Crystal Structures of Polymers

Rosa, Claudio De; Auriemma, Finizia

doi:10.1002/9781118541838.ch2

Cited by 40 publications

(117 citation statements)

References 278 publications

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“…The crystallization mechanism is influenced by crystallization temperature, cooling rate, and nucleating agents. The crystallization behavior of sPP has been studied for industrial applications over recent years owing to its interesting properties, such as high flexibility and electrical breakdown strength, and good mechanical ductility 2–5. Therefore, there have been many studies on crystallization kinetics and crystallinity of sPP over recent years 6–10…”

Section: Introductionmentioning

confidence: 99%

“…Besides its excellent elastic properties, the slow crystallization rate is a main disadvantage for the processing behavior, limiting commercial application of this polymer 5, 11. Nanocomposites consisting of sPP and inorganic fillers have attracted much interest of researchers during the last decade to broaden commercial applications of sPP 12, 13.…”

Section: Introductionmentioning

confidence: 99%

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Nonisothermal melt crystallization kinetics of syndiotactic polypropylene/alumina nanocomposites

Truong

Larsen

Holme

et al. 2012

J of Applied Polymer Sci

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Nonisothermal melt crystallization kinetics of syndiotactic polypropylene (sPP)/alumina nanocomposites were investigated via differential scanning calorimetry. The addition of alumina nanoparticles significantly increases the number of nuclei and promotes the crystallization rate of sPP. Nonisothermal melt crystallization kinetics was analyzed by fitting the experimental data to a Nakamura model using Matlab. The average values of Avrami exponent n are 1.7 for both sPP and sPP/Al2O3 nanocomposites during slow cooling, which implies a two‐dimensional growth is the predominant mechanism of crystallization following a heterogeneous nucleation. The two nanocomposites give n values equal to 2.3 during faster cooling, indicating that the main growth type taking place for sPP/alumina nanocomposites is also the two‐dimensional growth. The subsequent melting behavior shows that the presence of alumina nanoparticles changed both the cold crystallization and the recrystallization of sPP. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Nonisothermal melt crystallization kinetics of syndiotactic polypropylene/alumina nanocomposites

Truong

Larsen

Holme

et al. 2012

J of Applied Polymer Sci

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“…Another characteristic of these samples was the presence of a double melting peak, which was more evident in the samples with low syndiotacticities 22, 43–47. This phenomenon is associated with melt/recrystallization/remelt (MRCRM) processes 44.…”

Section: Resultsmentioning

confidence: 99%

“…However, for syndiotactic polypropylenes (sPP), the numbers of articles is considerably lower, despite its good properties. sPP has, in general, higher impact resistance, adhesion to difference surfaces, clarity, heat sealability, tear strength, tolerance to high‐energy radiation, oxidative degradation, and thermoplastic–elastomeric behavior than iPP 22, 23. Furthermore, sPP has a lower crystallinity and crystallization rate than iPPs; therefore, its mechanical properties are commercially insufficient; this makes the preparation of sPP/clay composites a viable alternative to overcome these limitations.…”

Section: Introductionmentioning

confidence: 97%

Effect of the polymer microstructure on the behavior of syndiotactic polypropylene/organophilic layered silicate composites

Palza

Zurita

2011

J of Applied Polymer Sci

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Syndiotactic polypropylenes (sPPs) with several microstructures (i.e., syndiotacticities and molecular weights) and synthesized by means of two metallocenic catalysts were melt-blended with 1 and 3 wt % organophilic layered silicates in the presence of a compatibilizer. X-ray diffraction and transmission electron microscopy analysis showed that the clay was well dispersed in the composites, although the filler morphology depended on the polymer microstructure. Polypropylenes with low syndiotacticities and molecular weights presented the best clay dispersion. Nonisothermal differential scanning calorimetry analysis showed that the polymer microstructure and the clay content modified the thermal behavior of the composites. The compatibilizer and the clay acted as nucleant agents to increase the crystallization temperature of the matrix. Moreover, the double endothermic peak observed during heating scan and associated with the melt/recrystallization/remelt processes of the pure polymer matrix was reduced in the composites. With regard to the mechanical properties under tensile conditions, a synergic effect of the compatibilizer and the clay was observed. In particular, the addition of the compatibilizer alone was able to increase by about 20% the elastic modulus relative to the neat samples, whereas increases between 35 and 50% were measured when the clay was also added, depending on the polymer microstructure. Our results show that the microstructure of sPPs had strong effects on the behavior of its composites with clay in the presence of a compatibilizer.

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“…However, for syndiotactic polypropylene (sPP), the number of research works reported is considerably lower. In general, sPP exhibits higher impact resistance, adhesion to different surfaces, transparency, heat sealability, tear strength, tolerance to high‐energy radiation, and oxidative degradation than iPP, as well as thermoplastic–elastomeric behavior . Furthermore, the almost perfect stereoregularity attained gives rise to a characteristic viscoelastic response and viscosity values several times higher than iPP .…”

Section: Introductionmentioning

confidence: 99%

Formulation and characterization of oleogels based on high‐oleic sunflower oil and ethylene vinyl acetate copolymer/polypropylene blends

Martín‐Alfonso

Franco

2015

Polymer Engineering & Sci

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New oleogel formulations based on high‐oleic sunflower oil (HOSO) and ethylene vinyl acetate copolymer (EVA)/polypropylene (PP) blends were prepared using the mixing rheometry technique and further characterized. The effects of PP tacticity and EVA vinyl acetate (VAc) content on the rheological, morphological, and thermal behavior of derived oleogels were investigated. Differential scanning calorimetry (DSC) and polarized‐light optical microscopy (PLOM) observations indicated that VAc segments markedly influence the crystalline structure of polymeric fractions and phase morphology of oleogels. The normalized crystallinity of isotactic polypropylene (iPP) phase increased linearly with its concentration whereas syndiotactic polypropylene (sPP) content does not exert a significant influence. PLOM observations showed that VAc content plays an important role in the phase morphology of PP frictions (size and shape of crystals). The viscoelastic response of oleogels depended on PP tacticity and VAc content, which may be explained attending to the different microstructures attained. POLYM. ENG. SCI., 55:1429–1440, 2015. © 2015 Society of Plastics Engineers

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Crystal Structures of Polymers

Cited by 40 publications

References 278 publications

Nonisothermal melt crystallization kinetics of syndiotactic polypropylene/alumina nanocomposites

Nonisothermal melt crystallization kinetics of syndiotactic polypropylene/alumina nanocomposites

Effect of the polymer microstructure on the behavior of syndiotactic polypropylene/organophilic layered silicate composites

Formulation and characterization of oleogels based on high‐oleic sunflower oil and ethylene vinyl acetate copolymer/polypropylene blends

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