Regime III crystallization in polypropylene

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

“…They found a discontinuity in the growth rate data at the crystallization temperature, T c , of 110ЊC. As T 0 m of these two fractions were estimated to be 160ЊC, this results in the regime II 3 III transition at the undercooling of 50ЊC, similar to the value estimated by Clark and Hoffman [7]. Based on their earlier value of DH 0 f for 100% crystallinity of 8.0 kJ mol Ϫ1 [20], and T g of 0ЊC [17], they estimated that s is approximately 11.2 erg cm Ϫ2 , s e being in the range of 42.2-47.7 erg cm Ϫ2 , and q being between 4.9 and 5.6 kcal mol Ϫ1 [19,21].…”

“…Regime II 3 III transitions have been observed in polyethylene [6], isotactic polypropylene (i-PP) [7], and poly(oxymethylene) [12]. The appearance of all of the three regimes was first observed in the studies of fractions of cis-polyisoprene by Phillips and Vatansever [13].…”

“…They also calculated the average work of chain folding q to be 6.8 kcal mol Ϫ1 . Later in 1984, Clark and Hoffman [7] re-examined the growth rate data published by Miller and Seeley [17,18], and estimated s e to be 49.9 erg cm Ϫ2 and q to be 5.8 kcal mol Ϫ1 , using the same value of T 0 m : They also suggested that a regime II 3 III transition should occur somewhere in the crystallization temperature range of 110-115ЊC, or at the undercooling DT of around 50ЊC. It was not clear, however, how they came up with these estimates.…”

“…the LH secondary nucleation theory) has been developed and revised repeatedly in subsequent publications essentially by Hoffman and his co-workers [4][5][6][7][8][9][10]. The theory suggests that polymers crystallize in three different regimes, as opposed to the classical theory of secondary nucleation in which the deposition of a single nucleus on a growth face is followed by a rapid lateral spreading process.…”

Isothermal Crystallization Kinetics of Novel Isotactic Polypropylene/MoS2 Inorganic Nanotube Nanocomposites

“…From T c (122º-139ºC) and Tº m values, we can determine that the crystallization of iPP and iPP/INT-MoS 2 nanocomposites occurred in crystallization regime III [28], and therefore the nucleation constant, K g , can be expressed as: [15], and 11.5 erg.cm -2 , respectively [28].…”