Rigid polyurethane foams from lignin based polyols

Rigid polyurethane (RPU) foams were synthesized using lignin-based polyols obtained by an oxypropylation process. Alcell, Indulin AT, Curan 27-11P and Sarkanda lignins have been oxypropylated using formulations deduced from an optimization study with Alcell. L/PO/C (ratio between lignin, PO and catalyst content) of 30/70/2 and 20/80/5 were used to obtain the desired polyols. The resulting RPU foams were characterized in terms of density, mechanical properties, conductivity and morphology. All Sarkanda lignin based polyols and the 30/70/2 Curan 27-11P polyol were found inadequate for RPU formulations. Alcell and Indulin AT based polyols and the 20/80/5 Curan 27-11P polyol resulted in RPU foams with properties very similar to those obtained from conventional commercial polyols. RPU foams produced with the 30/70/2 Alcell and the 30/70/2 Indulin AT polyols exhibited improved properties compared with those from 20/80/5 based formulations.Foundation for Science and Technology (grant SFRH/BD/18415/2004) and the French-Portuguese Scientific Cooperation Programme (action F-32/08

Lignin-based polyurethane materials

Four technical lignins (Alcell, Indulin AT, Sarkanda and Curan 27-11P) were used as macromonomers in the synthesis of polyurethane materials following two global approaches. In the first one Alcell and Indulin AT lignins were used directly as co-monomers in combination with a linear polycaprolactone (PCL) in order to produce polyurethane elastomers where lignin content varied between 10 and 25% (w/w) with respect to polyol mixture (PCL+lignin). The thermomechanical properties of the resulting materials were determined by dynamical mechanical analysis (DMA), differential scanning calorimetry (DSC) and swelling tests. In lignin-based elastomers Indulin AT showed to be more efficiently incorporated in the polyurethane network compared with Alcell lignin. Elastomers prepared with Indulin AT lignin exhibited a cross-linking density and storage modulus (rubbery plateau) higher than those of Alcell lignin-based counterpart and a lower soluble fraction. For both Alcell and Indulin AT based elastomers the glass transition temperature increased and extended over a wide temperature range with the increase of lignin content. The second approach consisted of producing rigid polyurethane foams (RPU) using ligninbased polyols obtained after chemical modification by an oxypropylation procedure. Two polyol formulations (20/80 and 30/70, in what concerns the weight ratios between lignin and propylene oxide, PO), were used in RPU formulations and their content varied from 0 to 100% (w/w with respect to a commercial polyol, used as a reference). The resulting RPU foams were characterized in terms of density, mechanical properties, conductivity and morphology. The prepared RPU foams with lignin-based polyols presented properties, very similar to those obtained from conventional commercial polyols. RPU foams prepared with 30/70 polyols exhibited improved properties comparatively to those arising from 20/80 formulations. Exceptions were however detected in RPU foams prepared with all Sarkanda lignin based polyols and Curan 27-11P 30/70 formulation, which were found to be inadequate for RPU formulation.Foundation for Science and Technology (grant SFRH/BD/18415/2004) and French-Portuguese Scientific Cooperation Programme (action F- 32/08)

Chemical composition and pulping of banana pseudo-stems

This paper deals with the determination of chemical composition and the study of the pulping potentialities of banana pseudo-stems growing in Madeira Island (Portugal). First, the raw material was both studied as a whole (type I) and as the outer bark part (type II), which is richer in cellulose fibres. Before starting the cooking of banana wastes, the main components of the two types of material were quantified, and showed that the polysaccharide content was high enough (about 60–70%) to justify the pulping investigations. Moreover, the lignin content was very low (approximately 12%). The only discouraging finding was the relative high amounts of ashes and extractives. The pulping of these residues was carried out using soda, kraft and soda-anthraquinone (AQ) cooking processes and the optimal pulping conditions were established. Thus, pulps with a yield of about 37–38% with a Kappa number (Kappa no.) about 30–32 were obtained when cooking in the presence of 0.25–0.35% of anthraquinone at 120 ◦C for a short cooking time, i.e. 30 min. The longer times and higher temperatures of cooking as well as the use of kraft pulping conditions did not give rise to better performances, comparing to those mentioned above. These severe conditions were detrimental to the hemicellulose preservation.info:eu-repo/semantics/publishedVersio

Biomass-based residues valorization for the removal of sertraline from waters by adsorption

Pharmaceutical drugs reach the environment through several anthropogenic sources being scattered and accumulated across flora, fauna and all types of aquifers. Many of these compounds are intensively worldwide medical prescribed for the relief of most common diseases related with modern society, such as hormones, antidepressants, analgesics, antibiotics, anti-inflammatories, among others. Sertraline is a pharmaceutical drug used for the relief of depressive severe situations. Recent studies refer that some compounds belonging to this pharmaceutical class of drugs, despite of its very low level of concentration in water can be responsible for several and severe side-effects in the environmental fauna and flora based on toxicity and risk predictions.info:eu-repo/semantics/publishedVersio

Urethanes and polyurethanes from suberin 2: synthesis and characterization

Polyurethanes based on suberin from cork of Quercus suber L. and conventional isocyanate monomers were prepared and fully characterized in terms of both structure (FTIR and 1 H NMR spectroscopy) and thermal properties (differential scanning calorimetry and thermogravimetric analysis). Two fractions were systematically isolated, namely (i) methylene-chloride soluble products, which corresponded to linear and branched macromolecules and (ii) methylene-chloride insoluble products, representing the crosslinked material. The structures of these polymers were regular and no appreciable side reactions were detected. DSC analyses provided information about the glass transition temperature of both fractions and this parameter was correlated with the stiffness of the isocyanate used. The TGA of these polyurethanes showed that they started to degrade at about 175°C and that the residue at 400°C was around 50%. The highest amounts of insoluble fractions, as well as the highest Tgs, were reached when an initial [NCO]/[OH] of unity was used.info:eu-repo/semantics/publishedVersio

Cork suberin as a new source of chemicals.: 1. isolation and chemical characterization of its composition

Extractive-free cork from Quercus suber L. was submitted to a solvolysis treatment with methanolic NaOH which yielded 37% (o.d. cork) of suberin. This mixture of compounds was thoroughly characterized by FTIR, 1 H- and 13C-NMR, gas chromatogra phy coupled with mass spectrometric (GC–MS) analysis, vapour pressure osmometry (VPO), mass spectrography (MS) and gel permeation chromatography (GPC). After derivatization, the main components of the volatile fraction, representing less than half of the total, were found to be v-hydroxymonocarboxylates, a,v-dicarboxylates, simple alkanoates and 1-alkanols, all with chain lengths ranging from C16 to C24. A second fraction, with an average molecular weight about three times higher, was detected by VPO, MS and GPC. The presence of this important fraction in cork suberin had not been recognized in earlier studies. Both fractions constitute interesting precursors for the elaboration of new materials.info:eu-repo/semantics/publishedVersio

Valorisation of kraft lignin by using vanillin and lignin-based polyurethanes: Use of the biorefinery concept

In kraft pulp mills, the capacity of the recovery boiler is very often a limiting factor to the increase of the pulp production. Until several decades ago, an upgrade to boiler system for dealing with higher quantities of black liquor was the only alternative. The possibility of lignin extraction from black liquor seems to be much more attractive, either for energy production or combustion elsewhere, or to serve as feedstock for chemicals production. Since the beginning of the 90’s, associate Laboratory LSRE/LCM has been focused on overcoming expansion limitations in pulp industries and, in this work, we show an alternative to this industry segment for the utilization of lignin and producing high added value chemicals from renewable biomass materials. Based on the biorefinery concepts, an integrated process for producing vanillin from kraft lignin oxidation has been proposed and each of the needed unit operations has been investigated to provide a deeper scientific understanding on this subject.FCT - projects POCTI/EQU/33198/99, POCI/EQU/61738/2004 and Grant SFRH/BD/18415/2004. CYTED IV.17/2002-2006. Luso-French actions F13/06 and F32/08

Evaluation of the almond shell oxypropylation process trough the surface response methodology

The efficiency of an oxypropylation process depends on several variables and operating conditions, which may not be generalized due to the diverse nature of subtracts. In lignocellulosic biomasses, the content of each fraction (lignin, cellulose and hemicellulose) can differ, as well as, the crystalline organization, which may limit reagent’s access to biomass. Also, the hydroxyl content can vary among biomasses; high values demand higher amounts of reactants, namely catalyst content, and more severe reaction conditions. Therefore, owing to biomass variability, selection of the operating conditions for oxypropylation their optimization is a key issue. In this context, one-factor-at-a-time approaches are commonly used to optimize processes; but it is well-known that optimal operating conditions or interactions between variables cannot be predicted by this simplistic method. Both problems may be overcome by employing the response surface methodology (RSM).info:eu-repo/semantics/publishedVersio

Biodegradation study of I lignin-based rigid polyrethane foams

Polyurethanes are considered as one of the most versatile polymeric materials offering a wide range of products with applications in diverse sectors. Rigid polyurethane (RPU) foams belong to this class of products and represent a commercially important class of expanded materials. In the present work RPU foams have been prepared from lignin-based polyols (LP) obtained by oxypropylation of two technical lignins (Alcell and Indulin AT) and biodegradability evaluated using respirometry tests in liquid and solid media. A RPU foam produced from a commercial polyether polyol (CP) based on sorbitol (Lupranol® 3323) was used as reference. Lignin biodegradation by P. chrysogenum, T. harzianum, T. reesei, T. versicolor and P. chrysosporium fungi was tested. Respirometry tests (in liquid and solid media) were performed and foam’s biodegradation evaluated based on the produced CO2.FCT (grant SFRH/BD/18415/2004) and the French-Portuguese Scientific Cooperation (actions F-13/06 and F-32/08)

Lignin-based polyurethane elastomers

The incorporation of lignin into polymeric materials, directly or after chemical modification, is recognized as one of the most viable approaches to accomplish its valorisation and properly exploit its unique intrinsic properties. In this work polyurethanes with elastomeric properties have been synthesised using a three component system based on lignin, 4,4’-methylene-diphenylene diisocyanate (MDI) and polycaprolactone (PCL). The following variables were studied: the lignin type (Alcell (A) and Indulin AT (IAT)), the PCL molecular weight (400, 750 and 1000) and the lignin content (10, 15, 20 and 25% (w/w)). The results pointed out for effective lignin incorporation into the generated polyurethane network, where Alcell has a predominant role of chain extender and Indulin AT acts more as a crosslinking agent.Financial support from French-Portuguese Programme (F13/06 and F32/08) and FCT (SFRH/BD/18415/2004)