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An investigation is reported on the flammability and thermal behavior of polyamide‐6, obtained by anionic polymerization of ϵ‐caprolactam, carried out in bulk, in the presence of the following N‐substituted phosphorus‐containing lactam... more
An investigation is reported on the flammability and thermal behavior of polyamide‐6, obtained by anionic polymerization of ϵ‐caprolactam, carried out in bulk, in the presence of the following N‐substituted phosphorus‐containing lactam derivatives: diethyl‐(N‐caprolactam)‐phosphonite (PL1), diethyl‐(N‐caprolactam)‐phosphonate (PL2), and 2,5‐dichlorophenyl‐bis(N‐caprolactam)‐phosphinate (PL3). Phosphorus‐containing lactam derivatives PL,1 and PL3 are used as activators of the anionic polymerization of ϵ‐caprolactam, and PL2, as a modifying additive. The phosphorus‐containing polyamide‐6 possesses improved flame retardancy, as well as improved thermo‐ and thermooxidative resistance. Destruction kinetics were studied in nitrogen and air atmospheres, and the activation energy for thermal and thermooxidative destruction have been determined. The effect of PL1 PL2, and PL3 on the melting temperature (Tm) and glass‐transition temperature (Tg) of polyamide‐6 was established. © 1993 John Wiley & Sons, Inc.
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Polymer microparticles are used in additive manufacturing, separation and purification devices, biocatalysis, or for the recognition of biomolecules. This study reports on the effect of metal fillers on the structure and molecular... more
Polymer microparticles are used in additive manufacturing, separation and purification devices, biocatalysis, or for the recognition of biomolecules. This study reports on the effect of metal fillers on the structure and molecular dynamics of polyamide 6 (PA6) microparticles (MPs) containing up to 19 wt.% of Al, Cu, or Mg. These hybrid MPs are synthesized via reactive microencapsulation by anionic ring-opening polymerization in solution, in the presence of the metal filler. 13C high-resolution solid-state NMR (ssNMR) spectroscopy is employed as the primary characterization method using magic angle spinning (MAS) and cross-polarization (CP)/MAS. Depending on the metal filler, the ssNMR crystallinity index of the MP varies between 39–50%, as determined by deconvolution of the 13C MAS and CP/MAS spectra. These values correlate very well with the crystallinity derived from thermal or X-ray diffraction data. The molecular dynamics study on PA6 and Cu-containing MP shows similar mobility ...
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Apresentacao efetuada no "PolyChar 23 - 23rd World Forum on Advanced Materials", em Lincoln, Nebraska, U.S.A., 2015
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nSTEP project NORTE-07-0124-FEDER-000039; SFRH/BPD/45252 co-financed by QREN-POPH program of the EU
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This work has been carried out with financial aid of the project TSSiPRO NORTE-01-0145-FEDER-000015, suported by the regional operation program NORTE2020 under the Portugal 2020 Partnership Agreement, through the European Regional... more
This work has been carried out with financial aid of the project TSSiPRO NORTE-01-0145-FEDER-000015, suported by the regional operation program NORTE2020 under the Portugal 2020 Partnership Agreement, through the European Regional Development Fund, as well as funding from FCT – Portuguese Foundation for Science and Technology within the strategic projects UID/CTM/50025/2013, LA25/2013-2014. FMO acknowledges also the PhD Grant PD/BD/114372/2016 of FCT (AdvaMTech – PhD Program in Advanced Materials and Processing).
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Neat and hybrid polyamide 12 (PA12) based powders are important raw materials for additive manufacturing. This study describes a facile method for the synthesis of pure, hybrid and copolymeric microparticulate materials based on one‐pot... more
Neat and hybrid polyamide 12 (PA12) based powders are important raw materials for additive manufacturing. This study describes a facile method for the synthesis of pure, hybrid and copolymeric microparticulate materials based on one‐pot activated anionic ring‐opening polymerization (AAROP) of laurolactam in solution. The results reveal the possibility to obtain in good yields, for reaction times of 2 h and temperatures of up to 110°C neat and hybrid PA12 microparticles (MP) carrying metal or carbon fillers. Copolymeric PA12/PA6 MP can also be successfully prepared. All MP materials are analyzed by spectral, microscopy, thermal, and synchrotron X‐ray scattering methods in order to clarify their morphology, chemical and crystalline structure, melting and degradation behavior. The melting temperature of the PA12 MP is lower than of the commercial PA12, the presence of metal particles or copolymerization with PA6 additionally decrease it well below 170°C. The composites prepared by comp...
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Anti-EFG1 2′-OMethylRNA is an antisense oligonucleotide (ASO) that has the ability to recognize and block the EFG1 gene and to control Candida albicans filamentation. However, it is important to pr...
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Herewith we report the first attempt towards non-covalent immobilization of Trametes versicolor laccase on neat and magnetically responsive highly porous polyamide 6 (PA6) microparticles and their application for catechol oxidation. Four... more
Herewith we report the first attempt towards non-covalent immobilization of Trametes versicolor laccase on neat and magnetically responsive highly porous polyamide 6 (PA6) microparticles and their application for catechol oxidation. Four polyamide supports, namely neat PA6 and such carrying Fe, phosphate-coated Fe and Fe3O4 cores were synthesized in suspension by activated anionic ring-opening polymerization (AAROP) of ε-caprolactam (ECL). Enzyme adsorption efficiency up to 92% was achieved in the immobilization process. All empty supports and PA6 laccase complexes were characterized by spectral and synchrotron WAXS/SAXS analyses. The activity of the immobilized laccase was evaluated using 2,2’-Azino-bis-(3- ethylbenzothiazoline-6-sulfonic acid (ABTS) and compared to the native enzyme. The PA6 laccase conjugates displayed up to 105% relative activity at room temperature, pH 4, 40 °C and 20 mM ionic strength (citrate buffer). The kinetic parameters of the ABTS oxidation were also det...
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This study reports a new strategy for enzyme immobilization based on passive immobilization in neat and magnetically responsive polyamide 4 (PA4) highly porous particles. The microsized particulate supports were synthesized by... more
This study reports a new strategy for enzyme immobilization based on passive immobilization in neat and magnetically responsive polyamide 4 (PA4) highly porous particles. The microsized particulate supports were synthesized by low-temperature activated anionic ring-opening polymerization. The enzyme of choice was laccase from Trametes versicolor and was immobilized by either adsorption on prefabricated PA4 microparticles (PA4@iL) or by physical in situ entrapment during the PA4 synthesis (PA4@eL). The surface topography of all PA4 particulate supports and laccase conjugates, as well as their chemical and physical structure, were studied by microscopic, spectral, thermal, and synchrotron WAXS/SAXS methods. The laccase content and activity in each conjugate were determined by complementary spectral and enzyme activity measurements. PA4@eL samples displayed >93% enzyme retention after five incubation cycles in an aqueous medium, and the PA4@iL series retained ca. 60% of the laccase....
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Single polymer laminate composites based on anionic polyamide 6 (PA6) matrix‐reinforced by PA6 knitted textile structures (KSPC) were produced by nylon reactive injection molding and powder coating/compression molding (PCCM) processing... more
Single polymer laminate composites based on anionic polyamide 6 (PA6) matrix‐reinforced by PA6 knitted textile structures (KSPC) were produced by nylon reactive injection molding and powder coating/compression molding (PCCM) processing techniques. The effect of the reinforcement's structure and the fiber volume fraction on the mechanical properties of the knitted‐reinforced PA6 composites resulting from the two methods were investigated and compared. The morphology and the crystalline structure of KSPC materials were studied to identify the main factors determining the tensile properties. The results showed that the PCCM method produced laminate composites with higher Young's modulus and mechanical strength in tension. Microscopy, differential scanning calorimetry and X‐ray diffraction experiments were carried out to correlate the morphology and crystalline structure of the composites and their precursors with the different tensile behavior of KSPC prepared using the two tec...
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A.M.S.C and S.G.C. acknowledge financial support from Fundacao para a Ciencia e Tecnologia (FCT) through the grants SFRH/BD/101748/2014 and SFRH/BPD/96797/2013. N.V.D. is grateful for the FCT support through nSTEP project... more
A.M.S.C and S.G.C. acknowledge financial support from Fundacao para a Ciencia e Tecnologia (FCT) through the grants SFRH/BD/101748/2014 and SFRH/BPD/96797/2013. N.V.D. is grateful for the FCT support through nSTEP project NORTE-07-0124-FEDER-000039.
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The authors gratefully acknowledge the financial support of FCT - Portugal (SFRH/BPD/45252 co-financed by QREN-POPH program of the EU) and of 11 MiNaXS beamline of DESY – Hamburg, Germany. This work was also supported by FEDER through the... more
The authors gratefully acknowledge the financial support of FCT - Portugal (SFRH/BPD/45252 co-financed by QREN-POPH program of the EU) and of 11 MiNaXS beamline of DESY – Hamburg, Germany. This work was also supported by FEDER through the COMPETE Program and by the Portuguese Foundation for Science and Technology (FCT) in the framework of the Strategic Project PEST-C/FIS/UI607/2013 and the project Matepro –Optimizing Materials and Processes”, ref. NORTE-07-0124-FEDER- 000037”, co-funded by the “Programa Operacional Regional do Norte” (ON.2 – O Novo Norte), under the “Quadro de Referencia Estrategico Nacional” (QREN), through the “Fundo Europeu de Desenvolvimento Regional” (FEDER).
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ABSTRACT Establishing the effect of the external load on the structural entities at nanometer scale is considered a key for the explanation of the unique properties of polymer nanocomposites. A possible way to do this is by performing... more
ABSTRACT Establishing the effect of the external load on the structural entities at nanometer scale is considered a key for the explanation of the unique properties of polymer nanocomposites. A possible way to do this is by performing mechanical tests while collecting the WAXS and/or SAXS patterns of the sample under investigation [1]. Synchrotron sources should be used especially if simultaneous deformation and X-ray experiments are desired. At this point simple X-ray diffraction experiments have been performed with nanocomposite polymer systems, mostly for characterization of the nanoclay distribution. Herein, a new method is presented for studying the structure-mechanical properties relationship in polymer nanocomposites based on a more complete evaluation of the two dimensional X-ray scattering patterns obtained during sample straining while irradiating in a synchrotron beamline. PA6 masterbatches containing up to 20 wt. % of organically treated montmorillonite (MMT) were diluted with neat PA6 through twin-screw extrusion obtaining exfoliated composites with MMT content in the 1.0-7.5% range. These systems were then mixed with HDPE by melt extrusion to obtain blends with 20 wt. % of PA6 nanocomposite. A subsequent cold drawing resulted in highly oriented, fibrillated HDPE-PA6 blends, in which the MMT was located predominantly in the PA6 fibrils. The oriented blends were compression molded at temperatures above the melting of HDPE and below that of the PA6, thus producing microfibrilar polymer composites with a HDPE isotropic matrix embedding oriented PA6 fibrils additionally reinforced by MMT. The WAXS and SAXS patterns under simultaneously applied static or cyclic load were obtained with a MARCCD two dimensional detector at the A2 beamline of HASYLAB at DESY, Hamburg, Germany.
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The objective of this study is to manufacture and investigate novel nanostructured polymer composites (NPC) based on oriented blends of high-density polyethylene (HDPE) and polyamide 6 (PA6). Conventional polymer processing techniques are... more
The objective of this study is to manufacture and investigate novel nanostructured polymer composites (NPC) based on oriented blends of high-density polyethylene (HDPE) and polyamide 6 (PA6). Conventional polymer processing techniques are used for this purpose including extrusion blending, cold drawing and compression molding. Thus, various polymer blends are prepared comprising 10 and 20 wt% of PA6 and 0-10 wt% of a copolymeric compatibilizer. These blends are cold-drawn to high draw ratios and the oriented strands so produced are further compression molded at various temperatures between the melting points of HDPE and PA6. All NPC obtained are characterized by microscopy techniques, solid state NMR, mechanical tests and wide- and small-angle X-ray scattering from synchrotron. The mechanical and structural data of NPCs are discussed with relation with the polyamide fibrils’ orientation, as well as with the effect of compatibilizer at the matrix-fibrils interface.
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Die Phosphinoxide (III) und (IV) entstehen unter den angegebenen Bedingungen in vergleichbaren Mengen.