The effect of plasticizers on the glass-to-rubber behavior of Desmo-phen~® 220p based elastomers used for composite propellants

摘要

The aim of this work was to evaluate the effect of changing the plasticizer type and its amount on the glass-rubber transition temperatures, the shape of the loss factor curve and mechanical properties of Desmophen~® 2200 based binders, using DMA loss factor curve, tensile testing and DSC. One of the main challenges concerning energetic materials regards not only on the establishments and evaluations of new energetic binders and plasticizers, but also on how their mixtures behave mechanically when concerning its glass-rubber transition range. Despite being inert, the polyester polyol Desmophen~® 2200 (D2200~®) has been investigated because of its potential glass-rubber transition properties when mixed with polar energetic plasticizers. Also previous work has indicated that composite propellant based on D2200~® binder mixed with 35 mass-% TMETN as energetic plasticizer can give good ballistic performance properties compared to HTPB and GAP based formulations, but with still poor strain capability and high glass-rubber transition. However, no screening has been done regarding the behaviour of D2200~® with different energetic plasticizers. Thus, in the present work different pure binders with plasticizers were formulated and characterized. The inert polar binder D2200~® was mixed individually with TMETN, Bu-NENA, BDNPF-A, GAP-A, EGBAA and TEGDA (BATEG) in amounts of 5, 20 and 35 mass-%, and cured with Desmodur~® N3400. The cured elastomers were characterized using torsion DMA, tensile properties and thermal properties (DSC). The loss factor curves obtained by DMA were modelled with exponentially modified Gaussian (EMG) functions, and the effects of the plasticizer on the EMG parameters were evaluated. The description of the shift of the glass-rubber transition temperature with plasticizer concentration is undertaken.