For the solid-solid transformation from form II to form I of isotactic polybutene-1 (iPB), the temperature dependence of form I nucleation and growth was deemed to control the transformation process. However, the relationship between form I formation and form II disappearance in the transformation process is not clear. In this work, the spontaneous crystal transformation from form II to I of iPB with 81 mol% mmmm sequence concentration is studied firstly by tracking the two processes, the decay of form II and the yielding of form I in a wide range of temperature spanning from 0 °C to 50 °C and in a long transformation time ranging from 5 min to 65 days with in situ FTIR and WAXD. Unlike the literature reports, the decay rate of form II is firstly found to be lower than the yielding rate of form I at all studied temperatures, especially at low transition temperature. This is attributed to the amorphous chains which locate near crystal lamella participating into the nucleation of form II. The regular chain folding and growth of iPB form I from amorphous chains containing short isotactic sequences also lead to an increase in crystallinity of form I compared with that of initial form II crystallized at 60 °C. An increase in the annealing temperature results in decrease in crystallinity and increase in lamellae thickness of iPB form I.

中文翻译：

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具有多个等规序列的聚丁烯-1的差分多态转化行为

对于从等规聚丁烯-1（i PB）的形式II到形式I的固-固转化，认为形式I成核和生长的温度依赖性控制了转化过程。但是，在转化过程中形式I的形成与形式II的消失之间的关系尚不清楚。在这项工作中，首先通过跟踪两个过程，即在宽广的温度范围内，II型的衰变和I型的产生，研究了i PB从81 mol％mmmm序列浓度的II型到I型的自发晶体转变。从0°C到50°C，且原位转化时间从5分钟到65天不等FTIR和WAXD。与文献报道不同，在所有研究温度下，尤其是在低转变温度下，首先发现晶型II的衰减率低于晶型I的屈服速率。这归因于位于晶体薄片附近的无定形链，其参与形式II的成核。与在60°C结晶的初始晶型II相比，从包含短等规序列的无定形链中i PB晶型I的规则链折叠和生长还导致晶型I的结晶度增加。退火温度的升高会导致i PB晶型I的结晶度降低和薄片厚度增加。