1,720,968 research outputs found
Polymers with complex macromolecular architecture having flame-retardant properties
No full textThe present invention relates to linear or branched polyamides obtainable by polymn. of a mixt. contg. a bifunctional monomer of type AB and/or a monomer mixt. of type ΛΛ+ΒΒ in the presence of: a) one or more mols., having one or more carboxyl and/or amino functional groups, selected from carboxylic acids or an ester or an anhydride thereof, and/or amines and/or polyhedral oligosilsequioxanes (POSS);; and b) one or more phosphorus contg. mols., reactive with only one reactive group during polymn., contg. at least a -POOH group and/or a salt thereof; and c) one or more metal hydroxides and/or metal salts, wherein the metal belongs to groups from 1 to 14 of the Periodic Table; provided that when the phosphorus contg. mols., as defined under b), contain the -POOH groups in salified form with a metal as defined under c), then the presence of the metal hydroxides and/or metal salts, as defined under c) is optional
Rheological and thermal behavior of nanocomposite PLAs with complex macromolecular architecture
Get PDFA poster presented in XVIII° Congresso Nazionale della Divisione di Chimica Industriale della Società Chimica Italiana (SCI) “Le sfide della chimica industriale per un’innovazione sostenibile” - Florence - 11-14 June 2012 dealing with Rheological and thermal behavior of nanocomposite PLAs with complex macromolecular architecture synthesised by the author
Synthesis and characterization of PLA nanocomposites containing nanosilica modified with different organosilanes II: Effect of the organosilanes on the properties of nanocomposites: Thermal characterization
No full textThermal behavior of polylactic acid (PLA)/nanosilica nanocomposites prepared via bulk ring opening polymerization from lactide was investigated by differential scanning calorimetry and thermogravimetric analysis (TGA). Both unmodified nanosilica and modified by surface treatments with different amounts of two distinct silanes were used. Samples containing pure silica show enhanced crystallization processes; with silane-modified silica this effect is magnified, especially in the case of materials with high loadings of epoxy silane. Nonisothermal crystallization temperatures become higher and isothermal crystallization kinetics show a marked increase of Kinetic constant (Kc). TGA analyses show that, when pure nanosilica is present, nanocomposites have a thermal stability far greater than the one of standard PLA, starting their degradation at temperatures up to 70°C higher than the ones of pure PLA. When silanes are present, thermal stability lowers as silane content increases, but it is anyway higher than the one of the pure polymer
Synthesis and characterization of polymers having complex architecture and low environmental impact
No full textIn this presentation, a general overview about the term "biopolymer" and "bioplastic" will be given, dealing also with the issues related to the production and use of the so-called "green polymers". Then, the basic principles regarding the definition of complex architecture polymers is introduced, to show the results obtained by authors in two different fields, one related to the synthesis of innovative PLAs and another dealing with the synthesis of intrinsically Flame Retardant Polyamide
Branched lactic acid polymers with high viscosity in the molten state and high shear sensitivity, and nanocomposites
No full textA PLA polymer is obtainable by bulk polymerization of lactide or a lactic acid polymer obtainable by copolymerization of lactide or lactic acid with glycolide, glycolic acid and/or hydroxyacids in open or closed (cyclic) form in the presence of >2 org. and/or org./inorg. chain regulators or a functionalized nanoparticle (nanosilica, montmorillonite
Synthesis and characterization of PLA nanocomposites containing nanosilica modified with different organosilanes I: Effect of the organosilanes on the properties of nanocomposites: Macromolecular, morphological, and rheologic characterization
No full textPolylactide nanocomposites containing different loadings of nanosilica were prepared by employing bulk ring opening polymerization from lactide. Nanosilica was used as such and after surface treatment with different amounts of two distinct silanes. The effects on the properties of the material were evaluated comparing the samples containing organosilane-modified nanosilica with poly(lactic acid) (PLA) containing unmodified nanosilica. A standard linear PLA and an industrial “film grade” PLA (PLA Natureworks 4032D) were used as reference. Pure silica tends to decrease the molecular weight of the material, deactivating the catalytic system but when silanes are present on the surface, molecular weights are similar to the ones of standard and industrial PLA. Transmission electron microscopy analysis shows that silanes improve the dispersion of the mineral, while rheologic curves suggest that when silanes are present melt viscosity increases markedly at zero shear and decreases faster as the shear rate increases
Evaluation of crystallinity and gas barrier properties of films obtained from PLA nanocomposites synthesized via ‘‘in situ’’ polymerization of L-lactide with silane- odified nanosilica and montmorillonite
No full textThe effects of nanoparticles shape and surface modification on crystallinity and on gas and vapor properties of nanocomposites polylactide (PLA) films were evaluated. Films were prepared via solvent casting from PLA nanocomposites obtained by in situ polymerization of L-lactide using two different nanoparticles: nanosilica (NS) and an organically-modified montmorillonite (MMT), Cloisite 15A. To improve the compatibility between the polymer and the nanoparticles, NS and MMT were also modified with different amounts of two silanes, 3-aminopropyltriethoxysilane or 3-glycidoxypropyltrimethoxysilane. Thermal analyses indicate that nanoparticles (both with and without silanes on the surface) enhance crystallization processes and the effect of NS is much higher than the effect of
MMT. The presence of NS nanoparticles, especially when modified with silanes, contribute in greatly enhancing crystallinity and in lowering permeability to O2 and CO2; values of O2 and CO2 permeability were reduced up to 80% and 50% respectively, compared to pure PLA; water vapor (WV) permeability is significantly affected by the presence of the nanoparticles but not by their shape and by modification with silanes. The in situ-synthesis permits to use lower amounts of nanoparticle in comparison to melt extrusion or blending processing techniques, in order to achieve the same or better performances, thanks to an improved dispersion of the fillers, that is obtained also due to the surface modification
Intrinsically flame retardant non halogenated polymides
No full textAuthors present a poster dealing with the synthesis of intrinsically Flame Retardant polyamides
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