Effects of Fiber Surface Grafting with Nano-Clay on the Hydrothermal Ageing Behaviors of Flax Fiber/Epoxy Composite Plates

Abstract

Flax fiber has high sensitivity to moisture, and moisture uptake leads to the decrease of mechanical properties and distortion in shape. This paper attempts to graft flax fabric with nano-clay, with assistance from a silane-coupling agent, in order to improve hygrothermal resistance. The nano-clay grafted flax fabric reinforced epoxy (FFRP) composite produced through vacuum assisted resin infusion (VARI) process were subjected to 80% RH chamber for 12 weeks at 20, 40 and 70 °C, respectively. Moisture uptake, dimensional stability, and tensile properties was studied as a function of humidity exposure. Through SEM and FTIR, the effects of hygrothermal exposure was elucidated. In comparison to control FFRP plates, nano-clay grafting decreases saturation moisture uptake and the coefficient of diffusion of FFRP by 38.4% and 13.2%, respectively. After exposure for six weeks, the retention rate of the tensile modulus of the nano-clay grafted flax fiber based FFRP increased by 33.8% compared with that of the control ones. Nano-clay grafting also reduces the linear moisture expansion coefficient of FFRPs by 8.4% in a radial direction and 10.9% in a weft direction.

Water Absorption and Hygrothermal Aging Behavior of Wood-Polypropylene Composites

“…This may be due to the damage of wood powder and the destruction of the interface between wood powder and polypropylene, thus affecting the transfer of stress. Compared with strength, the loss of modulus is greater, that is, the stiffness of the composite samples is very sensitive to water, which can not only confirm the damage of water on wood powder and the interface of composites but also prove that water has a plasticizing effect on the polymer matrix [16,23,28,34,35]. However, compared with the modulus of pure polypropylene, the modulus value of wood powder reinforced polypropylene composites is still relatively high.…”

“…It is known that the mechanical properties of the natural fiber-reinforced polymer composites can be improved by the modification of fibers or polymers [26,27]. What is more, several efforts have shown that the modification of the interface between natural fibers and polymers can also reduce the degradation effect of moisture on some mechanical properties [15,28].…”

Effects of Adhesive Coating on the Hygrothermal Aging Performance of Pultruded CFRP Plates

“…Moreover, fiber reinforced polymer plates have been widely used as strengthening materials of concrete members [2][3][4][5]. The long-term performance of FRP materials in harsh environments such as hygrothermal or alkaline environments is significant for their application [1] and has been widely investigated [6][7][8][9][10].…”

Natural Fibres and Their Composites

“…The effect of the addition of nano or micro additive as filler in natural fibre reinforced composite is investigated in several papers [ 6 , 7 , 8 , 9 ].…”

“…On the bases of the experimental data, the authors state that these simple treatments, potentially prone to further optimization, can represent a step toward producing natural fibre composites with mechanical profiles compatible with semi-structural applications. Similarly, Wang et al [ 8 ] improved the hygrothermal resistance of flax fibre reinforced epoxy composites through grafting flax fabric with nanoclay. In more detail, the introduction of nano-clay reduces both moisture uptake and the coefficient of diffusion of composites that show better dimensional stability than the untreated ones.…”