Syndiotactic polypropylene and its copolymers with alpha-olefins. Effect of composition and length of comonomer

Arranz-Andrés, Javier; Guevara, Juan Luis; Velilla, Teresa; Quijada, Raúl; Benavente, Rosario; Pérez, Ernesto; Cerrada, María L.

doi:10.1016/j.polymer.2005.10.078

Cited by 43 publications

(40 citation statements)

References 58 publications

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“…Therefore it would be associated with the CH 2 -CH 3 branch formed by the introduction of 1-butene comonomer. This relaxation has also been observed in isotactic polypropylene copolymers [51] and on syndiotactic polypropylene [52] copolymers with long chain -olefin, also named …”

Section: Mechanodynamical Propertiessupporting

confidence: 56%

Influence of structure on the properties of polypropylene copolymers and terpolymers

et al. 2017

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A set of Ziegler-Natta copolymers of iPP with ethylene or with 1-butene, and terpolymers with both counits have been characterized, devoting special attention to the effect of composition and processing conditions on the crystal structure and on the final properties.DSC and X-ray diffraction is used to study the polymorphism of copolymers and terpolymers.Comonomer insertion interrupts the isotactic sequences, acting as a structural defect, and the formation of  form is enhanced in the interval of studied compositions. Moreover, crystallinity decreases and crystal structure is modified. Comonomer type and concentration determine the extent of these modifications, resulting on important changes in macroscopicproperties. An important aspect to be considered is the higher ability of 1-butene units to be incorporated in the iPP crystals in relation to ethylene counits. From the balance of different properties, possible applications are suggested for the various types of samples. For instance, the excellent optical properties of the analyzed terpolymers make them very attractive for applications such as transparent film or packaging.

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Section: Mechanodynamical Propertiessupporting

confidence: 56%

Influence of structure on the properties of polypropylene copolymers and terpolymers

et al. 2017

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“…The influence of crystallinity in hardness values has been also found in other olefinic based polymers [47][48][49][50]. Effect of other morphological features, as particle agglomeration and dispersion heterogeneity among others, does not show straightforward trends on mechanical response and the obtained information may be sometimes contradictory.…”

Section: A C C E P T E D Accepted Manuscriptmentioning

confidence: 95%

Hybrid materials based on polyethylene and MCM-41 microparticles functionalized with silanes: Catalytic aspects of in situ polymerization, crystalline features and mechanical properties

Cerrada

Bento

Pérez

et al. 2016

Microporous and Mesoporous Materials

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Hybrid materials based on polyethylene and MCM-41 microparticles functionalized with silanes: Catalytic aspects of in situ polymerization, crystalline features and mechanical properties, Microporous and Mesoporous Materials (2016), doi: 10.1016/j.micromeso.2016 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. Mechanical response is observed to be dependent on the content in mesoporous MCM-41 and on the crystalline features of polyethylene. Accordingly, stiffness increases and deformability decreases in the nanocomposites as much as MCM-41 content is enlarged and polyethylene amount within channels is raised. Ultimate mechanical performance improves with MCM-41 incorporation without varying the final processing temperature.

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“…The absence of sPP with annealing time of diffraction at 18.88 confirms that Form I is still disordered. However, as it was also reported for sPP copolymers, [47] it is impossible to assure the non-coexistence of this polymorph with a certain small amount of disordered modification of Form II containing kink-bands, [9,48] appearing this latest contribution at 2y around 17-188. All of these changes within the crystalline regions significantly affect some other parameters such as density, [49] physical properties, [50] and mechanical behavior, as will be discussed below.…”

Section: Resultsmentioning

confidence: 77%

“…Additionally, a small endotherm is observed at 40 8C. This feature might arise from the annealing process related to maintenance of the sample at room temperature, as observed in other olefinic materials, [47,51,52] where the annealing peak appears at temperature around 15-308 higher than the annealing temperature (room temperature in most cases). Alternatively, considering the complicated polymorphic behavior of sPP aforementioned, this endotherm could also be associated with a transformation (or simply melting) from a polymorph different from the major crystalline structure that melts at 94 8C.…”

Section: Resultsmentioning

confidence: 77%

“…[55] Figure 7 clearly depicts this a relaxation in the variation of either storage or loss moduli at temperatures above T g . Previous studies [47] have suggested a relationship with mobility within the crystalline regions combining a continuous melting of the smaller crystallites with the motion of those with a slighty larger size. Since the enthalpy associated with this melting process is significant, the loss of rigidity is also important.…”

Section: Resultsmentioning

confidence: 92%

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Evolution of a Metallocenic sPP with Time: Changes in Crystalline Content and Enthalpic Relaxation

Arranz-Andrés

Benavente

Ribeiro³

et al. 2006

Macro Chemistry & Physics

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Summary: The structural evolution of a metallocenic syndiotactic poly(propylene), sPP, with time has been studied. Due to the low syndiotactic content, the analyzed sPP sample can be easily quenched to a completely amorphous state. This amorphous sample, when left at room temperature is able to crystallize at relatively long times. The degree of crystallinity, as a function of time, has been analyzed by X‐ray diffraction and DSC. The DSC melting curves show the presence of a very important low‐temperature endotherm, besides the main melting peak. Real‐time variable–temperature synchrotron experiments have been performed in order to analyze the origin of the two melting peaks. They seem to arise from the melting of two populations of sPP crystals with different size and/or perfection, rather than from the melting of different polymorphs. The changes in the crystalline regions are accompanied by important variations in the mechanical behavior, as revealed by DMTA and microhardness (MH) measurements. In addition, the sPP crystallization has been analyzed by MH measurements, showing the importance that a relative low crystallinity has on the stiffness of a polymeric material at temperatures above Tg. On the other hand, the kinetics of the enthalpic recovery of quenched amorphous sPP specimens has been analyzed by DSC with temperature modulation. It was found that this enthalpic relaxation can be described by the KWW model, and the relaxation times and shape parameters at three different aging temperatures have been determined, with the corresponding apparent activation energy of this process.Variation with temperature of the most probable long spacing of sPP.imageVariation with temperature of the most probable long spacing of sPP.

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Syndiotactic polypropylene and its copolymers with alpha-olefins. Effect of composition and length of comonomer

Cited by 43 publications

References 58 publications

Influence of structure on the properties of polypropylene copolymers and terpolymers

Influence of structure on the properties of polypropylene copolymers and terpolymers

Hybrid materials based on polyethylene and MCM-41 microparticles functionalized with silanes: Catalytic aspects of in situ polymerization, crystalline features and mechanical properties

Evolution of a Metallocenic sPP with Time: Changes in Crystalline Content and Enthalpic Relaxation

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