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Bellignat, France

Le Goff R.,Pole Europeen de Plasturgie | Boyard N.,CNRS Nantes Thermocinetique Lab | Sobotka V.,CNRS Nantes Thermocinetique Lab | Lefvre N.,CNRS Nantes Thermocinetique Lab | Delaunay D.,CNRS Nantes Thermocinetique Lab
Polymer Testing | Year: 2011

An instrumented injection mould was designed to determine the crystallization kinetics of semi-crystalline polymers and short fibre reinforced bulk composites. This set-up is an interesting alternative to other characterization devices since it is more representative of injection process conditions, and bulk samples are more suitable for studying reinforced polymers. We developed a methodology to estimate the Nakamura kinetic function K(T) by solving an inverse 1D heat conduction problem coupled to the kinetic equation. Estimated parameters are obtained in a temperature range which depends on the cooling rate. We first validated the experimental approach with a well characterized isotactic polypropylene. Then, we used this setup to determine the kinetic function of a technical polymer (poly m-xylylene adipamide-MXD6), for which the crystallization is complex since it contains nucleating agents. Our results are compared with a literature empirical model and with those obtained by DSC. © 2011 Elsevier Ltd. All rights reserved.

Jbilou F.,University of Lyon | Galland S.,University of Lyon | Ayadi F.,CNRS Agricultural Resources Fragmentation and Environment | Belard L.,Pole Europeen de Plasturgie | And 4 more authors.
Polymer Testing | Year: 2011

A material was produced by extrusion of corn flour with 8 wt% glycerol followed by injection-moulding. The corn flour based material biodegradation kinetics were assessed by an anaerobic biodegradation standard test (ISO 14853), an aerobic burial composting test (ISO/DIS 16929) and a test to assess the susceptibility of corn starch to hydrolysis by amylolytic enzymes. Biodegradation and hydrolysis were more rapid for corn flour based material than for native corn flour. This was probably due to corn flour starch amorphisation during thermomechanical processing at the expense of crystalline regions, which are more resistant to hydrolysis by amylolytic enzymes. This was substantiated by observations during burial composting showing that crystalline zones of this material were less degraded. A comparison of the kinetics of starch hydrolysis or biodegradation of corn flour based material samples with specific surface areas ranging from 0.67 to 30 mm-1 by amylolytic enzymes or microorganisms under anaerobic conditions in a liquid medium (ISO 14853) or aerobic conditions during burial composting (ISO/DIS 16929) allowed (i) observation that the biodegradation level by the latter method always exceeded 90% before 84 days, thus meeting this biodegradability criterion, and (ii) to propose that the test of hydrolysis by amylolytic enzymes might constitute a faster method for initial assessment of the biodegradability of starch based materials. © 2010 Elsevier Ltd. All rights reserved.

Jbilou F.,University of Lyon | Ayadi F.,French National Institute for Agricultural Research | Galland S.,University of Lyon | Joly C.,University of Lyon | And 3 more authors.
Journal of Applied Polymer Science | Year: 2012

Plasticized corn flour-based materials were prepared by extrusion and injection molding. Extrusion of corn flour blends (75% wet basis (wb)-glycerol (5 or 10% wb)-water) was performed in a twin-screw extruder with either one or three shearing zones. Native corn flour is mainly composed of corn starch granules surrounded by proteins layers. Therefore, the destructuration of corn flour by thermomechanical treatments was analyzed (i) by techniques essentially allowing to monitor corn starch amorphization (differential scanning calorimetry, X-ray diffractometry, determination of water sorption isotherms, susceptibility to hydrolysis by amylolytic enzymes) (ii) and via proteins layers role and distribution observed by confocal scanning laser microscopy and comparing the susceptibility of corn starch to hydrolysis by amylolytic enzymes in the presence or not of a protease. Both corn starch granules amorphization and proteins dispersion and aggregation were more pronounced for materials extruded in a screw profile with three shearing zones. For materials extruded in a screw profile with one shearing zone, the amorphization of starch was higher in materials made with 5% wb glycerol, whereas the proteins dispersion and aggregation was more pronounced in materials made with 10% wb glycerol. A barrier role of proteins to hydrolysis of corn starch by amylolytic enzymes was demonstrated and discussed. © 2011 Wiley Periodicals, Inc.

Jbilou F.,University of Lyon | Joly C.,University of Lyon | Galland S.,University of Lyon | Belard L.,Pole Europeen de Plasturgie | And 5 more authors.
Polymer Testing | Year: 2013

Plasticised corn flour/poly(butylene succinate-co-butylene adipate) (PBSA) materials were prepared by extrusion and injection in order to study the impact of PBSA ratio on their physicochemical properties and biodegradability. Scanning electron microscopy observations showed that corn flour and PBSA are incompatible. Three types of morphology have been observed: (i) starch dispersed in a PBSA matrix, (ii) a "co-continuous-like" morphology of starch and PBSA, and (iii) PBSA dispersed in a starch matrix. As expected, the extent of plasticised corn flour starch hydrolysis by amylolytic enzymes decreased when the amount of PBSA increased. Addition of a lipase to hydrolyse PBSA ester bonds enhanced enzymatic hydrolysis of starch by amylolytic enzymes in materials where PBSA formed a continuous phase. This suggests that PBSA formed a barrier restricting the access of amylolytic enzymes to starch. This was consistent with aerobic and anaerobic biodegradation assays, which also showed lower biodegradability of materials containing a majority of PBSA. © 2013 Elsevier Ltd. All rights reserved.

Sanz C.,Fundacion TEKNIKER IK4 CIC MarGUNE | Navas Garcia V.,Fundacion TEKNIKER IK4 CIC MarGUNE | Gonzalo O.,Fundacion TEKNIKER IK4 CIC MarGUNE | Vansteenkisteb G.,Pole Europeen de Plasturgie
Procedia Engineering | Year: 2011

Rapid Manufacturing like Direct Metal Laser Sintering (DMLS) is starting to be implemented in the development of functional components. Therefore, surface integrity of these parts must be carefully analysed for the fulfillment of current technical requirements. In this work, CoCr, Maraging Steel and Inconel parts subjected to different thermal and mechanical finishing treatments (shot peening and polishing) have been characterized with the objective of determining the optimum stress relieving treatment. It has been studied the effect of these stabilization treatments mainly on residual stresses and hardness. In general, the rapid manufacturing process generates detrimental residual stresses and shot peening, and final polishing improve and homogenize the surface residual state of the parts. © 2012 Published by Elsevier Ltd.

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