Effects of environmental conditions on the micro-mechanical properties of formulated waterborne coatings

Waterborne colloidal polymer coatings are widely used in architectural and agricultural applications where they subject to challenging environments, such as extremes of temperatures relative humidities (RH). This research investigates the effects adding two common co-formulants, poly(acrylic acid) (PAA) xanthan gum (XG), waterborne composite these environments. The mechanical properties resulting particular interest. Hardness, creep tack thick (~400 μm) formulated model were characterized using a micro-indentation technique operating single cycle within bespoke environmental chamber. Measurements made at three (16, 20 30 °C), which span glass transition temperature (Tg) acrylic copolymer binder, over RH values 10%, 43%, 90%. data analysed Burgers extract characteristic viscoelastic properties. was found by recording force when withdrawing probe from sample it obtain nominal stress (knowing indentation depth geometry) during indenter's withdrawal hence work adhesion (WAdh) detach coating. Tack is completely lost below binder's Tg but increases ambient increases. In coatings, both deformation increase humidity increases, this trend observed each temperature. There no evidence thermal analysis for plasticization moisture sorption, co-formulants hydrophilic. softening high can be attributed water sorption components. presence glassy PAA has effect raising hardness only low there water. addition hydrophilic XG surprisingly reduces while also viscosity These findings will inform formulation function range