Tacticity distribution of isotactic polypropylene prepared with heterogeneous Ziegler–Natta catalyst. 2. Application and analysis of SSA data for polypropylene

Virkkunen, Ville; Laari, Pasi; Pitkänen, Päivi; Sundholm, Franciska

doi:10.1016/j.polymer.2004.05.027

Cited by 46 publications

(40 citation statements)

References 33 publications

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“…Therefore, the emergence of multiple melting behaviors indicates that the chains with similar longest length of crystallizable sequences can also contain a broad intramolecular D ‐LA distribution. Similar results have been obtained for isotactic PP35 and commercial linear low‐density polyethylene (LLDPE) 51, 52. On the other hand, the intermolecular heterogeneity is evident on the different melting ranges of each fraction.…”

Section: Resultssupporting

confidence: 78%

“…If shorter sequences along the chain have crystallized, they will make their own contribution to the final melting curve 21, 33. This method has proved to be a very efficient molecular segregation, as demonstrated for polyethylene,34 ethylene copolymers,32 and PP 25, 35. Unlike in the TREF method, the analysis in SSA method is based on crystallization and melting of sample, and therefore, SSA method gives information only about the crystalline part of the polymer.…”

Section: Introductionmentioning

confidence: 99%

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Stereochemical heterogeneity of biodegradable poly(L‐lactide) homopolymer as revealed by temperature rising elution fractionation and successive self‐nucleation/annealing thermal fractionation

Luo

Huo

Lin

et al. 2012

J Polym Sci B Polym Phys

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Commercial poly(L‐lactide) is typically heterogeneous in chain structure due to the existence of a small amount of D‐lactyl units that are produced by the racemization reactions during the synthesis. In this article, the stereochemical heterogeneity of two commercial poly(L‐lactide) was investigated with temperature rising elution fractionation (TREF) and successive self‐nucleation/annealing (SSA) thermal fractionation. For both samples, three fractions were collected and characterized with rotatory power analysis and DSC. The fractions show distinct optical purity and DSC results, which reflect the structure differences among them directly. After SSA treatment, the observation of multiple endotherms for each physically separated fraction confirms the fractionated sample contains a heterogeneous intermolecular and intramolecular distribution of defects. © 2012 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2012

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Section: Resultssupporting

confidence: 78%

Section: Introductionmentioning

confidence: 99%

Stereochemical heterogeneity of biodegradable poly(L‐lactide) homopolymer as revealed by temperature rising elution fractionation and successive self‐nucleation/annealing thermal fractionation

Luo

Huo

Lin

et al. 2012

J Polym Sci B Polym Phys

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show abstract

“…The chain structure of isotactic polypropylene has frequently also been characterized by thermal fractionation methods. Virkkunen et al [10,11] proposed the SSA method for the fractionation of iPP in order to characterize the tacticity distribution of samples polymerized by different catalyst systems. Garoff et al [12] developed a method for the quantitative determination of average chain regularity.…”

Section: Thermal Fractionation Of Polymersmentioning

confidence: 99%

Chain regularity of isotactic polypropylene determined by different thermal fractionation methods

Horváth

Menyhárd

Doshev

et al. 2014

J Therm Anal Calorim

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The chain regularity of isotactic polypropylene (iPP) homo-and random copolymers was characterized by different thermal fractionation methods in this study. Different stepwise temperature programs were applied in a calorimeter (DSC), in order to develop a method which is significantly faster than SIST and provides reliable information about the chain regularity of iPP. Our studies prove that self-seeding accelerates the crystallization process during annealing in SSA-DSC experiments (successive self-nucleation and annealing). Consequently, the time of isothermal steps can be shortened significantly in the SSA-DSC method. On the other hand we found that step time should not be too short if the goal of the measurement is the determination of average chain regularity. Our results clearly indicate that both the experimental conditions and the evaluation technique influence the obtained results. A standard experimental procedure is proposed for reliably determining the average chain regularity of iPP. The length of the SSA-DSC temperature program developed in this study is much shorter compared to that of the conventional SIST (stepwise isothermal segregation technique) measurements used recently for such experiments. The proposed SSA-DSC program makes the reliable characterization of a large number of samples on an acceptable timescale possible.

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“…The equation has been used by several authors who have applied SSA fractionation [47,52,56,57]. According to Eq.…”

Section: Thermal Fractionationmentioning

confidence: 99%

Effect of small amount of ultra high molecular weight component on the crystallization behaviors of bimodal high density polyethylene

Song

et al. 2008

Polymer

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Tacticity distribution of isotactic polypropylene prepared with heterogeneous Ziegler–Natta catalyst. 2. Application and analysis of SSA data for polypropylene

Cited by 46 publications

References 33 publications

Stereochemical heterogeneity of biodegradable poly(L‐lactide) homopolymer as revealed by temperature rising elution fractionation and successive self‐nucleation/annealing thermal fractionation

Stereochemical heterogeneity of biodegradable poly(L‐lactide) homopolymer as revealed by temperature rising elution fractionation and successive self‐nucleation/annealing thermal fractionation

Chain regularity of isotactic polypropylene determined by different thermal fractionation methods

Effect of small amount of ultra high molecular weight component on the crystallization behaviors of bimodal high density polyethylene

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