Linear versus nonlinear determinations of equilibrium melting temperatures of poly(trimethylene terephthalate) and miscible blend with poly(ether imide) exhibiting multiple melting peaks

Wu, Pi Ling; Woo, Eamor M.

doi:10.1002/polb.10219

Cited by 47 publications

(44 citation statements)

References 38 publications

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“…The T 0 m value for PTT based on the NLHW procedure has previously been reported to be ca. 273 • C [38], which is in excellent agreement with the obtained value. The marked difference in the T 0 m values obtained by the LHW and the NLHW procedure should be noted.…”

Section: Determination Of the Equilibrium Melting Temperaturessupporting

confidence: 81%

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Isothermal melt-crystallization and melting behavior for three linear aromatic polyesters

et al. 2004

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Isothermal crystallization and subsequent melting behavior for three different types of linear aromatic polyester, namely poly(ethylene terephthalate) (PET), poly(trimethylene terephthalate) (PTT), and poly(butylene terephthalate) (PBT), were investigated (with an emphasis on PTT in comparison with PET and PBT). These polyesters were different in the number of methylene groups (i.e. 2, 3, and 4 for PET, PTT, and PBT, respectively). Isothermal crystallization studies were carried out in a differential scanning calorimeter (DSC) over the crystallization temperature range of 182-208• C. The wide-angle X-ray diffraction (WAXD) technique was used to obtain information about crystal modification and apparent degree of crystallinity. The kinetics of the crystallization process was assessed by a direct fitting of the experimental data to the Avrami, Tobin, and Malkin macrokinetic models. It was found that the crystallization rates of these polyesters were in the following order: PBT > PTT > PET, and the melting of these polyesters exhibited multiple-melting phenomenon. Lastly, the equilibrium melting temperature for these polyesters was estimated based on the linear and non-linear Hoffman-Weeks (LHW and NLHW) extrapolative methods.

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Section: Determination Of the Equilibrium Melting Temperaturessupporting

confidence: 81%

“…280 [34], 285 [35], and 291 • C [27], for PTT to be ca. 237 [36], 244 [37], 245 [38], and 248 • C [2], and for PBT to be ca. 235 [35], 244 [39] and 245 • C [36], respectively.…”

Section: Determination Of the Equilibrium Melting Temperaturesmentioning

confidence: 99%

Isothermal melt-crystallization and melting behavior for three linear aromatic polyesters

et al. 2004

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“…Nevertheless, Marand and co-workers 16,17 recently discussed the validity of the basic premise of the linear Hoffmann-Weeks treatment: that is, the thickening coefficient for lamellae, g, taken as independent of T c and time. [18][19][20] As demonstrated by some results in the literature, [16][17][18][19][20][21] the linear extrapolation, when carried out for lamellar crystals exhibiting a constant g value, invariably underestimates T m 1 and leads to an overestimation of the g value. In fact, the HoffmannWeeks procedure does not account for the significant contribution to the difference between the melting and crystallization temperatures that arises from the temperature dependence of the fold surface free energy and the thickness increment above the minimum (thermodynamic) lamellar thickness.…”

Section: Melting Behaviormentioning

confidence: 87%

Equilibrium melting temperature and crystallization kinetics of α- and β′-PBN crystal forms

Soccio

Lotti

Finelli

et al. 2011

Polym J

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The melting behavior and crystallization kinetics of PBN-PDEN and PBN-PTDEN copolymers were investigated using differential scanning calorimetry. Multiple endotherms were observed in all of the copolymers under investigation, originating from melting and recrystallization processes. By applying the Hoffman-Weeks method, the T m 1 of the a and b¢-PBN phases were derived. The T m 1 value of the b¢-form, which has not been determined before, is significantly higher, as expected, because the b¢-phase is thermodynamically favored and more tightly packed. The isothermal crystallization kinetics were analyzed according to the Avrami treatment. The presence of either oxygen or sulfur atoms in the PBN polymeric chain was found to reduce its crystallizability. In particular, the crystallization rate regularly decreased as the co-unit content was increased. Lastly, the a-PBN phase was found to crystallize faster than b¢-one, which is expected, as it the more kinetically favored phase. Polymer Journal (2012) 44, 174-180; doi:10.1038/pj.2011.112; published online 9 November 2011Keywords: equilibrium melting temperature; melt isothermal crystallization; random copolymers of poly(butylene naphthalate) INTRODUCTION Naphthalene-containing thermoplastic polyesters have attracted an increasing degree of interest in recent years. Poly(ethylene naphthalate), poly(butylene naphthalate) and poly(propylene naphthalate) are the best known members of this family of thermoplastics. These newly developed high-performance polymers that contain a rigid naphthalene ring and a flexible alkylene group in the repeat unit exhibit physical and mechanical properties superior to the widely used corresponding phthalate-based polyesters. In particular, poly(butylene 2,6-naphthalate) (PBN) is characterized by very good gas barrier properties, high UV resistance, high solvent-resistance, long-term electrical properties and thermostability. To date, two crystalline structures for PBN, denoted as a-and b-forms, have been acknowledged. The transition between these two forms can take place reversibly by mechanical deformation. 1 Ju et al. investigated the crystalline forms of PBN samples obtained by different thermal treatments in bulk. The a-form was produced by annealing a quenched sample in the solid state or by crystallizing PBN from the static melt at temperatures lower than 225 1C. An exclusive b¢-form was generated by performing non-isothermal crystallization from the melt at an extremely low cooling rate (0.1 1C per min). This thermally prepared b¢-form is characterized by a WAXD profile similar to that of the b-form obtained by mechanical deformation, except for the substantial d-spacing deviation in the (0-11) and (010) planes. 2 Nevertheless, if PBN is melt crystallized at high T c , both the a and b¢-forms are obtained simultaneously, and their relative ratio is dependent on the adopted crystallization temperature. Additionally, changes in the crystalline form never occur in the solid state. Lastly,

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“…In order to overcome these disadvantages, a correction of the effect of thermal lag and a calorimetric study using various heating rates have been carried out, according to the procedure adopted by Sohn and Wu. [19,20] As well known, the increment in the observed peak temperature is proportional to the square root of the heating rate at constant thermal resistance, heat of fusion and sample weight, on the basis of the theory of heatflow calorimetry. [21] The observed melting temperatures have been therefore plotted as a function of the square root of heating rate, r 1/2 , for the different T c s (see some typical curves in Figure 8).…”

Section: Resultsmentioning

confidence: 99%

Multiple Melting Behavior of Poly(thiodiethylene terephthalate): Further Investigations by Means of X‐ray and Thermal Techniques

Fichera

Finelli

Gazzano

et al. 2004

Macro Chemistry & Physics

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Summary: The complex multiple melting behavior of poly(thiodiethylene terephthalate) (PSDET) was investigated by means of differential scanning calorimetry, X‐ray diffraction and hot‐stage optical microscopy. The phenomenon was ascribed to the existence of two different crystal structures (α and β), each of them being able to melt and recrystallize under the experimental conditions adopted. Linear and nonlinear treatments were applied in order to estimate the equilibrium melting temperature for α PSDET, by using the corrected values of Tm. The nonlinear estimation led to a higher value by about 25 °C. Isothermal crystallization kinetics of each crystalline form were analyzed according to Avrami's treatment. In both cases, values of Avrami's exponent, n, close to 3 were obtained, in agreement with a crystallization process originating from predeterminated nuclei and characterized by three dimensional spherulitic growth. The rate of crystallization of each crystalline structure was found to become lower as the crystallization temperature is increased, as usual at low undercooling, where the crystallization process is controlled by nucleation.

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Linear versus nonlinear determinations of equilibrium melting temperatures of poly(trimethylene terephthalate) and miscible blend with poly(ether imide) exhibiting multiple melting peaks

Cited by 47 publications

References 38 publications

Isothermal melt-crystallization and melting behavior for three linear aromatic polyesters

Isothermal melt-crystallization and melting behavior for three linear aromatic polyesters

Equilibrium melting temperature and crystallization kinetics of α- and β′-PBN crystal forms

Multiple Melting Behavior of Poly(thiodiethylene terephthalate): Further Investigations by Means of X‐ray and Thermal Techniques

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