Influence of ozone treatment on structure and thermal properties of bis-2-hydroxyethyl terephthalate-based copolymers

Abstract

Polyesters are a particularly interesting group of polymers because of their ester bonds in the main chain, which are sensitive to degradation. It has been shown that aromatic polyesters [eg. poly(ethylene terephthalate) (PET)] can be degraded when they are copolymerized with aliphatic polyesters. In this regard, the objective of our previous study was to obtain and investigate new copolymers with some fragments of PET and its hydrolytic degradation. In this work, the impact of ozone degradation on properties of bis-2-hydroxyethyl terephthalate-based copolymers was researched. Apart from the bis-2-hydroxyethyl terephthalate, the copolymers comprised oligomers of lactic acid and glycolic acid in different combination. During ozone degradation, samples were kept for 24 h in atmosphere containing 0.51 vol.% of ozone. Structure changes were determined by means of FTIR spectroscopy. In the IR spectra of ozonised samples, new bonds characteristic for ozonised polymers were observed. Thermal properties of copolymers before and after degradation process were reviewed based on differential scanning calorimetry (DSC) and thermogravimetry. DSC results revealed that melting point increased, especially for copolymers displaying higher quantity of PET units.

Spray‐flame synthesis of La(Fe, Co)O3 nano‐perovskites from metal nitrates

“…A band at 1,722 cm −1 , assigned to (α, β) unsaturated esters, and a band at 1,248 cm −1 , assigned to C─O─C stretching vibrations . Furthermore, the intensity of the ester CO band at 1,197 cm −1 increased in comparison with the band at 1,222 cm −1 , what has been related to isomerism in the ester group, hinting to the formation of ordered interlinked ester structures. To summarize: esterification is preferred in case of cobalt‐containing solutions while iron shows some trend toward formation of carboxylates.…”

“…The ATR‐FTIR analysis concerning the esterification of the precursor solutions for LaFeO 3 and LaCoO 3 was performed at 50°C with 2‐EHA amounts from 0 vol% (only ethanol as solvent) to 70 vol% 2‐EHA. In the case of solutions containing iron and lanthanum nitrates (Figure a, the characteristic ester bands at 1,732, 1,222 and 1,197 cm −1 develop with increasing 2‐EHA concentration. Even at low 2‐EHA concentrations, the formation of the absorption band at 1,591 cm −1 (asymmetric CO vibration in coordination with iron [iron carboxylate]) is already present.…”

“…The spectra of the precursor‐free ethanol/2‐EHA mixture show in contrast to ethanol three specific bands at 1,732, 1,222, and 1,197 cm −1 . These bands are assigned to the ester CO (1,732 cm −1 ) and C─O (1,222 and 1,197 cm −1 ) stretching vibrations. The appearance of these peaks suggests an esterification reaction (see Equation 1 in the electronic Supporting Information) of 2‐EHA with ethanol.…”

Criegee Intermediates Beyond Ozonolysis: Synthetic and Mechanistic Insights

“…Ozonolysis also provides the means to investigate the degradation of polymers. [81][82][83] Identifying possible pathways and degradation products allows the design of tailor-made Reproducedf rom Ref. [80] with permission.C opyright2 018, American Chemical Society.…”

“…Ozonolysis also provides the means to investigate the degradation of polymers. [ 81 , 82 , 83 ] Identifying possible pathways and degradation products allows the design of tailor‐made polymers—either to be more durable or to be degraded more easily—as demonstrated by Tsuji et al. [84] They designed a curable resin that is degradable by ozonolysis.…”