International audienceThis papers aims to characterize the influence of moisture uptake on the mechanical behaviour of unidirectional flax fibre-reinforced epoxy laminates. Monotonic and cyclic tensile tests and free vibration characterization are carried out. Results show that LID flax-epoxy composites, when exposed to hygrothermal conditioning at 70 degrees C and 85% RH, exhibit a diffusion kinetic which follows a one dimensional Fickian behaviour. The mass uptake at equilibrium is approximately 3.3% and the diffusion coefficient 6.5 x 10(-6) m(2) s(-1). Water vapour sorption is shown to induce a significant change in the shape of the tensile stress-strain curve, a decrease in the dynamic elastic modulus of about 20% and a 50% increase in the damping ratio. Contrary to all expectations, water saturation does not degrade the monotonic tensile strength of such a flax-epoxy composites and leads to an increase in the fatigue strength for a high number of cycles. (C) 2016 Elsevier Ltd. All rights reserved
After a 4-week training period, Nordic walking training appeared more efficient than training without poles for increasing walk distance on the 6-min walk test for patients with ACS and PAOD.
Poly(lactic acid) or PLA is currently considered as one of the
most promising substitutes of conventional plastics, with low environmental
impact, especially for food packaging applications. Nevertheless,
some drawbacks, such as high permeability to oxygen, are still limiting
its industrial applications. The objective of this study was to highly
increase the oxygen barrier performance of PLA without compromising
its sustainable nature and following the principles of circular economy
perspective. Coproducts coming from mill industries, such as wheat
gluten proteins (WG), were used to produce PLA-WG-PLA multilayer complexes
with improved barrier performance. Different technologies of industrial
interest were considered: high-pressure homogenization of WG film
forming dispersions, corona treatment of industrial PLA films, wet
casting and spin coating for tailoring the WG coating thickness, and
hot-pressing for shaping the multilayers. The impact of all these
strategies on the properties (surface and bulk) and performances (barrier
and adhesion) were investigated on the single constituent layers as
well as on the final laminate. The most efficient complex increased
more than 20 times (or 2000%) the barrier properties to oxygen and
∼20% the barrier properties to water vapor, considering application
conditions (50% relative humidity and 25 °C). The low thickness
(∼60 μm) of this complex also matched the requirement
for flexible packaging applications. High-pressure homogenization,
WG coating thickness, and hot-pressing positively and highly impacted
the final properties of the multilayer, while the contribution of
corona treatment was limited. This study unambiguously evidenced the
potential of PLA-WG-PLA complexes as a valid sustainable substitute
for high performing conventional plastics, and it could open an unexplored
PLA market opportunity. In addition, it could motivate further investigations
on PLA-based laminates for industrial interest, using other biopolymers
from agro-industrial waste or byproducts.
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