many sectors. While the hydrophilicity of the nanocellulose interface has posed a challenge to the use of CNCs and CNFs as reinforcing agents in conventional plastics, it is a significant benefit for creating reinforced or structured hydrogel composites (or, when dried, aerogels) exhibiting both mechanical reinforcement and a host of other desirable properties. In this context, this Review describes the quickly growing field of hydrogels and aerogels incorporating nanocelluloses; over 200 references are summarized in comprehensive tables ...

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

Chitosan- graft -poly(acrylic acid)/rice husk ash based superabsorbent hydrogel composite: preparation and characterization

Abstract: Rice husk ash (RHA), an industrial waste, was incorporated in the preparation of high performance chitosan (CTS) and poly(acrylic acid) (PAA) based superabsorbent hydrogel. Hydrogels filled with RHA previously calcinated at 900 °C (RHA900) showed better water uptake (225 gwater/gabsorbent) than those with husk calcinated at 400 °C (RHA400) (198 gwater/gabsorbent) due to the higher purity and crystallinity, at same composition. The hydrogel composite at 5 wt-% of RHA900 showed the best water uptake (255 gwater/gabsorbent). A clear reduction in swelling degree is observed by increasing the amount of crosslinker from 1 to 3 wt-% due to the increase in the crosslinking density forming more rigid hydrogels. On the other hand, an increase in the initiator amount from 1 to 3 wt-% increased the water uptake due to the formation of greater numbers of active sites increasing the number of PAA chains grafted into CTS backbone. Furthermore, the hydrogel composites presented responsive behavior in relation to both pH and sat solution. The data shows it is possible to obtain high performance materials by incorporating an industrial waste, rice husk ash, in the preparation of hydrogel composites.