Recycling of anhydride -cured epoxy resin using
polyethylene glycol/ NaOH
Q.Zhou * 1, P.Yang 1 and Y.Z.Wang 1
1 Center for Degradable and Flame-Retardant Polymeric Materials (ERCEPMMoE), College of Chemistry, State Key Laboratory of Polymer Materials Engineering,
Sichuan University, Chengdu 610064, China; Tel: +86-28-85410755; Fax: +8628-85410755;
e-mail:qzhou@scu.edu.cn

Abstract
The use of polyethylene glycol/NaOH for solubilization of anhydride -cured
epoxy resin has been demonstrated. The effects of reaction conditions such asreaction temperature, alkaline species and concentration, as well as PEG
molecular weight were evaluated. The structure of the solvolysis products has beencharacterized by FT-IR, 1H-NMR, 13C-NMR, GPC and ESI-MS, indicating thedecomposition of the curing bond through ester hydrolysis accompanied bytransetherification as the plausible solvolysis mechanism.

Keywords: Epoxy resin;Transetherfication

Polyethylene

1. Introduction
Nowadays, recycling thermoset
composites such as epoxy resins at theend of their life cycle is very difficult
because of the cross-linked nature ofGlycol/NaOH;

Solvolysis; Hydrolysis;

is a typical thermosetting resin. Highdecomposition efficiency has been
proved under atmospheric pressure.

2. Materials and Methods

the resin. Solvolysis, using reactive

A model methyl tetrahydrophthalicsolvents to break down chemical

anhydride -cured epoxy resin has

bonds in thermoset resins, has been

been prepared. Typically, NaOH (0.8 g)

regarded as one of the most promising

was dissolved in PEG200 (40 mL),

recycling methods. Various solventsand then mixed with the model

have been used [1]. Developing a newepoxy resin (2.0 g). After reacting, theprocess with high efficiency under

unreacted epoxy resin could be

mild reaction conditions is ofseparated by filtration. Then waterconsiderable importance.

was added to the liquid products toIn this paper we have used

obtain an aqueous phase and an oilpolyethylene/NaOH to solvolyze

phase. The aqueous phase wasanhydride-cured epoxy resin, which

distilled to separate water, and then7th International Symposium on Feedstock Recycling of Polymeric Materials (7thISFR 2013)
New Delhi, India, 23-26 October 2013tetrahydrofuran was added, yieldinga white precipitate, characterized as
sodium methyl tetrahydrophalate.
The oil phase obtained has been
dried in a vacuum oven at 60 °C for
24 h, then characterized using FTIR,
GPC, 1H-NMR, 13C-NMR and ESI-MS.

3. Results and Discussion
Fig.

1

comparesthe solubilization

efficiency of different catalysts whencombining with PEG200. It can beseen that the solubilization degree isas high as 70.0 wt% with NaOH whenheated at 180 0C for 30 min, while
it is only 9.7% with NaHCO3. Whenusing HCl or without catalyst, almost
no change can be observed in theScheme 1 Plausible reaction
mechanism for solubilization ofepoxy resin using PEG200/NaOH.

4. Conclusions

epoxy resin, proving that PEG/NaOH

Solvolysis of anhydride-cured epoxy

is very efficient in catalyzing theresin using PEG/NaOH shows highsolubilization of epoxy resin.

efficiency under mild reaction

Solubilization rate (%)

conditions. The plausible
solubilization mechanism is ester

80

hydrolysis accompanied by the60

transetherification reaction.

40

5. Acknowledgments

20The authors thank the financial
support of the 863 program (Contract0none

NaOH

NaHCO3HCl

No: 2007AA06Z325) and theFig. 1. Comparing the solubilization

Program for New Century Excellent

efficiency of different catalysts

Talents in University (NCET-080366).

By characterization the degradation
products using FTIR, GPC, 1H-NMR,

References

13C-NMR and ESI-MS, it is found[1] T.Kamo, N.Akaishi, B.Wu,

that the main solubilization

M.Adachi, H.Yasuda, H.Nakagome.

mechanism is ester hydrolysis

Proceeding of the 4th International

accompanied by thesymposium on feedstock recycling oftransetherification reaction (Scheme 1).

plastics. pp.159-63. Jieju,Korea,2007.

7th International Symposium on Feedstock Recycling of Polymeric Materials (7thISFR 2013)
New Delhi, India, 23-26 October 2013