Character of crystallization nuclei in isotactic polypropylene

Rybnikář, F.

doi:10.1002/app.1982.070270507

Cited by 80 publications

(34 citation statements)

References 1 publication

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“…Beck and Ledbetter 11 stated that the supercooling, ‚T (‚T ϭ T m Ϫ T c ), i.e., the difference between the melting peak temperature and the crystallization peak temperature was a function of the overall rate of crystallization. Rybnikar 12,13 utilized the difference between the crystallization peak temperature of the nucleated polymer and that of virgin polymer, ‚T c , as a criterion for evaluating the nucleating effect. If ‚T c Ն 6.5°C, the nucleating efficiency was high.…”

Section: Resutls and Discussionmentioning

confidence: 99%

Effects of substituted aromatic heterocyclic phosphate salts on properties, crystallization, and melting behaviors of isotactic polypropylene

Zhang

Xin

2006

J of Applied Polymer Sci

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Nucleation effects of 2,2Ј-methylene-bis (4,6-di-tert-butylphenyl) phosphate metal salts as a nucleating agent for isotactic polypropylene (iPP) were investigated with differential scanning calorimeter and polarized optical microscope, and their effects on mechanical, optical, and heat resistance properties of iPP were also studied. The results showed that monovalent metal salts of substituted aromatic heterocyclic phosphate such as sodium salt, lithium salt, and potassium salt had a good performance. With 0.2 wt % of sodium salt, lithium salt, or potassium salt incorporated into iPP, the crystallization peak temperature of iPP could be increased by 13.5, 13.6, and 15.0°C, respectively; the mass fraction of crystallinity of iPP could be increased by about 5%; and crystallization rate was enhanced increasingly. Meanwhile the tensile strength and flexural modulus of iPP could be increased by about 10 and 30%, respectively, and the clarity and heat distortion temperature of iPP could also be improved significantly. But bivalent and trivalent metal salts of substituted aromatic heterocyclic phosphate had little effect on properties of iPP. Meanwhile the morphology study showed that the addition of monovalent sodium salt could decrease the spherulite size of iPP significantly.

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Section: Resutls and Discussionmentioning

confidence: 99%

Effects of substituted aromatic heterocyclic phosphate salts on properties, crystallization, and melting behaviors of isotactic polypropylene

Zhang

Xin

2006

J of Applied Polymer Sci

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“…It can be seen from Table 1 that super-cooling degree ( T) of iPP nucleated with HPN-68 was much less than that of virgin iPP, which indicates that addition of HPN-68 greatly increases the crystallization rate of iPP. Rybnikar [22,23] adopted the difference between the crystallization peak temperature (T c ) of the nucleated polypropylene and that of virgin polypropylene, T c , as a criterion for evaluating the nucleation efficiency. The nucleation efficiency was high for T c ≥ 6.5 • C, medium for T c = 5∼6.5 • C and low for a difference of 3-5 • C. This method for evaluating nucleation efficiency was consistent with the method of classifying nucleation efficiency according to the spherulite size observed by microscopy (high nucleation efficiency for mean size of spherulites less than 50 µm; medium nucleation efficiency for 50-100 µm of mean size and low nucleation efficiency for 100-200 µm mean size).…”

Section: Tablementioning

confidence: 99%

Nucleation Effects of a Novel Nucleating Agent Bicyclic [2,2,1] Heptane Di-carboxylate in Isotactic Polypropylene

Zhang

Yao

et al. 2010

Journal of Macromolecular Science, Part B

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Nucleation effects of a novel nucleating agent, bicyclic [2,2,1] heptane di-carboxylate (commercial product name: , in isotactic polypropylene (iPP) were studied by using differential scanning calorimetry (DSC) and wide-angle X-ray diffraction (WAXD). The results showed that HPN-68 is a typical nucleating agent for α-iPP and has high nucleation efficiency. Crystallization peak temperature and mechanical properties of iPP nucleated with HPN-68 can be greatly increased with only a low concentration of HPN-68. However, increased concentration of HPN-68 has a saturation value and properties of iPP, which tend to plateau when the concentration of HPN-68 exceeds the saturation value. When the concentration of HPN-68 was 0.2 wt%, the crystallization peak temperature was increased by about 15 • C, and the tensile strength and flexural modulus of iPP were increased by 13% and 18%, respectively.

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“…8,[9][10][11][12] Numerous results are also reported on glass fiber/iPP composites concerning transcrystallization phenomena, many of them being conIt is known that the presence of a solid surface flicting. It was recently shown that the transcrys-(substrate) in contact with thermoplastic polytalline zone appeared only if the glass fiber is mers during the crystallization from the melt genpulled out from the polymer melt or when shear eraly favors the heterogeneous nucleation 1,2 and stress is applied at given crystallization temperaoften a growth of the transcrystalline zone.…”

Section: Introductionmentioning

confidence: 99%

Isothermal crystallization of iPP in model glass-fiber composites

Janevski¹,

Bogoeva‐Gaceva²

1998

J. Appl. Polym. Sci.

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Isothermal crystallization of iPP in model glass-fiber composites is studied by DSC, and the basic energetic parameters of crystallization are determined. Unsized untreated and thermally treated glass fibers are used in model composites to determine the role of the surface on nucleation and crystallization processes. Thermally treated glass fibers are found to exhibit a predominant nucleating effect as compared to unsized untreated ones, and the crystallization proceeds faster, resulting in lower values for the halftime of crystallization (10-120 s). The energy of formation of a nuclei of critical dimensions at a given T c is also lower, and it decreases as the content of the fibers in the composite increases. The surface free energy of folding, s e Å 140 1 10 03 J/m 2 , was determined for iPP in the composite containing 50% glass fibers, while for pure iPP, s e Å 170 1 10 03 J/m 2 was found.

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Character of crystallization nuclei in isotactic polypropylene

Cited by 80 publications

References 1 publication

Effects of substituted aromatic heterocyclic phosphate salts on properties, crystallization, and melting behaviors of isotactic polypropylene

Effects of substituted aromatic heterocyclic phosphate salts on properties, crystallization, and melting behaviors of isotactic polypropylene

Nucleation Effects of a Novel Nucleating Agent Bicyclic [2,2,1] Heptane Di-carboxylate in Isotactic Polypropylene

Isothermal crystallization of iPP in model glass-fiber composites

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