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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 ...
Materials from renewable resources based on furan monomers and furan chemistry:...
Gandini, Alessandro; Coelho, Dora; Gomes, Mónica; Reis, Bruno; Silvestre, ArmandoThe polymerisation of furan monomers and the exploitation of some of the chemical peculiarities of the furan heterocycle have generated a wide diversity of macromolecular materials based on renewable resources. We present here recent contributions to this field, including ongoing studies on the synthesis and characterisation of novel furan polyesters and on the application of the Diels-Alder reaction to the pre...
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...
The application of the Diels-Alder reaction to polymer syntheses based on furan...
Gandini,AlessandroThe furan heterocycle is a dienic reagent particularly suitable for the Diels-Alder reaction and maleimides represent a typical family of complementary reagents because of their strong dienophilic character. This paper reviews critically the studies devoted to the exploitation of the Diels Alder reaction between those moieties to synthesise macromolecular materials possessing different structures and properties...
Surface modification of cellulose fibres
Belgacem,Mohamed Naceur; Gandini,AlessandroSeveral approaches to the modification of cellulose fibres are described, namely: (i) physical treatments such as corona or plasma treatments under different atmospheres; (ii) grafting with hydrophobic molecules using well-known sizing compounds; (iii) grafting with bi-functional molecules, leaving one of the functions available for further exploitation; and (iv) grafting with organometallic compounds. The modi...
Hidroxietil celulose enxertada com poliéteres
Regiani,Anelise M.; Pawlicka,Agnieszka; Curvelo,A. Aprigio S.; Gandini,Alessandro; Le Nest,Jean-FrançoisForam preparadas amostras de hidroxietil celulose (HEC) enxertada com poliéteres para aplicação como eletrólitos sólidos poliméricos. Amostras comerciais de HEC foram caracterizadas por ¹H e 13C RMN, FTIR e viscosimetria, visando a determinação dos respectivos graus de substituição molar (MS), grau de substituição (DS) e grau de polimerização (DP). Amostras comerciais de diaminas de poli(óxido de etileno) (POE)...
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