Recycled polymers and agricultural waste could be used as important tools to reduce the environmental impact of plastic manufacturing and to valorize agricultural waste. In this work, recycled polypropylene (PP) and hazelnut shells were used in order to produce green composites to be applied in the production of fittings for irrigation systems. In order to improve the poor adhesion between the matrix and filler, an adhesion promoter was also used. The adhesion was particularly improved in composites including recycled polymers, probably because of the presence of polar groups in the recycled sample. The rheological properties clearly indicate that the composites show a processability similar to that of the pure polypropylene, and this feature was corroborated by industrial preliminary injection molding tests where the fitting was easily produced. The deformability of the composites was reduced with respect to the pure matrix, although slightly improved by the presence of the adhesion promoter. Composites utilizing recycled polypropylene (RPP) as the matrix and 5% hazelnut shells with and without the adhesion promoter were also used to produce fittings by injection molding, all of which were resistant to a water pressure of 3.50 bar according to the internal test used by the company.
Author Contributions
Conceptualization, M.C.C. and F.P.L.M.; methodology, M.C.C.; software, M.C.C.; validation, M.C.C.; formal analysis, M.C.C.; investigation, M.C.C., G.B. and S.C.; resources, C.G., R.S. and F.P.L.M.; data curation, M.C.C. and F.P.L.M.; writing—original draft preparation, M.C.C.; writing—review and editing, M.C.C., R.S. and F.P.L.M.; visualization, M.C.C.; supervision, R.S. and F.P.L.M.; project administration, C.G., E.G.R., R.S. and F.P.L.M.; funding acquisition, C.G., R.S. and F.P.L.M. All authors have read and agreed to the published version of the manuscript.
Funding
This work was carried out within the framework of the project PNRR MUR–M4C2–CN00000022 “National Research Centre for Agricultural Technologies” (AGRITECH), funded by the European Union—NextGenerationEU, Mission 4 Component 2 CUP: B13D21011580004. However, the views and opinions expressed are those of the authors alone and do not necessarily reflect those of the European Union or the European Commission. Neither the European Union nor the European Commission can be held responsible for them.
Institutional Review Board Statement
Not applicable.
Informed Consent Statement
Not applicable.
Data Availability Statement
The data presented in this study are available on reasonable request from the corresponding author.
Conflicts of Interest
Authors Carmelo Giuffré, Erica Gea Rodi and Simone Corviseri were employed by the company Irritec S.p.A. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.
Disclaimer/Publisher’s Note: The statements, opinions and data contained in all publications are solely those of the individual author(s) and contributor(s) and not of MDPI and/or the editor(s). MDPI and/or the editor(s) disclaim responsibility for any injury to people or property resulting from any ideas, methods, instructions or products referred to in the content. |
© 2025 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).