**5. Conclusions**

Novel sustainable castor oil-based polyurethane (COPU) biocomposites reinforced with piassava fiber powder waste were characterized for possible application as a highperformance coating floor (HPCF). The following conclusions were drawn:

FTIR results suggested interaction occurring between the piassava powder and COPU matrix.

Both flexural strength and modulus were substantially improved for the 30 vol% piassava powder biocomposite, with values reaching more than 500% the strength and more than 800% the stiffness of the plain COPU.

Izod notch impact resistance and absorbed energy displayed a tendency to decrease with the amount of piassava powder incorporated into the biocomposite. However, within the statistical precision, the values might be considered unchanged up to 20 vol% of incorporated piassava powder.

The loss of material in wear tests was accentuated in biocomposites with the incorporation of piassava powder. However, the maximum attained value of 1.06 mm/km for the 30 vol% biocomposite was significantly lower than the maximum abrasion of 2.30 mm/km specified by the standard.

Preliminary results from greener biocomposites made of a castor oil-based polyurethane matrix added with a natural piassava industrial waste revealed a promising material for high-performance coating floors. Ongoing research is being conducted aiming to improve the mechanical resistance of the biocomposites by enhancing the adhesion between the piassava and polyurethane matrix.

**Author Contributions:** Conceptualization, S.N.M. and C.M.F.V.; data curation, J.P.R.G.d.C., N.T.S. and F.P.D.L.; formal analysis, J.P.R.G.d.C., N.T.S., F.P.D.L. and C.M.F.V.; funding acquisition, C.M.F.V.; investigation, J.P.R.G.d.C., N.T.S. and F.P.D.L.; methodology, F.P.D.L., S.N.M. and C.M.F.V.; project administration, C.M.F.V.; resources, F.P.D.L. and C.M.F.V.; supervision, S.N.M. and C.M.F.V.; validation, S.N.M. and C.M.F.V.; visualization, S.N.M. and C.M.F.V.; writing—original draft, J.P.R.G.d.C. and N.T.S.; writing—review and editing, S.N.M. and C.M.F.V. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research was funded by Fundação Carlos Chagas Filho de Amparo à Pesquisa do Estado do Rio de Janeiro (FAPERJ) grant numbers: E-26/202.773/2017, E-26/200.847/2021 and E-26/201.628/2021, and Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) grant number: 301634/2018-1.

**Institutional Review Board Statement:** Not applicable.

**Informed Consent Statement:** Not applicable.

**Acknowledgments:** The authors would like to thank FAPERJ and CNPQ as well as, Imperveg for the resin, the Laboratory of Advanced Materials—LAMAV/UENF for the support, Geovana Girondi (LAMAV/UENF), Rômulo Loiola (LAMAV/UENF), Gabriel Valeriolete (LAMAV/UENF) and Marcelo Mathias (LCQUI/UENF).

**Conflicts of Interest:** The authors declare no conflict of interest.
