Solvent gradient fractionation of Polybutene-1 resin and its molecular weight dependency of Form II to I transformation

Xue, Yanhu; Shi, Linna; Liu, Wei; Bo, Shuhui; Cui, Yongyan; Ji, Xiangling

doi:10.1016/j.polymer.2020.122536

Cited by 9 publications

(12 citation statements)

References 26 publications

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“…It was reported that the increase of molecular weight is beneficial to phase transition in early stage, where there are more intercrystallite links to facilitate the internal stress to trigger phase transition. [ 60 ] In this work, BVH copolymers have relatively higher molecular weights but exhibit slower phase transition. It is reasonable to believe that the difference in molecular weight does not change the dominant role of co‐units in determining phase transition.…”

Section: Resultsmentioning

confidence: 95%

Crystallization and Phase Transition of 1‐Butene Copolymers with Distinct Cyclic Co‐Units

Liu

Lou

et al. 2022

Chin. J. Chem.

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Comprehensive Summary The dimethylpyridylamidohafnium catalyst was used to synthesize 1‐butene/cyclohexene and 1‐butene/vinylcyclohexane random copolymers, which have extra six‐membered cyclic co‐units in main chain and side chain, respectively. For the obtained copolymers of different incorporations, the crystallization from amorphous melt and the solid phase transition from tetragonal to trigonal phases were investigated with differential scanning calorimetry. Both of the incorporated cyclic co‐units decrease the crystallization kinetics, but the presence of cyclohexene keeps the melting temperature of copolymers constant. Interestingly, the strong memory effect of crystallization can appear at the elevated temperature even above the equilibrium melting temperature, as the content of co‐units was increased. The 1‐butene/vinylcyclohexane copolymer with 1.52 mol% co‐units exhibits a rather strong memory effect with the broad Domain IIa width of 43°C and the crystallization temperature raising of 24°C. Furthermore, the transition of tetragonal phase into trigonal phase was also explored for different co‐units and incorporations. It was found that both of the cyclohexene co‐units and vinylcyclohexane co‐units effectively slow down the kinetics of phase transition. However, the vinylcyclohexane co‐units have a much higher efficiency in suppressing phase transition than the cyclohexene co‐units, where 0.53 mol% vinylcyclohexane can completely stop phase transition within 1320 h. Considering the fact that copolymers with vinylcyclohexane co‐units actually have lower glass transition temperatures, it was indicated that the suppression of phase transition is also largely influenced by the steric co‐units in the side chain for the helical and positional adjustments, not only by the segmental mobility.

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Section: Resultsmentioning

confidence: 95%

Crystallization and Phase Transition of 1‐Butene Copolymers with Distinct Cyclic Co‐Units

Liu

Lou

et al. 2022

Chin. J. Chem.

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“…Xue et al designed a new preparative temperature rising elution fractionation (P-TREF) equipment with a wide temperature range, which could separate PB-1 successfully according to the crystallization ability [ 25 ]. Xue et al also separated PB-1 according to molecular weight using the solvent gradient fractionation (SGF) method, and the weight average molecular weight of the fractions increased from 31.9 to 1217.4 k with the content of good solvent from 0 to 100 vol% [ 26 ]. The chain structure of PB-1 resin obtained in industrial production is usually complex, the results obtained from original resins often present only average values, which are insufficient to study the relationship between chain microstructure and property [ 25 , 26 , 27 ].…”

Section: Introductionmentioning

confidence: 99%

“…Xue et al also separated PB-1 according to molecular weight using the solvent gradient fractionation (SGF) method, and the weight average molecular weight of the fractions increased from 31.9 to 1217.4 k with the content of good solvent from 0 to 100 vol% [ 26 ]. The chain structure of PB-1 resin obtained in industrial production is usually complex, the results obtained from original resins often present only average values, which are insufficient to study the relationship between chain microstructure and property [ 25 , 26 , 27 ]. The molecular weight of PB-1 resin and its distribution, isotacticity, and co-monomer content all affect its crystallization behavior; it was difficult to clearly understand the influence of a certain factor on its crystallization behavior just using the original sample.…”

Section: Introductionmentioning

confidence: 99%

Effect of Annealing Process and Molecular Weight on the Polymorphic Transformation from Form II to Form I of Poly(1-butene)

Zhang

Xue

et al. 2023

Polymers

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Poly(1-butene) (PB-1) resin has excellent mechanical properties, outstanding creep resistance, environmental stress crack resistance and other excellent properties. However, PB-1 resin experiences a crystal transformation for a period, which seriously affects the production efficiency and directly restricts its large-scale commercial production and application. The factors affecting the crystal transformation of PB-1 are mainly divided into external and internal factors. External factors include crystallization temperature, thermal history, nucleating agent, pressure, solvent induction, etc., and internal factors include chain length, copolymerization composition, isotacticity, its distribution, etc. In this study, to avoid the interference of molecular weight distribution on crystallization behavior, five PB-1 samples with narrow molecular weight distribution (between 1.09 and 1.44) and different molecular weights (from 23 to 710 k) were chosen to research the influence of temperature and time in the step-by-step annealing process and molecular weight on the crystal transformation by differential scanning calorimetry (DSC). When the total annealing time was the same, the step-by-step annealing process can significantly accelerate the rate of transformation from crystal form II to I. PB-1 samples with different molecular weights have the same dependence on annealing temperature, and the optimal nucleation temperature (i.e., low annealing temperature, Tl) and growth temperature (i.e., high annealing temperature, Th) were −10 °C and 40 °C, respectively. At these two temperatures, the crystal form I obtained by step-by-step annealing had the highest content; other lower or higher annealing temperatures would reduce the rate of crystal transformation. When the annealing temperature was the same, crystal form I first increased with annealing time tl, then gradually reached a plateau, but the time to reach a plateau was different. The crystalline form I contents of the samples with lower molecular weight increased linearly with annealing time th. However, the crystalline form I contents of the samples with higher molecular weight increased rapidly with annealing time th at the beginning, and then transformation speed from form II to form I slowed down, which implied that controlling Tl/tl and Th/th can tune the different contents of form I and form II. At the same Tl/tl or Th/th, with increasing molecular weight, the transformation speed from form II to form I via the step-by-step annealing process firstly increased and then slowed down due to the competition of the number of linked molecules and molecular chain mobility during crystallization. This study definitely provides an effective method for accelerating the transformation of poly(1-butene) crystal form, which not only has important academic significance, but also has vital industrial application.

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“…It has been reported that lots of factors would affect the phase transition kinetics, such as the blending with other polymers, [25][26][27][28] copolymerization, [29][30][31][32][33][34] molecular weight, [35][36][37] temperature, 13,38,39 pressure, 40,41 extension, 11,12,42,43 nanofillers, [44][45][46] crystallization conditions, [47][48][49][50][51][52] and so on. Among all these factors, adding nanofillers and changing the crystallization conditions of form II are of significant value which can be used in the practical processing process to promote the phase transition process.…”

Section: Introductionmentioning

confidence: 99%

Investigation of the synergistic effect of melt-extension and nanofiller on the crystal–crystal phase transition from form II to I of isotactic polybutene-1

et al. 2022

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Solvent gradient fractionation of Polybutene-1 resin and its molecular weight dependency of Form II to I transformation

Cited by 9 publications

References 26 publications

Crystallization and Phase Transition of 1‐Butene Copolymers with Distinct Cyclic Co‐Units

Crystallization and Phase Transition of 1‐Butene Copolymers with Distinct Cyclic Co‐Units

Effect of Annealing Process and Molecular Weight on the Polymorphic Transformation from Form II to Form I of Poly(1-butene)

Investigation of the synergistic effect of melt-extension and nanofiller on the crystal–crystal phase transition from form II to I of isotactic polybutene-1

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