Depolymerization of poly(butylene terephthalate) in sub- and supercritical ethanol in a fused silica capillary reactor or autoclave reactor

Depolymerization of poly(butylene terephthalate) (PBT) in sub- and supercritical ethanol was performed both in a fused silica capillary reactor (FSCR) or a batch autoclave reactor. The phase behavior of PBT in ethanol during heating and cooling was studied in the FSCR under a microscope and captured...

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Bibliographic Details
Published in:Polymer degradation and stability 2013-07, Vol.98 (7), p.1287-1292
Main Authors: Pan, Zhiyan, Shi, Yinghai, Liu, Li, Jin, Zanfang
Format: Article
Language:English
Subjects:
activation energy
Applied sciences
Autoclaves
cooling
Depolymerization
Ethanol
Ethyl alcohol
Exact sciences and technology
gas chromatography-mass spectrometry
heat
liquid chromatography
Mass spectrometry
Phase behavior
Poly(butylene terephthalate)
Polybutylene terephthalates
Polymer industry, paints, wood
reaction kinetics
Reactors
silica
Supercritical ethanol
Technology of polymers
temperature
Terephthalate
Waste treatment
yields
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Summary:Depolymerization of poly(butylene terephthalate) (PBT) in sub- and supercritical ethanol was performed both in a fused silica capillary reactor (FSCR) or a batch autoclave reactor. The phase behavior of PBT in ethanol during heating and cooling was studied in the FSCR under a microscope and captured by a digital camera. The results showed that PBT could dissolve in supercritical ethanol at 330 °C and form a homogeneous solution. Under autogenous pressure in the batch autoclave reactor, the effects of the ethanol/PBT mass ratio (8 g/2 g to 24 g/2 g), reaction temperature (200–280 °C) and reaction time (5–60 min) on depolymerization of PBT in sub- and supercritical ethanol were investigated. The main liquid products of depolymerization were identified and quantified as diethyl terephthalate (DET) and 1,4-butanediol (1,4-BD) by liquid chromatography mass spectrometry, gas chromatography mass spectrometry, and gas chromatography, respectively. PBT could be completely depolymerized at 240 °C in 60 min with an optimal ethanol/PBT mass ratio of 20 g/2 g (10:1). The highest yields of DET and 1,4-BD were 97.7% and 89.4%, respectively. Reaction kinetics analysis showed that the PBT depolymerization in sub-critical ethanol reaction was first order and activation energy was 38.8 kJ mol−1. A reaction pathway was proposed based on the experimental results.
ISSN:0141-3910
1873-2321
DOI:10.1016/j.polymdegradstab.2013.04.004