Exploring the Effects of MXene on Nonisothermal Crystallization and Melting Behavior of β-Nucleated Isotactic Polypropylene

In this study, one of the commonly used MXene (Ti3C2Tx) and beta nucleated isotactic polypropylene (beta-iPP)/MXene composites of different compositions were fabricated. The effects of MXene on non-isothermal crystallization and polymorphic behavior of beta-iPP/MXene composites were comparatively studied. The non-isothermal crystallization kinetics indicates that for all samples, the lower cooling rates promote composites to crystallize at higher temperatures. When MXene and beta-Nucleating agent (beta-NA) are added separately, the crystallization temperature of composites shifts towards higher temperatures at all cooling rates. When MXene and beta-NA are added simultaneously, the composite shows different cooling rate dependence, and the effects of improving crystallization temperatures is more obvious under rapid cooling. The activation energy of four samples iPP, iPP/MXene, iPP/beta-NA, and iPP/MXene/beta-NA were -167.5, -185.5, -233.8, and -218.1 kJ/mol respectively, which agree with the variation tendency of crystallization temperatures. The polymorphic behavior analysis obtained from Differential Scanning calorimetry (DSC) is affected by two factors: the ability to form beta-crystals and the thermal stability of beta-crystals. Because beta-crystals tend to recrystallize to alpha-crystals below a critical temperature, to eliminate the effect of beta-alpha recrystallization, the melting curves at end temperatures T-end = 50 & DEG;C and T-end = 100 & DEG;C are comparatively studied. The results show that more thermally unstable beta-crystals would participate in beta-alpha recrystallization with higher cooling rates. Moreover, thermal stability of beta-crystals is improved by adding MXene. To further verify these findings, samples of three different thermal conditions were synthesized and analyzed by DSC, X-Ray Diffraction (XRD), and Polarized Light Optical Microscopy (PLOM), and the results were consistent with the above findings. New understandings of synthesizing beta-iPP/MXene composites with adjustable morphologies and polymorphic behavior were proposed.

Automated summary

This study investigated the effects of MXene on non-isothermal crystallization and polymorphic behavior of beta-iPP/MXene composites. The results showed that MXene and beta-NA additives can enhance the crystallization temperature of composites, with MXene showing a more significant effect under rapid cooling. Additionally, the thermal stability of beta-crystals was found to improve with the addition of MXene.