A rheological method to characterize the molecular weight changes of polyamide 1012 during solid state polymerization

Liu, Xinran; Wang, Yu; Pang, Yongyan; Dong, Xia; Wang, Dujin

doi:10.1002/app.53131

Cited by 3 publications

(1 citation statement)

References 40 publications

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“…Long-chain PAs (LCPAs) refer to an emerging family of PAs in which the number of methylene groups between adjacent amide groups in the main chain is no less than 10. , Some advantages of LCPAs over conventional PAs (such as PA6 and PA66) attributed to the relatively long methylene segments include good dimensional stability, excellent low-temperature performance, and high processability. − Thus, LCPAs have been widely used in automotive manufacturing and electronic applications. PA1012 is a kind of typical AABB-type even–even LCPA, and it has been developed in recent decades.…”

Section: Introductionmentioning

confidence: 99%

Structural and Morphological Evolution upon Heating of Quenched Polyamide 1012

Yang,

Dong,

Yuan

et al. 2024

Macromolecules

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In this study, the crystal form transition and semicrystalline morphology evolution of quenched polyamide 1012 (PA1012) during heating were investigated. Quenched PA1012 displayed a pseudohexagonal γ′ form at room temperature, in which the methylene segments adopted a trans conformation, the methylene group directly attached to the amide group was twisted, and the hydrogen bonding pointed in all directions. During heating, the γ′ form gradually transformed into the γ form as the trans methylene sequences that are away from the amide group further twisted, and the dihedral angle between the amide and methylene plane exhibited a narrow distribution. The transition onset temperature was near the glass transition temperature of quenched PA1012. The semicrystalline morphology of quenched PA1012 was characterized as a loose network consisting of a disordered arrangement of thin lamellae with poorly defined boundaries. As the annealing temperature increased, the lamellae became more perfect and thicker, while the morphological type remained the same.

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Section: Introductionmentioning

confidence: 99%

Structural and Morphological Evolution upon Heating of Quenched Polyamide 1012

Yang,

Dong,

Yuan

et al. 2024

Macromolecules

Self Cite

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Effect of post-polymerization on the crystallization and melting behavior of poly(butylene terephthalate)

Chen,

Li,

Wang

et al. 2024

Polymer

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Multistage Crystal Transformation and Mechanism of PA1012 γ′ Phase by Uniaxial Stretch

Yang,

Li,

Yuan

et al. 2024

Macromolecules

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The pseudohexagonal γ′ phase of polyamide 1012 can be obtained by melt-quenching and gradually transformed into the γ form during heating, in which the trans methylene segments away from the amide group are further twisted. What happens during uniaxial stretching? In this work, the multistage structural evolution of the γ′ phase during uniaxial stretching has been studied by using in situ wide-angle X-ray scattering (WAXS) and Fourier transform infrared spectroscopy (FTIR). The multistage conformational evolution of the γ′ phase during stretching was studied by quantitative analysis of the infrared progression bands and was found to be closely correlated with the mechanical response during tensile deformation. In the yield stage, the twisted methylene segments in the initial γ′ phase undergo conformational ordering under stress activation, and the γ′ phase spontaneously transforms into a defective α phase. Furthermore, in the plateau stage, strain induces significant conformational disorder and the transient α phase transforms into the most conformationally disordered γ phase. Finally, at the strain hardening stage, the reversible crystal form transition from the γ phase to the regular γ′ phase is induced by stress, accompanied by an obvious conformational ordering process. The stress- and strain-induced conformational torsional motions are found to be completely opposite, with the former inducing conformational order and the latter inducing conformational disorder.

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A rheological method to characterize the molecular weight changes of polyamide 1012 during solid state polymerization

Cited by 3 publications

References 40 publications

Structural and Morphological Evolution upon Heating of Quenched Polyamide 1012

Structural and Morphological Evolution upon Heating of Quenched Polyamide 1012

Effect of post-polymerization on the crystallization and melting behavior of poly(butylene terephthalate)

Multistage Crystal Transformation and Mechanism of PA1012 γ′ Phase by Uniaxial Stretch

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