Acrylic-based thermosets are the current industry standard for protective coatings due to their favorable mechanical properties. Although polyesters offer a range of other benefits such as favorable application viscosity and easily tunable properties, their ultimate film mechanical properties have yet to match those of competing acrylic thermosets. By improving the ultimate thermomechanical properties of polyester-urethane coatings, polyesters can become more competitive in the global coatings market. In this study, we investigate the film properties of model polyester-urethane films with systematically varied amounts of a rigid diol, 2,2,4,4-tetramethyl 1,3-cyclobutanediol (TMCD), incorporated into the polyester backbone. Differential scanning calorimetry results indicate a linear increase in T<sub>g</sub> with increasing TMCD content. Room temperature nanoindentation results display a similar trend in the surface modulus at low TMCD values, but reach a plateau modulus at higher TMCD loading levels. As expected, bulk mechanical properties also change with increasing TMCD content. To explain these variations, we examine the cross-link density for different specimens as well. Observed property improvement in polyester-urethane thermosets by controlled chemical variation constitutes a step closer toward bridging the performance gap between acrylic and polyester coatings.

Bridging the performance gap: Relating thermomechanical properties to polymer composition in polyester-urethane thermoset coatings

255th National Meeting (2018)

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