Influence of PVC compound composition on the performance properties and flame retardant efficiency of polymer materials

Introduction. In the last few years, plasticized PVC filled with intumescent materials was used as a passive fire protection component. Important characteristics of such materials are physical and mechanical properties, degree and temperature profile of foaming and flammability. These characteristics significantly depend on the properties of the polymer matrix of the intumescent material. In this paper, the relationship between the composition of PVC compound and the properties of flame-retardant materials based on it is investigated.

Materials and methods of research. Intumescent flame-retardant materials based on PVC compound of different compositions were used in this paper: with changes in the molecular weight of PVC and plasticizer content in the composition of the PVC compound. The PVC compound was obtained by intensive mixing of PVC powder with a plasticizer and a complex stabilizer. The flame retardant material was obtained by dry mixing powders of PVC compound, elastomeric component, flame retardant and intumescent material, followed by extrusion of the mixture through a flat slot die. A set of properties was determined for the obtained materials: density, hardness, tensile strength and elongation, heat resistance, degree of foaming in the range of 300–800 °C, flammability, fracture surface morphology, melt flow index.

Results and their discussion. The paper presents the results of the study of physical, mechanical and thermal properties of the flame retardant materials and their flame retardant effectiveness. It was found that tensile strength when introducing fillers into polymer material decreases by 20–62 %, which is typical for fillers with low adhesion to the polymer. At the same time, hardness increases up to 32 %. The viscosity of the polymer matrix at the base of the flame retardant material determines the process of its foaming.

Conclusions. For the flame retardant materials based on PVC compound, the following is observed:

1) reduction of physical and mechanical properties relative to the polymer material;

2) the presence of oxidized graphite in the composition of the flame retardant material determines the decrease in the thermal resistance of the polymer matrix when producing fire-retardant materials;

3) viscosity of polymer base in the composition of the flame retardant material is an indicator that determines the change in heat resistance and degree of foaming.

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