Selection Criteria for Tackifier Addition to Paraffin Wax based Hybrid Rocket Fuels

Thermal, Viscosimetric and Thermomechanical Combined Assessment of Mixture Modelled Composite Fuels for Hybrid Propulsion

“…Regarding both pure paraffins and thermoplastic polymers-paraffin composite fuels, literature has pointed out the performance relevance of fuel sample production assessment [10][11][12] and formulation selection based on physical properties [10,13,15]. Moreover, polyethylene-paraffin composite fuels have been shown to deliver both mechanical quality and combustion efficiency, while keeping appreciable gains in regression rates as compared to pure polymers [15][16][17].…”

“…Regarding polyethylene‐paraffin based fuels, chiefly characterized by melt‐layer formation [3], it seems reasonable to state that fuel's melting enthalpy would play, to a considerable extent, the role of vaporization enthalpy in the abovementioned inverse relation, i. e., melt layer development would control regression rate [18, 23, 24]. Likewise, dynamic viscosity's inverse relation to regression rate has been pointed out for paraffin‐based fuels [3, 15, 25, 26] and the possibility of predicting regression rate through viscosity measurements has been raised as well [27, 28]. By its turn, linear coefficient of thermal expansion, hereinafter designated as LCTE, may bring useful data regarding solid fuel dimensional stability under simultaneous thermal and mechanical loads common in rocket motor operation, given its role in restrained thermal expansion stresses and thermal shock resistance [29].…”