Investigations on the influences of paper intrinsic properties and flame retardants on paper materials fire properties

The use of materials made from renewable raw materials, such as paper, has increased more and more due to the steadily growing idea of sustainability. The very good properties of paper and the possibility of individually adjusting these properties through the manufacturing process or a variety of additives and modifications offer a very wide range of possible applications. In this context, it is essential for effective use to generate an understanding of the changed intrinsic properties in the paper and thus optimize them for applications. In relation to the flame retardancy of paper, the influence of intrinsic paper properties on fire behaviour should therefore first be fundamentally investigated. To better understand this interaction systematically, a matrix of papers with gradually different intrinsic properties was created and the fire behaviour of these was first analysed. By developing a video analysis method, it was possible to map the variations in the burning speeds. The key finding was that increasing calendering leads to increasing burning speeds, which contradicts the common view of the fire behaviour of compacted materials. To define the reason for this behaviour, the results of this analysis were correlated with the intrinsic properties and the influence of increasing thermal conductivity could be proposed as the central conclusion. Here, the increasing thermal conductivity resulted from an increase in density and specific heat capacity, which increases due to the shift in the ratios of crystalline and amorphous fractions caused by calendering. Subsequently, the influence of the paper on the flame retardancy was investigated. The influence of papers made from bleached and unbleached fibers on the effectiveness of flame retardants was analysed. Bio-based phosphate flame retardants were used for flame retardancy. A correlation was observed between the amount and type of flame retardants applied to both papers and the decrease in heat release rate and tot