<?xml version="1.0" encoding="UTF-8"?><xml><records><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Cordeiro, N.</style></author><author><style face="normal" font="default" size="100%">Neto, C. P.</style></author><author><style face="normal" font="default" size="100%">Rocha, J.</style></author><author><style face="normal" font="default" size="100%">Belgacem, M. N.</style></author><author><style face="normal" font="default" size="100%">Gandini, A.</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">The organosolv fractionation of cork components</style></title><secondary-title><style face="normal" font="default" size="100%">HOLZFORSCHUNG</style></secondary-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">C-13 NMR</style></keyword><keyword><style  face="normal" font="default" size="100%">Cork</style></keyword><keyword><style  face="normal" font="default" size="100%">ethanol/water extraction</style></keyword><keyword><style  face="normal" font="default" size="100%">FTIR</style></keyword><keyword><style  face="normal" font="default" size="100%">organosolv fractionation</style></keyword><keyword><style  face="normal" font="default" size="100%">Quercus Suber L</style></keyword><keyword><style  face="normal" font="default" size="100%">suberin</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">2002</style></year><pub-dates><date><style  face="normal" font="default" size="100%">2002///</style></date></pub-dates></dates><volume><style face="normal" font="default" size="100%">56</style></volume><pages><style face="normal" font="default" size="100%">135 - 142</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">Extractive-free cork from Quercus suber L. was submitted to organosolv fractionation and the effects of different process variables, such as ethanol/water ratio, temperature, time and the presence of acidic or alkaline catalysts, were studied. The variation of the relative proportions of extracted components, as a function of the processing conditions, could thus be established. Whereas the addition of 0.1 M acetic acid only increased the yield of extracted materials from about 15 to 23 %, the use of sodium hydroxide, at the same concentration, produced a jump to 76 %. In the case of the alkaline organosolv fractionation. an increase in process temperature, time and catalyst concentration led to an increase in the extraction yield, although in some cases this increase did not follow a sustained trend, as in the case of reaction time. Increasing the ethanol/water ratio led to a higher selectivity in favour of suberin extraction. Residual cork from different organosolv processes was characterised by FTIR and C-13 solid-state NMR. The latter technique provided some valuable information about both process selectivity and cork morphology, particularly with respect to the positioning of suberin macromolecules in the cell wall.</style></abstract><issue><style face="normal" font="default" size="100%">2</style></issue><notes><style face="normal" font="default" size="100%">The following values have no corresponding Zotero field:&lt;br/&gt;pub-location: GENTHINER STRASSE 13, D-10785 BERLIN, GERMANY&lt;br/&gt;publisher: WALTER DE GRUYTER &amp; CO</style></notes></record><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Lopes, M. H.</style></author><author><style face="normal" font="default" size="100%">Sarychev, A.</style></author><author><style face="normal" font="default" size="100%">Neto, C. P.</style></author><author><style face="normal" font="default" size="100%">Gil, a M.</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Spectral editing of 13C cp/MAS NMR spectra of complex systems: application to the structural characterisation of cork cell walls.</style></title><secondary-title><style face="normal" font="default" size="100%">Solid state nuclear magnetic resonance</style></secondary-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">13CCPrMAS NMR</style></keyword><keyword><style  face="normal" font="default" size="100%">Cork</style></keyword><keyword><style  face="normal" font="default" size="100%">Polymer</style></keyword><keyword><style  face="normal" font="default" size="100%">Quercus suber L.</style></keyword><keyword><style  face="normal" font="default" size="100%">Relaxation</style></keyword><keyword><style  face="normal" font="default" size="100%">Spectral editing</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">2000</style></year><pub-dates><date><style  face="normal" font="default" size="100%">2000///</style></date></pub-dates></dates><urls><web-urls><url><style face="normal" font="default" size="100%">http://www.ncbi.nlm.nih.gov/pubmed/10868562</style></url></web-urls></urls><volume><style face="normal" font="default" size="100%">16</style></volume><pages><style face="normal" font="default" size="100%">109 - 121</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">A mathematical method of obtaining 13C CP/MAS subspectra of single components of a complex system is presented and applied to three- and four-component systems. The method is based on previously reported work that exploits different proton relaxation properties for different domains of an heterogeneous system. However, unlike the original method that obtained subspectra through a trial-and-error approach, the method here presented solves the problem mathematically, thus avoiding the time-consuming and non-rigorous trial-and-error step. The method is applied to mixtures of three and four polymers and to a more complex system: cork cell walls. As expected, as the number of components increases, the sharing of relaxation properties between different components is increasingly probable, either due to incidental coincidence of relaxation times or to specific interactions and intimate mixing of compounds. While this hinders the calculation of the subspectra of single chemical components, it may provide useful information about inter-component interactions. This possibility was demonstrated by the application of this method to cork cell walls. Both three-component and four-component approaches showed that three domains exist in cork cell walls: carbohydrate/lignin matrix, mobile suberin close to (probably bonded to) lignin groups (about 42% w/w) and hindered suberin close to (probably bonded to) carbohydrate-OCH2O groups (about 4% w/w).</style></abstract><issue><style face="normal" font="default" size="100%">3</style></issue><notes><style face="normal" font="default" size="100%">The following values have no corresponding Zotero field:&lt;br/&gt;accession-num: 10868562</style></notes></record><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Cordeiro, N.</style></author><author><style face="normal" font="default" size="100%">Belgacem, M. N.</style></author><author><style face="normal" font="default" size="100%">Gandini, A.</style></author><author><style face="normal" font="default" size="100%">Neto, C. P.</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Urethanes and polyurethanes from suberin 2: synthesis and characterization</style></title><secondary-title><style face="normal" font="default" size="100%">INDUSTRIAL CROPS AND PRODUCTS</style></secondary-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">Cork</style></keyword><keyword><style  face="normal" font="default" size="100%">glass transition</style></keyword><keyword><style  face="normal" font="default" size="100%">polyurethanes</style></keyword><keyword><style  face="normal" font="default" size="100%">Quercus suber L.</style></keyword><keyword><style  face="normal" font="default" size="100%">suberin</style></keyword><keyword><style  face="normal" font="default" size="100%">thermal properties</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">1999</style></year><pub-dates><date><style  face="normal" font="default" size="100%">1999///</style></date></pub-dates></dates><volume><style face="normal" font="default" size="100%">10</style></volume><pages><style face="normal" font="default" size="100%">1 - 10</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">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 H-1 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 degrees C and that the residue at 400 degrees C was around 50%. The highest amounts of insoluble fractions, as well as the highest T-g,s, were reached when an initial \{[\}NCO]/\{[\}OH] of unity was used. (C) 1999 Elsevier Science B.V. All rights reserved.</style></abstract><issue><style face="normal" font="default" size="100%">1</style></issue><notes><style face="normal" font="default" size="100%">The following values have no corresponding Zotero field:&lt;br/&gt;pub-location: PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS&lt;br/&gt;publisher: ELSEVIER SCIENCE BV</style></notes></record><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Cordeiro, N.</style></author><author><style face="normal" font="default" size="100%">Belgacem, N. M.</style></author><author><style face="normal" font="default" size="100%">Gandini, A.</style></author><author><style face="normal" font="default" size="100%">Neto, C. P.</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Cork suberin as a new source of chemicals: 2. Crystallinity, thermal and rheological properties</style></title><secondary-title><style face="normal" font="default" size="100%">Bioresource technology</style></secondary-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">Alkaline methanolysis</style></keyword><keyword><style  face="normal" font="default" size="100%">cork of Quercus suber L.</style></keyword><keyword><style  face="normal" font="default" size="100%">crystallinity</style></keyword><keyword><style  face="normal" font="default" size="100%">Density</style></keyword><keyword><style  face="normal" font="default" size="100%">rheological properties</style></keyword><keyword><style  face="normal" font="default" size="100%">suberin</style></keyword><keyword><style  face="normal" font="default" size="100%">thermal characterization</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">1998</style></year><pub-dates><date><style  face="normal" font="default" size="100%">1998///</style></date></pub-dates></dates><urls><web-urls><url><style face="normal" font="default" size="100%">http://www.sciencedirect.com/science/article/pii/S0960852497000734</style></url></web-urls></urls><volume><style face="normal" font="default" size="100%">63</style></volume><pages><style face="normal" font="default" size="100%">153 - 158</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">Suberin samples, obtained by alkaline methanolysis from cork (Quercus suber L.), were submitted to various physical characterizations; DSC, TGA, optical microscopy, density and rheological properties. A sub- stantial proportion of these oligomers possessed a microcrystalline character with a melting range between 0 and 50°C. The amorphous part was liquid at room temperature and did not display a detectable glass transition upon cooling because of its wide molecular weight distribution. The viscous behaviour of suberin at room temperature was both plastic and thixotropic because of the structuring role of the micro- crystals</style></abstract></record><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Cordeiro, N.</style></author><author><style face="normal" font="default" size="100%">Neto, C. P.</style></author><author><style face="normal" font="default" size="100%">Gandini, A.</style></author><author><style face="normal" font="default" size="100%">Naceur Belgacem, M.</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Characterization of the cork surface by inverse gas chromatography</style></title><secondary-title><style face="normal" font="default" size="100%">Journal of colloid and interface science</style></secondary-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">Cork</style></keyword><keyword><style  face="normal" font="default" size="100%">Inverse Gas Chromatography (IGC)</style></keyword><keyword><style  face="normal" font="default" size="100%">surface properties (PG)</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">1995</style></year><pub-dates><date><style  face="normal" font="default" size="100%">1995///</style></date></pub-dates></dates><urls><web-urls><url><style face="normal" font="default" size="100%">http://www.sciencedirect.com/science/article/pii/S0021979785713872</style></url></web-urls></urls><volume><style face="normal" font="default" size="100%">174</style></volume><pages><style face="normal" font="default" size="100%">246 - 249</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">Inverse gas chromatography (IGC) at infinite dilution has been used to study the surface properties of cork from Quercus suber. The dispersive component of its surface energy was determined at different temperatures using n-alkanes as probes, and a GDS value of 38+-1mJ.m-2 at 40ºC was obtained. The surface acid (A)/base(B) properties were also evaluated by using polar probes and the results indicate that cork has an amphoteric character, with a KA/KB=1.1. The advantages of IGC, compared with the technique of contact angle measurements in the characterization of the cork surface, are discussed</style></abstract></record></records></xml>