Investigation of the effect of water absorption on thermomechanical and viscoelastic properties of flax‐hemp‐reinforced hybrid composite

Abstract

The recent development of natural fiber-reinforced polymer composites have shown innumerable economic and environmental benefits for a vast array of engineering applications. It is quintessential to investigate the effect of water absorption on the composites that remain in the water for a maximum of their intended service period. This study is an effort in this direction that investigates the effect of water absorption on thermo-mechanical properties of flaxhemp-reinforced epoxy composites fabricated using compression hand layup technique with different weight fraction of fiber. The fabricated composites have been characterized physically (density and water absorption), thermomechanically (tensile, flexural, thermal conductivity, and dynamical mechanical analysis), and morphologically (scanning electron microscopy [SEM]). The analysis revealed that hemp-reinforced composites (S1) had the highest water absorption capabilities in comparison to the flax-reinforced composites (S5).Higher water absorption capability had an adverse effect on the mechanical properties of fabricated composites. However, hybrid composites (S2, S3, and S4) reported better performance with regard to S1. The increased water content, however, increased the thermal conductivity of composites and maximum has been revealed for S1 (0.82 W/mK) and minimum for S5 (0.48 W/mK). The water molecules showed detrimental effects on the viscoelastic properties and revealed S3 have better interlocking bond with the lowest reduction in storage modulus (12%) and glass transition temperature (4 C) in comparison to S1 (30%) under wet conditions. A comparative analysis of the thermo-mechanical properties was also made for developed composites under dry, saturated, and re-dried conditions. The SEM has been used to characterize the morphological and fracture behavior of the fabricated composites under the influence of water uptake. The effects of water molecules on the hygrothermal aging index and diffusion co-efficient have also been discussed. Overall, the hybridization of

Simplified cooperative viscoplasticity theory based on overstress model for nanocomposites

“…Storage modulus initially showed a slight drop as the temperature increased, and then a rapid drop in the glass transition region. Similar behaviors and results are observed in studies in the literature 55–57 . While the storage modulus of pure epoxy at room temperature is 2.5 GPa, the storage modulus of nanocomposites with content 0.1 and 0.5% f‐GNF is 3.3 and 3.8 GPa, respectively.…”

“…Similar behaviors and results are observed in studies in the literature. [55][56][57] While the storage modulus of pure epoxy at room temperature is 2.5 GPa, the storage modulus of nanocomposites with content 0.1 and 0.5% f-GNF is 3.3 and 3.8 GPa, respectively. By adding 0.1 and 0.5 wt.% f-GNF to pure epoxy, molecular mobilization of epoxy chains was prevented, a better resistance was created and an increase of 32% and 52%, respectively, was observed in the storage modulus.…”

Poly(phosphorus‐silicon‐alkyne): Widening the application potential in epoxy resin with excellent flame retardancy, mechanical property, and unimpaired thermal stability

“…The addition of PPSA increases the modulus values in EP and shows that the addition of PPSA resulted in higher storage modulus compared with pure EP because it may enhance the bonding between PPSA and EP 36–39 . As the temperature increases, the values of storage modulus gradually decreases due to the close packing of the molecules becomes weak and the increases in the molecular mobility 40,41 …”

“…[36][37][38][39] As the temperature increases, the values of storage modulus gradually decreases due to the close packing of the molecules becomes weak and the increases in the molecular mobility. 40,41 E" is the measurement of released heat energy per cycle and decided by the molecular motion. 42 Owing to the glass-rubber transition of EP, a maximum of E" and tan δ are reached (Figure 4b,c) followed by a drop as the temperature increases, which is related to the energy dissipation by chain movement in high temperature.…”

Improvement of osteogenic properties using a 3D-printed graphene oxide/hyaluronic acid/chitosan composite scaffold

“…The water swelling rate and biodegradation rate of the composite scaffolds are important factors in determining cell adhesion and proliferation. 35,36 At the same time, the higher the water swelling rate is, the stronger its ability to absorb exudate. The results showed that (Figure 5(a)) with increasing GO content, the water swelling rate of the composite scaffold materials also increased, and compared with the 0% GO content, the water swelling rate of the composite scaffolds with GO contents of 0.5% and 1% increased significantly.…”