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Bouza R.,University of La Coruña | Abad M.J.,University of La Coruña | Barral L.,University of La Coruña | Lasagabaster A.,Complutense University of Madrid | And 2 more authors.
Journal of Applied Polymer Science | Year: 2011

In this work, the aim was to analyze the efficacy of hindered amine light stabilizers (HALS) in woodflour-polypropylene composites compatibilized with vinyltrimethoxysilane after moisture absorption and accelerated weathering. Moisture uptake of materials decreased with incorporation of silane due to diminished accessibility of water molecules to reactive regions. In dynamic mechanical experiments performed on wet samples, a marked reduction in the storage modulus in the glassy and rubbery zone was observed, since water has a plasticizing effect. After sample weathering, in a xenon-arc apparatus, the changes in chemical structure and physical properties after exposure were analyzed by attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy, color measurement, flexural properties, and morphological analysis by scanning electron microscopy (SEM). The data showed that HALS maintain the brightness of the materials after aging and prevent sample whitening. They also reduced color loss after aging and the SEM micrographs revealed that they inhibit surface cracking during weathering. Although a slight decline in the mechanical properties was not completely avoided, the combination of the additives studied (UV absorbers and HALS) successfully prevented the deterioration of surface materials by UV radiation. © 2010 Wiley Periodicals, Inc.


Dopico-Garcia M.S.,University of La Coruña | Dopico-Garcia M.S.,Centro Galego do Plastico | Lopez-Vilarino J.M.,University of La Coruña | Fernandez-Martinez G.,University of La Coruña | Gonzalez-Rodriguez M.V.,University of La Coruña
Analytica Chimica Acta | Year: 2010

A simple, robust and sensitive analytical method to determine three polyamines commonly used as hardeners in epoxy resin systems and in the manufacture of polyurethane is reported. The studied polyamines are: one tetramine, TETA (triethylenetetramine), and two diamines, IPDA (Isophorone diamine) and TCD-diamine (4,7-methano-1H-indene-5,?-dimethanamine, octahydro-). The latter has an incompletely defined structure, and, as far as we know, has not been previously determined by other methods. All three polyamines contain primary amines; TETA also contains secondary amines.The analytical method involves derivatization with 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate, used for the first time for these compounds, followed by high performance liquid chromatography (HPLC) analysis with a fluorescence (FL) detector (λ excitation 248nm, λ emision 395nm). The HPLC-DAD-LTQ Orbitrap MS was used in order to provide structural information about the obtained derivatized compounds. The hybrid linear ion trap LTQ Orbitrap mass spectrometer has been introduced in recent years and provides a high mass accuracy. The structures of the derivatized analytes were identified from the protonated molecular ions [M+H]+ and corresponded to the fully labelled analytes.The following analytical parameters were determined for the method using the HPLC-FL: linearity, precision (2.5-10%), instrumental precision intraday (0.8-1.5%) and interday (2.9-6.3%), and detection limits (0.02-0.14mgL-1). The stability of stock solutions and derivatized compounds was also investigated. The method was applied to determine the amine free content in epoxy resin dust collected in workplaces. © 2010 Elsevier B.V.


Gonzalez-Rodriguez M.V.,University of La Coruña | Dopico-Garcia M.S.,University of La Coruña | Dopico-Garcia M.S.,Centro Galego Do Plastico | Noguerol-Cal R.,University of La Coruña | And 4 more authors.
Journal of Separation Science | Year: 2010

This article investigates the applicability of HPLC-UV, ultra performance LC-evaporative light-scattering detection (UPLC-ELSD), HPLC-ESI(+)-MS and HPLC-hybrid linear ion trap (LTQ) Orbitrap MS for the analysis of different non-ionic antistatic additives, Span 20, Span 60, Span 65, Span 80, Span 85 (sorbitan fatty acid esters), Atmer 129 (glycerol fatty acid ester) and Atmer 163 (ethoxylated alkylamine). Several alkyl chain length or different degrees of esterification of polyol derivatives can be present in commercial mixtures of these polymer additives. Therefore, their identification and quantification is complicated. Qualitative composition of the studied compounds was analysed by MS. HPLC-UV, UPLC-ELSD and HPLC-LTQ Orbitrap MS methods were applied to the quantitative determination of the different Spans, Atmer 129 and Atmer 163, respectively. Quality parameters of these methods were established and no derivatization was necessary. Copyright © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Dopico-Garcia M.S.,University of La Coruña | Dopico-Garcia M.S.,Centro Galego do Plastico | Ares-Pernas A.,University of La Coruña | Gonzalez-Rodriguez M.V.,University of La Coruña | And 2 more authors.
Polymer International | Year: 2012

Control of the durability of commercial biodegradable materials when used as food packaging is relevant to guarantee the safety of food. The service life performance of a commercial material based on poly(lactic acid) was assessed through an aging test which mimics its real use (immersion in water at 40 °C for up to 6.5 months). The ability of different techniques for the evaluation of polymer decomposition was investigated and two types of degradation were shown, a reversible physical aging and a permanent deterioration due to hydrolysis. Physical aging was reflected in differential scanning calorimetry scans by increased glass transition temperature and corresponding enthalpy. A gradual decrease of crystallization temperature and increase of melting temperature and crystallinity were also observed. The progressive loss of mechanical properties reflected the sum of both types of degradation. Hardness, flexural modulus and flexural strength were more sensitive to deterioration than strain. The highest toughness of the material was achieved at two months. The cleavage of polymer chains and release of substances caused increased migration levels, especially marked for long time periods. Water uptake and migration levels followed a concordant pattern and experienced the highest increases. A simple protocol for quality control based on the obtained results is suggested. © 2012 Society of Chemical Industry.

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