Bio‐Based Piezo‐ and Thermoresistive Photocurable Sensing Materials from Acrylated Epoxidized Soybean Oil

Abstract

Bio-based photocurable polymers are increasingly in demand as environmentally friendly materials for advanced applications. Together with functional fillers, these represent a next step for the generation of functional and active smart materials, compatible with additive manufacturing technologies. Herein, acrylated epoxidized soybean oil (AESO) mixed with different amounts of reduced graphene oxide (rGO) up to 6 wt% in order to obtain UV-curable piezoresistive and thermoresistive materials, is reported. It is shown that the addition of rGO to AESO hinders the curing process, but always maintains double bond conversions higher than 50%. Composites are characterized by a good dispersion of micrometric filler clusters. Further, the thermal stabilities are close to 300 °C and crosslinking degrees are above 1.75 mmol cm -3 . The Young modulus of the composites decreases with the addition of the rGO fillers, in particular for the higher filler contents, and electrical conductivities up to 0.13 S m -1 are obtained for the composites with the highest rGO content. UV-curable composites with piezoresistive and thermoresistive responses suitable for applications are thus obtained, characterized by gauge factors around 26 for deformations up to 2% and maximum thermoresistive sensitivity of S = 0.43, values similar to the values obtained for petroleum-based materials.

Combined Thermomechanical Effect of Graphene Oxide and Montmorillonite on Biobased Epoxy Network Formation for Coatings

“…Such an effect could be attributed to the formation of a thermally stable protective layer that prevented the decomposition of the polymeric matrix underneath it. This mechanism was also reported by Mendes et al for an AESO-based system reinforced with 0.5 wt % acr-RGO, which obtained an increased char yield from 1.2 wt % at 600 °C to 3.5 wt % for added 1% acr-RGO; 40 in our case, the functionalities are more numerous, considering the starting GO respectively MMT, and thus a slight increase is observed.…”

Flexible 3D Printed Acrylic Composites based on Polyaniline/Multiwalled Carbon Nanotubes for Piezoresistive Pressure Sensors

“…The conductivity values achieved are higher than those reported for printable photocurable resins using other fillers such as nanoparticles of Ag (10 −6 –10 −11 S cm −1 ) [ 59,60 ] or reduced graphene oxide (rGO) (10 −7 S cm −1 ). [ 61 ] By contrast, some authors have reported higher conductivity [ 62 ] values in the order of 10 −2 –10 −3 S cm −1 , although using a much higher amount of fillers such as 6% of rGO [ 63 ] or 20% of PEDOT. [ 55 ] The use of high amounts of filler is not desirable considering their cost and the negative effect on the performance of the material.…”

“…[ 55 ] The use of high amounts of filler is not desirable considering their cost and the negative effect on the performance of the material. [ 63 ]…”

Lignin as a High-Value Bioaditive in 3D-DLP Printable Acrylic Resins and Polyaniline Conductive Composite

“…Simultaneously, the conductivity values achieved are similar or higher than those reported for printable photocurable resins using 16 wt.% (10 −6 S cm −1 ) [ 83 ] and 1 wt.% (10 −11 S cm −1 ) [ 84 ] of Ag nanoparticles or 2 wt.% reduced graphene oxide (rGO) (10 −7 S cm −1 ) [ 85 ]. By contrast, some authors have reported conductivity values of the order of 10 −2 –10 −3 S cm −1 with 6 wt.% of rGO [ 86 ] or using 20 wt.% of PEDOT [ 60 ]. Nevertheless, the use of high amounts of filler is not desirable considering their cost and the negative effect on the printing process of the material [ 86 ].…”

“…By contrast, some authors have reported conductivity values of the order of 10 −2 –10 −3 S cm −1 with 6 wt.% of rGO [ 86 ] or using 20 wt.% of PEDOT [ 60 ]. Nevertheless, the use of high amounts of filler is not desirable considering their cost and the negative effect on the printing process of the material [ 86 ].…”