Hebei Meixi Biological Co., Ltd. said that PVC is also a common thermoplastic general plastic, which is widely used in films, pipes, wall panels and electrical materials (especially cable insulation skins) and other fields, and can be divided into hard PVC and soft PVC. Rigid PVC has a lower plasticizing dose, and its flame retardant performance is better than that of flexible PVC. However, PVC contains chlorine, which produces hydrogen chloride gas when it is burned and decomposed, and at the same time produces a large amount of toxic and harmful smoke, so it is necessary to pay attention to the large amount of smoke generated when PVC is burned while improving the flame retardancy of PVC. Magnesium hydroxide flame retardant can improve the flame retardant performance of PVC while reducing the emission of toxic and harmful gases, and can be applied to PVC composites.
Different modifiers were used to modify the surface of magnesium hydroxide, and the effects of modified magnesium hydroxide on the mechanical properties and flame retardant ability of PVC were studied. The results showed that zinc stearate as the modifier had the best modification effect, the oil absorption value was 33.39%, the obtained magnesium hydroxide particles were evenly dispersed, the agglomeration phenomenon was significantly improved, and the flame retardant ability of PVC was significantly improved, but the tensile strength of PVC was affected to a certain extent.
The ultrafine magnesium hydroxide was prepared by physical grinding, modified by silane coupling agent, and the modified magnesium hydroxide was added to PVC to make composite materials, and the thermal properties and combustion properties of the composites were studied. The results show that the addition of magnesium hydroxide can significantly increase the LOI value, significantly decrease the smoke density level, and significantly improve the thermal stability and carbon residue rate of PVC composites, which will not adversely affect the hardness, density and tensile strength of PVC composites.
3000 mesh and 6000 mesh magnesium hydroxide were prepared by physical grinding, in which 3000 mesh magnesium hydroxide was modified, and three kinds of magnesium hydroxide were added to PVC to make composite materials. The results show that the PVC composites prepared by 6000 mesh magnesium hydroxide have the best comprehensive properties, and the LOI value can reach 47.0%. The thermal stability and final carbon residue rate were significantly improved, and the highest carbon residue rate was 37.3% at 800°C. The smoke density decreased significantly to 74.64%; The tensile strength and notched impact strength were also improved, which were 28.9 MPa and 5.42 kJ/m2, respectively.
To study the effect of different fineness of magnesium hydroxide on the flame retardant properties of PVC. The results show that the smaller the particle size of magnesium hydroxide, the higher the LOI value of the prepared composites, and the more obvious the decrease of the maximum smoke emission and smoke release grade.