TY - JOUR
T1 - Ageing of autoclaved epoxy/flax composites
T2 - effects on water absorption, porosity and flexural behaviour
AU - Santos, Júlio Cesar dos
AU - Ávila de Oliveira, Lívia
AU - Panzera, Túlio Hallak
AU - Remillat, Chrystel D L
AU - Farrow, Ian R
AU - Placet, Vincent
AU - Scarpa, Fabrizio L
PY - 2020/12/1
Y1 - 2020/12/1
N2 - This work investigates the effects of ageing on autoclaved composites made with unidirectional prepreg epoxy and flax tape in environments with 50% and 100% of relative humidity. A Design of Experiment (DoE) has been used first to determine the effect of the ageing time (0, 2, 4, 6, 8 and 16 days), type of bending (3-point and 4-point bending) and fibre orientation (longitudinal and transverse) on the water absorption and flexural properties of 50% saturated composites. A second experiment at 100% humidity has been also performed to further characterise the composites and to identify the equivalent ageing time that provides the mechanical behaviour of the 50% humidity samples after sixteen days. The water absorption and apparent porosity levels increase progressively with the ageing time, in particular for the case of transverse laminates; these features compromise the flexural properties of the composites. The laminates subjected to 4-point bending showed increased water absorption levels and improved flexural properties compared to the samples under 3-point bending. The flexural properties of flax composites at 50% humidity after 16 days are equivalent to those shown by composites immersed in water for less than one day.
AB - This work investigates the effects of ageing on autoclaved composites made with unidirectional prepreg epoxy and flax tape in environments with 50% and 100% of relative humidity. A Design of Experiment (DoE) has been used first to determine the effect of the ageing time (0, 2, 4, 6, 8 and 16 days), type of bending (3-point and 4-point bending) and fibre orientation (longitudinal and transverse) on the water absorption and flexural properties of 50% saturated composites. A second experiment at 100% humidity has been also performed to further characterise the composites and to identify the equivalent ageing time that provides the mechanical behaviour of the 50% humidity samples after sixteen days. The water absorption and apparent porosity levels increase progressively with the ageing time, in particular for the case of transverse laminates; these features compromise the flexural properties of the composites. The laminates subjected to 4-point bending showed increased water absorption levels and improved flexural properties compared to the samples under 3-point bending. The flexural properties of flax composites at 50% humidity after 16 days are equivalent to those shown by composites immersed in water for less than one day.
KW - flax composite
KW - prepreg
KW - ageing process
KW - fibre orientation
KW - flexural properties
KW - water absorption
KW - apparent porosity
U2 - 10.1016/j.compositesb.2020.108380
DO - 10.1016/j.compositesb.2020.108380
M3 - Article (Academic Journal)
SN - 1359-8368
VL - 202
JO - Composites Part B: Engineering
JF - Composites Part B: Engineering
M1 - 108380
ER -