DMA of polyester-based polyurethane elastomers for composite rocket propellants containing different energetic plasticizers

Abstract

The aim of this work is to evaluate the effect of several types of plasticizers on the glass–rubber transition temperatures (Tg) of polyester-based polyurethane binders, using dynamic mechanical analysis (DMA). The polyester polyol commercially named Desmophen® 2200 (D2200®) has been investigated for use as binder for composite propellant applications due to its good ballistic properties and also due to its potential glass–rubber transition temperature when mixed with polar energetic plasticizers. Therefore, it is important to evaluate the behavior of D2200® with different energetic plasticizers. In the present work, this inert polar binder was mixed individually with several different plasticizers and cured with a polyisocyanate commercially named Desmodur® N3400. The plasticizers used were: nitrate ester methyl trimethylol ethane trinitrate (TMETN), N-(n-butyl)-N-(2-nitroxyethyl) nitramine (Bu-NENA), bis-(2,2-dinitropropyl) formal and bis-(2,2-dinitropropyl) acetal mix 1:1 (BDNPF-A), nearly monodispersed low molar mass azido-terminated glycidyl azide polymer (GAP-A), ethylene glycol bis-(azidoacetate) (EGBAA) and 1,2-bis-(2-azidoethoxy) ethane (TEGDA) or BATEG, bis-azido-triethylene glycol, in an amount of 35 mass/%. The cured elastomers were characterized using torsion DMA at several frequencies, and the loss factor curves were described with exponentially modified Gaussian (EMG) distribution functions. Increasing deformation frequency in DMA increases Tg, and an apparent activation energy was correlated with plasticizer performance. The plasticizer ability to decrease Tg follows the order: TEGDA > butyl-NENA > GAP-A > EGBAA > BDNPF-A > TMETN. The ability of each energetic plasticizer could be related to its molecular structure, as well as to its molar mass and interaction possibilities with the polymer chains

On the functionalization and characterization of hydroxyl‐terminated polybutadiene with octyl‐1‐azide and the evaluation of polyurethane elastomers based on such modified HTPB

“…41 The quantities obtained from the parametrization of the glass-rubber transition temperature T g shift with deformation frequency are shown in Table 7, using also standard and modified form of Arrhenius equations described previously. The decrease of Ea f followed by the DOA addition in both PU-HTPB and PU-modHTPB agrees with the literature, 40 suggesting that the plasticizer is compatible in both cases, and acts by removing "mobility barriers" and decreases the interaction between elastomer chains.…”

“…The increase in polarity between polymeric chains tends to increase energetic (electrostatic) interactions and the chain mobility is therefore reduced. 40 Besides, the insertion of Ncontaining groups can enhance the hydrogen bonding with urethane groups. This can explain the increase in T g , the decrease in tanδ intensity and the enhanced stiffness of the solid binder obtained with modified HTPB.…”

Tin Complexes Containing an Atenolol Moiety as Photostabilizers for Poly(Vinyl Chloride)

“…PVC additives should be inexpensive to produce, and effective at producing the desired stabilizing effect at low concentrations [ 13 , 14 ]. Also, they should be stable, nonvolatile, nontoxic, nonhazardous, compatible with PVC, and they should not change the color of polymeric blends [ 13 , 14 ]. PVC industrial additives include tris (di- tert -butylphenyl)phosphite, bis (2-ethylhexyl)phthalate, 3,3′,4,4′-tetrachlorobiphenyl, and inorganics such as barium-zinc stabilizers [ 14 ].…”

Thermal degradation and aging behavior of polytriazole polyethylene oxide‐tetrahydrofuran elastomer based on click‐chemistry

“…DMA is an effective method to study the glass transition ( T g ), loss modulus, storage modulus and tan δ of an elastomer . DMA measurements of the aging PTPET elastomer formed at 60°C are demonstrated in Figure .…”