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Alfonso, Giovanni Carlo; Azzurri, Fiorenza; Castellano, Maila

doi:10.1023/a:1012499918018

Cited by 111 publications

(87 citation statements)

References 21 publications

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“…Crystallization in cast films of iPB-1 occurs on rapid cooling by formation of needle-like crystals, in which the macromolecules are oriented parallel to the long axis of the needles. Furthermore, after melt-crystallization, iPB-1 transforms spontaneously from the tetragonal crystal modification II into a hexagonal crystal modification I [26][27][28][29]. This phase transformation is connected with a reduction of the density by about 5%, and is controlled in its kinetics by the molecular architecture, and perhaps the superstructure, in which crystals may be confined.…”

Section: Introductionmentioning

confidence: 99%

Structure of blown films of polyethylene/polybutene‐1 blends

Nase¹,

Funari²,

Michler³

et al. 2009

Polymer Engineering & Sci

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The structure of blown films of blends of low-density polyethylene (PE-LD) and isotactic polybutene-1 (iPB-1) with different content of iPB-1 was investigated using wide-and small-angle X-ray scattering (WAXS and SAXS), transmission electron microscopy (TEM), and polarizing optical microscopy (POM). TEM proves formation of a matrix-particle phase structure due to immiscibility of the blend components. Within the iPB-1 particles, needle-like crystals with c-axis orientation were observed. The PE-LD matrix showed two populations of crystals. WAXS data indicate that the majority of crystals were oriented with the c-axis perpendicular to machine direction (MD), while SAXS data prove additional presence of stacks of lamellae, oriented parallel to MD. Quantitative birefringence measurements showed that the majority of molecule segments were oriented in the direction of the circumference of the film, confirming the WAXS data. The crystal orientation has direct impact on mechanical properties, which was demonstrated by measurement of the anisotropy of the modulus of elasticity. POLYM. ENG. SCI., 50:249-256, 2010.

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Section: Introductionmentioning

confidence: 99%

Structure of blown films of polyethylene/polybutene‐1 blends

Nase¹,

Funari²,

Michler³

et al. 2009

Polymer Engineering & Sci

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“…[3 -5] Unstable Form II is usually obtained by crystallization from the melt under atmospheric pressure and it slowly transforms to stable Form I. [6,7] Form III and I can be generated from certain dilute solutions. [8] Form I is also obtained by crystallization from the melt of Form III under high hydrostatic pressure or by annealing above 90…”

Section: Introductionmentioning

confidence: 99%

“…Fourier transform infrared (FTIR) measurement is applied to analysis of the crystal-crystal transition of Form III into I . The influence of supercritical CO 2 on the melting behavior [6][7][8]12,13] of Form I generated after supercritical CO 2 treatment is also studied by DSC measurement.…”

Section: Introductionmentioning

confidence: 99%

Supercritical CO₂ induced phase transition of Form III in isotactic poly‐1‐butene

Liu

Zhao

et al. 2009

Asia-Pacific J Chem Eng

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The effect of supercritical or high-pressure CO 2 on the recrystallization of Form II in isotactic poly-1-butene (iPB-1) during the melting of Form III was investigated using high-pressure differential scanning calorimetry (DSC). The results showed that the recrystallization of Form II was inhibited by CO 2 . The crystal-crystal transition of Form III to I in ambient nitrogen and supercritical CO 2 was studied using fourier transform infrared spectroscopy (FTIR) and DSC. The results showed that CO 2 promoted the phase transition and the transition proportion of Form III increased with the CO 2 pressure increasing. Form III completely transformed into Form I at 18 MPa. Moreover, supercritical CO 2 could induce the amorphous region to transit into Form I . The probable mechanism of the CO 2 effects on Form III multiple transitions was also proposed. 

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“…1,2 The degree of crystallinity is typically about 50-70%. 3,4 iPB-1 is polymorphic, i.e., the crystalline phase can adopt different structures. Crystal polymorphs include forms I, II, and III and forms I 0 and II 0 .…”

Section: Introductionmentioning

confidence: 99%

“…7,10,14 Form II and II 0 , similarly, have identical crystal structures, with the prime, in case of form II 0 , pointing to formation of crystals from the melt at elevated pressure, leading again to less perfect crystals with a lower temperature of melting than form II crystals. 14 The unit cell of forms II and II 0 is tetragonal, and the conformation of the molecules is characterized by a 11 3 helix. Form III is orthorhombic with the chains showing a 4 1 helical conformation.…”

Section: Introductionmentioning

confidence: 99%

Effect of polymorphism of isotactic polybutene‐1 on peel behavior of polyethylene/polybutene‐1 peel systems

Nase

Androsch

Langer³

et al. 2007

J of Applied Polymer Sci

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The effect of polymorphism of isotactic polybutene-1 (iPB-1) on the peel behavior of the specific peel system low-density polyethylene/polybutene-1 (LDPE/iPB-1) was investigated using wide-angle X-ray scattering, calorimetry, and the T-peel test. Melt-crystallization of iPB-1, initially, yields tetragonal form II crystals which transform as a function of time to trigonal form I crystals. The kinetics of transformation at ambient temperature follows an exponential function, and is completed after about 50-75 h. The presence of LDPE in the peel system does not affect the transformation kinetics. The structure of the crystalline phase of iPB-1 controls the peel force which decreases by about 25% during the crystal-crystal transformation in a blend with 20 m% iPB-1. The reduction of the peel force depends linearly on the mass fraction of iPB-1 crystals in the peel system which further evidences the correlation between the crystalcrystal transformation of iPB-1 and the peel-characteristics of LDPE/iPB-1 blends. Isothermal reorganization of crystals of LDPE is excluded as reason for the change of the peel-performance of LDPE/iPB-1 blends, since it is 5 to 10 times faster than the decrease of the peel force, and crystal-crystal transformation of iPB-1, respectively.

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Untitled

Cited by 111 publications

References 21 publications

Structure of blown films of polyethylene/polybutene‐1 blends

Structure of blown films of polyethylene/polybutene‐1 blends

Supercritical CO₂ induced phase transition of Form III in isotactic poly‐1‐butene

Effect of polymorphism of isotactic polybutene‐1 on peel behavior of polyethylene/polybutene‐1 peel systems

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Untitled

Cited by 111 publications

References 21 publications

Structure of blown films of polyethylene/polybutene‐1 blends

Structure of blown films of polyethylene/polybutene‐1 blends

Supercritical CO2 induced phase transition of Form III in isotactic poly‐1‐butene

Effect of polymorphism of isotactic polybutene‐1 on peel behavior of polyethylene/polybutene‐1 peel systems

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Supercritical CO₂ induced phase transition of Form III in isotactic poly‐1‐butene