The Study Of Flame Retardant Gradient Distribution And The Relationship Between Polymer Flame Retarded Materials And Various Properties (Fire Resistance Etc.)

In this dissertation, flame retardant gradient distribution and the relationship between polymer flame retarded materials and various properties were investigated. Heat preservation design, layering and gradient design, gradient design with different number of layers and gradient design with various rungs were made for various flame retarded systems. Also BDP/ABS; BDP/PC; flame retardant master batch with bromine/EVA and IFR/EVA flame retarded systems were prepared through extruding, injecting and molding, and mixing etc., furthermore, the relationship between the gradient distribution of the flame retardants and the properties, such as flame retarded and mechanical properties, of the polymer flame retarded materials were investigated.The experimental results showed that heat preservation design could get the target of rendering the flame retardants in the matrix move to the surface of the flame retarded materials and could improve the flame retarded properties. However, it was still a very slow process that the macromolecules of flame retardant move to the surface of the material under the condition of heat preservation with a high temperature. Especially after the material solidifying and molding, the inner macromolecules'movements were hindered badly. The cost of time will be a little higher and the time needed to keep heat preservation will be a little longer to see a much more obvious improvement.The results from the experiment of layering and gradient design showed that layering will not affect the flame retarded and mechanical properties of the material generally, and the number of the layers will have little affect on the two properties stated above. The materials with gradient design, especially wrapped in the experiments, were more close to the design of making the flame retardants distributed in a gradient way naturally and gradually from the center to all the directions in the materials. This design realized that much more flame retardants distributed in the surface of the material which could increase the flame retarded properties and improve the mechanical properties of the materials. The research results from gradient design with various rungs showed that this kind of gradient distribution could attained the goal of getting the same flame retarded effect with the situation of using more FR (25%) by using much less FR (21%) which could reduce the cost meanwhile improve the flame retarded efficiency. The results from the mechanical experiments showed that materials with less FR and gradient design could reach the goal of having the same or even more tensile strength when compared to the samples with the same volume of the FR but distributed homogeneously.Evaluation and investigation were made by using TGA,XPS,CONE,SEM & EDX etc. in order to analyze the thermal degradation behavior, element content in the surface, burning behavior and the photos of the fracture surface and the carbon residue. The results showed that heat preservation design was beneficial to make the flame retardants move to the surface of the material and that the gradient design was helpful for the materials to form much more char layer after they were burnt which increase the carbon residue rate, restrain the heat release rate and increase the burning time effectively. The analysis of the photos of the fracture surface and char layer of the materials also proved the conclusions from burning and mechanical experiments. Furthermore, layering and gradient design could not bring about harmful affects to the thermal degradation behavior of the materials.