Chemorheological analysis and model-free kinetics of acid catalysed furfuryl alcohol polymerization (original) (raw)
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Kinetics of resinification of furfuryl alcohol in aqueous solution
Journal of Applied Polymer Science, 1974
Kinetic information on the resinification of furfuryl alcohol has been derived from the rate of increase of color intensity measured with a photoelectric colorimeter, the resinification being carried out isothermally in Clark-Lubs aqueous buffer solutions in the pH range of 1.0-2.2. The activation energy for polymerization is found to increase exponentially with pH. The time required for emulsification (which is quickly followed by separation of resin layer) to occur in an aqueous solution of furfuryl alcohol also increases exponentially with pH, but it decreases exponentially with temperature. This is described quantitatively by a single expression.
The acid-catalyzed polycondensation of furfuryl alcohol: Old puzzles unravelled
Macromolecular Symposia, 1997
This paper describes mechanistic studies aimed at understanding the origin of two important side events accompanying the linear polycondensation of furfuryl alcohol in acidic media. The first process concerns the formation of conjugated sequences along the polymeric chains. The use of model monomers and compounds simulating the structure of the linear polymer provided for the first time a full understanding of the reactions leading to multiple unsaturations. The main culprits for this process are the labile hydrogen atoms on the methylene moiteties bridging the furan rings. The second anomaly in these systems concerns the formation of networks following a complex branching mechanism. Again, model structures helped to pinpoint the origin of this process and to propose plausible reactions to describe it.
Kinetics of Resinification of Furfuryl Alcohol in Acidic Buffer Solutions
Journal of the Indian Institute of Science, 2013
Kinetic informations on the resinification of furfuryl alcohol have been derived from the rate of increase of colour intensity measured with a photoelectric colorimeter. the resinification being carried out isothermally in McIlvaine's aqueous buffer solutions in the pH range 2-2-3-4. The activation energy for resinffication is found to increase exponentially with pH. The time required to reach the extent of reaction at which a resin layer separates out from the aqueous solution increases with increasing pH and decreases with increasing temperature. An exponential expression relating the tune of separation with pH and temperature has been derived.
The Journal of Physical Chemistry B, 2008
The acid-catalyzed polymerization and resinification, in the 300-673 K interval, of furfuryl alcohol adsorbed in the framework of a protonic Y zeolite is studied by means of FTIR, Raman, and UV-vis spectroscopies. The idea is that restricted spaces can impose a constraint to the growth of the oligomeric chains, therefore moderating the formation of conjugated sequences responsible for the color of the products and allowing their observation by means of spectroscopic techniques. The detailed study of the evolution of UV-vis, FTIR, and Raman spectra upon dosed amount, contact time, and temperature has allowed the spectroscopic features of some of the single species, either neutral and positively charged (carbocationic intermediates), to be singled out and assigned to understand the mechanism of initiation. The vibrational assignments have been confirmed by computer simulations on model compounds and compared with the results of the mechanistic description of the reaction mechanism made in the past (Choura, et al. Macromolecules 1996, 29, 3839-3850). The spectroscopic methods have been applied in a large temperature range in order to follow also the formation of more complex products into the pores, associated with longer conjugated sequences, gradually filling the open spaces of the zeolite. For samples contacted with furfuryl alcohol at 673 K, this methodology gives information also on the incipient carbonization process, leading to the formation of a carbonaceous replica phase inside the internal porosity of the zeolite.
Composites Part B: Engineering, 2012
Bio-based polyfurfuryl alcohol (PFA) matrix nanocomposites were fabricated by in situ polymerization of furfuryl alcohol (FA) using (natural or organomodified) montmorillonite nanoclays (MMT) or cellulose whiskers (CW) as catalysts and as matrix modifiers, providing enhanced thermal performance. FTIR analysis shows the catalyst-dependent formation of gamma-diketones that are generated from hydrolytic ring cleavage of the furan rings along the PFA chain. Thermogravimetric Analysis (TGA) shows that the PFA-based nanocomposites exhibit a notable increase in the onset of degradation temperature compared to pure PFA. The oxidative degradation behavior, including degradation onset temperature and residual weight, was analyzed and compared for the various nanocomposites. The higher thermal stability of 30BMMT-PFA as compared with NaMMT-PFA is tentatively attributed to blocking of Brönstedt acidic sites on the clay surface by residues of the organic modifier. However, the highest thermal stability among the various PFA-based nanocomposites that were studied in this work was observed in those containing nanocellulose whiskers (CW), even at much lower volume loadings. Finally, in addition to their surprisingly remarkable thermal stability, CW-PFA nanocomposites also exhibited improved mechanical toughness over previously reported PFA systems.
Understanding the Polymerization of Polyfurfuryl Alcohol: Ring Opening and Diels-Alder Reactions
Polymers
Polyfurfuryl alcohol (PFA) is one of the most intriguing polymers because, despite its easy polymerization in acid environment, its molecular structure is definitely not obvious. Many studies have been performed in recent decades, and every time, surprising aspects came out. With the present study, we aim to take advantage of all of the findings of previous investigations and exploit them for the interpretation of the completely cured PFA spectra registered with three of the most powerful techniques for the characterization of solid, insoluble polymers: Solid-State 13C-NMR, Attenuated Total Reflectance (ATR), Fourier Transform Infrared (FTIR) spectroscopy, and UV-resonant Raman spectroscopy at different excitation wavelengths, using both an UV laser source and UV synchrotron radiation. In addition, the foreseen structures were modeled and the corresponding 13C-NMR and FTIR spectra were simulated with first-principles and semi-empiric methods to evaluate their matching with experimen...
Polymer Bulletin, 1984
Furfurylldene acetone and some of its homologues were polymerised by various typical anionic initiators. Low-DP products were obtained and characterised by IR and NMR spectroscopy. The structural analysis and the markedly different behaviour of certain homologues indicate that isomerisation polymerisation involving a proton migration predominates, but that some propagation through C=O opening also occurs under some conditions.
Acetalization of polyvinyl alcohol with furfural
European Polymer Journal, 1997
Ahatra&-The condensation reaction of 2-furaldehyde (Fu) with poly(vinyl alcohol) (PVA) to give the corresponding a&al was studied in detail. In order to assess in a satisfactory manner the ensuing modified polymers in quantitative terms, a model reaction involving Fu and pentaerythritol was investigated and the bis-a&al obtained submitted to a thorough characterization. Two solvents were. used for the polymer modification, viz. water and DMSO. The maximum degree of substitution attained was about 60% in both media.