Dynamic Mechanical Behavior of Thermoplastic Polyurethane in Magnetic Coatings
Thermoplastic polyurethane has been widely used as the major binder system in the magnetic coating layer along with various magnetic pigments and several other ingredients. For simplicity, the magnetic coating layer can be treated as a composite system with magnetic pigment being well dispersed in the polyurethane matrix. The effect of CrO2 magnetic pigment and pigment-polyurethane interaction is investigated in this study using the Rheovibron dynamic mechanical analysis technique. Differences in storage modulus and tanδ were observed for different pigment/polyurethane ratios for a variety of polyurethane binders. The presence of CrO2 magnetic pigment resulted in modulus reinforcement. The shift of tanδ max toward higher temperature in the pigmented system suggests the possibility of binder-pigment interaction. The addition of dispersant weakens the interface between binder and pigment which then results in lower tanδ max temperature and lower storage modulus.
KeywordsStorage Modulus Composite System Pigment System Thermoplastic Polyurethane Dynamic Mechanical Behavior
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