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Molecular weight dependence of the growth rate of spherulite of cyclic poly (ε-caprolactone) polymerized by ring expansion reaction
Polymer ( IF 4.6 ) Pub Date : 2020-03-19 , DOI: 10.1016/j.polymer.2020.122403
Ryogo Ono , Hironori Atarashi , Shinichi Yamazaki , Kunio Kimura

To elucidate the molecular weight (Mw) dependence of the growth rate of spherulite (G) of cyclic polymers polymerized by the ring expansion reaction, we studied the G of cyclic poly(ε-caprolactone) (C-PCL) growing from the melt as a function of the crystallization temperature (Tc) and degree of supercooling (ΔT) using polarizing optical microscopy. We prepared C-PCLs comprising an exclusively repeating unit, excluding other structural units with Mw = 17000, 33000, 41000, 74000 and 85000 and linear PCLs (L-PCL) with Mw = 16000, 35000 and 60000, where Mw was determined by GPC using linear polystyrene standards.

G obeyed the equation, G = G0exp(−B/TΔT), for all the samples. The activation energies of secondary nucleation (B) of C-PCL were almost identical except for the C-PCL with the lowest Mw. Since B is proportional to the end surface free energy of the secondary nucleus, it implies that the regularity of the folding surface of C-PCL with high Mw is independent of Mw.

Compared to C-PCL and L-PCL having almost the same Mw, G of L-PCL is higher than that of C-PCL at the same TΔT. This suggests that G of C-PCL and L-PCL is not solely controlled by the entanglement because the entanglement of C-PCL is lower than that of L-PCL. We found the following associations: G0Mw−1.2 for C-PCL and G0Mw−0.67 for L-PCL. The difference in the power of the G0 dependence on Mw reflects the difficulty of performing sliding diffusion in the secondary nucleus. This strongly supports the hypothesis that the absorption behavior of C-PCL chains in the secondary nucleus on the growth front is significantly different from that of L-PCL.



中文翻译:

扩环反应聚合的环状聚ε-己内酯球晶生长速率的分子量依赖性

为了阐明通过扩环反应聚合的环状聚合物球晶(G)的增长速率对分子量(M w)的依赖性,我们研究了从熔体中生长的环状聚(ε-己内酯)(C-PCL)的G作为结晶化温度(的函数Ť ç)和过冷却度(Δ Ť使用偏光显微镜)。我们制备了C-PCLS包括只重复单元,但不包括其他的结构单元与中号瓦特 与= 17000,33000,41000,74000和85000和线性PCLS(L-PCL)中号瓦特 = 16000,35000和60000,在那里中号瓦特 由GPC使用线性聚苯乙烯标准品测定。

ģ服从等式中,g ^  =  g ^ 0 EXP( -/ Ť Δ Ť),对于所有样品。C-PCL的二次成核(B)的活化能几乎相同,除了M- w最低的C-PCL 。由于B与次级核的端面自由能成正比,因此暗示具有高M w的C-PCL折叠表面的规则性独立于M w

相比于C-PCL和具有几乎相同的L-PCL中号瓦特G ^ L-PCL的比C-PCL在相同的更高Ť Δ Ť。这表明C-PCL和L-PCL的G不仅仅由纠缠控制,因为C-PCL的纠缠比L-PCL的纠缠低。我们发现以下关联:C-PCL的G 0M w -1.2和L-PCL的G 0M w -0.67。在的功率差ģ 0的依赖中号瓦特反映了在次核中进行滑动扩散的困难。这有力地支持了这样一个假说:在生长前沿,次生核中C-PCL链的吸收行为与L-PCL明显不同。

更新日期:2020-03-20
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