Freestanding Fe3O4 / Ti3C2Tx MXene / polyurethane composite film with efficient electromagnetic shielding and ultra-stretchable performance

Electromagnetic pollution seriously affects the human reproductive system, cardiovascular system, people’s visual system, and so on. A novel versatile stretchable and biocompatible electromagnetic interference (EMI) shielding film has been developed, which could effectively attenuate electromagnetic radiation. The EMI shielding film was fabricated with a convenient solution casting and steam annealing with 2D MXene, iron oxide nanoparticles, and soluble polyurethane. The EMI shielding effectiveness is about 30.63 dB at 8.2 GHz, based on its discretized interfacial scattering and high energy conversion efficiency. Meanwhile, the excellent tensile elongation is 30.5%, because of the sliding migration and gradient structure of the nanomaterials doped in a polymer matrix. In addition, the film also demonstrated wonderful biocompatibility and did not cause erythema and discomfort even after being attached to the arm skin over 12 hours, which shows the great potential for attenuation of electromagnetic irradiation and protection of human health.

Thermic Characteristics Of Rice Husk And Polyurethane Composite Materias As Insulation In Fish Cold Storage

The process of freezing fish always requires a cooler as a temporary storage place for fish. The ability of the storage to maintain cold temperatures is a serious problem to be considered so that the freshness of the fish can be maintained. Therefore, an appropriate technology is required to support the cold chain system so that fish quality can be maintained. The purpose of this study was to test the thermal conductivity of composite materials for fish storage insulation from a mixture of rice husks and polyurethane so that the price of the box can be reduced but still maintain the quality of the fish. The composition of the composite material was made with a volume ratio of 1:0.5, 1:1, 1:1.5, and 1:2. The thermal conductivity test of the material uses the ASTM E1225-99 standard. All test results were compared with 100% polyurethane material. The results of testing the thermal conductivity of 100% polyurethane material obtained 0.023 W/m.C. From all the test results, the material that is most likely to be applied to fish cooler box insulation is a 1:1 composition having a thermal conductivity value of 0.067W/m.C. Materials with this composition do not affect the expansion of the polyol and isocyanate reactions. This composition is the most economical to be used as insulation for fish storage boxes which can save the use of polyurethane by 50%.

EXPERIMENTAL STUDY ON MECHANICAL PROPERTIES OF POLYURETHANE POWDER COMPOSITES

In this paper, the effects of emery, lime, quartz sand and cement on the mechanical properties of polyurethane powder composites were studied by three-point flexural test, and the stress-strain curve was drawn. In the flexural test, the polyurethane cement composite formed a control group by changing the content of polyester polyol. When polyester polyol: isocyanate: cement =1:1:2, the average flexural strength of polyurethane cement was 37.1 MPa, and the strain was 10854 με.When polyester polyol: isocyanate: cement =1.15:1:2, the average flexural strength is 38.9 MPa and the strain is 23520 με.When polyester polyol: isocyanate: cement =1.3:1:2, the average flexural strength is 42.5 MPa and the strain is 32942 με. The flexural strength and ductility are improved to a certain extent due to the addition of polyester polyol.The average flexural strength of other polyurethane powder composites such as polyurethane emery test block is 45.1 MPa and the strain is 6203 με, the average flexural strength of polyurethane lime test block is 33.4 MPa and the strain is 6470 με, the average flexural strength of polyurethane quartz sand test block is 49.23 MPa and the strain is 7521 με. The results show that the flexural strength of polyurethane emery material and polyurethane quartz sand material is higher than that of polyurethane cement, which can be used to replace cement to a certain extent to reduce the cost of polyurethane composite material.