Dynamic vulcanization of novel nanostructured polyamide 6/fluoroelastomer thermoplastic elastomeric blends with special reference to morphology, physical properties and degree of vulcanization

摘要

Dynamic vulcanization characteristics of fluoroelastomer during simultaneous mixing with a plastic, polyamide 6, for thermoplastic elastomeric compositions were analyzed in terms of induction time, scorch time, optimum cure and dynamic cure rate for the first time to understand their processing behavior. Also, a new derivative torque vs. time plot was proposed to gain insight into dynamic curing behavior of the rubber. Evolution of morphology and properties during different stages of mixing and dynamic vulcanization was captured. Size of the dispersed rubber phase decreased from similar to 450 to similar to 130 nm with increasing degree of cure and mixing time. Interestingly, it was revealed for the first time the role of injection molding in transforming the morphology and hence properties of such vulcanizates drastically. Nanometer-sized rubber particles (60-80 nm) were generated in thermoplastic vulcanizates (TPVs) after injection molding, which were clearly reflected from field emission scanning electron microscopy and atomic force microscopy and also theoretically predicted from the critical breakup law of viscoelastic droplets in a matrix. Significant improvement of tensile properties was recorded during dynamic vulcanization and also after injection molding of the samples. Tensile strength and Young's modulus of a TPV were 34.5 MPa and 200 MPa respectively as compared to 26.5 MPa and 92 MPa for the specimen before injection molding. (C) 2014 Elsevier Ltd. All rights reserved.