Strain rate sensitivity of polyurea coatings: Viscous and elastic contributions. (June 2020)

• Record Type: Journal Article
• Authors: Tripathi, Manorama; Parthasarathy, Surekha; Kumar, Davinder; Chandel, Pradeep; Sharma, Prince; Roy, Prasun Kumar
• Is Part Of: Polymer testing. Volume 86(2020)
• Publication Date: 2020-06
• Subjects: Strain rate sensitivity -- Polyurea -- Viscoelasticity; Polymers -- Testing -- Periodicals; Polymères -- Tests -- Périodiques; 620.1920287
• DOI: 10.1016/j.polymertesting.2020.106488
• Languages: English
• ISSNs: 0142-9418

Abstract

Abstract: Polyurea, a reaction product of isocyanates and an amine blend has been reported to be highly strain rate sensitive, which responds in its own unique way when subjected to increasing strain rates. The amine blend comprise of a long chain amine, forming the soft segments, chain extender, which brings the urea linkages closer and a crosslinker, which serves as a chemical bond between the chains. In this work, we attempt to tune the viscous contribution in polyurea, by increasing crosslinking density, while keeping the amount of chain extender more or less constant. The viscoelastic behavior and its effect on the time dependant behavior was established by extensive dynamic studies. Quasi-static tests and Split Hopkinson testing was performed over large deformation rates (10 −4 to 10 3 s −1 ). It was observed that polyureas with larger viscous contribution (tan δ), were capable of exhibiting larger strain rate sensitivity. Highlights: The viscoelasticity of polyurea has been related to its strain rate sensitivity. Crosslinking density in polyurea was increased to obtain polyurea coating with varying viscous contribution. Quasi-static, dynamic and high strain rate testing was performed over large deformation rates (10 −4 s −1 to 10 3 s −1 ). Polyurea with a larger viscous contribution was found to exhibit larger strain rate sensitivity.