This CASE study examines the performance of a new amine molecule that is based on Michael Addition chemistry.
Michael Addition of Conjugated Nitriles with Amines
Several commercially available products based on this chemistry begin with IPDA and acrylonitrile. Literature references suggests that the addition of nitrile functionality improves chemical resistance and hydrophobicity.
This chemistry has never been studied using INVISTA’s DYTEK®A amine in coating applications. Because we don’t like handling acrylonitrile, we also decided to use Dytek® 2PN (2-Pentenenitrile), which essentially does this same reaction but adds an ethyl branch.
The resulting aliphatic polyurea formulation compared to the IPDA/acrylonitrile product showed:
- 3x slower gel time
- 5x higher max tensile strength
- 4x higher tensile modulus
- Higher onset temperature for thermal degradation (266.8°C vs. 217.8°C)
- 2x improvement in mechanical properties after heat aging
- Equivalent Shore D hardness, elongation, and chemical resistance
Where does this lead us
These results suggest that using an aliphatic polyurea with DYTEK®A/2PN outperforms the traditional IPDA/ACN polyurea in areas such as hardness, scratch resistance and reduced brittleness. Thermal aging results indicate that this new aliphatic polyurea formulation may be better suited for outdoor applications, due to its ability to maintain mechanical performance after prolonged heat exposure.
Future studies will investigate the effects of the additional ethyl branch of 2PN versus ACN on cure time and coating performance reacted with other primary diamines. Initial studies using IPDA as the diamine showed that the steric hindrance from the additional ethyl branch resulted in a 10x slower gel time.
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