LAUSR

The growth of spherulites is an intricate process and the final morphology is dependent on many process conditions. The spherulitic morphologies of poly(3-hydroxybutyrate) (PHB) crystallized from melt film are observed under various crystallization temperature gradient (the non-isothermal crystallization) in this work. Characterization reveals that the crystal morphologies (banded or nonbanded spherulites) of PHB film are determined significantly by nucleation temperature (not growth temperature). Interestingly, banded spherulites, nucleated between 60-135 °C, are able to grow completely above growth temperature 135 °C or below 60 °C yet and non-banded shperulites nucleated at above 135 °C can also develop steadily till below growth temperature 135 °C under temperature gradient condition. Therefore, the conclusion drawn from the temperature gradient or non-isothermal process is novel and different from the result of isothermal crystallization (morphology mainly depending on the growth temperature). In addition, the growth and evolution kinetics of banded and non-banded spherulites are both investigated for some polymer thin films under the temperature gradient in detail.