Effects of Aluminum Hydroxide Modification on Properties of Natural Rubber
Aluminum hydroxide flame retardant has played an important role in the field of polymer flame retardant due to its advantages of smoke suppression, flame retardant, non-toxic, non-volatile and low price, and its dosage is far ahead of other flame retardants.
Ultrafine aluminum hydroxide is a product with a regular crystal structure produced by a special production process. It has the advantages of high purity, small particle size, good crystal form, low surface activity, and small specific surface area. It can be filled in large quantities in rubber and plastics. Applicable to all kinds of processing technology.
Its flame retardant principle is that a large amount of crystal water is released during the thermal decomposition process. Because the evaporation of crystal water needs to absorb a lot of heat, it plays the role of cooling the polymer material; the generated water vapor can dilute the flammable gas and inhibit the spread of combustion; new The generated metal oxides have high activity and can adsorb solid particles and play a role in suppressing smoke. In addition, the metal oxides covering the surface of the polymer material can promote the formation of carbon on the surface of the substrate and prevent the spread of flame.
However, due to the extremely strong polarity and hydrophilicity of aluminum hydroxide inorganic flame retardants, it has poor compatibility with non-polar polymer materials. In order to improve the compatibility between aluminum hydroxide and polymers, it is usually necessary to For surface treatment, one of the most effective methods is to use a coupling agent for surface treatment of aluminum hydroxide.
Using natural rubber as the base material, the effects of superfine aluminum hydroxide surface treatment on the mechanical properties and flame retardant properties of vulcanized rubber before and after surface treatment were studied. The results show that:
(1) When the superfine aluminum hydroxide flame retardant natural rubber, the mechanical properties decrease obviously with the increase of the addition amount. When the addition amount reaches 150 parts, the flame retardant reaches the FV0 level, the oxygen index reaches 29%, and the smoke generation is small. Under the conditions of low smoke and low halogen, it can be properly considered to be synergistic with a small amount of halogen-based flame retardants to improve the mechanical properties.
(2) Surface modification treatment of ultrafine aluminum hydroxide with silane coupling agent can effectively improve the compatibility between aluminum hydroxide and natural rubber, improve the processing performance and the mechanical properties of vulcanizate, and the flame retardant performance changes relatively. Small. When the amount of silane coupling agent added was 1.5% of the mass of aluminum hydroxide, the performance improved the most.
(3) Under this formula system, within a certain range, the oxygen index of the vulcanizate increases by about 2 units for every 30 parts of superfine aluminum hydroxide added.