Surface Glass Transition Temperature of Amorphous Polymers. A New Insight with SFM

摘要: The surface glass transition temperature, Tg, of several amorphous polystyrene (PS) samples each with a narrow molecular weight distribution covering the range Mn from 3 900 to 1 340 000 has been measured by force−distance measurements using scanning force microscope (SFM). Hysteresis in loading−unloading cycles curves is observed above Tg and ascribed viscoelasticity at polymer surface. hysteresis behavior for different described terms contact mechanics tip−surface interaction, consideration relative roles bulk peeling viscoelasticity. Data on mass dependence thick films are presented, along film thickness thin films, annealing Langmuir−Blodgett overlayer. results related existing theories describing depression lower as result increased free volume ...