Browsing by Author "Gandini, Alessandro"
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- Chemical modification as a strategy to modulate properties of oxypropylated productsPublication . Barbosa, Mariana Martinho; Matos, Marina; Barreiro, M.F.; Gandini, AlessandroNowadays a great interest is devoted to the production and use of biobased products. The main scope of the oxypropylation process is to obtain polyols, in the form of viscous liquids, which can be interesting co-monomers to produce polyurethanes and polyesters. Due to the high hydroxyl content of natural polymers (suitable substrates to be oxypropylated), the generated polyols are multifunctional, hence most adequate to be used in rigid polyurethane foam formulations. Additionally, their properties can be modulated through chemical modification, thus opening new avenues for their exploitation. Following that strategy, an oxypropylated product (IOH of 350) used as a model polyol, was modified by reacting it with a mixture containing phenyl isocyanate (PI) and toluene diisocyanate (TDI) at PI/TDI molar ratios of 100/0, 80/20, 50/50, 20/80 and 0/100. This chemical system was chosen in order to guarantee a homogeneous medium during the course of the reaction. Syntheses were performed in dichloromethane solution at room temperature under nitrogen, using DBTDL as catalyst, with a reaction time of 6 hours. Kinetics was followed by FTIR in transmittance mode using a liquid cell equipped with NaCl windows. For that purpose, sample aliquots were taken from the reaction medium at time intervals of 10 minutes during the first hour, 30 minutes during the second hour and at one hour intervals until the end of the reaction. After the established reaction time of 6 hours, residual isocyanates were neutralized with methanol and the final product purified, dried and characterized by FTIR and DSC.
- From oxypropylated olive stone towards novel polymeric materialsPublication . Matos, M.C.; Barreiro, M.F.; Gandini, AlessandroThe oxypropylation of OH-bearing substrates constitutes an original approach to the rational exploitation of the biomass. Total oxypropylation of a variety of natural polymers, including chitosan and chitin residues, different types of lignins, cork and more complex structures like sugar beet pulp, converts these solids, often otherwise intractable biomass residues, into liquid polyols thanks to the introduction of oligo(propylene oxide) grafts. The transformation of these polyols into rigid polyurethane (RPU) foams has been to date the main studied application. Following our previous work dealing with the optimization of the OS oxypropylation process, the purpose of this work is to explore the possibility of chemically modify the generated polyols through reactions with isocyanates and acid chlorides (or carboxylic acid esters) to produce polyurethanes and polyesters, respectively. Two different approaches have been used, namely (1) the use of monofunctional reagents in order to modulate the final polyol properties, namely lowering the hydroxyl functionality and (2) the use of difunctional reagents to produce more elaborate macromolecular materials, including networks.
- From oxypropylated olive stone towards novel polymeric materialsPublication . Matos, M.C.; Barreiro, M.F.; Gandini, AlessandroThe oxypropylation of OH-bearing substrates constitutes an original approach to the rational exploitation of the biomass. Total oxypropylation of a variety of natural polymers, including chitosan and chitin residues, different types of lignins, cork and more complex structures like sugar beet pulp, converts these solids, often otherwise intractable biomass residues, into liquid polyols thanks to the introduction of oligo(propylene oxide) grafts. The transformation of these polyols into rigid polyurethane (RPU) foams has been to date the main studied application. Following our previous work dealing with the optimization of the OS oxypropylation process, the purpose of this work is to explore the possibility of chemically modify the generated polyols through reactions with isocyanates and acid chlorides (or carboxylic acid esters) to produce polyurethanes and polyesters, respectively. Two different approaches have been used, namely (1) the use of monofunctional reagents in order to modulate the final polyol properties, namely lowering the hydroxyl functionality and (2) the use of difunctional reagents to produce more elaborate macromolecular materials, including networks.
- New polyurethanes from oxypropylated olive stonePublication . Barbosa, Mariana Martinho; Matos, M.C.; Barreiro, M.F.; Gandini, AlessandroThe purpose of this work is to explore the possibility of chemically modifying the generated polyols (oxypropylated olive stone) through reactions with isocyanates to produce polyurethanes, other than rigid polyurethane foams. This could be achieved by the chemical modification of the oxypropylation products (condensation with isocyanates) by using mono and difunctional reagents to modulate properties and/or produce useful polymer networks.
- Olive stone as a renewable source of biopolyolsPublication . Matos, M.C.; Barreiro, M.F.; Gandini, AlessandroThe purpose of this work was to establish the feasibility of converting the olive stone residue by means of both total and partial oxypropylation. In the first case, the oxypropylation reaction conditions are chosen in order to promote extensive grafting, thus assuring a complete “liquefaction” of the material and, in the second case, partial oxypropylation would limit the reaction to the outer shell in view of the preparation of all-“olive stone” composites. This approach involves a straightforward transformation of the olive stone particles outer layer, giving rise to a thermoplastic matrix around its unreacted reinforcing inner structure, as already applied to cellulose and starch. To the best of our knowledge, oxypropylation was never applied to olive-stone.
- Olive stone as a renewable source of biopolyolsPublication . Matos, M.C.; Barreiro, M.F.; Gandini, AlessandroThe development of polyols from abundant and renewable biomass resources constitute an attractive choice for polyurethanes and other industrial sectors, where green chemistry and sustainable processes are in focus. The purpose of this study was to establish the feasibility of converting olive stone (OS) residues by means of both total and partial oxypropylation. In the first case, the oxypropylation reaction conditions were chosen in order to promote extensive grafting leading to a viscous product, whereas in the second the reaction was limited to the outer shell of the OS grains in order to prepare single-source composites. The results obtained demonstrated the viability of using this reaction to generate OS-based polyols, thus opening new perspectives for the exploitation of this by-product of the olive oil industry.
- Search for novel biobased materials within the OLIVPOL projectPublication . Matos, M.C.; Barbosa, Mariana Martinho; Barreiro, M.F.; Gandini, AlessandroWithin the context of the project OLIVPOL, olive stone (OS) residue was successfully converted into viscous polyols, as such, or containing reinforcing stone cores, by total or partial oxypropylation, respectively. Moreover, the synthesis of new macromolecular materials using the oxypropylated products, such as polyesters and polyurethanes, demonstrated a promising approach to the production of original value-added products based on renewable resources.
- The oxypropylation of olive stone and the use of the ensuing polyols for the synthesis of novel polyesters and polyurethanes based on renewable resourcesPublication . Matos, M.C.; Barreiro, M.F.; Gandini, AlessandroThe development of polyols by the oxypropylation of abundant and renewable vegetable and animal resources constitutes an original approach to the exploitation of the biomass. Cellulose, starch, chitosan, chitin, different types of lignins, cork and more complex structures like sugar beet pulp, are among the documented examples. All these systems displayed a similar pattern in terms of the grafting of short poly(propylene oxide) (POP) chains from the OH groups of the substrate, albeit of course each situation required a specific set of optimized experimental conditions to transform the natural solid into a viscous polyol. The transformation of these polyols into polyurethanes is the only operation which has been studied to date as a form of their exploitation into polymer materials. In this work, the more promissing promising polyols were selected for chemical modifications involving first ester and urethane formations with aliphatic and aromatic monofunctional reagents.
- The oxypropylation of olive stone and the use of the ensuing polyols for the synthesis of novel polyesters and polyurethanes based on renewable resourcesPublication . Matos, M.C.; Barreiro, M.F.; Gandini, AlessandroThe development of polyols by the oxypropylation of abundant and renewable vegetable and animal resources constitutes an original approach to the exploitation of the biomass. Cellulose, starch, chitosan, chitin, different types of lignins, cork and more complex structures like sugar beet pulp, are among the documented examples. All these systems displayed a similar pattern in terms of the grafting of short poly(propylene oxide) (POP) chains from the OH groups of the substrate, albeit of course each situation required a specific set of optimized experimental conditions to transform the natural solid into a viscous polyol. The transformation of these polyols into polyurethanes is the only operation which has been studied to date as a form of their exploitation into polymer materials. In this work, the more promissing were selected for chemical modifications involving first ester and urethane formations with aliphatic and aromatic monofunctional reagents.