Preparation methods of SiO2 nano particle modified expandable graphite and flame retardant polypropylene

Abstract

The invention discloses preparation methods of SiO2 nano particle modified expandable graphite and flame retardant polypropylene. The preparation method of the SiO2 nano particle modified expandable graphite comprises the following steps of step 1, adding expandable graphite into an ethanol aqueous solution, performing dispersion to form a suspension, regulating the pH value of the suspension to be 7-9 to obtain an expandable graphite suspension; step 2, slowly dropwise adding tetraethyl orthosilicate into the expandable graphite suspension obtained in the step 1 for reaction; and step 3, performing pumping filtration after reaction is complete, performing washing until a filtrate is neutral, and performing drying to obtain the SiO2 nano particle modified expandable graphite. The preparation method of the flame retardant polypropylene comprises the following steps of adopting polypropylene particles and an SiO2 nano particle modified expandable graphite flame retardant with the mass ratio of 8 to 2, performing melt blending, extruding pelletizing and injection moulding to obtain a halogen-free flame retardant polypropylene composite. The prepared flame retardant polypropylene composite is remarkably improved in flame retardant property, heat stability, carbon formation ability, impact property, tensile strength and the like and has the advantages of no halogen, low smoke, nontoxicity, corrosion resistance and the like.

Description

technical field [0001] The invention relates to an expandable graphite modification technology and a preparation method of flame-retardant polypropylene, in particular to a SiO 2 The invention discloses a preparation method of nano particle modified expandable graphite and flame retardant polypropylene. Background technique [0002] Polypropylene is a typical general-purpose plastic, with large output, wide application and low price; in terms of performance, it has excellent electrical insulation and chemical corrosion resistance, the highest mechanical properties and heat resistance among general-purpose plastics, and good fatigue resistance. In terms of processing and molding, its processing performance is excellent; however, polypropylene is extremely flammable, and its limiting oxygen index is only 17.4%. Applications in electrical and electronics, building materials and other fields. [0003] In order to improve the flame retardancy of polypropylene and maximize its p...

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Problems solved by technology

[0002] Polypropylene is a typical general-purpose plastic, with large output, wide application and low price; in terms of performance, it has excellent electrical insulation and chemical corrosion resistance, the highest mechanical properties and heat resistance among general-purpose plastics, and good fatigue resistance. In terms of processing and molding, its processing performance is excellent; however, polypropylene is extremely flammable, and its limiting oxygen index is only 17.4%. Applications in electrical and electronics, building materials and other fields

[0003] In order to improve the flame retardancy of polypropylene and maximize its performance during the period, there have been many studies in recent years. On the basis of halogen-free environmental protection, a relatively effective method is to add intumescent flame retardants; compared to traditional non-toxic Halogenated intumescent flame retardants, expandable graphite stands out as another class of intumescent flame retardants that, when in contact with a flame, rapidly expand into a swollen multi-voided "worm-like" structure; resulting in a polymer surface covered with a large Combustion residues, which can slow down the heat transfer properties and can interrupt the continued degradation of the polymer matrix; meanwhile, during the expansion of expandable graphite, CO 2 、H 2 O and SO 2 When the gases are released, they can dilute the concentration of combustible gases released in the flame zone; however, when expandable graphite is used as a flame retardant, the rapid reaction during the heat flow process leads to non-directional expansion, resulting in a loose carbon layer structure It is easy to fall off, that is, the "popcorn effect" is produced, resulting in low flame retardant efficiency; and the compatibility of expandable graphite with the polymer matrix is ​​not good, which seriously deteriorates the mechanical properties of the polymer matrix; in order to overcome its shortcomings, the researchers They have also adopted a variety of modification methods for expandable graphite. Although these methods have improved the flame retardant efficiency of expandable graphite and the compatibility of organic polymer materials to a certain extent, they have not yet effectively solved the problem. High loading when used as a flame retardant and low mechanical properties of flame retardant polymer composites

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