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Inverse gas chromatography and XPS of extracted kraft pulps
Gamelas, José A.F.; Duarte, Gustavo V.; Ferreira, Paulo J.Kraft pulps at the kappa number level of 15 obtained from Acer saccharum (sugar maple) and Eucalyptus globulus prepared with and without hot water pre-extraction (HWE) were analysed by inverse gas chromatography (IGC) and X-ray photoelectron spectroscopy (XPS). In the case of A. saccharum pulps, the dispersive component of the surface energy (γsd) at 40ºC determined by IGC was 39.8 mJ m-2 (control pulp without ...
Polyoxometalate/laccase-mediated oxidative polymerization of catechol for texti...
Kim, Suyeon; Silva, Carla Manuela; Evtuguin, D. V.; Gamelas, José A. F.; Paulo, Artur CavacoThe synergistic effect between polyoxometalates (POMs), namely K5[SiW11VVO40]·11H2O and H5[PMo10 VV2O40]·13H2O and laccase from ascomycete Myceliophthora thermophila has been employed for the first time in oxidative polymerization of catechol. Such a laccase-mediator system allowed the formation of a relatively high molecular weight polycatechol as confirmed by size exclusion chromatography and electrospray ion...
A New Approach for the Modification of Paper Surface Properties Using Polyoxome...
Saraiva, Mikhail S.; Gamelas, José A. F.; Sousa, António P. Mendes de; Reis, Bruno M.; Amaral, José L.; Ferreira, Paulo J.A new approach for the chemical modification of the surface of paper based on the application of colloidal mixtures containing cationic starch and polyoxometalates on uncoated base paper is presented. Polyoxometalates with the Keggin-type structure and physical properties similar to those presented by coating pigments, namely H3PW12O40·23H2O, H4SiW12O40·24H2O, and K7PW11O39·9H2O, have been used in order to impr...
The influence of paper surface sizing on inkjet
Costa, Tiago G.; Gamelas, José A.; Moutinho, Isabel M.; Figueiredo, M. Margarida; Ferreira, Paulo J.The effect of paper surface sizing on inkjet pigment penetration was evaluated by studying four different paper samples: one taken as reference, without surface sizing (paper RP), one surface sized with cationic starch (RPS1), one with a mixture of cationic starch and poly(styrene-co-maleic anhydride) (RPS2), and one with a mixture of cationic starch and poly(styreneco- acrylate) (RPS3). Assessment was based on...
Application of FT-IR-ATR Spectroscopy to Evaluate the Penetration of Surface Si...
Ferreira, Paulo J.; Gamelas, José A.; Moutinho, Isabel M.; Ferreira, Ana G.; Gómez, Nuria; Molleda, Cristina; Figueiredo, M. MargaridaIt is widely recognized that the surface properties of paper depend on the fibrous matrix and the final surface treatment applied to the paper. Regarding chemical paper surface treatments, an important issue is the evaluation of the penetration of chemical compounds into the fibrous matrix, as the chemicals can potentially cause changes in the intrinsic properties of paper. The work presented here aimed to use ...
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