National Nanotechnology Laboratory for Agriculture LNNA

São Carlos, Brazil

National Nanotechnology Laboratory for Agriculture LNNA

São Carlos, Brazil

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Carmona V.B.,Federal University of São Carlos | Carmona V.B.,National Nanotechnology Laboratory for Agriculture LNNA | De Campos A.,National Nanotechnology Laboratory for Agriculture LNNA | Marconcini J.M.,National Nanotechnology Laboratory for Agriculture LNNA | Mattoso L.H.C.,National Nanotechnology Laboratory for Agriculture LNNA
Journal of Thermal Analysis and Calorimetry | Year: 2014

The thermal degradation behavior of the biocomposite with thermoplastic starch (TPS), poly(ε-caprolactone) (PCL) and bleached sisal fibers were investigated by thermogravimetry analysis (TG/DTG) under synthetic air atmosphere, differential scanning calorimetry, and their crystal structure by X-ray diffraction. Applying the non-isothermal Ozawa method, the TG/DTG curves average activation energy could be obtained for thermal degradation of the biocomposites with 5, 10, and 20 % of bleached sisal fibers. The apparent activation energy values for the biocomposites decreased when compared with the TPS/PCL blend, requiring lower energy to recycle this material. However, continuous addition of sisal fibers increased the activation energy of composites. © 2013 Akadémiai Kiadó, Budapest, Hungary.


Bortolin A.,Federal University of São Carlos | Bortolin A.,National Nanotechnology Laboratory for Agriculture LNNA | Aouada F.A.,National Nanotechnology Laboratory for Agriculture LNNA | Aouada F.A.,São Paulo State University | And 5 more authors.
Journal of Applied Polymer Science | Year: 2012

This article studied the applicability of poly(acrylamide) and methylcellulose (PAAm-MC) hydrogels as potential delivery vehicle for the controlled-extended release of ammonium sulfate (NH4) 2SO4 and potassium phosphate (KH2PO 4) fertilizers. PAAm-MC hydrogels with different acrylamide (AAm) and MC concentrations were prepared by a free radical polymerization method. The adsorption and desorption kinetics of fertilizers were determined using conductivity measurements based on previously built analytical curve. The addition of MC in the PAAm chains increased the quantities of (NH 4)2SO4 and KH2PO4 loaded and extended the time and quantities of fertilizers released. Coherently, both loading and releasing processes were strongly influenced by hydrophilic properties of hydrogels (AAm/MC mass proportion). The best sorption (124.0 mg KH2PO4/g hydrogel and 58.0 mg (NH4) 2SO4/g hydrogel) and desorption (54.9 mg KH 2PO4/g hydrogel and 49.5 mg (NH4) 2SO4/g hydrogel) properties were observed for 6.0% AAm-1.0% MC hydrogels (AAm/MC mass proportion equal 6), indicating that these hydrogels are potentially viable to be used in controlled-extended release of fertilizers systems. © 2011 Wiley Periodicals, Inc.


Teixeira E.D.M.,National Nanotechnology Laboratory for Agriculture LNNA | Lotti C.,National Nanotechnology Laboratory for Agriculture LNNA | Correa A.C.,National Nanotechnology Laboratory for Agriculture LNNA | Teodoro K.B.R.,National Nanotechnology Laboratory for Agriculture LNNA | And 3 more authors.
Journal of Applied Polymer Science | Year: 2011

This work evaluates the use of cotton cellulose nanofibers (CCN) as a reinforcing agent to prepare thermoplastic corn starch (TPS) matrix plasticized with 30 wt % of glycerol. The nanocomposites were filled with 0.5-5.0 wt % of CCN on a dry-starch basis. The dried nanofibers were resuspended through the use of an ultrasonicator and then introduced in the fixed water formulation for obtaining TPS. The nanocomposites were compounded in a corotating twin-screw extruder. Scanning transmission electron microscopy (STEM), field emission gun (FEG), X-ray diffraction (XRD) and thermogravimetric analysis (TGA), in air atmosphere, were used to characterize nanofibers, neat TPS, and nanocomposites. The results showed that the nanofibers had needlelike structure with an average length of about 135 ± 50 nm and an average diameter of about 14 ± 4 nm. The addition of CCN was effective to enhance the mechanical properties of neat TPS in compositions above 2.5 wt %, although some agglomeration could be observed. The resulting nanocomposites showed good structural stability, because the amylopectin transcrystallization phenomena on the surface of nanofibers had not occurred. Only a slight decrease in the crystallinity index and a minor increase in the water absorption in relation to neat TPS were observed. An increase in the thermal stability of TPS nanocomposites with respect to neat TPS was verified, but it was independent of the CCN content. © 2010 Wiley Periodicals, Inc.


Teixeira E.D.M.,National Nanotechnology Laboratory for Agriculture LNNA | De Campos A.,National Nanotechnology Laboratory for Agriculture LNNA | Marconcini J.M.,National Nanotechnology Laboratory for Agriculture LNNA | Bondancia T.J.,Federal University of São Carlos | And 4 more authors.
RSC Advances | Year: 2014

Composites of starch, fiber, and poly(lactic acid) (PLA) were made using a foam substrate formed by dehydrating starch or starch/fiber gels. PLA was infiltrated into the dry foam to provide better moisture resistance. Foam composites were also compressed into plastics using force ranging from 4-76 MPa. Tensile strength increased with increasing compression force applied to the foam sample. The samples became increasingly transparent with compression forces approaching 76 MPa. PLA infusion into starch and starch/fiber foam composites resulted in PLA content of 20% and 33%, respectively and provided moisture resistance to the outer regions of the foam samples. The PLA-infused foam samples increased in tensile strength when compressed up to 29 MPa. The PLA-infused compressed samples had greater moisture resistance and had intermediate rates of mineralization compared to the control samples. © 2014 The Royal Society of Chemistry.


Teixeira E.D.M.,National Nanotechnology Laboratory for Agriculture LNNA | Bondancia T.J.,National Nanotechnology Laboratory for Agriculture LNNA | Bondancia T.J.,Federal University of São Carlos | Teodoro K.B.R.,National Nanotechnology Laboratory for Agriculture LNNA | And 4 more authors.
Industrial Crops and Products | Year: 2011

This work evaluates the use of sugarcane bagasse (SCB) as a source of cellulose to obtain whiskers. These fibers were extracted after SCB underwent alkaline peroxide pre-treatment followed by acid hydrolysis at 45 °C. The influence of extraction time (30 and 75 min) on the properties of the nanofibers was investigated. Sugarcane bagasse whiskers (SCBW) were analyzed by transmission electron microscopy (TEM), X-ray diffraction (XRD) and thermogravimetric analysis (TGA) in air atmosphere. The results showed that SCB could be used as source to obtain cellulose whiskers and they had needle-like structures with an average length (L) of 255 ± 55 nm and diameter (D) of 4 ± 2 nm, giving an aspect ratio (L/. D) around 64. More drastic hydrolysis conditions (75 min) resulted in less thermally stable whiskers and caused some damage on the crystal structure of the cellulose as observed by XRD analysis. © 2010 Elsevier B.V.


Teixeira E.D.M.,National Nanotechnology Laboratory for Agriculture LNNA | Curvelo A.A.S.,University of Sao Paulo | Correa A.C.,National Nanotechnology Laboratory for Agriculture LNNA | Marconcini J.M.,National Nanotechnology Laboratory for Agriculture LNNA | And 2 more authors.
Industrial Crops and Products | Year: 2012

Cassava bagasse is an inexpensive and broadly available waste byproduct from cassava starch production. It contains roughly 50% cassava starch along with mostly fiber and could be a valuable feedstock for various bioproducts. Cassava bagasse and cassava starch were used in this study to make fiber-reinforced thermoplastic starch (TPS B and TPS I, respectively). In addition, blends of poly (lactic acid) and TPS I (20%) and TPS B (5, 10, 15, 20%) were prepared as a means of producing low cost composite materials with good performance. The TPS and PLA blends were prepared by extrusion and their morphological, mechanical, spectral, and thermal properties were evaluated. The results showed the feasibility of obtaining thermoplastic starches from cassava bagasse. The presence of fiber in the bagasse acted as reinforcement in the TPS matrix and increased the maximum tensile strength (0.60MPa) and the tensile modulus (41.6MPa) compared to cassava starch TPS (0.40 and 2.04MPa, respectively). As expected, blending TPS with PLA reduced the tensile strength (55.4MPa) and modulus (2.4GPa) of neat PLA. At higher TPS B content (20%) the maximum strength (19.9MPa) and tensile modulus (1.7GPa) were reduced about 64% and 32%, respectively, compared to the PLA matrix. In comparison, the tensile strength (16.7) and modulus (1.2GPa) of PLA blends made with TPS I were reduced 70% and 51% respectively. The fiber from the cassava bagasse was considered a filler since no increase in tensile strength of PLA/TPS blends was observed. The TPS I (33.1%) had higher elongation to break compared to both TPS B (4.9%) and PLA (2.6%). The elongation to break increased from 2.6% to 14.5% by blending TPS I with PLA. In contrast, elongation to break decreased slightly by blending TPS B with PLA. Thermal analysis indicated there was some low level of interaction between PLA and TPS. In PLA/TPS B blends, the TPS B increased the crystallinity of the PLA component compared to neat PLA. The fiber component of TPS B appeared to have a nucleating effect favoring PLA crystallization. © 2011 Elsevier B.V.


Pereira M.M.,Federal University of Juiz de fora | Raposo N.R.B.,Federal University of Juiz de fora | Brayner R.,University Paris Diderot | Teixeira E.M.,National Nanotechnology Laboratory for Agriculture LNNA | And 5 more authors.
Nanotechnology | Year: 2013

Cellulose nanofibers (CNF) have mechanical properties that make them very attractive for applications in the construction of polymeric matrices, drug delivery and tissue engineering. However, little is known about their impact on mammalian cells. The objective of this study was to evaluate the cytotoxicity of CNF and their effect on gene expression of fibroblasts cultured in vitro. The morphology of CNF was analyzed by transmission electron microscopy and the surface charge by Zeta potential. Cell viability was analyzed by flow cytometry assay and gene expression of biomarkers focused on cell stress response such as Heat shock protein 70.1 (HSP70.1) and Peroxiredoxin 1 (PRDX1) and apoptosis as B-cell leukemia (BCL-2) and BCL-2 associated X protein (BAX) by RT-PCR assay. Low concentrations of CNF (0.02-100 μg ml-1) did not cause cell death; however, at concentrations above 200 μg ml-1, the nanofibers significantly decreased cell viability (86.41 ± 5.37%). The exposure to high concentrations of CNF (2000 and 5000 μg ml-1) resulted in increased HSP70.1, PRDX1 and BAX gene expression. The current study concludes that, under the conditions tested, high concentrations (2000 and 5000 μg ml-1) of CNF cause decreased cell viability and affect the expression of stress- and apoptosis-associated molecular markers. © 2013 IOP Publishing Ltd.


Aouada F.A.,São Paulo State University | Aouada F.A.,National Nanotechnology Laboratory for Agriculture LNNA | Mattoso L.H.C.,National Nanotechnology Laboratory for Agriculture LNNA | Longo E.,São Paulo State University
Journal of Thermoplastic Composite Materials | Year: 2013

The aim of this article is to propose advances for the preparation of hybrid nanocomposites prepared by the combination of intercalation from solution and melt-processing methods. This research investigates the effect of the laponite RDS content on the thermal, structural, and mechanical properties of thermoplastic starch (TPS). X-ray diffraction was performed to investigate the dispersion of the laponite RDS layers into the TPS matrix. The results show good nanodispersion, intercalation, and exfoliation of the clay platelets, indicating that these composites are true nanocomposites. The presence of laponite RDS also improves the thermal stability and mechanical properties of the TPSmatrix due to its reinforcement effect which was optimized by the high degree of exfoliation of the clay. Thus, these results indicate that the exfoliated TPS-laponite nanocomposites have great potential for industrial applications and, more specifically, in the packaging field. © The Author(s) 2011 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.


de Lima R.,University of Sorocaba | Feitosa L.O.,University of Sorocaba | Maruyama C.R.,University of Sorocaba | Barga M.A.,University of Sorocaba | And 6 more authors.
International Journal of Nanomedicine | Year: 2012

Background: Agricultural products and by products provide the primary materials for a variety of technological applications in diverse industrial sectors. Agro-industrial wastes, such as cotton and curaua fibers, are used to prepare nanofibers for use in thermoplastic films, where they are combined with polymeric matrices, and in biomedical applications such as tissue engineering, amongst other applications. The development of products containing nanofibers offers a promising alternative for the use of agricultural products, adding value to the chains of production. However, the emergence of new nanotechnological products demands that their risks to human health and the environment be evaluated. This has resulted in the creation of the new area of nanotoxicology, which addresses the toxicological aspects of these materials. Purpose and methods: Contributing to these developments, the present work involved a genotoxicological study of different nanofibers, employing chromosomal aberration and comet assays, as well as cytogenetic and molecular analyses, to obtain preliminary information concerning nanofiber safety. The methodology consisted of exposure of Allium cepa roots, and animal cell cultures (lymphocytes and fibroblasts), to different types of nanofibers. Negative controls, without nanofibers present in the medium, were used for comparison. Results: The nanofibers induced different responses according to the cell type used. In plant cells, the most genotoxic nanofibers were those derived from green, white, and brown cotton, and curaua, while genotoxicity in animal cells was observed using nanofibers from brown cotton and curaua. An important finding was that ruby cotton nanofibers did not cause any significant DNA breaks in the cell types employed. Conclusion: This work demonstrates the feasibility of determining the genotoxic potential of nanofibers derived from plant cellulose to obtain information vital both for the future usage of these materials in agribusiness and for an understanding of their environmental impacts. © 2012 de Lima et al, publisher and licensee Dove Medical Press Ltd.


Aouada F.A.,São Paulo State University | Aouada F.A.,National Nanotechnology Laboratory for Agriculture LNNA | Mattoso L.H.C.,National Nanotechnology Laboratory for Agriculture LNNA | Longo E.,São Paulo State University
Industrial Crops and Products | Year: 2011

A simple method based on the combination of the intercalation from solution and melt-processing preparation methods was used to prepare highly exfoliated and compatible thermoplastic starch (TPS) and montmorillonite clay (MMT) nanocomposites. The effects of the MMT content on the thermal, structural, and mechanical properties of the nanocomposites were investigated. XRD diffraction was used to investigate the MMT exfoliation/intercalation degrees in the TPS matrix. Data from thermogravimetric analysis and differential scanning calorimetry revealed that the addition of MMT increased the thermal stabilities of TPS nanocomposites. Young's modulus and tensile strength increased from 8.0 to 23.8. MPa and 1.5 to 2.8. MPa with an increasing MMT content from 0 to 5. wt% without diminishing their flexibility. The improvement in such properties can be attributed to the good dispersion/exfoliation of MMT in the TPS matrix. Combining both methods, it was possible to obtain homogenous and transparent nanocomposites with excellent thermal and mechanical properties for application as packaging materials. © 2011 Elsevier B.V.

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