Massó, M.; Moré-Ollé, P.; Carrasco, F.; Santana, O.; Maspoch, M.; Bou, J. J. European Meeting on Chemical Industry and Environment p. 351-352 Presentation's date: 2015-06 Presentation of work at congresses
In this study the dynamic viscoelastic properties of three structurally modified poly(lactic acid) (PLA) samples processed through reactive extrusion were analyzed. While classical chromatographic and spectroscopic techniques exhibited limited sensitivity to the presence of topological changes, rheological measurements confirmed the presence of non-uniform branched macromolecules, holding sparsely long chain branches. According to the processing conditions used, the flow activation energy and the thermorheologically simple behavior remained roughly unaffected for PLA-REX containing an amount of modified chains up to 24%. Distinctly separated relaxation processes in a broader transition zone were observed in the complex viscosity function (|¿*(¿)|) of all PLA-REX samples. The “extended Carreau-Yassuda” model and an extension of the Havriliak-Negami model, proposed in this work, were used to capture the main characteristics of |¿*(¿)| experimental data. Both fitted models were inverted to molecular weight distribution (MWD) spectrum using the numerical inversion technique of Shaw and Tuminello and these were compared with size exclusion chromatography (SEC) MWDs. It was shown that the resolution of the predicted bimodal MWDs was enhanced when the model used to fit|¿*(¿)| data was exempted from the Cox-Merz rule and included a complex time dependence. Based on the MWDs deduced from solely melt measurements, a procedure was described to quantitatively estimate the amount of modified chains.
Cyclic butylene terephthalate (CBT (R)) is an interesting matrix material for the preparation of nanocomposites due to its very low, water-like melt viscosity which favours clay exfoliation. Nevertheless, polymerized CBT (pCBT) is inherently brittle. This paper reports the preparation of isocyanate-toughened nanocomposites made from CBT and organo-modified montmorillonite. The role of the organoclay as reinforcement and the polymeric isocyanate (PMDI) as toughening agent on the properties of pCBT was studied. The organoclay increased the stiffness and strength by up to 20% whereas the PMDI improved the deformation behaviour. However, the PMDI did not affect the degree of clay dispersion or exfoliation and flocculated-intercalated structures were observed. The compatibility between the pCBT matrix and clay was further increased by preparing PMDI-tethered intercalated organoclay. The modified organoclay then exfoliated during ring-opening polymerization and yielded true pCBT/clay nanocomposites. This work demonstrates that reactive chain extension of CBT with a polyfunctional isocyanate is an effective method to obtain toughened pCBT nanocomposites. Moreover, isocyanates can enhance the compatibility between pCBT and nanofiller as well as the degree of exfoliation.
Cailloux, J.; Santana, O.; E Franco-Urquiza; Bou, J. J.; Carrasco, F.; Maspoch, M. Journal of materials science Vol. 49, num. 11, p. 4093-4107 DOI: 10.1007/s10853-014-8101-y Date of publication: 2014-06-01 Journal article
The architectural modifications of a linear poly(D,L-Lactide) acid (PD,L-LA) commercial grade were induced by a one-step reactive extrusion-calendering process using a styrene-glycidyl acrylate copolymer as reactive agent. The melt degradation was counteracted by chain extension and branching reactions, leading to a stabilization of the melt properties and an increase in the molecular weight. For such modified samples [poly(lactic acid) (PLA)-reactive extrusion (REX)], the rate of physical aging at 30 A degrees C was investigated during 1 week in order to simulate industrial storage conditions. Fracture behavior of "de-aged" and "controlled aged" (1 week) samples was investigated using the essential work of fracture (EWF) methodology and the critical tip opening displacement at the crack propagation onset, respectively. These analyses were complemented by digital image correlation analysis and inspection of the fractured surfaces by scanning electronic microscopy. As a result of the architectural modifications, the entanglement network density was increased. Those accounted for a slight decrease in the physical aging rate. Under uniaxial loading, aged reactive extrusion (REX) samples exhibited multiple crazing, leading to a slight increase in strain at break. Nevertheless, as a result of a similar dynamic environment of the entangled polymer coils, de-aged REX samples disclosed similar mechanical properties as compared to their neat counterparts. Regarding de-aged samples, the EWF analysis revealed no changes in the work required for the onset of crack propagation. However, the energy consumed up to the onset of crack propagation of aged PLA-REX samples decreased due to an apparently decreased network extensibility, promoting a premature craze-crack transition.
The architectural modifications of a linear poly(D,L-Lactide) acid (PD,L-LA) commercial grade were induced by a one-step reactive extrusion-calendering process using a styrene-glycidyl acrylate copolymer as reactive agent. The melt degradation was counteracted by chain extension and branching reactions, leading to a stabilization of the melt properties and an increase in the molecular weight. For such modified samples [poly(lactic acid) (PLA)-reactive extrusion (REX)], the rate of physical aging at 30 A degrees C was investigated during 1 week in order to simulate industrial storage conditions. Fracture behavior of
The aim of this work is to develop new systems of nanocomposites to confer new functions to materials used for seats of public vehicles and public spaces. Specifically, this study focuses on antibacterial effect for leather and technical textile substrates.
The first stage of the research consists of a selection of micro/nanomaterials and active principles: selection and evaluation of nanoparticles, antibacterial and antifungal substances. In the second stage, the process of encapsulation of active principles was studied. The research includes optimization of the encapsulation process by improving the size and stability of the capsules. In addition, the synthesis of a hybrid organic-inorganic polymer acting as a nanomaterial carrier was developed.
To understand the mechanisms of synthesis and action of micro/nanomaterials, characterization techniques have been used: scanning electron microscopy SEM and optical microscopy, analysis and distribution of particle size (DLS, Zetasizer). Regarding the antibacterial and antifungal ability of nanocomposites, we adapted standard ASTM 2180-07 "Test methods for determining the activity or incorporated antimicrobial agent (s) in polymeric or hydrophobic materials."
Different products have been developed and the results obtained allow us to conclude that the synthesized products showed inhibition to the growth of bacteria and fungi on the contact surface
Electronic version of an article published as "Express polymer letters" vol. 7, nº. 2, February 2013, p. 172-185.
Cyclic butylene terephthalate oligomers (CBT) were reacted in a ring-opening polymerization with three types of
isocyanates: a bifunctional aromatic type, a bifunctional aliphatic type and a polymeric aromatic isocyanate. All reactions
took place in a batch mixer. The use of 0.5 to 1 wt% isocyanate led to a dramatic increase in elongation at break of polymerized
cyclic butylene terephthalate (pCBT), from 8 to above 100%. The stiffness and strength of the modified pCBT, however,
were found to slightly decrease. Proton nuclear magnetic resonance (NMR) analysis shows that the formation of thermally
stable amide groups is the dominant chain extension reaction mechanism. Gel content measurements suggest a linear structure
for samples containing bifunctional isocyanates while pCBT modified with polyfunctional isocyanate exhibited some
gel formation at higher isocyanate content. Melting and crystallization temperatures as well as degree of crystallinity were
found to decrease with increasing isocyanate content. No phase separation was detected by scanning electron microscopy
(SEM) analysis. Moreover, a high degree of polymerization is deduced due to the absence of CBT oligomer crystals.
Poly (y-glutamic acid), a novel polyanionic and multifunctional macromolecule synthesized by Bacillus species, has attracted considerable attention because of its eco-friendly, biodegradable and biocompatible characteristics. Recently, its application in a wide range of fields such as food, agriculture, medicine, hygiene, cosmetics and the environment has been explored. This book discusses the chemistry, food sources and health benefits of glutamic acid.
This study examines the behavior of three different types of humic acids (natural humic acids, regenerated humic acids, and sulphited humic acids) with regard to their penetration and fixation to the leather. More specifically, through the tests carried out the curves of penetration and fixation were drawn, and from these the optimum pH intervals of penetration and fixation to the leather were determined. The data obtained is essential in view of the subsequent application of humic acids as tanning agents and/or retanning agents
Three types of humic acids of different sources have been analysed in order to quantify the functional groups that may be liable to react with the proteins of leather. The quantification serves to determine the extent to which each of these acids can be used as tanning or retanning agents. The three types of humid acids have been compared mathematically according to their content within the aforementioned functional groups. Humic acids have structures similar to those of vegetable tannins.
Gamez, J.; Nascimento, L.; Bou, J. J.; E Franco-Urquiza; Santana, O.; Carrasco, F.; Maspoch, M. Journal of applied polymer science Vol. 120, num. 2, p. 896-905 DOI: 10.1002/app.33191 Date of publication: 2011-04-15 Journal article
The aim of this work was to study the effect of crystallinity degree on the thermal, mechanical, and fracture properties of poly(lactic acid)/organomodified montmorillonite (PLA/OMMT) nanocomposites. Samples with two different compositions (0.5 and 2.5% weight OMMT in PLA) were prepared by melt mixing in a twin-screw extruder and injection molding. An annealing treatment was applied to increase the percentage of PLA crystallinity. The thermal behavior was analyzed by differential scanning calorimetry (DSC), and the mechanical properties were determined via tensile tests and the fracture behavior using the linear elastic fracture mechanics theory, using SENB specimens at low and high testing rates. Gel permeation chromatography (GPC) from granulates and injected specimens were also carried out, finding some polymer degradation during extrusion and injection processes. The results show a toughening effect of the nanocomposites on amorphous specimens but embrittlement on the annealed ones.
García Grillasca, G.; Rodriguez, A.; Calafell, M.; Bou, J. J.; Almajano, M.P.; Marques, M.S. New biotechnology Vol. 25, num. Supplement 1, p. s129-s130 DOI: 10.1016/j.nbt.2009.06.437 Date of publication: 2009-09 Journal article
Bou, J. J.; Davila, M.; Bover, L.; Diaz, J.; Cañameras, N.; Almajano, M.P. Congreso Nacional de Ciencia y Tecnologia de Alimentos p. 71 Presentation's date: 2009-05-29 Presentation of work at congresses
Bover, L.; Rodriguez-Luna, M.; Davila, M.; Bou, J. J.; Lopez-Perez, D.; Almajano, M.P. Congreso Nacional de Ciencia y Tecnologia de Alimentos p. 79 Presentation's date: 2009-05-27 Presentation of work at congresses