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

Abstract

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. ᭧

Nonisothermal bulk crystallization and subsequent melting behavior of syndiotactic polypropylenes: Crystallization from the melt state

“…[5][6][7] Studies of the kinetics of polymer crystallization are of great importance in polymer processing, due to the fact that the resulting physical properties are strongly dependent on the morphology formed and the extent of crystallization during processing. 8,10,[12][13][14] Importantly, few publications 8,15 have been dedicated to the studies of nonisothermal crystallization behavior of s-PP, and to the best of our knowledge, only one publication 16 has been dedicated to the subject of nonisothermal crystallization kinetics of s-PP thus far. Investigations related to the chain conformation, crystal structure, morphology, and phase transitions in s-PP have been reported extensively in recent years.…”

Isothermal melt crystallization and melting behaviour of syndiotactic polypropylene

“…Investigations concerning the chain conformation, crystal structure, morphology and phase transitions in s‐PP have been reported extensively in recent years. These studies up to 1994 were reviewed and discussed in a publication by Rodriguez‐Arnold et al 4 Studies on the subject of isothermal crystallization of s‐PP include the Avrami kinetics of the crystallization process,11–13 the kinetics of the linear growth rates,12, 14, 15 and the morphology of the single crystals 16…”

Kinetics of Non-Isothermal Crystallization Syndiotactic Polypropylene

“…These researches up to 1995 were reviewed and published by Rodriguez-Amold et al 10 Published studies on crystallization kinetics of sPP include isothermal Avrami crystallization kinetics, [11][12][13][14] and the isothermal kinetics of the linear growth rates. 11,[15][16][17] There have been a number of published reports concerning non-isothermal crystallization behavior of sPP, 11,[18][19] but none had reported on the kinetics of non-isothermal crystallization.…”