Microwave absorbing properties and mechanical properties of PLA/TPU based graphite/graphene composites prepared by MEX

Abstract

Carbon materials has low density and high conductivity, but it is difficult to choose suitable absorbent and matrix material because of its many kinds and great differences in performance, which brings great challenges for researchers to explore the design and manufacture of "high strength, high toughness and strong absorption" wave absorbers. In this paper, micropowder graphite (MPG), spherical graphite (SG), graphene (GR), graphene nanoplatelets (GNPs) and copper-coated graphite (CCG) were used as absorbents, which were first compounded with PLA/TPU matrix by extrusion molding process, and then the composite samples were printed by MEX. By analyzing the electromagnetic parameters and tensile test results, the effects of composites on the absorbing properties and mechanical properties were studied that different carbon-based absorbents whose shape，types and dispersion state in the matrix. It is found that GR, GNPs and CCG have better wave-absorbing effects compared with MPG and SG. This is due to the abundant wrinkles and defects on GR surface, which promotes polarization (interface polarization, dipole polarization) and multiple scattering; GNPs has high graphitization degree and the best impedance matching; the existence of Cu in CCG increases the heterogeneous interface and conductivity, and the electromagnetic attenuation ability is enhanced. Compared with SG, GR, GNPs and CCG, MPG has good dispersity because of its lamellar adhesion to the matrix, and its interfacial bonding strength is improved because of the formation of hydrogen bond and covalent interface, which makes it that the tensile strength and elongation at break of its composites reach 34.73MPa and 22.84%.