Encontrados 13 documentos, a visualizar página 1 de 2
Supercritical fluid extraction of Eucalyptus globulus bark: a promising approac...
Domingues, Rui M. A.; Oliveira, Eduardo L. G.; Freire, Carmen S. R.; Couto, Ricardo M.; Simões, Pedro C.; Neto, Carlos P.; Silvestre, Armando J. D.Eucalyptus bark contains significant amounts of triterpenoids with demonstrated bioactivity, namely triterpenic acids and their acetyl derivatives (ursolic, betulinic, oleanolic, betulonic, 3-acetylursolic, and 3-acetyloleanolic acids). In this work, the supercritical fluid extraction (SFE) of Eucalyptus globulus deciduous bark was carried out with pure and modified carbon dioxide to recover this fraction, and ...
Extraction of vanillin using ionic-liquid-based aqueous two-phase systems
Cláudio, Ana Filipa M.; Freire, Mara G.; Freire, Carmen S.R.; Silvestre, Armando J.D.; Coutinho, João A.P.To explore proper extractive solvents and to design an optimized separation process it is highly imperative to understand the molecular-based phenomena governing the solutes partitioning. Moreover, the development of new techniques for the biomolecules separation and purification, while maintaining their functional characteristics unchanged, is still ongoing. Therefore, in this work, the partition coefficients ...
Suberin of Potato (Solanum tuberosum Var. Nikola): Comparison of the Effect of ...
Jarvinen, Riikka; Silvestre, Armando J. D.; Holopainen, Ulla; Kaimainen, Mika; Nyyssola, Antti; Gil, Ana M.; Neto, Carlos Pascoal; Lehtinen, PekkaChemical and enzymatic depolymerizations of suberin isolated from potato peel (Solanum tuberosum var. Nikola) were performed under various conditions. Enzymatic hydrolysis with cutinase CcCut1 and chemical methanolysis with NaOMe of suberin yielded monomeric fragments, which were identified as TMS derivatives with GC-MS and GC-FID. The solid, hydrolysis-resistant residues were analyzed with solid state (13)C CP...
Surface hydrophobization of bacterial and vegetable cellulose fibers using ioni...
Tomé, Liliana C.; Freire, Mara G.; Rebelo, Luís Paulo N.; Silvestre, Armando J. D.; Carlos Pascoal Neto; Marrucho, Isabel M.; Freire, Carmen S. R.The surface hydrophobization through heterogeneous chemical modification of bacterial (and vegetable) cellulose fibers with several anhydrides (acetic, butyric, hexanoic and alkenyl succinic anhydrides) and hexanoyl chloride suspended in an ionic liquid, tetradecyltrihexylphosphonium bis(trifluoromethylsulfonyl) imide, [TDTHP][NTf(2)], was studied. Furthermore, in the reaction with hexanoyl chloride, another io...
Reversible click chemistry at the service of macromolecular materials
Gandini, Alessandro; Silvestre, Armando J. D.; Coelho, DoraThe application of the reversible Diels-Alder (DA) reaction to the realm of furan polymers has recently bloomed, because of its potential for the preparation of a wide variety of novel macromolecular materials based on renewable resources, possessing, among other properties, thermoreversible, mendable and recycling features. In this study, the synthesis and characterisation of novel furan-maleimide monomers, vi...
Transparent bionanocomposites with improved properties prepared from acetylated...
Tomé, Liliana C.; Pinto, Ricardo J. B.; Trovatti, Eliane; Freire, Carmen S. R.; Silvestre, Armando J. D.; Neto, Carlos Pascoal; Gandini, AlessandroThe preparation and characterization of biocomposite materials with improved properties based on poly(lactic acid) (PLA) and bacterial cellulose, and, for comparative purposes, vegetal cellulose fibers, both in their pristine form or after acetylation, is reported. The composite materials were obtained through the simple and green mechanical compounding of a PLA matrix and bacterial cellulose nanofibrils (or ve...
Determination of the Hydroxy and Carboxylic Acid Groups in Natural Complex Mixt...
Sousa, Andreia F.; Gandini, Alessandro; Silvestre, Armando J. D.; Neto, Carlos PascoalThe use of trichloroacetyl isocyanate (TAI) to mark both hydroxyl and carboxyl groups borne by the hydrolysis or methanolysis of suberin fragments (a complex mixture of hydroxy fatty acids), allowed the quantitative assessment of the ratio between carboxyl and hydroxy groups, as well as the ratio between primary and secondary hydroxy groups, to be carried out reliably by (1)H nuclear magnetic resonance (NMR) sp...
Quercus suber and Betula pendula outer barks as renewable sources of oleochemic...
Pinto, Paula C. R. O.; Sousa, Andreia F.; Silvestre, Armando J. D.; Neto, Carlos Pascoal; Gandini, Alessandro; Eckerman, Christer; Holmbom, BjarneA comparative study on the chemical composition of oak cork (Quercus suber L.) and corresponding industrial residues and birch (Betula pendula L.) outer bark is reported. Cork oak samples have lower extractives contents (6-9%) and higher contents of carbohydrates and lignin (23-27 and 33-38%, respectively) than those found for birch outer bark (40, 6 and 9%, respectively); suberin contents accounted for around ...
Novel transparent nanocomposite films based on chitosan and bacterial cellulose
Fernandes, Susana C. M.; Oliveira, Lúcia; Freire, Carmen S. R.; Silvestre, Armando J. D.; Neto, Carlos Pascoal; Gandini, Alessandro; Desbriéres, JacquesNew nanocomposite films based on different chitosan matrices (two chitosans with different DPs and one water soluble derivative) and bacterial cellulose were prepared by a fully green procedure by casting a water based suspension of chitosan and bacterial cellulose nanofibrils. The films were characterized by several techniques, namely SEM, AFM, X-ray diffraction, TGA, tensile assays and visible spectroscopy. T...
Composites based on acylated cellulose fibers and low-density polyethylene: Eff...
Freire, Carmen S. R.; Silvestre, Armando J. D.; Neto, Carlos Pascoal; Gandini, Alessandro; Martin, Loli; Mondragon, IñakiLow-density polyethylene was filled with unmodified and fatty acid (hexanoic, dodecanoic, octadecanoic and docosanoic acids) esterified cellulose fibers. The thermal and mechanical properties, morphology and the water absorption behavior of the ensuing composites were investigated. The chemical modification of the cellulose fibers with fatty acids clearly improved the interfacial adhesion with the matrix and he...
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