Crystallisation of polypropylene containing nucleators

Nagasawa, Shinta; Fujimori, Atsuhiro; Masuko, Tōru; Iguchi, Masatoshi

doi:10.1016/j.polymer.2005.03.099

Cited by 52 publications

(47 citation statements)

References 16 publications

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“…The resulting complex frame can be simplified based on some experimental evidences, supported by several references. 19,[22][23][24] As for the b phase, it basically shows up only if specific b nucleants are added; therefore, for commercial non-bnucleated iPPs, it does not form [22][23][24] ; traces of g form crystals are often present, but always in minor amount and in a narrow window of operating conditions (i.e., cooling rates), hence its presence is neglected without affecting the reliability of the results. 19 Under the aforementioned hypotheses, as two different crystalline phases are formed (a and mesomorphic), at least two kinetic processes take place simultaneously.…”

Section: Theory: Crystallization Kinetics Modelmentioning

confidence: 99%

“…Different configurations (isotacticity and head-to-tail sequences) or addi-tion of small monomeric units and nucleating agents can also influence the final structure. [18][19][20][21][22][23][24][25] Influence of molecular weight on polymer crystallization is controversial. Stem length indeed interferes with entanglement density, thus determining a rate-controlled segregation regime of topological constraints in noncrystalline regions.…”

Section: Introductionmentioning

confidence: 99%

“…This typical effect of enhancement of the overall crystallization kinetics allows one to infer that crystallization kinetics is nucleation-controlled, being the nucleation step the rate-determining one, while the growth rate remains almost unaffected. 22,23 On the other hand, the incorporation of a small content of ethylene units in the polypropylene chains has an influence on the regularity of the molecular structure. In fact, a change in tacticity induced by the shortening of isotactic sequences was observed.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Crystallization kinetics of iPP: Influence of operating conditions and molecular parameters

Carrubba

Piccarolo

Brucato

2007

J of Applied Polymer Sci

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An analysis of the crystallization kinetics of different grades of isotactic polypropylene (iPP) is here presented. To describe the crystallization kinetics as a function of molecular and operating parameters, the methodological path followed was the preparation of quenched samples of known cooling histories, calorimetric crystallization isotherms tests, differential scanning calorimetry cooling ramps, wide angle X-ray diffraction (WAXD) measurements, and density determination. The WAXD analysis performed on the quenched iPP samples confirmed that during the fast cooling at least a crystalline structure and a mesomorphic one form. The diffractograms were analyzed by a deconvolution procedure, to identify the relationship between the cooling history and the distribution of the crystalline phases. The whole body of results (including calorimetric ones) provides a wide basis for the identification of a crystallization model suitable to describe solidification in polymer-processing operations, based on the KolmogoroffAvrami-Evans nonisothermal approach. The kinetic parameters, determined for all the materials, are discussed, highlighting the effect of molecular parameters on the crystallization kinetics: molecular mass and distribution, tacticity, nucleating agents, and ethylene units content.

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Section: Theory: Crystallization Kinetics Modelmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Crystallization kinetics of iPP: Influence of operating conditions and molecular parameters

Carrubba

Piccarolo

Brucato

2007

J of Applied Polymer Sci

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“…(7). If spherulites are assumed to grow in a free space without impingement, the total volume relative to the unit volume transformed by time, t, is given by the following equation 30 :…”

Section: Spherulitic Growth Rate and Number Of Effective Nucleimentioning

confidence: 99%

Quiescent crystallization of natural fibers–polypropylene composites

Somnuk

Eder

Phinyocheep

et al. 2007

J of Applied Polymer Sci

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The effect of natural fibers (vetiver grass and rossells) on quiescent crystallization of polypropylene (PP) composites was analyzed in this study. Also, equilibrium melting temperature (T 0 m ) of the composites was elucidated. Natural fiber-PP composites showed lower T 0 m when compared to neat PP. Thermal analysis was performed via differential scanning calorimeter to study the crystallization kinetics. Natural fiber-PP composites exhibited higher rate of crystallization than that of neat PP. Furthermore, spherulitic growth rate and transcrystallinity of the composites were investigated under a polarized light optical microscope. It was found that the growth rates of the composites were lower than that of neat PP. The spherulitic growth rates combined with the crystallization rates were used to calculate number of effective nuclei. It was shown that the number of effective nuclei of the composites was higher than that of neat PP. This suggested that natural fibers could act as a nucleating agent in the composite.

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“…Therefore the ability of conventional NA for iPP is inefficient, because a NA is in order mm. 18 If a NA could be decreased from 1 mm to 1 nm, it is predicted that I of iPP mixed with nano NA (I(nano NA) (a NA ¼ 1 nm) will become 10 3 times as large as that mixed with macro NA (I(macro NA)) (a NA ¼ 1 mm). The third purpose of this study is to develop significantly high-performance NA by producing nano-sized NA with sharp distribution.…”

Section: High-performance Na For Polymersmentioning

confidence: 99%

Acceleration Mechanism of Nucleation of Polymers by Nano-sizing of Nucleating Agent

Urushihara¹,

Okada

Watanabe

et al. 2006

Polym J

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ABSTRACT:Role of nucleating agent (NA) in nucleation mechanism of polymers was solved based on kinetic study. Theoretical prediction in our previous study that I / C NA a NA À1 (1) was experimentally confirmed by changing C NA and a NA , where I is nucleation rate of polymers, C NA is a concentration of NA in the mixture of NA and a polymer and a NA is lateral size of a NA crystal. As the eq 1 is formulated by assuming an important role of epitaxy between NA and polymer crystals, the confirmation of eq 1 confirmed the essential role of the epitaxy in acceleration mechanism of nucleation of polymers. a NA was decreased from the order of mm to nm and narrow distribution of a NA ( f ða NA Þ) was obtained by improving ''bottom up'' method. We have an important conclusion in polymer science and industries that decreasing a NA from the order of mm to nm and narrowing f ða NA Þ are the most effective methods to improve the performance of NA. [doi:10.1295/polymj.PJ2006040] KEY WORDS Nucleating Agent / Nano / Epitaxy / Nucleation / Crystal / Polypropylene / Nucleating agent (NA) is widely used industrially for improving performance of semicrystalline polymer materials, such as isotactic polypropylene (iPP).1,2 NA accelerates nucleation rate I and improves mechanical and optical properties of polymers. Reduction of processing time is also attributed to the effect of NA. Hikosaka et al. 3 showed that the number density of crystals of polyethylene (PE) increased by 10 4 times after adding NA, which enabled direct observation of nucleation by means of small angle X-ray scattering (SAXS). In this study sodium 2,2 0 -methylene-bis-(4,6-di-t-butylphenylene)phosphate (ADEKA Corp., NA-11) was mixed with PE. The concentration of NA was 3 wt %. Improvement of properties of polymers by NA is the most effective way, because that is achieved by adding small amount of NA without modifying processing facilities. But we have not had a criterion for designing high-performance NA, because acceleration mechanism of nucleation of polymers by NA has not been solved well based on kinetic study. Clarification of the mechanism by NA is significant and interesting for polymer science and industries.

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Crystallisation of polypropylene containing nucleators

Cited by 52 publications

References 16 publications

Crystallization kinetics of iPP: Influence of operating conditions and molecular parameters

Crystallization kinetics of iPP: Influence of operating conditions and molecular parameters

Quiescent crystallization of natural fibers–polypropylene composites

Acceleration Mechanism of Nucleation of Polymers by Nano-sizing of Nucleating Agent

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