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De Araujo M.A.M.,PPG CEM UFSCar | De Sena Neto A.R.,PPG CEM UFSCar | Hage E.,Jr. | Mattoso L.H.C.,National Nanotechnology Laboratory for Agrobusiness LNNA | Marconcini J.M.,National Nanotechnology Laboratory for Agrobusiness LNNA
Polymer Composites

Formulations of poly(lactic acid) (PLA) reinforced by curaua leaf fibers were prepared and characterized. This biocomposite has material characteristics such as biodegradability and renewability. This work aimed to develop a PLA/curaua leaf fiber composite as a sustainable biodegradable polymer composite. The PLA and composites were thermally, mechanically, and morphologically evaluated. The critical fiber length was studied to check its influence on the mechanical properties. Predictions of the Young's modulus were done to compare with the experimental data, having a reasonable agreement. The Young's modulus increased above 70%, and the impact strength increased 20% compared with the pure PLA. Thermal analysis showed that formulations with up to 20% by weight of fibers were more thermally stable. The fiber modified the crystallinity of the PLA matrix. The best overall balance of properties was attained in composites containing 15% curaua fiber. © 2014 Society of Plastics Engineers. Source

Sena Neto A.R.,Federal University of Santa Catarina | Araujo M.A.M.,Federal University of Santa Catarina | Barboza R.M.P.,Federal University of Sao Carlos | Fonseca A.S.,Federal University of Lavras | And 4 more authors.
Industrial Crops and Products

Vegetable fiber reinforced polymer composites have enormous potential to replace materials originated from non-renewable resources. For an adequate use of vegetable fibers as reinforcements, however, the relationships between technological properties and chemical, structural and morphological characteristics of the fibers must be fully understood. In this work, fibers from 12 different varieties of pineapple ( Ananas genus) were characterized on their morphology, structure, chemical composition, mechanical and thermal properties. The elastic modulus ranged from 37 to 86. GPa, the tensile strength from 629 to 1309. MPa, and the onset oxidation temperature from 240 to 272. °C; indicating the potential of using all selected pineapple fibers as reinforcing fillers (depending on the polymer matrix and processing method). Direct correlations were observed between the thermo-mechanical properties of the fibers and their chemical features, such as holocellulose and cellulose contents, and also the cellulose crystallinity index. The mechanical properties showed an inversely proportional relation with the lignin content and diameter of the fiber bundle. These correlations provided indexes for the direct selection and/or for a genetic improvement program of the Ananas genus for the development of pineapples whose fibers may be adequate as mechanical reinforcement in polymer composite. An example of methodology is presented, aiming to help with materials selection within the group of vegetable fibers used in composites. © 2014 Elsevier B.V. Source

Claro P.I.C.,Federal University of Sao Carlos | Neto A.R.S.,National Nanotechnology Laboratory for Agrobusiness LNNA | Bibbo A.C.C.,National Nanotechnology Laboratory for Agrobusiness LNNA | Mattoso L.H.C.,National Nanotechnology Laboratory for Agrobusiness LNNA | And 2 more authors.
Journal of Polymers and the Environment

Poly(lactic acid) (PLA) is a biodegradable polymer that exhibits high elastic modulus, high mechanical strength, and feasible processability. However, high cost and fragility hinder the application of PLA in food packaging. Therefore, this study aimed to develop flexible PLA/acetate and PLA/chitosan films with improved thermal and mechanical properties without the addition of a plasticizer and additive to yield extruder compositions with melt temperatures above those of acetate and chitosan. PLA blends with 10, 20, and 30 wt% of chitosan or cellulose acetate were processed in a twin-screw extruder, and grain pellets were then pressed to form films. PLA/acetate films showed an increase of 30 °C in initial degradation temperature and an increase of 3.9 % in elongation at break. On the other hand, PLA/chitosan films showed improvements in mechanical properties as an increase of 4.7 % in elongation at break. PLA/chitosan film which presented the greatest increase in elongation at break proved to be the best candidate for application in packaging. © 2016 Springer Science+Business Media New York Source

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