## 4 Conclusions  
This is a new attempt to make a hybrid composite that includes biosynthesized nanoparticles with different concentrations and fibre content with NaOH processing. The flax/sisal-fibre-reinforced epoxy-based hybrid nano Al\({}_{2}\)O\({}_{3}\) NPs particle accompaniments of biocomposites were successfully fabricated through the compression moulding method and the following observations were made.  
* The XRD characteristic of Al\({}_{2}\)O\({}_{3}\)-NPs exhibits three diffraction patterns (115, 119, and 215). Powder X software was used to identify these peaks, which were discovered to correlate with the composition of Al\({}_{2}\)O\({}_{3}\) NPs. TEM images were also used to confirm the spherical structure of Al\({}_{2}\)O\({}_{3}\) NPs.
* According to the HPLC results, the leaf's overall concentrations of flavonoids (gallocatechin, carnosic acid, and camellia) are determined to be 0.250 mg/g, 0.264 mg/g, and 0.552 mg/g, respectively. The catechin concentration is higher than the phenolic and caffe acid levels, which could have resulted in a faster rate of reduction. This contributes to the formation of Al\({}_{2}\)O\({}_{3}\) NPs.
* Among many of the varying configurations, 4 wt.% nano Al\({}_{2}\)O\({}_{3}\) NPs, 10 wt.% flax and sisal fibres, as well as 4 h of NaOH with a 5 wt.% concentration, produce the maximum mechanical properties (59.94 MPa tension, 149.52 MPa bending, and 37.9 K)/m\({}^{2}\) impact resistance).
* In comparison to 0, 2, 4 as well as 6 wt.% nano Al\({}_{2}\)O\({}_{3}\) NPs, 4 wt.% nano Al\({}_{2}\)O\({}_{3}\) NPs incorporation has the maximum mechanical properties owing to the Al\({}_{2}\)O\({}_{3}\) particles being well combined in the epoxy matrix and exhibiting good interfacial adhesion strength.
* Compared to plain epoxy, the maximum moisture uptake of aluminium-loaded epoxy nanomaterials is reduced by 12.1, 19.4, and 22.4%, respectively, with the inclusion of 2, 4, and 6 wt.% aluminium oxide. This is because the resistance characteristics of natural composites loaded with aluminium oxide outperform those of other unfilled biocomposites.  
Conceptualization, N.L. and V.G.; methodology, N.L.; software, S.D.; validation, N.L., V.G., P.P. and S.D.; formal analysis, N.L., V.G., P.P. and S.D.; investigation, N.L., V.G., P.P. and S.D.; resources, N.L., V.G., P.P. and S.D.; data curation, N.L., V.G., P.P. and S.D.; writing--original draft preparation, N.L., V.G., P.P. and S.D.; writing--review and editing, N.L., V.G., P.P. and S.D.; visualization, N.L., V.G., P.P. and S.D.; supervision, N.L., V.G., P.P. and S.D.; project administration, N.L., V.G., P.P. and S.D. All authors have read and agreed to the published version of the manuscript.  
Authors declared that no funding was received for this Research.  
Not applicable.  
The data used to support the findings of this study are included within the article. Should further data or information be required, these are available from the corresponding author upon request.  
The authors thank the Saveetha School of Engineering, SIMATS, and Chennai for the technical assistance. The authors appreciate the support from Mettu University, Ethiopia and UiT, the Arctic University of Norway.  
The authors declare no conflict of interest.