Regularity modes in Raman spectra of polyolefins: Part I. Propylene/olefin copolymers

Prokhorov, K. A.; Nikolaeva, G. Yu.; Sagitova, E.A.; Пашинин, П. П.; Недорезова, П. М.; Klyamkina, A. N.

doi:10.1016/j.vibspec.2016.03.021

Cited by 14 publications

(10 citation statements)

References 32 publications

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“…An additional line was added only in the case when we clearly observed the Raman band that could not be described by the selected number of lines. Shape of each spectral line was described by a weighted sum of Lorentz and Gauss functions [26]:…”

Section: Analysis Of the Experimental Raman Spectramentioning

confidence: 99%

Raman spectra of n-pentane, n-hexane, and n-octadecane: experimental and density functional theory (DFT) study

et al. 2019

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We carried out a density functional theory (DFT) modeling of the stable conformations of n-pentane (C 5 H 12 ), n-hexane (C 6 H 14 ), and n-octadecane (C 18 H 38 ) as well as their Raman spectra. The functional/basis combination OLYP/4z provides the best agreement between the calculated and experimental characteristics (the angles and bond lengths, Raman shifts, depolarization ratios, and relative Raman intensities) among the twelve approximations considered here.Using the DFT calculations, we obtained the Raman spectra of individual conformations of n-pentane and n-hexane molecules. We modeled the n-pentane and n-hexane Raman spectra by summing the spectra of individual conformations, taking into account the conformation energies and the Boltzmann distribution. Such spectra turned out to describe the experimental spectra quite well. This fact indirectly confirms that the conformational composition of n-pentane and n-hexane molecules is well described by the Boltzmann distribution.The calculated contents of n-pentane and n-hexane molecules in the all-trans-conformation were in a good agreement with the experimental values calculated by using the integral intensities of the Raman lines. We specified the experimental Raman bands belonging to the symmetric C-C stretching mode of the n-alkane molecules in accordance to our DFT calculations. In the cases of both n-pentane and n-hexane, mostly the vibrations of molecules in the all-trans-conformation contribute to this band intensity, while the contributions of molecule vibrations in all other conformations are negligible. We also defined the assignment of the Raman bands in the range 700-900 cm −1 to the vibrations of molecules in different conformations.

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Section: Analysis Of the Experimental Raman Spectramentioning

confidence: 99%

Raman spectra of n-pentane, n-hexane, and n-octadecane: experimental and density functional theory (DFT) study

et al. 2019

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“…Among them, black numbers represent the characteristic peaks of PE, while red numbers represent that of PP. During the analysis of the Raman spectra of PP, the sharp peak at 1463 cm –1 is often selected to normalize the spectra . Considering the composition of the separator, the spectra of Celgard 2325 were normalized based on the characteristic peaks of PP.…”

Section: Results and Discussionmentioning

confidence: 99%

“…During the analysis of the Raman spectra of PP, the sharp peak at 1463 cm −1 is often selected to normalize the spectra. 37 Considering the composition of the separator, the spectra of Celgard 2325 were normalized based on the characteristic peaks of PP. By comparing the peaks of the separators under different conditions, it can be seen that the characteristic peaks of PP and PE in both separators did not show any change in the position or disappearance, which indicated that DMC immersion and low temperature cannot cause fundamental changes in the molecular structure of PP and PE.…”

Section: Characterization Analysismentioning

confidence: 99%

Coupled Effect of Low Temperature and Electrolyte Immersion on the Tensile Properties of Separators in Lithium-Ion Batteries

Zhao,

Guo,

et al. 2023

ACS Appl. Mater. Interfaces

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The performance degradation at low temperatures and frequent safety accidents have aggravated security risks and inhibited the long-term service of lithium-ion batteries (LIBs). As a key component of LIBs, the separator has a great impact on the performance and safety of the battery. In this study, tensile tests of two commercial polyolefin separators (Celgard 2325 and Celgard PE) are performed under low-temperature and immersion conditions. Four representative temperature points and dimethyl carbonate [(DMC), the common solvent in electrolytes] are selected to investigate the coupling effect on the mechanical properties of the separators. The results show that both the separators have anisotropy, but the performance of Celgard 2325 varies more significantly than that of Celgard PE along different directions. Additionally, it is found that with a decrease in the temperature, the tensile strength of the two separators increases, while the elongation decreases. Electrolyte immersion induces a softening tendency in Celgard 2325. Due to the special effect of the residual electrolyte on polyethylene fibers, Celgard PE shows the opposite result. Furthermore, the effect of low temperature is revealed by the analysis of the crystallinity and molecular structure, which can be obtained by X-ray diffraction and Raman spectroscopy, respectively. In addition, the contact angle is measured to describe the wettability variation related to low temperature. The present work provides a theoretical basis and experimental data for the application and development of separators.

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“…Generally, macromolecules in the crystallites (orthorhombic crystalline phase) are in the all-trans conformation. The noncrystalline regions (interphase and liquid-like amorphous phase) contain both macromolecules in the trans conformation and gauche conformers 36 . Hence, cross-linking appears to occur more frequently in the non-crystalline region, in the case of OBC and SEBS, which consists of polyethylene and alpha-olefin monomers (mainly 1-octene and 1-butylene) cross-linking with each other (as seen in Supplementary Fig.…”

Section: Characterizations Of F-fspcmsmentioning

confidence: 99%

Ultraflexible, cost-effective and scalable polymer-based phase change composites for wearable thermal management

Jing

Zhao

Cao

et al. 2023

Preprint

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Phase change materials (PCMs) offer great potential for realizing zero-energy thermal management due to superior thermal storage and stable phase-change temperature. However, the liquid leakage and solid rigidity of PCMs are two long-standing challenges for PCM-based wearable thermal management applications. Herein, a facile and cost-effective strategy is reported, which utilizes the peroxide radical-initiated mechanism to develop ultraflexible polymer-based phase change composites with a dual 3D crosslinked network of olefin block copolymers (OBC) and styrene-ethylene-butylene-styrene (SEBS) inside PCMs. The synergistic effect of OBC-SEBS dual network on brittleness and elasticity enhancement enables the resultant paraffin wax (PW) composites of PW@OBC-SEBS to present outstanding flexibility (strain at break of 20-560%), high latent heat enthalpy (~ 176 J/g), superior thermal stability, and leakage-proof properties. Notably, the proposed peroxide-assisted sequential blending approach overcomes the limitations of traditional heavy processing equipment, achieving low-cost and efficient large-scale production. Furthermore, the applicability of a portable and flexible PW@OBC-SEBS module for wearable thermal management is demonstrated. The energy module can maintain a thermal comfort temperature range of 39-41°C, highlighting the realization of stable temperature control for personal thermotherapy. Our work provides a promising route to fabricate scalable and flexible polymer-based phase change composite for wearable thermal management.

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Regularity modes in Raman spectra of polyolefins: Part I. Propylene/olefin copolymers

Cited by 14 publications

References 32 publications

Raman spectra of n-pentane, n-hexane, and n-octadecane: experimental and density functional theory (DFT) study

Raman spectra of n-pentane, n-hexane, and n-octadecane: experimental and density functional theory (DFT) study

Coupled Effect of Low Temperature and Electrolyte Immersion on the Tensile Properties of Separators in Lithium-Ion Batteries

Ultraflexible, cost-effective and scalable polymer-based phase change composites for wearable thermal management

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