Documents disponibles écrits par cet auteur

Optimization of the methylation conditions of kraft cellulose pulp for its use as a thickener agent in biodegradable lubricating greases / J. E. Martin-Alfonso in Industrial & engineering chemistry research, Vol. 48 N° 14 (Juillet 2009) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 48 N° 14 (Juillet 2009) . - pp. 6765–6771 Titre : Optimization of the methylation conditions of kraft cellulose pulp for its use as a thickener agent in biodegradable lubricating greases Type de document : texte imprimé Auteurs : J. E. Martin-Alfonso, Auteur ; R. Yañez, Auteur ; C. Valencia, Auteur Année de publication : 2009 Article en page(s) : pp. 6765–6771 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Kraft  cellulose  pulp  Methylation  conditions  Thickener  agent Résumé : This work evaluates the influence of the operating conditions used in the derivatization of commercial Kraft cellulose pulp (mercerization time (1−3 h) methylation process temperature (30−60 °C), methylation process time (1−4 h), (initial pulp)/(final wet alkali pulp) ratio (S/S) (1/7−1/12), and pulp/acetone ratio (S/L) concentration (1/3−1/12)) on the obtained methylcellulose pulp characteristics such as degree of polymerization of cellulose, substitution degree, water solubility, and viscosity of the resulting pulps in order to determine the best process conditions of this pulp for its use as a thickener agent in biodegradable lubricating grease formulations. Efficient use of the raw material (i.e., obtaining a degree of polymerization with suitable substitution degree) entailed using a 2.5 h methylation time and a 45 °C methylation temperature. The substitution degree (DS) and consistency index thus obtained are only 14.5% and 36.3% respectively lower than the optimum value, and an increment of 28.6% could be obtained for the degree of polymerization. Some methylcellulose-based oleogels display rheological properties very similar to those found in traditional lubricating greases. Methylcellulose with DS values of around 0.4 produces oleogels with better mechanical properties than highly derivatized cellulose and much better than the original Kraft cellulose pulp. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie9002766 [article] Optimization of the methylation conditions of kraft cellulose pulp for its use as a thickener agent in biodegradable lubricating greases [texte imprimé] / J. E. Martin-Alfonso, Auteur ; R. Yañez, Auteur ; C. Valencia, Auteur . - 2009 . - pp. 6765–6771. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N° 14 (Juillet 2009) . - pp. 6765–6771 Mots-clés : Kraft  cellulose  pulp  Methylation  conditions  Thickener  agent Résumé : This work evaluates the influence of the operating conditions used in the derivatization of commercial Kraft cellulose pulp (mercerization time (1−3 h) methylation process temperature (30−60 °C), methylation process time (1−4 h), (initial pulp)/(final wet alkali pulp) ratio (S/S) (1/7−1/12), and pulp/acetone ratio (S/L) concentration (1/3−1/12)) on the obtained methylcellulose pulp characteristics such as degree of polymerization of cellulose, substitution degree, water solubility, and viscosity of the resulting pulps in order to determine the best process conditions of this pulp for its use as a thickener agent in biodegradable lubricating grease formulations. Efficient use of the raw material (i.e., obtaining a degree of polymerization with suitable substitution degree) entailed using a 2.5 h methylation time and a 45 °C methylation temperature. The substitution degree (DS) and consistency index thus obtained are only 14.5% and 36.3% respectively lower than the optimum value, and an increment of 28.6% could be obtained for the degree of polymerization. Some methylcellulose-based oleogels display rheological properties very similar to those found in traditional lubricating greases. Methylcellulose with DS values of around 0.4 produces oleogels with better mechanical properties than highly derivatized cellulose and much better than the original Kraft cellulose pulp. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie9002766

Rheological modification of lubricating greases with pecycled polymers from different plastics waste / J. E. Martin-Alfonso in Industrial & engineering chemistry research, Vol. 48 N° 8 (Avril 2009) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 48 N° 8 (Avril 2009) . - pp. 4136–4144 Titre : Rheological modification of lubricating greases with pecycled polymers from different plastics waste Type de document : texte imprimé Auteurs : J. E. Martin-Alfonso, Auteur ; C. Valencia, Auteur ; M. C. Sánchez, Auteur Année de publication : 2009 Article en page(s) : pp. 4136–4144 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Lubricating  greases  Recycled  polymers  Plastics  waste  Small-amplitude  oscillatory  shear  Viscous  flow  measurements Résumé : There is a growing interest on the development of new materials based on recycled polymers from plastics waste, since the use of such plastics represents a low-cost source of raw material. The purpose of the present work is to evaluate, from a comparative point of view, the effect that different waste and virgin polymers, used as viscosity modifier additives, exert on the rheological properties of standard lithium lubricating greases. Grease formulations containing diverse polymers, differing in nature and/or origin, were manufactured and rheologically characterized. Particularly, the influences of the type of polymer, the molecular weight and the presence of carbon black, used as filler in recycled polymers, have been evaluated. Small-amplitude oscillatory shear (SAOS) and viscous flow measurements were carried out, as well as calorimetric and thermogravimetric analysis. In general, recycled polymers induce a more important rheological modification than virgin polymers of the same nature. Thus, the addition of some recycled polymers such as HDPE, LDPE, PP, and EVA copolymer to lithium lubricating grease significantly increases the values of the rheological parameters analyzed. The crystallinity degree, mainly dependent on the nature of the polymer, and the carbon black content of recycled polymers have been pointed out as the most highly influencing parameters on the rheology of the lubricating greases studied. However, an apparent loss in mechanical stability for lubricating greases containing recycled polymers has been found when they were submitted to a severe mechanical treatment. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801359g [article] Rheological modification of lubricating greases with pecycled polymers from different plastics waste [texte imprimé] / J. E. Martin-Alfonso, Auteur ; C. Valencia, Auteur ; M. C. Sánchez, Auteur . - 2009 . - pp. 4136–4144. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N° 8 (Avril 2009) . - pp. 4136–4144 Mots-clés : Lubricating  greases  Recycled  polymers  Plastics  waste  Small-amplitude  oscillatory  shear  Viscous  flow  measurements Résumé : There is a growing interest on the development of new materials based on recycled polymers from plastics waste, since the use of such plastics represents a low-cost source of raw material. The purpose of the present work is to evaluate, from a comparative point of view, the effect that different waste and virgin polymers, used as viscosity modifier additives, exert on the rheological properties of standard lithium lubricating greases. Grease formulations containing diverse polymers, differing in nature and/or origin, were manufactured and rheologically characterized. Particularly, the influences of the type of polymer, the molecular weight and the presence of carbon black, used as filler in recycled polymers, have been evaluated. Small-amplitude oscillatory shear (SAOS) and viscous flow measurements were carried out, as well as calorimetric and thermogravimetric analysis. In general, recycled polymers induce a more important rheological modification than virgin polymers of the same nature. Thus, the addition of some recycled polymers such as HDPE, LDPE, PP, and EVA copolymer to lithium lubricating grease significantly increases the values of the rheological parameters analyzed. The crystallinity degree, mainly dependent on the nature of the polymer, and the carbon black content of recycled polymers have been pointed out as the most highly influencing parameters on the rheology of the lubricating greases studied. However, an apparent loss in mechanical stability for lubricating greases containing recycled polymers has been found when they were submitted to a severe mechanical treatment. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801359g