Synthesis and characterizations of random copolyamide PA(56-co-66): Excellent toughness and transparency

• Published in: Polymer (Guilford) Vol. 307; p. 127271
• Main Authors: Lin, Na, Wang, Zhe, Kang, Hongliang, Hao, Xinmin, Liu, Ruigang
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 24.07.2024
• Subjects: Copolyamide; Crystallization; Mechanical properties; Random copolymers; Transparency; Mechanical properties; Transparency; Copolyamide; Random copolymers; Crystallization
• ISSN: 0032-3861; 1873-2291
• DOI: 10.1016/j.polymer.2024.127271

Random copolyamides PA(56-co-66) (coPA-n) with various comonomer compositions were synthesized by a one-pot polycondensation reaction of pentamethyleneammonium adipate (PMA) salt and hexamethyleneammonium adipate (HMA) salt in aqueous solution. All copolymers have high Mn (≥15000 g/mol). The molecular segment composition can be regulated by controlling the feed ratio of PMA salt and HMA salt. Tc and Tm of copolymers obtained by nonisothermal crystallization depend on the composition, showing a clear pseudo-eutectic behavior. Copolyamide coPA-50 exhibits a eutectic phenomenon with the melting point decreasing to a minimum of 218.9 °C. WAXD and SAXS results confirm that the crystalline structure of the copolyamides follows that of the rich component, exhibiting a typical isodimorphic characteristic. Mechanical properties of the copolyamides indicate that the elongation at break could be improved significantly with slight sacrifice of strength, which provides a promising approach for fabricating polyamide materials with desired properties. The tensile strength, tensile modulus, and elongation at break of coPA-50 was 65.2 MPa, 1.0 GPa, and 758.1 %, respectively. These copolymers can be melt-spun into fibers with excellent mechanical properties. Especially, the transmittance of coPA-60 reaches a high value of 88.01 % due to its low crystallinity and small crystal size. [Display omitted] •Random copolyamides PA(56-co-66) were synthesized.•PA(56-co-66) shows a clear pseudo-eutectic behavior.•The crystalline structure of the copolyamides follows that of the rich component.•The elongation at break of PA(56-co-66) is improved significantly without sacrifice of strength.•High transparent was achieved at the PA56 content of 60 mol.%.