Bio-based poly(hexamethylene 2, 5-furandicarboxylate-co-2, 6-naphthalate) copolyesters: a study of thermal, mechanical, and gas-barrier properties. Issue 39 (28th September 2022)

• Record Type: Journal Article
• Authors: Mao, Hsu-I; Yang, Zhi-Yu; Chen, Chin-Wen; Rwei, Syang-Peng
• Is Part Of: Soft matter. Volume 18:Issue 39(2022)
• Page Start: 7631
• Page End: 7641
• Publication Date: 2022-09-28
• Subjects: Soft condensed matter -- Periodicals; 530.413
• DOI: 10.1039/d2sm00689h
• Languages: English
• ISSNs: 1744-683X

Abstract

Abstract : The gas barrier properties of PHFN copolyesters were improved with the introduction of 2, 6-naphthalene dicarboxylic acid, and the chain flexibility was increased to enhance processability when 1, 6-hexanediol was introduced. Abstract : A series of poly(hexamethylene 2, 5-furandicarboxylate- co -2, 6-naphthalate) copolyesters were synthesized using various amounts of poly(hexylene 2, 5-furandicarboxylate) (PHF) and poly(hexylene 2, 6-naphthalate) (PHN) via melt polymerization. The effects of introducing 2, 6-naphthalene dicarboxylic acid (NDCA) on the thermal, mechanical, and gas-barrier properties were investigated. When the NDCA content was less than 30 mol%, the temperatures of crystallization ( T c ) and melting ( T m ) decreased as the amount of NDCA was increased owing to disturbance of the polymer-chain regularity. When the NDCA content was above 50 mol%, the T c and T m of the materials increased as the NDCA content was increased, showing that the dominant crystallization behavior varied from 2, 5-furandicarboxylic acid to NDCA. Hence, the glass transition temperature ( T g ) increased as the NDCA content was increased, which was attributed to the incorporation of NDCA with a more rigid naphthalate structure compared with the furan ring. The gas-barrier properties of the samples were observed to improve with the introduction of NDCA; this tendency could be explained by the β-relaxation behavior and free volume values of the samples in the amorphous state. The activation energy ( E a ) of β-relaxation increased with the NDCA content, indicating that higher amounts of energy were needed to trigger the onset of long-range molecular motions. Free-volume calculations of the polymer structure showed that the introduction of NDCA hindered the space for gas penetration. For these reasons, the gas-barrier properties were improved and evaluated.