## 4 Conclusions  
Adding values to agricultural residues is highlighted nowadays especially, using it for manufacturing particleboards for thermal insulation. Therefore, in this study, the possibility of using rice straw for manufacturing particleboards are investigated. Different rice straw treatments, particleboards density, types, and ratios of used resin were studied and compared with the corresponding values of flax shives particleboards. The results indicated that particleboards made from flax shives had superior mechanical properties compared to the rice straw particles. Whereas, the thermal insulation of rice straw particleboards was better than flax shives particleboards. For the resin type, rice straw particleboards blended with UF had better mechanical properties compared to the particleboards blended with cornstarch or those without resin material. In contrast, the thermal conductivity of particleboards blended by cornstarch was lower than that blended by UF and without a binder. Additionally, increasing the ratio of resin material improved the mechanical properties of the boards, except for the MOR and MOE, which decreased with increasing resin content, and reached the peak value at a resin content of 10%. The higher amounts of urea formaldehyde resin caused a higher thermal conductivity. Referring to particleboards' density, increasing the particleboard's density significantly improved the mechanical properties of the particleboards, except for the IB, which was initially increased then decreased with an increasing density, and reached the peak value at a density of 0.5 g/cm\({}^{3}\). The maximum mechanical strength was obtained at a density of 0.7 g/cm\({}^{3}\) and a UF resin content of 14%. Despite the improvement of mechanical properties through the increased density of boards, it led to increasing the thermal conductivity, which indicates a lower insulation performance. Finally, the treatment of rice straw by hot water induced a better performance on the mechanical properties of produced particleboards, except for MOE, which reached the peak value with NaOH treatment. The thermal conductivity of particleboards manufactured by untreated rice straw was the lowest. The treatment of straw increases the thermal conductivity, which leads to lower thermal insulation efficiency. Using other agricultural residues such as rape straw, wheat straw, corn straw, and solid fraction of anaerobic digestate for insulation particleboards manufacturing and studying the effects of different ratios and types of natural resin materials on thermal and mechanical properties could be an interesting work in the future. Z.H. : Realization of experiments in the laboratory; T.A. : support of laboratory experiments developing the research idea, designing the work experiments, preparing the materials and writing the manuscript; M.K. : support of laboratory experiments on thermal conductivity and other measuring instruments and developing the research idea; A.B. : Data analysis and design of the work; S.A.: Data analysis and design of the work; J.H. : extension of the research idea; rewriting the manuscript, correcting English language and managing the manuscript; A.K. : head of team; support in sharpening the research idea, designing the experiments  
This research received no external funding  
The authors express their sincere thanks to Tanta Company of Flax and Oils, Tanta, Al Gharbiyah Governorate, Egypt for providing facilities during preparation of the specimens and the Egyptian Organization for Standardization and Quality (EOS), Cairo, Egypt for reducing costs of the tests. The authors acknowledge the Open Access Funding by TU Wien.