Melt Memory Effects in Poly(Butylene Succinate) Studied by Differential Fast Scanning Calorimetry.

Alejandro J. Müller,Connie Ocando,Dario Cavallo,Leire Sangroniz

doi:10.3390/polym12122796

Alejandro J. Müller, Connie Ocando + Show 2 more

Open Access

https://doi.org/10.3390/polym12122796

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Abstract

It is widely accepted that melt memory effect on polymer crystallization depends on thermal history of the material, however a systematic study of the different parameters involved in the process has been neglected, so far. In this work, poly(butylene succinate) has been selected to analyze the effect of short times and high cooling/heating rates that are relevant from an industrial point of view by taking advantage of fast scanning calorimetry (FSC). The FSC experiments reveal that the width of melt memory temperature range is reduced with the time spent at the self-nucleation temperature (Ts), since annealing of crystals occurs at higher temperatures. The effectiveness of self-nuclei to crystallize the sample is addressed by increasing the cooling rate from Ts temperature. The effect of previous standard state on melt memory is analyzed by (a) changing the cooling/heating rate and (b) applying successive self-nucleation and annealing (SSA) technique, observing a strong correlation between melting enthalpy or crystallinity degree and the extent of melt memory. The acquired knowledge can be extended to other semicrystalline polymers to control accurately the melt memory effect and therefore, the time needed to process the material and its final performance.

Highlights

The crystallization process of semicrystalline polymers depends on the thermal history of the material
We systematically study by differential fast scanning calorimetry (FSC), for the first time, the effects of the following variables on the self-nucleation behavior of PBS: (a) the time employed during the self-nucleation protocol, (b) the cooling rate and (c) the effect of the generated standard state before self-nucleation
CrystallinityFigure level,2 shows since the theresults mass obtained of the sample employed in the flash differential scanning calorimeter (DSC) procedure was not determined in this

Summary

Introduction

The crystallization process of semicrystalline polymers depends on the thermal history of the material. To erase the thermal history, polymers have to be heated to 25–30 ◦ C above their melting temperature In this way, a homogeneous or isotropic melt is obtained. When the temperatures employed are high enough to produce an isotropic melt, during subsequent cooling in a differential scanning calorimeter (DSC), the material will always crystallize at the same temperature. This temperature is usually denoted as the standard crystallization temperature and it only depends on the cooling rate employed. If the sample is heated to temperatures that are not high enough to reach an isotropic melt state (or erase melt memory), some self-seeds or self-nuclei survive, which can trigger crystallization at a higher temperature during the subsequent cooling run [1,2,3,4]

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