Application Of 3D Printing Polymer Composites And Stretchable Flexible Electronics

3D printing,a prototyping technique,has attracted a wide attention because of its facile and scal-up processing character and a wide variety of products.In recent years,3D printing products have shown potential applications in various areas including life,aerospace,medical and electronic fields.In this paper,with the aid of 3D printing technique,both a high-performance strain sensor based on thermoplastic polyurethane(TPU)/Ag composite and a toughened polylactic acid(PLA)/natural rubber latex(NR)composite were fabricated.We characterized their structure and measured their properties in detail.The results are shown as follows:1.Herein,high-performance stretchable strain sensors based on Ag nanoparticles(NPs)sandwiched between two thermoplastic polyurethane(TPU)fibrous textiles are fabricated by combining 3D-printed TPU elastomer and solution-coated Ag NP pulp,in which a conductive network is formed at a low loading of 4.3 wt% Ag NPs.The printed TPU fibers in each textile are arranged in parallel,while perpendicular to each other between the upper and lower textiles,forming an oblique lattice structure with their diagonal being the same direction as the external force.Under stretching,the deformed TPU fibers in the upper and lower textiles squeezed Ag NPs to undergo shearing motion,such that the disconnected electrical circuit can be compensated by some Ag NPs to retain the electrical pathway.Consequently,the printed TPU/Ag strain sensors showed high sensitivity(gauge factor of 38220 at a strain of 120–138%),wide working strain range(0–138%),and long-term durability(>2500 cycles at 50% strain).Their promise as flexible electronic components is demonstrated in wearable motion detection systems for monitoring human motions and recognizing facial expressions.2.A toughened PLA/NR composite was fabricated by dipping natural latex into the3 D printed PLA fibrous mesh,in which the natural latex filled in the gap between the printed PLA fibers.After vulcanization,the natural rubber nework formed and penetrated PLA fibrous mesh,causing a double constrainted network structure.Given the rubber-toughed plastic mechanism,the existence of natural rubber network can actas a cushion to protect the PLA matrix from damage because it can improve the energy absorption within the PLA/NR composites by viscoelastic deformation.It is found that the impact strength of the composites is related with the NR concentraion.When the concentraion of NR was 18%,the impact strength of the composite was 3 times higher than that of the pure PLA sample.In addition,the impact-resistance of the composites is and affected by the vacancy,which can also absorb energy.With the decrease of PLA filling percentage,the tensile strength and bending modulus of the composites decreased.