Additive manufacturing of TPU/C and PVDF/graphene composites with adjustable mechanical and conductive properties for sensor applications

Polymers are usually not electrical conductors, but polymer-based composites reinforced with conductive materials can overcome this limitation, opening new possibilities in producing innovative and useful components. Their application in industry has been greatly enhanced by their applications in sm...

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Main Authors: Ana C. Pinho, Ana P. Piedade
Format: Article
Language:English
Published: Elsevier 2025-09-01
Series:Results in Engineering
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Online Access:http://www.sciencedirect.com/science/article/pii/S2590123025018316
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author Ana C. Pinho
Ana P. Piedade
author_facet Ana C. Pinho
Ana P. Piedade
author_sort Ana C. Pinho
collection DOAJ
description Polymers are usually not electrical conductors, but polymer-based composites reinforced with conductive materials can overcome this limitation, opening new possibilities in producing innovative and useful components. Their application in industry has been greatly enhanced by their applications in smart sensors, such as optical sensors, chemical sensors and biosensors. Currently, additive manufacturing technologies are used to produce different polymeric-based components. However, the processing parameters may alter the properties of the materials, especially if the processing technology involves temperature, such as in the case of fused filament fabrication. The present work investigated two filaments FilaFlex®, a composite made of polyurethane reinforced with carbon fibres, and Koltron G1®, a composite with a matrix of poly(vinyl difluoride) and graphene reinforcement. The pre- and post-printed composites were characterized regarding their chemical structure, thermal stability, and surface morphology. The mechanical performance and electric conductive properties were also simultaneously evaluated during static, dynamic and cyclic tensile tests. The results showed that the conductivity decreases after printing, as FilaFlex® and Koltron G1® filaments present electrical conductivity of 33 and 30 μS⋅mm-1, respectively, while their corresponding printed specimens present electrical conductivity of 11 (FilaFlex®) and 15 μS⋅mm-1 (Koltron G1®). The dynamic tensile strength tests performed on both filaments and 3D-printed specimens showed that overall, FilaFlex® displayed greater electrical stability and lower electrical resistance when compared with Koltron G1®. Tensile cyclic tests exhibited a response pattern for the electrical resistance of the FilaFlex® as a function of the load-unload cycle with a very constant variation, between maximal and minimum values, of around 20 Ω. Koltron G1® presented an entirely different profile with variations of 2000 Ω occurring during the cycles. To the best of our knowledge, this is one of the very few works where the mechanical and conductive properties were simultaneously evaluated during static, dynamic and cyclic tensile tests. This aspect is a significant innovation of the study, which aims to evaluate the suitability of these CPC and processing technology for the production of customisable sensors.
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spelling doaj-art-8360ae738c604927bc1eb6fa967b99b42025-08-20T03:31:24ZengElsevierResults in Engineering2590-12302025-09-012710576010.1016/j.rineng.2025.105760Additive manufacturing of TPU/C and PVDF/graphene composites with adjustable mechanical and conductive properties for sensor applicationsAna C. Pinho0Ana P. Piedade1University of Coimbra, CEMMPRE, Department of Mechanical Engineering, Rua Luís Reis Santos, 3030-788 Coimbra, PortugalCorresponding author.; University of Coimbra, CEMMPRE, Department of Mechanical Engineering, Rua Luís Reis Santos, 3030-788 Coimbra, PortugalPolymers are usually not electrical conductors, but polymer-based composites reinforced with conductive materials can overcome this limitation, opening new possibilities in producing innovative and useful components. Their application in industry has been greatly enhanced by their applications in smart sensors, such as optical sensors, chemical sensors and biosensors. Currently, additive manufacturing technologies are used to produce different polymeric-based components. However, the processing parameters may alter the properties of the materials, especially if the processing technology involves temperature, such as in the case of fused filament fabrication. The present work investigated two filaments FilaFlex®, a composite made of polyurethane reinforced with carbon fibres, and Koltron G1®, a composite with a matrix of poly(vinyl difluoride) and graphene reinforcement. The pre- and post-printed composites were characterized regarding their chemical structure, thermal stability, and surface morphology. The mechanical performance and electric conductive properties were also simultaneously evaluated during static, dynamic and cyclic tensile tests. The results showed that the conductivity decreases after printing, as FilaFlex® and Koltron G1® filaments present electrical conductivity of 33 and 30 μS⋅mm-1, respectively, while their corresponding printed specimens present electrical conductivity of 11 (FilaFlex®) and 15 μS⋅mm-1 (Koltron G1®). The dynamic tensile strength tests performed on both filaments and 3D-printed specimens showed that overall, FilaFlex® displayed greater electrical stability and lower electrical resistance when compared with Koltron G1®. Tensile cyclic tests exhibited a response pattern for the electrical resistance of the FilaFlex® as a function of the load-unload cycle with a very constant variation, between maximal and minimum values, of around 20 Ω. Koltron G1® presented an entirely different profile with variations of 2000 Ω occurring during the cycles. To the best of our knowledge, this is one of the very few works where the mechanical and conductive properties were simultaneously evaluated during static, dynamic and cyclic tensile tests. This aspect is a significant innovation of the study, which aims to evaluate the suitability of these CPC and processing technology for the production of customisable sensors.http://www.sciencedirect.com/science/article/pii/S2590123025018316Additive manufacturingPolymer conductive compositesElectric propertiesMechanical propertiesSensor applications
spellingShingle Ana C. Pinho
Ana P. Piedade
Additive manufacturing of TPU/C and PVDF/graphene composites with adjustable mechanical and conductive properties for sensor applications
Results in Engineering
Additive manufacturing
Polymer conductive composites
Electric properties
Mechanical properties
Sensor applications
title Additive manufacturing of TPU/C and PVDF/graphene composites with adjustable mechanical and conductive properties for sensor applications
title_full Additive manufacturing of TPU/C and PVDF/graphene composites with adjustable mechanical and conductive properties for sensor applications
title_fullStr Additive manufacturing of TPU/C and PVDF/graphene composites with adjustable mechanical and conductive properties for sensor applications
title_full_unstemmed Additive manufacturing of TPU/C and PVDF/graphene composites with adjustable mechanical and conductive properties for sensor applications
title_short Additive manufacturing of TPU/C and PVDF/graphene composites with adjustable mechanical and conductive properties for sensor applications
title_sort additive manufacturing of tpu c and pvdf graphene composites with adjustable mechanical and conductive properties for sensor applications
topic Additive manufacturing
Polymer conductive composites
Electric properties
Mechanical properties
Sensor applications
url http://www.sciencedirect.com/science/article/pii/S2590123025018316
work_keys_str_mv AT anacpinho additivemanufacturingoftpucandpvdfgraphenecompositeswithadjustablemechanicalandconductivepropertiesforsensorapplications
AT anappiedade additivemanufacturingoftpucandpvdfgraphenecompositeswithadjustablemechanicalandconductivepropertiesforsensorapplications