Effect of Silane-Modified Aluminum Hydroxide on Flame-Retardant Cable Material Properties

Surface of aluminum hydroxide powder was treated with silane coupling agent at 70 ℃. The effect of silane coupling agent surface treatment on aluminum hydroxide was studied by sedimentation experiment, Fourier transform infrared spectroscopy characterization and water contact angle test. Results showed that silane coupling agent was chemically coated on the surface of aluminum hydroxide powder, significantly improving the hydrophobicity and dispersion stability of powder. Further, mechanical, water resistance and flame retardant properties of low smoke and halogen-free flame retardant polyolefin cable materials filled with modified and unmodified aluminum hydroxide powder were studied. Results showed that modified aluminum hydroxide powder filled in cable material could significantly improve mechanical properties, flame retardant properties and water resistance of the material. Elongation at break of the material increased from 150% to 200%; the maximum heat release rate during combustion decreased from 152.6 to 140 kW·m⁻². Moreover, with the increase of the amount of silane coupling agent treatment, carbon layer of the material did not break after combustion, the second peak of heat release rate was delayed, and the peak value of the second heat release rate decreased. Microstructure of the material after immersion in water indicated that the silane modification of aluminum hydroxide could significantly reduce erosion of water on the material, as shown by the change rate of elongation at break of the material after immersion in hot water increasing from −50% to −23.8%. Therefore, the bridging effect of silane coupling agents could improve the interface between aluminum hydroxide and the matrix resin, thereby enhancing comprehensive performance of the material.