Study on the synergistic flame retardancy of PA6 by nano-vinyl silicone microspheres/modified magnesium hydroxide

Polyamide 6 (PA6) is widely used in many fields due to its excellent mechanical properties, but its flammability limits its application in some special occasions. In order to improve the flame retardant properties of PA6, this study used nano-vinyl silicone microspheres and modified magnesium hydroxide as synergistic flame retardants to develop a composite material with excellent flame retardant properties.

Polyamide 6 (PA6) is a commonly used engineering plastic and is widely used due to its good mechanical properties and processing properties. However, the flammability of PA6 limits its application in some fields that require high flame retardant properties. Magnesium hydroxide (MH) is a halogen-free flame retardant with good thermal stability, but its flame retardant efficiency is relatively low. The flame retardant properties of PA6 can be further improved by improving the dispersibility and interfacial compatibility of MH through surface modification and combining with other additives.

Materials and methods

Polyamide 6 (PA6): as a matrix material.

Nano-vinyl silicone microspheres (VMS): as a synergistic flame retardant, providing additional flame retardant properties.

Modified magnesium hydroxide (MH): Surface treatment was performed to improve its dispersibility in the PA6 matrix.

Composite material preparation

Surface modification: The magnesium hydroxide was surface modified using a suitable surfactant or coupling agent.

Blending extrusion: PA6 was mixed with modified magnesium hydroxide and nano-vinyl silicone microspheres in a certain proportion, and a composite material was prepared by a twin-screw extruder.

Performance test

Flame retardant performance test: The flame retardant properties of the composite material were evaluated by vertical burning test (UL-94) and limiting oxygen index (LOI) test.

Thermal stability test: The thermal stability of the composite material was determined by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC).

Mechanical property test: The mechanical properties of the composite material were evaluated by tensile test and bending test.

Results and discussion

Modification effect: The successful modification of the magnesium hydroxide surface was verified by characterization methods such as FTIR and XRD.

Flame retardant properties: The synergistic effect of nano-vinyl silicone microspheres and modified magnesium hydroxide significantly improved the flame retardant properties of PA6.

Thermal stability: The thermal stability of the composite material was significantly improved, which was attributed to the endothermic effect of magnesium hydroxide decomposition at high temperature and the isolation layer formed by nano-vinyl silicone microspheres.

Mechanical properties: Despite the addition of flame retardants, the composite material still maintained good mechanical properties.

Conclusion

This study successfully prepared PA6 composites containing nano-vinyl silicone microspheres and modified magnesium hydroxide. Through synergistic effects, the composite material exhibited excellent flame retardant properties and good thermal stability while maintaining sufficient mechanical properties. This new composite material is expected to be widely used in application scenarios requiring strict flame retardant properties.