Crystallization and Performance of Polyamide Blends Comprising Polyamide 4, Polyamide 6, and Their Copolymers

Yajing Zhang; Mingda Wang; Di Zhang; Yibing Wang; Li Wang; Yongjun Qiu; Liquan Wang; Tao Chen; Liming Zhao

doi:10.3390/polym15163399

Crystallization and Performance of Polyamide Blends Comprising Polyamide 4, Polyamide 6, and Their Copolymers

Polymers (Basel). 2023 Aug 14;15(16):3399. doi: 10.3390/polym15163399.

Authors

Yajing Zhang^{1

2}, Mingda Wang^{1

2}, Di Zhang^{1

2}, Yibing Wang^{1

2}, Li Wang^{1

2}, Yongjun Qiu^{1

2

3}, Liquan Wang⁴, Tao Chen^{2

4}, Liming Zhao^{1

2

3}

Affiliations

¹ State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai 200237, China.
² Key Laboratory of Biobased Material Engineering, China National Light Industry, East China University of Science and Technology, Shanghai 200237, China.
³ Shanghai Collaborative Innovation Center for Biomanufacturing Technology (SCICBT), Shanghai 200237, China.
⁴ Shanghai Key Laboratory of Advanced Polymeric Materials, School of Materials Science and Engineering, East China University of Science and Technology, Shanghai 200237, China.

Abstract

Polyamide 4 (PA4) is a biobased and biodegradable polyamide. The high hydrogen bond density of PA4 bestows it with a high melting point that is close to its thermal decomposition temperature, thereby limiting the melt processing of PA4. In this study, PA4 was blended with polyamide 6 (PA6) and further modified with copolyamide 4/6 (R46). The effects of composition on the crystallization behavior of the blends were studied. The results demonstrated that the binary PA4/PA6 (B46) and ternary PA4/PA6/R46 (B46/R46) blends formed two crystalline phases (PA4- and PA6-rich phases) through crystallization-induced phase separation. With increasing PA6 content, the thermal stability and crystallinity of the B46 blend increased and decreased, respectively, and the contribution of PA6 toward the crystallization of the PA4-rich phase diminished. Molecular dynamics simulations showed the molecular chain orientation of the B46 blends well. The melting points, crystallinities, and grain sizes of the B46/R46 blends were lower than those of the B46 blends. The crystallization of the PA4-rich phase was restrained by the dilution effect of molten-state PA6, and the nucleation and crystallization of the PA6-rich phase were promoted by the presence of crystallized PA4. The B46 blends with 30-40 wt% PA6 had the best mechanical properties.

Keywords: PA4/PA6 blends; copolyamides 4/6; crystallization; polyamide 4.

Abstract

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