Study on crystal structure and phase transitions of polyamide 12 via wide-angle X-ray diffraction with variable temperat
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ORIGINAL RESEARCH
Study on crystal structure and phase transitions of polyamide 12 via wide-angle X-ray diffraction with variable temperature Ruixin Dai 1 & Miaoming Huang 1 & Lili Ma 1 & Wentao Liu 1 Zhenya Zhang 3 & Aihua Sun 4
&
Suqin He 1,2 & Hao Liu 1 & Chengshen Zhu 1 & Yujie Wang 1 &
Received: 8 October 2020 / Revised: 31 October 2020 / Accepted: 14 November 2020 # Springer Nature Switzerland AG 2020
Abstract Polyamide 12 (PA12) is a long carbon chain polyamide with plenty of excellent properties. In this work, PA12 samples were prepared in three ways: solution casting (α-crystal form at 30 °C and α + γ-crystal form at 40, 50, 60, and 80 °C, respectively), melt slow cooling (γ-crystal form), and melt quenching (γ-crystal form), which undergoes isothermal crystallization in the range from room temperature to the temperature close to the melting point. The crystallization behaviors, including the crystal transition, d-spacing, and crystallinity, upon heating and cooling were measured by the wide-angle X-ray diffraction (WAXD) from 30 to 235 °C. The results show that the α-crystal form gradually transforms into γ-crystal form during heating, indicating the occurrence of Brill transition. The γ-crystal form is stable below Tm, whereas the γ-crystal form can transform into γ-crystal form above 110 °C. Only γ-crystal form appears when cooling, and most of the crystallization has been completed before cooling to 170 °C. The investigation provides more theoretical supports of phase transitions in PA12 for deep understanding of the modification, optimization, and application. Keywords Polyamide 12 . Variable temperature . Brill transition . Crystal structure . Wide-angle X-ray diffraction
1 Introduction Polyamide (PA), normally known as nylon, is a kind of polymers that contain reduplicative polar amide groups (-NHCO-) in the main chain. Nowadays, PA has a wide application * Wentao Liu [email protected] * Suqin He [email protected] 1
School of Materials Science and Engineering, Zhengzhou University, No.100 Kexue Avenue, Zhengzhou 450001, Henan, People’s Republic of China
2
Henan Key Laboratory of Advanced Nylon Materials and Application, Zhengzhou University, No.100 Kexue Avenue, Zhengzhou 450001, Henan, People’s Republic of China
3
Isotope Institute Co., Ltd., Henan Academy of Sciences, Zhengzhou 450015, Henan, People’s Republic of China
4
Key Laboratory of Additive Manufacturing Material of Zhejiang Province, Department of Functional Materials and Nano-Devices, Ningbo Institute of Materials Technology & Engineering, Chinese Academy of Sciences, No.1219 Zhongguan West Road, Ningbo 315201, Zhejiang, People’s Republic of China
range, such as automobile parts [1], military equipment [2], aerospace materials [3], insulation materials [4], textile materials [5], bonding agent [6], and coating [7]. PA products can be used to achieve the effect of reducing self-weight and ameliorating properties instead of ultrahard inorganic materials and metal materials, owing to the good properties of dimensional stability [8
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