Influence of the memory effect of a mesomorphic isotactic polypropylene melt on crystallization behavior

Li, Xiangyang; Su, Fengmei; Ji, Youxin; Tian, Nan; Lü, Jie; Wang, Zhen; Qi, Zeming; Li, Liangbin

doi:10.1039/c3sm51799c

Cited by 63 publications

(50 citation statements)

References 49 publications

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“…So far, it is clearly seen that the memory effect of thermodynamically metastable β‐TPI is stronger than that of stable α‐TPI, namely, higher memory temperature and faster crystallization kinetics. Similar phenomena were also observed in mesomorphic iPP we studied before,[9b] indicating this memory effect may be the universal feature of thermodynamically metastable phases.…”

Section: Resultssupporting

confidence: 87%

“…As the holding time is extended to 5 min, large aggregates break down into small ones, which favors diffusion to the growth front and thus increases the growth rate. [9b]…”

Section: Resultsmentioning

confidence: 99%

“…Intuitively, it may have similar or weak memory effect due to a relatively poor thermal stability. However, our recent studies on metastable mesomorphic iPP illustrated that its memory effect is totally different from that of thermodynamically stable α phase . It was found that only when the melting temperature reached 185 °C, the melt memory could be erased, which is close to the equilibrium melting point of iPP.…”

Section: Introductionmentioning

confidence: 93%

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Strong Memory Effect of Metastable β Form Trans‐1,4‐Polyisoprene above Equilibrium Melting Temperature

Lü

Yang

et al. 2017

Macro Chemistry & Physics

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The memory effect of metastable β form crystals of trans‐1,4‐polyisoprene (TPI) is investigated with its thermodynamically stable α‐TPI as reference. Unexpectedly, β‐TPI exhibits a stronger memory effect over α‐TPI. The memory temperature of β‐TPI can be 20 °C higher than its equilibrium melting point (78 °C), while α‐TPI has lost memory below the equilibrium melting point (87 °C). Moreover, the ordered structures in β‐TPI memorized melt accelerate spherulite growth, and the growth rate depends on melting time, similar to previous mesomorphic isotactic polypropylene studies, implying metastable phase may have universal memory effects: wide memory temperature range, crystal nucleation and growth accelerating. The higher memory temperature of metastable phase may be from weak entropic difference with isotropic melt, which cannot overcome the barrier from entanglements as thermodynamically stable phase, leading to slow relaxation. This discovery can regulate crystalline morphologies of polymers by controlling the locations of different form crystals.

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Section: Resultssupporting

confidence: 87%

“…As the holding time is extended to 5 min, large aggregates break down into small ones, which favors diffusion to the growth front and thus increases the growth rate. [9b]…”

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 93%

See 1 more Smart Citation

Strong Memory Effect of Metastable β Form Trans‐1,4‐Polyisoprene above Equilibrium Melting Temperature

Lü

Yang

et al. 2017

Macro Chemistry & Physics

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“…On the other hand, an increasing number of experimental results indicate that some kind of ordered structures might exist in supercooled polymer melt before the beginning of real crystallization and affect the crystallization behavior [32][33][34][35][36][37][38][39]. When the fusion temperature (T f ) is not high enough for the polymer to achieve complete melting, an amount of ordered structures may survive in the melt [40][41][42][43].…”

Section: Introductionmentioning

confidence: 99%

Influence of melt structure on the crystallization behavior and polymorphic composition of polypropylene random copolymer

et al. 2015

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“…Recently, more and more evidences were reported, pointing out that some ordered structures may exist in the supercooled polymer melt before the occurrence of real crystallization . However, since it is quite difficult to directly measure polymer melt status using the current characterization techniques, a wise method was usually used to explore the effect of ordered structure in polymer crystallization, self‐nucleation . When heating temperature (fusion temperature, T f ) applied on the polymer is not high enough to make it fully molten, an amount of ordered structures will survive within the melt.…”

Section: Introductionmentioning

confidence: 99%

Influences of pre‐ordered melt structures on the crystallization behavior and polymorphic composition of β‐nucleated isotactic polypropylene with different stereo‐defect distribution

Kang

Chen

Yang

et al. 2015

J of Applied Polymer Sci

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As part of continuous efforts to understand the surprising synergetic effect between β‐nucleating agent and pre‐ordered structures of isotactic polypropylene (iPP) in significant enhancement of β‐crystallization (Ordered Structure Effect, OSE), two β‐nucleated iPP with different uniformities of stereo‐defect distribution (WPP‐A and WPP‐B) were prepared, their crystallization behaviors with variation of melt structures were studied in detail. The results revealed that β‐phase can hardly form in WPP‐A (whose stereo‐defect distribution is less uniform) because of its strong tendency of α‐nucleation caused by its less uniform stereo‐defect distribution, while WPP‐B is more favorable for β‐crystallization; As fusion temperature decreases, similar variation trends of crystallization temperature and β‐phase proportion can be observed from WPP‐A and WPP‐B, indicating the occurrence of OSE behavior, which provides unsurpassed β‐nucleation efficiency and induces β‐crystallization even in WPP‐A which is less favorable for β‐crystallization; moreover, the upper and lower limiting temperatures of Region II of WPP‐A and WPP‐B are identical, suggesting the uniformity of stereo‐defect distribution has little influence on temperature window for OSE (denoted as Region II). To explore the physical nature of Region II, self‐nucleation behavior and equilibrium melting temperature (Tm0) of PP‐A and PP‐B were studied. The lower limiting temperatures of exclusive self‐nucleation domain of both PP‐A and PP‐B are identical with the lower limiting temperatures of Region II in OSE (168°C); moreover, the Tm0 of both PP‐A and PP‐B are close to their upper limiting temperatures of Region II in OSE behavior (189°C). The possible explanation was proposed. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42632.

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Influence of the memory effect of a mesomorphic isotactic polypropylene melt on crystallization behavior

Cited by 63 publications

References 49 publications

Strong Memory Effect of Metastable β Form Trans‐1,4‐Polyisoprene above Equilibrium Melting Temperature

Strong Memory Effect of Metastable β Form Trans‐1,4‐Polyisoprene above Equilibrium Melting Temperature

Influence of melt structure on the crystallization behavior and polymorphic composition of polypropylene random copolymer

Influences of pre‐ordered melt structures on the crystallization behavior and polymorphic composition of β‐nucleated isotactic polypropylene with different stereo‐defect distribution

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