# Improving Mechanical Properties of Carboxyl-Terminated Polybutadiene (CTPB) Binder System Using a Cure Accelerator

## TL;DR

This study improves the mechanical properties of a CTPB/EP binder system used in solid propellants by adding a cure accelerator, resulting in higher strength and flexibility.

## Contribution

The use of 593 aliphatic amine as a cure accelerator enhances the mechanical and curing properties of the CTPB/EP binder system.

## Key findings

- Adding 0.3 wt.% of the cure accelerator increased tensile fracture strength to 0.37 MPa and elongation at break to 655%.
- The crosslink density reached 4.3 × 10−4 mol/cm3 at 0.3 wt.% cure accelerator addition.
- The cure accelerator reduced the activation energy of the curing reaction.

## Abstract

To address the issues of slow curing rate, post-curing reactions, and suboptimal mechanical properties in the carboxyl-terminated polybutadiene (CTPB)/epoxy resin (EP) binder system used for solid propellants, this study optimized the curing system by introducing 593 aliphatic amine compounds containing primary and secondary amine groups as a cure accelerator. It is found that the incorporation of the cure accelerator improved the fracture strength and elongation at break of the CTPB/EP binder system. With the addition of 0.3 wt.% cure accelerator, the tensile fracture strength increased to 0.37 MPa, while the elongation at break reached 655%. Moreover, augmenting the quantity of cure accelerator can substantially elevate the crosslink density and gel fraction of the binder system. When the addition reaches 0.3 wt.%, the crosslink density is 4.3 × 10−4 mol/cm3. Further studies showed that 593 cure accelerator reduced the activation energy of the curing reaction of the CTPB/EP binder system, with higher levels of cure accelerator resulting in lower activation energy. This study established a preparation methodology for a CTPB/EP binder system with high elongation and tensile strength. These findings provide a solid scientific foundation for the application of CTPB-based binder systems in solid propellants.