How to achieve both toughness and enhanced electromagnetic interference shielding effectiveness(EMI SE)of carbon fibers(CFs)reinforced rigid polyurethane(RPU)composites is a significative challenge at present.In this ...How to achieve both toughness and enhanced electromagnetic interference shielding effectiveness(EMI SE)of carbon fibers(CFs)reinforced rigid polyurethane(RPU)composites is a significative challenge at present.In this work,a ring-shaped zinc coating was deposited on the short CFs by electrodeposition technique.It is expected to improve the interfacial properties between the fibers and the resin matrix as well as enhance the EMI shielding properties of the composites by changing the surface morphology and roughness of the fibers.Results showed that the surface free energy of the ring-shaped zinc modified carbon fibers(RS-CFs)increased from 49.0 mJ/m^(2) to 53.2 mJ/m^(2),indicating that the surface roughness and wettability of the CFs were effectively improved.In comparison with the pristine short carbon fibers/rigid polyurethane(CFs/RPU)composites,tensile strength and tensile toughness of RS-CFs modified composites were increased by 27.1% and 121.4%,respectively.In addition,the bending and impact strengths of RS-CFs reinforced RPU composites were also improved.Notably,the electrical conductivity of RS-CFs/RPU composites reached 1.2×10^(-5) S/m,which was much higher than that of CFs/RPU composites at 1.4×10^(-10) S/m.Moreover,the EMI SE of the modified composites reached 22 dB,which was 152.9% higher than that of CFs/RPU composites.The enhanced electrical conductivity and EMI shielding properties of the composites could be attributed to the synergistic effect of the porous structure in the RPU matrix and the CFs modified by the metal coating.展开更多
Short carbon fibers were treated at high temperatures around 1100℃ through chemical vapor infiltration technology. A thinner layer ofpyrocarbon was deposited on the fiber surface. The dispersion of carbon fibers in a...Short carbon fibers were treated at high temperatures around 1100℃ through chemical vapor infiltration technology. A thinner layer ofpyrocarbon was deposited on the fiber surface. The dispersion of carbon fibers in a cement matrix and the mechanical properties of carbon fiber/cement composites were investigated by scanning electron microscopy （SEM） and other tests. The reflec- tivity of electromagnetic waves by the composites was measured in the frequency range of 8.0-18 GHz for different carbon fiber contents of 0.2wt%, 0.4wt%, 0.6wt%, and 1.0wt%. The results show that the reflectivity tends to increase with the increase of fiber content above 0.4wt%. The minimum reflectivity is -19.3 dB and the composites exhibit wave-absorbing performances. After pyrocarbon is deposited on the fiber, all the refiectivity data are far greater. They are all above -10 dB and display mainly wave-reflecting performances.展开更多
基金financially supported by Ningbo Natural Science Foundation(No.2022J103).
文摘How to achieve both toughness and enhanced electromagnetic interference shielding effectiveness(EMI SE)of carbon fibers(CFs)reinforced rigid polyurethane(RPU)composites is a significative challenge at present.In this work,a ring-shaped zinc coating was deposited on the short CFs by electrodeposition technique.It is expected to improve the interfacial properties between the fibers and the resin matrix as well as enhance the EMI shielding properties of the composites by changing the surface morphology and roughness of the fibers.Results showed that the surface free energy of the ring-shaped zinc modified carbon fibers(RS-CFs)increased from 49.0 mJ/m^(2) to 53.2 mJ/m^(2),indicating that the surface roughness and wettability of the CFs were effectively improved.In comparison with the pristine short carbon fibers/rigid polyurethane(CFs/RPU)composites,tensile strength and tensile toughness of RS-CFs modified composites were increased by 27.1% and 121.4%,respectively.In addition,the bending and impact strengths of RS-CFs reinforced RPU composites were also improved.Notably,the electrical conductivity of RS-CFs/RPU composites reached 1.2×10^(-5) S/m,which was much higher than that of CFs/RPU composites at 1.4×10^(-10) S/m.Moreover,the EMI SE of the modified composites reached 22 dB,which was 152.9% higher than that of CFs/RPU composites.The enhanced electrical conductivity and EMI shielding properties of the composites could be attributed to the synergistic effect of the porous structure in the RPU matrix and the CFs modified by the metal coating.
基金supported by the National Natural Science Foundation of China (No.50172039)
文摘Short carbon fibers were treated at high temperatures around 1100℃ through chemical vapor infiltration technology. A thinner layer ofpyrocarbon was deposited on the fiber surface. The dispersion of carbon fibers in a cement matrix and the mechanical properties of carbon fiber/cement composites were investigated by scanning electron microscopy （SEM） and other tests. The reflec- tivity of electromagnetic waves by the composites was measured in the frequency range of 8.0-18 GHz for different carbon fiber contents of 0.2wt%, 0.4wt%, 0.6wt%, and 1.0wt%. The results show that the reflectivity tends to increase with the increase of fiber content above 0.4wt%. The minimum reflectivity is -19.3 dB and the composites exhibit wave-absorbing performances. After pyrocarbon is deposited on the fiber, all the refiectivity data are far greater. They are all above -10 dB and display mainly wave-reflecting performances.
