Thermoplastic Starch–Based Composite Reinforced by Conductive Filler Networks: Physical Properties and Electrical Conductivity Changes during Cyclic Deformation

Abstract

Conductive polymer composites (CPC) from renewable resources exhibit many interesting characteristics due to their biodegradability and conductivity changes under mechanical, thermal, chemical, or electrical stress. This study is focused on investigating the physical properties of electroconductive thermoplastic starch (TPS)–based composites and changes in electroconductive paths during cyclic deformation. TPS–based composites filled with various carbon black (CB) contents were prepared through melt processing. The electrical conductivity and physicochemical properties of TPS–CB composites, including mechanical properties and rheological behavior, were evaluated. With increasing CB content, the tensile strength and Young’s modulus were found to increase substantially. We found a percolation threshold for the CB loading of approximately 5.5 wt% based on the rheology and electrical conductivity. To observe the changing structure of the conductive CB paths during cyclic deformation, both the electrical conductivity and mechanical properties were recorded in parallel using online measurements. Moreover, the instant electrical conductivity measured online during mechanical deformation of the materials was taken as the parameter indirectly describing the structure of the conductive CB network. The electrical conductivity was found to increase during five runs of repeated cyclic mechanical deformations to constant deformation below strain at break, indicating good recovery of conductive paths and their new formation.

Physical Properties of Thermoplastic Cornstarch/Hibiscus sabdariffa Fiber Obtained by Evaporation Casting

“…[ 47 ] In the case of plasticizers, their effect is evident in the final mechanical properties added to the starch. [ 48 ] The flexibility increases because of the reduction of hydrogen bonds in the starch. [ 45 ]…”

“…Starch is a biodegradable, recyclable, and low-cost polymer [44,45] ; however, its mechanical performance is limited due to its high water sensitivity and its brittle response. [46][47][48][49] To diminish these issues, starch has been combined with other polymers, plasticizers, or other alternatives, like cellulose-based fibers. [47] In the case of plasticizers, their effect is evident in the final mechanical properties added to the starch.…”

Microscopic Softening Mechanisms of an Ionic Liquid Additive in an Electrically Conductive Carbon‐Silicone Composite

“…The CB filler alone increases the ultimate strength and Young's modulus but lowers the ultimate strain. [ 34 ] It is often desirable to obtain CECs with large elongations at break, and the effect of IL on the elongation at break is depicted in Figure 1c. The addition of IL increased the elongation at break from 50% in PDMS‐CB‐IL‐0 to more than 180% in PDMS‐CB‐IL‐2, where the composite had the same value as pure (non‐filled) PDMS, while reducing the Young's modulus from 4.27 to 2.52 MPa.…”

Selection of straw waste reinforced sustainable polymer composite using a multi-criteria decision-making approach

“…Currently, considerable efforts are being devoted to replacing petrochemical plastics using vegetable-based polymeric materials, such as biopolymers [6] and natural fiberfilled composites [7]. These latter integrate the vegetable fillers -including straw -with polymers and enable the resulting composites to be structural materials with various uses [7][8][9].…”