resumo
The sustainable utilization of polymers depends on efficient recycling and the ability to retain their critical physical properties for further processing. In this study, high-density polyethylene (HDPE) nanocomposite properties were enhanced by the integration of carbon dots (CDs), in terms of processability and optical traceability during recycling. HDPE composites with varying CDs loadings were prepared to assess their effects on optical and mechanical properties over three consecutive recycling cycles. The composite containing 0.5 wt% CDs demonstrated a 17% increase in tensile strength after recycling, with a maximum strain of 11%, significantly outperforming the neat HDPE while preserving its crystalline structure. Additionally, incorporating 0.1 wt% CDs reduced the wear rate by up to 98%, highlighting a substantial improvement in durability. Improved process- ability of the recycled material was confirmed by producing 3D-printed specimens at each CDs concentration. Notably, composites containing 0.1 wt% CDs exhibited excellent printability even after three recycling cycles. CDs have also been utilized as luminescence tracers. This study revealed that the quenching of the blue phosphorescence associated to the carbonyl groups of the polymer backbone was highly dependent on the CDs content. Importantly, nanocomposites with 0.1 wt% CDs exhibited progressive luminescence changes corresponding to the number of recycling cycles, enabling quick and reliable traceability and sorting using standard mobile phone cameras. These findings are highly promising, paving the way for rapid, automated, and scalable HDPE recycling. This innovation offers significant potential for advancing the circular economy of HDPE and enhancing the sustainability of polymer materials.
palavras-chave
CRYSTALLIZATION BEHAVIOR; LUMINESCENCE; POLYMER; WASTE; IDENTIFICATION; DEGRADATION
categoria
Engineering; Materials Science
autores
Simoes, R; Rodrigues, J; Podvratnik, Z; Girao, AV; Alberto, N; Emami, N; Neto, V; Monteiro, T; Gonçalves, G
nossos autores
Ana Violeta Girão
Investigador JúniorProjectos
CICECO - Aveiro Institute of Materials (UIDB/50011/2020)
CICECO - Aveiro Institute of Materials (UIDP/50011/2020)
Associated Laboratory CICECO-Aveiro Institute of Materials (LA/P/0006/2020)
agradecimentos
This work was supported by the projects LA/P/0037/2020, i3N UIDB/50025/2020 & UIDP/50025/2020, LA/P/0037/2020 financed by I.P./MCTES FCT (Portugal) (Fundacao para a Ciencia e Tecnologia) . Raul Simoes also acknowledges the support of FCT for the Scholarship 2021.07198. Gil Goncalves thanks to the FCT for the Program Stimulus of Scientific Employment-Individual Support (CEECIND/01913/2017) and financial support of project CarboNCT-2022.03596.PTDC (DOI: 10.54499/2022.03596.PTDC) . The financial support of TEMA (Portugal) is also acknowledged by the projects UIDB/00481/2020 and UIDP/00481/2020 from FCT and CENTRO-01-0145-FEDER-022083-Centro Portugal Regional Operational Program (Portugal-Centro 2020) , under the PORTUGAL2020 Partnership Agreement, through the European Regional Development Fund. Joana Rodrigues also acknowledges FCT for Program Stimulus of Scientific Employment-Individual Support (2022.00010.CEECIND) . Ana Violeta Girao thanks to the support of the project CICECO (Portugal) (UIDB/50011/2020, UIDP/50011/2020 & LA/P/0006/2020) , financed by national funds through the FCT/MEC. Nelia Alberto is supported by the Scientific Employment Stimulus 2022.00250.CEECIND/CP1716/CT0002, DOI: 10.54499/2022.00250.CEECIND/CP1716/CT0002. This work was supported by FCT, I.P. by project reference UIDB/50008 and DOI: 10.54499/UIDB/50008.