Equilibrium Melting Temperature and Undercooling Dependence of the Spherulitic Growth Rate of Isotactic Polypropylene

Xu, Jiannong; Srinivas, Srivatsan; Marand, Herve; Agarwal, Pawan

doi:10.1021/ma980748q

Cited by 145 publications

(142 citation statements)

References 75 publications

Supporting

Mentioning

133

Contrasting

Unclassified

Order By: Relevance

“…15 The popularity of this approach is a result of its simplicity, as only the experimental melting temperature of the crystallites formed at T c is required. 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.…”

Section: Melting Behaviormentioning

confidence: 99%

“…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: 99%

See 1 more Smart Citation

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

Soccio

Lotti

Finelli

et al. 2011

Polym J

View full text Add to dashboard Cite

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,

show abstract

Section: Melting Behaviormentioning

confidence: 99%

Section: Melting Behaviormentioning

confidence: 99%

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

Soccio

Lotti

Finelli

et al. 2011

Polym J

View full text Add to dashboard Cite

show abstract

“…Their proposed method is hereafter called the "data-fitting" procedure. So far, this method has been successfully applied to the cases of poly(pivalolactone) [31] and its blends [31,32], isotactic polystyrene [33], poly(l-lactide-co-meso-lactide) copolymers [34], and isotactic polypropylene [35].…”

Section: Further Discussion On the T 0 M Value Used In The Analysismentioning

confidence: 99%

“…By assuming that the LH secondary nucleation theory can be applied to describe the temperature dependence of the growth rate data of polymers, other than that of polyethylene which is the basis for the development of theory, and that the measured growth rate data is of high quality, the true T 0 m value for the polymer of interest is taken as the value which results in the ratio of the corresponding nucleation exponents of 2.0. Xu et al [35] applied both the alternative approaches of the data-fitting procedure on the growth rate data of isotactic polypropylene, and found that the resulting T 0 m values from both approaches are comparable (ca. 215ЊC).…”

Section: Further Discussion On the T 0 M Value Used In The Analysismentioning

confidence: 99%

Regime crystallization in syndiotactic polypropylenes: re-evaluation of the literature data

Supaphol

Spruiell

2000

Polymer

View full text Add to dashboard Cite

The Lauritzen and Hoffman secondary nucleation theory was applied to linear growth rate data of syndiotactic polypropylene taken from the literature. Observation of the distinctive upward change of slope in plots of log G ϩ U ‫ء‬ /2.303R(T c Ϫ T ∞ ) versus 1/2.303T c (DT)f suggested the regime II 3 III transition at the crystallization temperature of 110ЊC. Based on the input parameters judged to be the most accurate, the ratios of K g,III /K g,II were found to range from 1.7 to 2.2. Regardless of the crystal structure, if the growth is assumed to occur on the bc plane, the lateral surface free energy, s 11.3 erg cm Ϫ2 and the fold surface free energy s e 63.7^7.1 erg cm Ϫ2 were found. The latter leads to the average work of chain folding of q 7:4^0:8 kcal mol Ϫ1 . If the growth is assumed to occur on the ac plane, the fold surface free energy is found to be s e 82.4^9.1 erg cm Ϫ2 , while the lateral surface free energy is the same as previously noted. In this case, the work of chain folding of q 9:6^1:1 kcal mol Ϫ1 is found. These values are applicable to both regimes II and III. A detailed evaluation of the effects of changes in input parameters was also carried out. ᭧

show abstract

“…When the lamellar thickness for GT is determined at room temperature, an increase of the crystal height can occur during melting. A correct extrapolation is only possible for the HW method when the thickening coefficient is independent of the crystallization temperature, i.e., only samples crystallized at different temperatures, but with the same value for c, can be used to correctly determine T m0 [51].…”

Section: Flow-induced Crystallization Experimentsmentioning

confidence: 99%

Flow-induced crystallization of propylene/ethylene random copolymers

Housmans

Peters

Meijer

2009

J Therm Anal Calorim

View full text Add to dashboard Cite

The influence of the co-monomer content and processing conditions on the crystallization kinetics of propylene/ethylene (P/E) random copolymers is studied using DSC and rheometry. The presence of ethylene lowers the melting and crystallization temperature compared to pure polypropylene, and the quiescent crystallization rate, _ X; increases at equal nominal undercooling, because both the crystal growth rate, G, and number of nuclei, N, increases. The effect of flow on the kinetics of crystallization decreases with the ethylene content. Still, different regimes of flow-induced crystallization are observed, but their size and the position of the transitions between them depend on the ethylene content, and can be expressed in terms of the level of molecular orientation, molecular stretch, and crystallization capacity of the system.

show abstract

Equilibrium Melting Temperature and Undercooling Dependence of the Spherulitic Growth Rate of Isotactic Polypropylene

Cited by 145 publications

References 75 publications

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

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

Regime crystallization in syndiotactic polypropylenes: re-evaluation of the literature data

Flow-induced crystallization of propylene/ethylene random copolymers

Contact Info

Product

Resources

About