Quantitative hydrolysis-gas chromatographic methods for the determination of selected acids and glycols in polyesters

Abstract

The objective of this work was to develop precise quantitative methods of analysis for determining repeat units of polyesters. These methods have In common an alkaline hydrolysis of polyesters followed by gas chromatographic determination of the glycols and acids produced from the hydrolyses. In order to obtain rapid chromatographic analyses, trimethylsllyl derivatives of the glycols and acids were formed by a reaction with /V,0-bis(trlmethylsllyl)trifluoracetamlde. The relative standard deviation varies from 0.8 % for the determination of 1,4-butanedlol to approximately 2% for 1,4-cyclohexanedlmethanol. For the determination of different concentrations of Isophthalic acid, the standard deviation varies from 0.7 to 2.4%. These methods provide rapid and precise determinations for selected acids and glycols In polyesters.Several methods have been described for determining the diethylene glycol content of poly(ethylene terephthalate) (PET) (1-3). These methods have in common the decomposition of the polyester through alkaline hydrolysis or hydrazinolysis followed by the determination of the diethylene glycol content by titration or gas chromatographic methods (4-8). However, none of these methods describe the quantitative determination of other glycol or acid content of polyesters. The objective of this work was to develop a precise, accurate method to determine the glycols and methyl ester end groups in PET and to develop a method for general use in determining glycols and acids in polyesters.

Synthesis, Structure, Hydrodynamics and Thermoresponsiveness of Graft Copolymer with Aromatic Polyester Backbone at Poly(2-isopropyl-2-oxazoline) Side Chains

“…As is known [ 52 ], the density of side chain grafting affects a number of physical characteristics of comb-like polymers, in particular, their behavior in solution. For determining side chains molar mass as well as their grafting density, polymer samples were subjected to alkali hydrolysis under conditions providing the quantitative scission of the polyester chain: 1 M KOH solution in ethyl 2-ethoxyethanol at 120 °C for 10 min [ 53 ]. The density of side chain grafting was found from the molar mass ratio of the backbone and side chains.…”

Analytical Study of Free and Ester Bound Benzoic and Cinnamic Acids of Gum Benzoin Resins by GC-MS and HPLC-frit FAB-MS

“…In contrast to the use of methyl esters as derivatives for GC analysis of carboxylic acids obtained by hydrolysis of resins and some condensation type polymers, trimethylsilyl (TMS) esters have been used in only a limited number of applications (Herrman et al, 1986;Allen et al, 1977). Diazomethane is the most convenient method for the preparation of methyl esters of resin-like samples.…”

Thermoresponsive Molecular Brushes with a Rigid-Chain Aromatic Polyester Backbone and Poly-2-alkyl-2-oxazoline Side Chains

“…It should be noted, however, the asymmetric shape of the GPC trace of the graft copolymer (Figure 6), which probably indicates some unevenness in the distribution of the side chains along the main one. In order to determine the molecular weight characteristics of the grafted chains and their grafting density, the main chains of copolymers were destroyed by alkaline hydrolysis under conditions that provide quantitative cleavage of ester groups [76] (Figure 7). A comparison, for example, of the 1 H NMR spectra of the macroinitiator an grafted copolymer APEr.ch.-graft-PEtOx shows (Figure 5) that both signals of aro protons of the main chain and signals related to the PEtOx side chains are present i spectrum of the copolymer.…”

“…Together with the monomodality of the obtained poly these data allow us to assert that the sample under investigation is a graft copolym should be noted, however, the asymmetric shape of the GPC trace of the graft copol (Figure 6), which probably indicates some unevenness in the distribution of the chains along the main one. In order to determine the molecular weight characterist the grafted chains and their grafting density, the main chains of copolymers wer stroyed by alkaline hydrolysis under conditions that provide quantitative cleava ester groups [76] (Figure 7). The molar masses and hydrodynamic characteristics of the macroinitiator and the graft copolymers are given in Table 1.…”