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

: Lemos, Mauricio Ferrapontoff; Mendes, Luis Claudio; Bohn, Manfred


Journal of applied polymer science 138 (2021), No.10, Art. 49981, 13 pp.
ISSN: 0021-8995
ISSN: 1097-4628
Journal Article
Fraunhofer ICT ()
adhesives; functionalization of polymers; polyurethane; rheology

Hydroxyl‐terminated polybutadiene (HTPB) has been modified with azido‐containing substances to be applied in propulsion systems. Pristine HTPB has compatibility issues with energetic polar substances and plasticizers, which is a drawback to develop new high‐energy propellants. This work presents a path for the functionalization of HTPB, carried out through a controlled bulk reaction of it with octyl‐1‐azide. Then it was reacted with isophorone diisocyanate with or without dioctyl adipate (DOA). Structural, thermal, rheological, and dynamic‐mechanical assessments were accomplished. Infrared revealed the arising of absorption bands associated to the CN stretching. From 13C and 1H nuclear magnetic resonances, it is possible to deduce the presence of amine, aziridine, and imine chemical groups, which may promote compatibilization with other polar and energetic substances. The chemical modification induced an increase of viscosity. With respect to the glass–liquid and glass–rubber transitions, the modification shifted them slightly to higher temperatures, but created stiffer networks, in agreement with the increase of polarity and chain interaction due to the presence of N‐containing functionalities. Regarding the solid elastomer binder, the storage shear modulus and molecular mobility were influenced by the type of HTPB and DOA content. In general, the modified HTPB has physical properties like pristine HTPB.