Since our studies were mainly focussed on controlling the flammability of polyolefin materials, we were mainly interested in studying the thermal degradation of such materials. It is reported earlier that polyolefins produce significant amounts of aliphatic hydrocarbons, which are highly flammable, and also, they easily melt, flow and drip during burning causing pool fire. Luyt et al reported that polyethylene polymers are among the most inflammable materials with high heat of combustion, low LOI and high heat release, leaving little or no residual char. They proposed that Phosphorus-and phosphorus-nitrogen-based compounds, including intumescent flame-retardant systems (IFRs), present a viable alternative to inorganic flame-retardant additives due to their negative influence on the mechanical, physical, and rheological properties, as well as on their processing ability. It was shown that in the presence of oxygen-containing polymers, phosphorus-nitrogen based HFFR additives could produce derivatives with strong dehydration and that these derivatives in the presence of oxygen could dehydrogenate the substrate increasing the amount of residue formed after combustion. The influence of branching on the flammability of LDPE or LLDPE due to different processing methods using degradation kinetics was presented in this study. It was shown that thermal stability decreased with increasing degree of branching and increased with increasing number of tertiary carbon atoms in the polymer backbone.