Crystallization behavior, crystal transformation, and morphology of polypropylene/polybutene-1 blends

ABSTRACT:The nonisothermal crystallization, melting behavior, and morphology of blends of polypropylene (PP) and a metallocene-catalyzed polyethylene (mPE) elastomer were studied with differential scanning calorimetry, scanning electron microscopy, polarized optical microscopy, and X-ray diffraction. The results showed that PP and mPE were partially miscible and could form some cocrystallization, although the extent was very small. A modified Avrami analysis and the Mo method were used to analyze the nonisothermal crystallization kinetics of the blends. The values of the Avrami exponent indicated that the crystallization nucleation of the blends was homogeneous, the growth of the spherulites was three-dimensional, and the crystallization mechanism of PP was not affected by mPE. The crystallization activation energy was estimated with the Kissinger method. Interesting results were obtained with the modified Avrami analysis and Mo and Kissinger methods, and the conclusions were in good agreement. The addition of less mPE increased the overall crystallization rate of PP. The relationship between the composition and morphology of the blends was examined.

Section: Resultssupporting

confidence: 81%

Nonisothermal crystallization, melting behavior, and morphology of polypropylene/metallocene‐catalyzed polyethylene blends

Gao

Wang

et al. 2004

“…Research, for evaluation of the effect of the presence of a second component on the transition kinetics, employed low molecular weight compounds including biphenyl, stearic acid, dioctyl phthalate, or 1-naphtylacetamide, polymers, including isotactic polypropylene (iPP) or high-density polyethylene (HDPE), and nanofillers. 22,25,26 Blending of iPB-1 with iPP, for instance, was found to accelerate the rate of the transition from form II to form I crystals of iPB-1. 25 For pure iPB-1, at ambient temperature, full conversion of form II to form I was achieved after aging for at least 6 days, whereas in blends with 25 m% iPP, the transition was completed after 3 days.…”

Section: Introductionmentioning

confidence: 98%

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

Nase

Androsch

Langer³

et al. 2007

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.

“…[15][16][17] One is the stable hexagonal crystal form (I) with a characteristic peak at around 10 (2y), the other is the metastable tetragonal one (II) with that at around 12 (2y). It is well known that PB spontaneously exhibits a crystal phase transformation from II to I crystal forms.…”

Section: Introductionmentioning

confidence: 99%

“…It is well known that PB spontaneously exhibits a crystal phase transformation from II to I crystal forms. [15][16][17] In addition, it is well known that the transformation occurs during the PB plastic deformation and brings about a much more ductile behavior. 18 The good mechanical properties of the PB/cellulose must be originated from the crystal phase transformation.…”

Section: Introductionmentioning

confidence: 99%

Effects of crystal phase transformation on tensile properties of polybutene‐1/cellulose composites

Nakatani¹,

Yamada²,

Takahashi³

et al. 2011

Morphologies and tensile properties of polybutene-1 (PB), PB/fibrous cellulose (FC), and the PB/silanized FC with 3-aminopropyltrimethoxysilane (APTMS) composites were studied. The scanning electron microscope micrographs exhibited the adherent PB parts on the FC and the silanized FC, suggesting that there was a certain affinity of PB to them. The spherulite observation suggested that there existed a secondary bonding between the PB and the FC or the silanized FC. These tensile properties were remarkably affected by the PB crystal phase transformation from the metastable tetragonal (II) to the stable hexagonal (I) phase. The transformation caused the ageing embrittlement even at r.t. In particular, the ageing embrittlement rate of the PB/silanized FC was much higher than other samples. Because the silanized FC became the excellent nucleating agent for the PB crystallization, the PB/silanized FC was found to easily form the thicker lamella having a higher probability of containing a crystal defect to serve as a starting point of the transformation. The higher transformation rate depended on the thicker lamella formation rate and its amount.