Effect of relative humidity and temperature on PVC degradation under gamma irradiation: Evolution of HCl production Yields

International audienceThe separate and combined effects of the relative humidity and temperature were investigated on theHCl production yields arising from two types of PVC subjected to gamma irradiation (pure PVC and PVCformulated with plasticizing additives). The test procedure developed included experiments performedat different dose rates (400 Gy h 1 and 4 kGy h1), temperatures (room temperature and 70 1C) andrelative humidity values (o 10%, 70 75%, and 100%), for irradiation doses ranging from 0.1 to 4 MGy.These operating conditions are representative of applications in a nuclear environment. For theplasticized PVC at low dose rates, raising the temperature increases the HCl production by a factor ofabout 1.3, with either low or high relative humidity. For pure PVC, depending on the humidity and doserate, G(HCl) varies differently with the temperature: at low humidity and low dose rates, G(HCl)increases by a factor of 1.7 for a 45 1C temperature increase; at high humidity, the same temperatureincrease does not result in a significant increase of G(HCl). The influence of the relative humidity on HClproduction has not been clearly identified and interpreted. The relative humidity appears to be a factorlimiting the effects of temperature on the formation of HCl from pure PVC at high dose rates. The Gvalues remain constant and even diminish under some experimental conditions. For plasticized PVC,the relative humidity has no influence on the HCl production yields

A Periodic Homogenization Model Including Porosity to Predict Elastic Properties of 3D-Printed Continuous Carbon Fiber-Reinforced Composites

Adding continuous carbon fiber into the Fused Filament Fabrication (FFF) process is critical to get reinforced composite structures with improved mechanical properties. However, it remains difficult for the designer to create optimized complex composite structures. Indeed, performing numerical simulations on these materials require to know their elastic coefficients, which are difficult to determine. Using a model of periodic homogenization which considers both the fiber content and the porosity, would be a quick solution to predict the mechanical properties of the printed composite. Based on material studies and validated mechanical tests, this simulation model allows the use of a homogeneous material to replace the composite material for the finite element analysis. This will greatly reduce the number of elements required in the model, leading to a big decrease of the computation cost. Hence, the numerical model has potential to perform simulation-driven design processes, such as generative design.Mechanical Engineerin

Investigation of gamma radiation effect on the anion exchange resin Amberlite IRA-400 in hydroxide form by Fourier transformed infrared and 13C nuclear magnetic resonance spectroscopies

International audienceRadiation-induced decomposition of the anion exchange resin Amberlite IRA-400 in hydroxide form by gamma radiolysis has been studied under different irradiation doses and irradiation atmospheres. In this work, we focused on the degradation of the solid part of the resin by Fourier transformed infrared (FTIR) and 13 C nuclear magnetic resonance (NMR) spectroscopies associated with chemometric treatments. FTIR and 13 C NMR techniques showed that only CH 2 N + (CH 3) 3 groups were detached from the resin whereas the polystyrene divinylbenzene backbone remains intact. The quaternary ammonium groups were replaced by amine or carbonyl groups according to the irradiation atmosphere (with or without water or oxygen). Principal components analysis (PCA) was used to classify the degraded resins according to their irradiation conditions by separating the effect of the dose or the environment. The PCA loadings have shown spectral regions which discriminate the irradiated resins whereas SIMPLe-to-use Interactive Self-modeling Mixture Analysis (SIMPLISMA) allows to identify families of component characterizing the chemical structure of resins and estimate their relative contributions according to the irradiation atmospheres