Composition, thermal properties, and biodegradability of a new biodegradable aliphatic/aromatic copolyester

Abstract

A series of new aliphatic/aromatic copolyesters [poly(hexylene terephthalate-co-hexylene adipate) (PHTA)] were synthesized on the bases of 1,6-hexanediol, adipic acid, and dimethyl terephthalate and characterized by gel permeation chromatography, 1 H-NMR, wide-angle X-ray diffraction (WAXD), differential scanning calorimetry (DSC), and compost testing.1 H-NMR results show that the compositions of the copolyesters were in accordance with the feed molar ratios. The WAXD patterns indicated that the crystal structures of the PHTA copolyesters were determined by the dominant crystal units, and the copolyesters became less crystallizable, even amorphous, with increasing comonomer content. The DSC curves showed that the glass-transition temperatures (T g 0 s) of the PHTA copolyesters decreased linearly, and both the melting temperature (T m ) and heat of fusion decreased first and then increased with increasing hexylene adipate unit content. Under compost conditions, PHTA copolyesters with less than 60 mol % aromatic units were biodegradable. Particularly, compared with the copolyester poly(butylene terephthalate-co-butylene adipate), the PHTA copolyester with the same aliphatic/aromatic composition possessed a lower T g and T m and better biodegradability. Additionally, the biodegradability of the copolyesters could be predicted by the number-average sequence length of aromatic units, T g , and the temperature difference between T m and the temperature at which biodegradation took place.

Isothermal crystallization kinetics and melting behaviors of poly(butylene terephthalate) and poly(butylene terephthalate‐co‐fumarate) copolymer

“…However, in the 1 H‐NMR spectrum of PBTF10, there are three new peaks appearing at 7.04 (d), 4.15 (e), and 1.57 ppm (f), attributable to the protons of CHCH, OCH 2 , and next CH 2 in butylene fumarate segments. The copolymer composition of butylene terephthalate (BT) and butylene fumarate (BF) segments is calculated from the integrals of the peaks at 8.08 (C 6 H 4 of BT segments) and 7.04 ppm (CHCH of BF segments) [26]. The PBTF5 and PBTF20 are characterized in the same manner.…”

A novel nanosilica‐supported ultraviolet absorber for the preparation of robust biodegradable plastic film with high ultraviolet aging resistance

“…Poly(butylene adipate‐co‐terephthalate) (PBAT) is one of the aliphatic–aromatic polyesters with the degradation ability of aliphatic polyester (PBA) and the mechanical strength of aromatic polyester (PBT) . In addition, the comparable softness, ductility, and processability to LDPE make PBAT one of the promising candidates for agricultural films . However, PBAT is susceptible to ultraviolet (UV) aging , which is not acceptable for agricultural application .…”

Environmentally Friendly Copolyesters Containing 1,4‐Cyclohexane Dicarboxylate Units, 1‐Relationships Between Chemical Structure and Thermal Properties

“…[8] A number of other aliphatic-aromatic copolyesters are proposed in literature, for example poly[(butylene succinate)-co-(butylene terephthalate)]-b-poly(tetramethylene glycol), [9] a copolyester composed of 1,3-propanediol, sebacic acid, and terephthalic acid, [10] poly(butylene adipate-co-succinate)/PBT copolyester, [11] poly(butylene succinate-co-ethylene succinate-coethylene terephthalate), [12] poly(hexylene terephthalateco-hexylene adipate). [13] Moreover, polymer blending is also a simple and economic way to modify the physical properties and to extend the application field of aliphatic polyesters. Yang et al, for example, recently proposed biodegradable poly(butylene succinate-co-butylene adipate)/poly(vinyl phenol) blends.…”