| Because the conventional scanning calorimetry technology is difficult to achieve a high temperature scanning rate,Ultrafast scanning calorimetry(UFSC)technology has gradually attracted people’s attention in the field of materials science.This calorimetric technique has played an important role in the crystallization kinetics and phase separation kinetics of polymers,especially for the study of some metastable states,which can more accurately capture the dynamic process of thermodynamic changes in the sample.In recent years,Schick et al.used a vacuum heat conduction gauge based on silicon nitride film technology as a sensor to establish a non-adiabatic power compensating film chip calorimeter with a controllable temperature rise rate of 10~6K/s,which has been successfully applied to various high levels.Research on molecular materials such as melt crystallization and remelting of polymer materials,volatilization of ionic liquids,and silk protein materials.As the high-speed calorimetry technology continues to mature and improve,the possibility of development and application of high-speed scanning calorimeters further increases.We focuses on the development and application of ultrafast scanning calorimetry technology.the isothermal crystallization kinetics of Poly(ethylene oxide)(PEO)droplets was studied by fast scanning calorimetry(FSC)at a scanning rate up to10000K/s over a wide temperature region from glass transition temperature to melting temperature,It was observed that the nucleation in PEO bulk sample during cooling is unavoidable even at a scanning rate up to 50000 K/s because of numerous heterogeneity and showed an obvious cold crystallization peak in the subsequent heating curves.when the sample was prepared by film dewetting and dispersed to several droplets smaller than 2μm in diameter,and a fully amorphous sample could be obtained at a scanning rate of 10000 K/s.compared with that of PEO bulk sample,the droplets sample with less heterogeneity mainly nucleated from homogeneous nucleation showed a slower crystallization rate comparing to the unavoidable heterogeneous nucleation in bulk sample which enhanced the crystallization rate in the low temperature region.Secondly,this paper also explored the application of high-speed scanning calorimetry technology in the field of phase separation kinetics of polymer blending systems.In this paper,PVME/PS blends of LCST-type binary compatible polymer are taken as samples.The time dependence of the phase composition,which can be derived from the glass transition temperature(Tg)of PVME in the PVME-rich phase,shows a distinct change when the annealing temperature(Ta)changes from below to above 380 K.This corresponds to the transition from the nucleation and growth(NG)mechanism to the spinodal decomposition(SD)mechanism,which was verified by microscopy at the later stage of the separation.For the NG and SD mechanisms,the temperature dependences of the kinetics of composition evolution were found to follow the Arrhenius and Williams-Landel-Ferry(WLF)laws,In this study,different shapes of the curve were observed at a very early stage of phase separation,different mechanisms can be identified by UFDSC even before the patterns appear in optical experiments.At last,we concluded our work,and made a series of prospects and plans for follow-up research work.The research work in this paper is expected to provide some reference and reference for the development and application of FSC technology. |
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