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Perez E.,University of Buenos Aires | Fama L.,University of Buenos Aires | Pardo S.G.,University of La Coruna | Pardo S.G.,Centro Galego Do Plastico CGaP | And 2 more authors.
Composites Part B: Engineering | Year: 2012

Polypropylene/wood flour composites with different fibre content were prepared. The effect of composition and the incorporation of maleinated polypropylene on the materials tensile and fracture and failure behaviour was investigated. Reliable fracture toughness data that will be useful for structural applications were obtained. In unmodified composites an increase in Younǵs modulus was found with the addition of wood flour to PP, whereas tensile strength, strain at break and fracture toughness were observed to decrease as fibre content increased. The presence of MAPP was beneficial to tensile strength and ductility and had no significant effect on fracture toughness, as a result of enhanced fibre dispersion within the matrix and improved interfacial adhesion. Although reduced ductility and toughness were observed for the composites respect to the matrix, in the case of modified composites, environmentally friendly stiffer materials were obtained with cost saving without sacrificing strength. © 2012 Elsevier Ltd. All rights reserved. Source


Noguerol-Cal R.,University of La Coruna | Noguerol-Cal R.,Centro Galego Do Plastico CGaP | Lopez-Vilarino J.M.,University of La Coruna | Gonzalez-Rodriguez M.V.,University of La Coruna | Barral-Losada L.F.,University of La Coruna
Journal of Separation Science | Year: 2010

A chromatographic method using ultra performance LC with ultraviolet spectrophotometry detection system (UPLC-UV-visible (UV/Vis)) (UPLC, ultra performance LC) was developed to determine Chimassorb 944 and Tinuvin 770, high- and low-molecular mass hindered amine light stabilizers, respectively. The use of a bridge ethylene hybridbased particles C18 UPLC column, being compatible with a buffered mobile phase adjusted to pH 11.5, was used to achieve a satisfactory elution of possible non-ionizated units of polymeric Chimassorb 944. In addition, a HPLC with positive ion mode ESI and hybrid linear ion trap (LTQ) Fourier transform (FT) Orbitrap MS detection system (HPLCUV/ Vis-ESI-LTQ(FT)Orbitrap) was used for screening and identification purposes. Reliable determinations of monomeric units of Chimassorb 944 and molecule of Tinuvin 770 were achieved by HPLC-ESI(1)-LTQ FT Orbitrap MS method using scan mode. Quality parameters of UPLC-UV/Vis method were evaluated. Obtained LODs and LOQs were 3.41 and 11.4 mg/L for Tinuvin 770 and 0.83 and 2.78 mg/L for Chimassorb 944, respectively. Satisfactory quality parameters of this chromatography method provided the chance to count on a good tool to know the compliance with legal requirements. © 2010 Wiley-VCH Verlag GmbH & Co. KGaA. Source


Pardo S.G.,University of La Coruna | Pardo S.G.,Centro Galego Do Plastico CGaP | Bernal C.,CONICET | Abad M.J.,University of La Coruna | And 2 more authors.
Journal of Thermoplastic Composite Materials | Year: 2014

In this work, the fracture and thermal behaviour of environmentally friendly composites based on polypropylene (PP), an olefin block copolymer (OBC) and ash from biomass combustion was investigated. PP/OBC/ash composites with different ash contents and 10 wt% OBC were prepared by extrusion followed by compression moulding. Ash particles were treated with a silane coupling agent before blending to promote interfacial adhesion between polymer matrix, OBC and ash. An approach to fracture mechanics was investigated and showed that the fracture parameters increased when OBC was used. Fracture surface analysis by scanning electron microscope revealed that the presence of OBC promotes the material ductile failure and that one of the main failure mechanisms was fibrillised debonding of ash particles encapsulated by OBC from the matrix and its subsequent elongation around them. Free OBC inclusions distributed within the PP matrix would have also induced toughening in the composites investigated. The crystalline state of PP analysed by differential scanning calorimetry is clearly modified by the presence of ash particles, increasing the crystallisation rate and the crystallinity degree of the matrix due to the nucleating effect of the filler. However, the presence of the copolymer counteracted these effects and the PP crystalline state remained practically unchanged in the composites with OBC. Finally, environmentally friendly composites with significantly higher toughness than the matrix or binary PP/ash composites were obtained by introducing an OBC copolymer in the formulation. © The Author(s) 2012. Source


Igarza E.,University of Buenos Aires | Pardo S.G.,University of La Coruna | Pardo S.G.,Centro Galego Do Plastico CGaP | Abad M.J.,University of La Coruna | And 4 more authors.
Materials and Design | Year: 2014

The deformation and fracture behavior of PP/ash composites with and without maleic anhydride functionalized iPP (MAPP) as coupling agent was investigated, focusing on the effect of ash content and loading conditions. A decreasing trend of tensile strength and strain at break values with filler content was observed for unmodified composites, whereas these properties were roughly independent of ash content for the composites with MAPP. In quasi-static fracture tests, all materials displayed ductile behavior. Most composites exhibited improved fracture properties with respect to the matrix as a result of the toughening mechanisms induced by the ash particles. Under impact loading conditions, in contrast, all materials displayed fully brittle behavior. Impact critical fracture energy values of the composites were higher than those of PP and they also presented a maximum which was explained in terms of the comprehensive analysis of the crystallinity development in PP. The incorporation of MAPP led to better dispersion of ash particles in the matrix but was detrimental to the material fracture behavior independently of loading conditions. Increased interfacial adhesion promoted by MAPP hindered particle-induced toughening mechanisms. © 2013 Elsevier Ltd. Source


Noguerol-Cal R.,Centro Galego Do Plastico CGaP
Talanta | Year: 2011

Capacity to migrate of a representative group of polymeric additives, dyes, antioxidants, hindered amine light stabilizers (HALS) or antistatics, from plastic toys to saliva was analyzed to protect children in their habits of sucking and biting. Most of target additives appear no-regulated in toys normative but adverse effects on human health of some of them have been demonstrated and their presence in others commercial articles normative has been included. In order to offer an effective and easy tool to perform these controls, migration tests by dynamic and static contact, followed by a preconcentration step by liquid-liquid extraction (LLE) and ultra performance liquid chromatographic analysis with ultraviolet-visible and evaporative light scattering detections (UPLC-UV/Vis-ELSD) have been optimized to evaluate the migrated amounts of the additives in saliva simulant. The detection limits of the migration methodologies were ranged from 8.68 × 10 -2 to 1.30 × 10 -3 mg migrated (L simulant) -1. Influence of several variables on this mass transport, as time, temperature and friction, was also analyzed to achieve the most aggressive methodology to protect consumers. Migration of several studied additives, whose presence has been demonstrated in several purchased commercial toys, has been observed. © 2011 Elsevier B.V. All rights reserved. Source

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