Carbon-13 NMR analysis of ethylene-propylene rubbers

Cheng, H. N.

doi:10.1021/ma00140a012

Cited by 124 publications

(129 citation statements)

References 7 publications

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“…The peak assignments for the 13 C NMR spectra are given in Table 3. These assignments were made according to literature [41][42][43][44][45]. Assignments for the methylene carbons in Table 3 are identified by the letter S and a pair of Greek letters that indicate its distance in both directions from the nearest tertiary carbons.…”

Section: Resultsmentioning

confidence: 99%

Molecular composition and properties of impact propylene copolymers

Aj¹,

Nc²

2012

Express Polym. Lett.

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Abstract. Impact polypropylene copolymers (IPCs) are important commercial materials, but their morphology and molecular architecture are not yet fully understood. In this study the focus was on selectively removing specific fractions from the original IPC, recombining the remaining fractions, and studying the properties and morphology of these recombined polymers. It was found that some properties of the samples changed remarkably, depending on the fraction of material that was removed before recombination. In a similar fashion, morphological changes could be observed. For example, the degree of phase separation and the crystalline morphology of the recombined materials varied noticeably. It was further established that specific copolymer fractions present in the original polymer affect not only the morphology of the final polymer, but also the hardness and impact resistance.

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Section: Resultsmentioning

confidence: 99%

Molecular composition and properties of impact propylene copolymers

Aj¹,

Nc²

2012

Express Polym. Lett.

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“…The nomenclature and assignments of the different carbon atoms along the molecular chain adopted for the absorption bands in the NMR spectra are those of Carman & Wilkes, Randall and Cheng. [25][26][27][28] FT-IR FT-IR spectra are measured with a Nicolet Fourier transform infrared spectrophotometer (MAGNA-IR 760). The samples are first compression-molded into films in 10-100 µm thick.…”

Section: Nmr Analysismentioning

confidence: 99%

“…Here each spectrum relates to the fraction polymer with certain ethylene content, and they are positioned from F2-F12 according to ethylene content. The peaks of 13 C NMR spectra are assigned according to the methods of Carman & Wilkes, 25 Randall 26,27 and Cheng, 28 and Table IV lists the assignment of the important peaks, chemical shifts and intensity of each carbon atom in the 13 C NMR spectra of the fraction polymers. In 13 C NMR spectrum, S α γ (37.9 ppm), S α δ (37.5 ppm), and S γ δ (30.4 ppm) are thought to relate to the following sequence structure, (1) only an ethylene monomer, PEP; (2) more than two-linked ethylene monomers, P(E)nP, n 2; (3) more than three ethylene monomers, P(E)mP, m 3, respectively.…”

Section: Fractionation and Characterization Trefmentioning

confidence: 99%

“…Figure 4 indicates fine assignment of some peaks of the fraction polymers, including S α γ , S α δ . According to Randall and Cheng,[26][27][28] the S α γ reflects sequence structure of the PEP, namely, only an ethylene monomer between two propylene monomers, and the experiment suggests that this kind of sequence structure occupies the majority of the macromolecular chains; S α δ reflects sequence structure of the P(E)nP, n 2, namely, more than two-linked ethylene monomers between two propylene monomers. Figure 4 shows S α γ consists of two main peaks: 1a and 1b, which can be assigned to molecular sequence structure of the PPPEP(m 1 r 2 ) and PPPEP (m 1 m 2 ), respectively.…”

Section: Nmrmentioning

confidence: 99%

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Fractionation and Characterization for a Propylene–Ethylene Random Copolymer

Zhang

Zhu

2002

Polym J

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ABSTRACT:A random copolymer of propylene with 3.5 mol% ethylene comonomer is firstly fractionated by temperature rising elution fractionation (TREF). Techniques including 13 C nuclear magnetic resonance (NMR) spectroscopy, Fourier transform infrared spectroscopy (FT-IR), gel-permeation chromatography (GPC), crystallization analysis fractionation (Crystaf) and differential scanning calorimetry (DSC) are used to characterize the obtained fraction polymers. The results show that each fraction polymer is composed mainly of isotactic propylene sequence plus a small amount of ethylene comonomer and has uniform molecular weight and ethylene content. The PPP, PPE, and PEP are main part of triad sequence unit. As the elution temperature increasing, ethylene content of the fraction polymers decreases, number average molecular weight increases, and meanwhile number average sequence length of propylene, n P , increases, while that of ethylene, n E , decreases, close to 1. The results show that ethylene content affects linearly the melting temperature (T m ) in a range of ethylene content being as low as less than 10.23 mol%; there is a linear relationship between the reciprocal melting temperature (1000/T m , K −1 ) and reciprocal number average molecular weight (M Polypropylene is a common semi-crystalline synthetic polymer, and its macromolecular chain structure is an important factor to affect such properties of propylene polymers as crystallization behavior, morphologies, melting temperature, degree of crystallization, toughness, and rheological and optical properties. By the way of introducing some comonomers (e.g., ethylene) into its macromolecular chain, the performance of propylene polymers can be improved purposefully and effectively. Because propylene tacticity and ethylene comonomer complicate the macromolecular chain structure, and can farther lead to complex crystallization behaviors and morphologies, it is very important to firstly characterize the macromolecular chain structure well. In order to investigate thoroughly the relationship between performance and macromolecular chain structure, it is necessary to make samples uniform. Temperature rising elution fractionation (TREF) [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15] has been shown to be a powerful technique to make crystal polyolefins uniform on the basis of their crystallizability and molecular weight. Through TREF experiments, a set of fraction polymers with uniform molecular weight and content of ethylene comonomer can be obtained; hereafter crystallization analysis fractionation (Crystaf) will be used to check the effect of fractionation by analyzing such parameters as σ and R, 16 which can define the broadness of the crystallization temperature distribution of the fraction polymers. [16][17][18][19][20][21][22] Up to now most samples of propylene copolymers on investigation are the impact propylene-ethylene copolymers, a very complex blend. Even though after they have been fractionated by TREF, 3-11 each fraction polymer also consists of PE, ...

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“…13 C NMR spectra were measured at lOOoC using JEOL FX-900 and FX-200 spectrometers operating at 22.5 and 50 MHz, respectively. Only the CH peaks of the sample were obtained from the INEPT ( Figure 1 shows 13 C NMR spectra of E-P copolymer 5 (22.5 MHz), [1,[2][3][4][5][6][7][8][9][10][11][12][13] C] E-P copolymer 1 (22.5 and 50 MHz) prepared with Polymer J., Vol. 19, No.…”

Section: N M R Measurementsmentioning

confidence: 99%

C-13 NMR Analysis of Isolated Ethylene Units in Ethylene-Propylene Copolymer

Asakura

Nishiyama

Doi

et al. 1987

Polym J

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ABSTRACT:13 C NMR spectra of isolated ethylene units in [1,2-13 C] enriched ethylenepropylene copolymer prepared with syndiotactic-specific catalyst were observed. The use of [1,2-13C] enriched ethylene units made it possible to determine the fractions of three kinds of the structures, mEm, mEr, rEr where m means meso propylene dyad, E isolated ethylene unit and r racemo propylene dyad in the copolymer. This is based on change in the NMR spectral pattern depending on the relative magnitude between 13 C-13 C coupling constant and chemical shift difference.

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Carbon-13 NMR analysis of ethylene-propylene rubbers

Cited by 124 publications

References 7 publications

Molecular composition and properties of impact propylene copolymers

Molecular composition and properties of impact propylene copolymers

Fractionation and Characterization for a Propylene–Ethylene Random Copolymer

C-13 NMR Analysis of Isolated Ethylene Units in Ethylene-Propylene Copolymer

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