Designing formulation variables of extrusion-based manufacturing of carbon black conductive polymer composites for piezoresistive sensing

Abstract

Highly sensitive conductive polymer composites for piezoresistive sensing are developed by a design of the formulation variables of extrusion-based manufacturing (filler type/amount, polymer amount) and annealing (a), considering thermoplastic polyurethane (TPU) and/or olefin block copolymer (OBC) as polymer matrix and carbon black (CB) as conductive filler. With ternary composites - based on a CB type with stronger filler-matrix interactions and an appropriate OBC/TPU blend mass ratio (40/60 with CB amount of 5–10 m%; 50/50 with CB amount of 10 m%), the challenging region of both high sensitivity and static strain (maximal gauge factors (GFmax) > 50 and εmax > 100%) can be realized: GFmax > 104 and εmax = 20–240%. OBC binary composites with a high CB2 amount (e.g. 15 m%) are however needed for ultrahigh static strains (εmax > 600%). Well-designed ternary composites (e.g. OBC40-CB/TPU60-7-a and OBC30-CB/TPU70-7-a) possess a large dynamic resistance change, negligible hysteresis and high stability and display strain sensor application potential. Highly CB2 loaded binary (≥12 m%) and ternary composites (10 m%) exhibit a more obvious strain-dependent dynamic hysteretic behavior, as they switch from a dual peak to single peak pattern toward the sensing strain limit, which is interesting for self-diagnose.