Influences of tacticity and molecular weight on crystallization kinetic and crystal morphology under isothermal crystallization: Evidence of tapering in lamellar width

Rungswang, Wonchalerm; Jarumaneeroj, Chatchai; Patthamasang, Supanan; Phiriyawirut, Phairat; Jirasukho, Prapasinee; Soontaranon, Siriwat; Rugmai, Supagorn; Hsiao, Benjamin S.

doi:10.1016/j.polymer.2019.03.052

Cited by 15 publications

(14 citation statements)

References 45 publications

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“…The addition of BAEA/AA segments restricted the ordered arrangement of hydrogen-bonded of the α form, thus promoting the formation of γ crystal in the PA6 copolymer, and the better packing of the methylene chains can make γ form more stable [ 23 , 26 , 27 ]. Furthermore, the crystallite size ( L HKL ) was confirmed using the Scherrer equation (Equation (1)) to more clearly explain the relationship between the crystallization behavior and the crystal size of the copolyamides [ 28 , 29 , 30 , 31 , 32 ].

where K is the shape factor, which adopts a value of 0.89 of all peaks, and β is the full-width at half maximum (FWHM) of the diffraction peak in radians (i.e., FWHM × π/180).…”

Section: Resultsmentioning

confidence: 99%

Effect of Bis (2-Aminoethyl) Adipamide/Adipic Acid Segment on Polyamide 6: Crystallization Kinetics Study

et al. 2020

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The crystallization behavior of novel polyamide 6 (PA6) copolyamides with different amounts of bis (2-aminoethyl) adipamide/adipic acid (BAEA/AA) segment was investigated. The wide-angle X-ray diffraction (WAXD) results showed that as the amount of BAEA/AA segment increased to 10 mole%, the crystalline forms of all PA6 copolyamide were transferred from the stable α-form to the unstable γ-form because of the complex polymer structure. According to studies of crystallization kinetics, the Avrami exponent (n) values for all copolyamide samples ranged from 1.43 to 3.67 under isothermal conditions, implying that the crystallization is involved in the two- to three-dimensional growth at a high temperature of isothermal condition. The copolyamides provided a slower crystallization rate and higher crystallization activation energy (ΔEa) than neat PA6. Polyamide containing 10 mole% of BEAE/AA content exhibited a unique crystallization behavior in the coexistence of the α and γ forms. These results deepen our understanding of the relationship between BAEA/AA content, crystal structure, and its crystallization behavior in low-melting PA6, and they make these types of copolyamides useful for their practical application.

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where K is the shape factor, which adopts a value of 0.89 of all peaks, and β is the full-width at half maximum (FWHM) of the diffraction peak in radians (i.e., FWHM × π/180).…”

Section: Resultsmentioning

confidence: 99%

Effect of Bis (2-Aminoethyl) Adipamide/Adipic Acid Segment on Polyamide 6: Crystallization Kinetics Study

et al. 2020

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“…The influence of the molecular order on the glass-transition temperature was also observed for polypropylene (PP) . Literature data also show that crystallization kinetics is influenced by the tacticity of the polymers. ,, For polypropylene, it has been found that the crystallization rate and melting temperature depend on the spatial configuration . On the other hand, it has been shown that the degree of isotacticity of PP has a large impact on the nucleation rate, while not as that significant on the crystallization rate and the crystal morphology .…”

Section: Introductionmentioning

confidence: 84%

“…Polymers have been the subject of interest to scientists around the world − mainly because of their potential application in medicine, pharmacy, or modern technologies. − As known, the polymeric materials’ physicochemical properties can modify under the influence of various factors. Literature data show that the chain length (molecular weight) affects the molecular dynamics and the fragility of polymers. ,− It has also been observed that molecular weight might affect the crystallization process. − The chain length impacts both the crystal morphology and the crystallization rate. , The properties of the polymer materials can also be modified by compression. The increased pressure causes changes in the glass-transition dynamics.…”

Section: Introductionmentioning

confidence: 99%

“…Literature data also show that crystallization kinetics is influenced by the tacticity of the polymers. ,, For polypropylene, it has been found that the crystallization rate and melting temperature depend on the spatial configuration . On the other hand, it has been shown that the degree of isotacticity of PP has a large impact on the nucleation rate, while not as that significant on the crystallization rate and the crystal morphology . It should also be mentioned that syndiotactic polystyrene (PS) crystallizes faster than isotactic PS .…”

Section: Introductionmentioning

confidence: 99%

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Influence of Tacticity on the Glass-Transition Dynamics of Poly(methyl methacrylate) (PMMA) under Elevated Pressure and Geometrical Nanoconfinement

Chat

Unni

et al. 2021

Macromolecules

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The physicochemical properties of polymers can be modified by spatial configuration. Here, dielectric spectroscopy (DS) was employed to investigate the effect of the tacticity on the glass-transition dynamics of confined polymer films. We have also carried out dielectric relaxation studies at ambient and elevated pressure conditions. High-pressure measurements provide information on the sensitivity of the glass-transition dynamics to density changes, which can be helpful to better understand the confinement effect. For our study, we have chosen a glass-forming polymer, poly(methyl methacrylate) (PMMA), with two different tacticities (isotactic and syndiotactic) and an approximately equal molecular weight. We have shown that the segmental relaxation for the bulk syndiotactic PMMA is observed at a higher temperature range compared to the bulk isotactic PMMA. The experimental data analysis has also revealed that the molecular order influences the behavior of the polymer under increased pressure. The glass-transition dynamics of isotactic PMMA is more sensitive to the pressure/density changes than syndiotactic PMMA. Finally, we have also demonstrated that tacticity has a significant impact on the segmental dynamics of the confined polymer films. Syndiotactic PMMA has a stronger interaction with the substrate than isotactic PMMA, which is indicated by the higher amount of irreversibly adsorbed polymer chains. For this reason, the segmental dynamics of s-PMMA thin films follows the bulk behavior. In contrast, for i-PMMA, the confinement effects are pronounced, and the glass-transition dynamics accelerate with the reduction of the thickness of thin films.

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“…The details of the lamellar structure were analyzed using the 1D‐electron density correlation function ( K (z) ) (Equation ) of the 2D SAXS results

K_{(z)} = 〈 [η_{(z')} - 〈 η 〉] [η_{(z+z')} - 〈 η 〉] 〉 = 2 \int_{0}^{\infty} {false(π false)}^{- 1} q^{2} I_{(q)} \cos false(q z false) d q

where 〈〉 is denoted as the ensemble average, η ( z ) and 〈η〉 are the electron densities along the lamella normal and the averaged electron density, respectively.…”

Section: Crystal Structure Analysismentioning

confidence: 99%

Structure–Property–Process Relationship for Blown Films of Bimodal HDPE and Its LLDPE Blend

Rungswang

Wongpanit

Jarumaneeroj

et al. 2019

Macro Materials & Eng

Self Cite

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Blown films of bimodal‐high‐density polyethylene (HDPE) (BPE) and its blend containing 40 wt% of linear low‐density polyethylene (LLDPE) are prepared in various neck‐heights (NHs). The crystal structures of both films are investigated in detail using small‐angle X‐ray scattering and wide‐angle x‐ray diffraction techniques. The results show that the blending of LLDPE notably modifies the crystal structure of BPE, including crystal density (ρc), crystallite size of the 110 plane (〈L110〉), thickness of the lamellar crystal (Lc), and grain widths of the lamellae. The relationships between NH, crystal structure, and the resistance of dart‐drop impact (DDI) are investigated for both BPE and BPE/LLDPE films. The results indicate that the reorientation of lamellae might be a primary factor responsible for the DDI property. However, large values of ρc, Lc, and 〈L110〉 are required for the film to achieve high DDI.

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Influences of tacticity and molecular weight on crystallization kinetic and crystal morphology under isothermal crystallization: Evidence of tapering in lamellar width

Cited by 15 publications

References 45 publications

Effect of Bis (2-Aminoethyl) Adipamide/Adipic Acid Segment on Polyamide 6: Crystallization Kinetics Study

Effect of Bis (2-Aminoethyl) Adipamide/Adipic Acid Segment on Polyamide 6: Crystallization Kinetics Study

Influence of Tacticity on the Glass-Transition Dynamics of Poly(methyl methacrylate) (PMMA) under Elevated Pressure and Geometrical Nanoconfinement

Structure–Property–Process Relationship for Blown Films of Bimodal HDPE and Its LLDPE Blend

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