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ABSTRACT:Temperature-modulated differential scanning calorimetry (T-MDSC) has been applied to the isothermal crystallization of poly(vinylidene fluoride), isotactic polypropylene, syndiotactic polypropylene, poly(ethylene terephthalate), poly(caprolactam) and poly(ethylene succinate). It has been confirmed that the imaginary part of the apparent heat capacity determined by T-MDSC gives the temperature dependence of linear growth rate. The proper choice of the baseline for the phase angle of the complex heat capacity has been discussed and it is concluded that the change in the crystallinity evaluated from the integration of mean exothermic heat flow can be used as the baseline.KEY WORDS Temperature-Modulated Differential Scanning Calorimetry / Crystallization Kinetics / Phase Angle / Temperature-modulated differential scanning calorimetry (T-MDSC) 1 -3 applies a thermal modulation in temperature to a conventional DSC run and determines a dynamic heat capacity from the relationship between the modulation components of temperature and of heat flow. Primary application of this technique is the measurement of specific heat capacity and the examination of the anomaly in a relaxation process such as et. process related to the glass transition. 4 -8 The subject of the present paper is the application to the firstorder phase transition of crystallization. The driving force of the transition is supercooling, and hence the modulation in temperature causes the modulation in the kinetics. We have recently proposed an analysis of the transformation kinetics of crystallization and applied to the crystallization of polyethylene and poly(ethylene terephthalate). 9 -12 It has been experimentally confirmed that the temperature dependence of growth rate is obtainable by the analysis. It has been noticed that the important point is the determination of the phase angle in the apparent heat capacity. The determination is influenced by the choice of baseline which is dependent on the heat capacity and thermal conductivity of the sample. Many arguments have been raised on the choice in the glass transition and melting region of polymers. 13 -15 In the present paper, we have examined the crystallization kinetics of several polymers to establish the phase angle correction for polymer crystallization.In the following, we firstly review our analysis method of crystallization kinetics of polymers with T-MDSC. Secondly, the calibration method of T-MDSC is outlined. The experimental results will be discussed subsequently.MODEL 9 -12

Wehave examined the free surface of a banded spherulite of poly(vinylidene fluoride) (PVDF) by an atomic force microscopy. The directions of the slope of multilayer terraces of lamellar crystals are retained in each half of a banded spherulite; this evidence confirms the macroscopic selection of one handedness in the formation of spiral terraces in each growth direction of the sheaf at the center of a banded spherulite of PVDF. In a previous paper it was confirmed that the three-dimensional morphology of all single crystals of PVDF grown from the melt is chair-type, and hence it is most probable that the stress in the chair crystal is responsible for the formation of spiral dislocations and terraces keeping the same handedness in each growth direction. The chair-type morphology is created because of the chain tilting to the fold surface, which can introduce symmetry breaking and consequently the selection of handedness in non-chiral polymers such as PVDF.

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