Dynamic crystallization and melting behavior of β-nucleated isotactic polypropylene with different melt structures

摘要: In the previous work, we reported that β-selectivity, morphology and tensile behavior of isotactic polypropylene (iPP) can be efficiently tuned by combination controlling melt structure status (namely, creation ordered tuning fusion temperature Tf) addition β-nucleation agent (β-NA, tradename WBG-II, concentration 0.01 wt%), which was called “Ordered Structure Effect” (OSE). This study further investigates dynamic crystallization melting β-iPP with a different differential scanning calorimentry (DSC) non-isothermal kinetics. The results revealed under all cooling rates studied (2, 5, 10, 20 40 °C/min), on curves increased gradually decrease Tf; meanwhile, when Tf in range 168–186 °C where OSE occurs (defined as Region II), activation energy ΔE found to evidently lower, compared higher than 186 or lower 168 °C. subsequent heating showed occurrence observed at studied; location II constant rate varied. Low encouraged formation more β-phase triggered OSE. Moreover, role β-α recrystallization comparatively end recooling (Tend) after held Tf, it high thermal stability low part II, while enhancing β-crystal relatively II.