RECOVERY OF USEFUL MATERIALS FROM THERMOSET COMPOSITE
MATERIALS BY LIQUEFACTION
H. Itou1, K.Hosokawa2, Y.Ohki2, H. Nakagome1 and T. Kamo3
1Chiba University, 1-33, Yayoicho, Inage-ku, Chiba-shi, Chiba, 263-8522, Japan
2Chugoku Kogyo, 1-3-1, Hironata, Kure-shi, Hiroshima, 737-0192, Japan

3 National Institute of Advanced Industrial Science and Technology (AIST), 16-1, Onogawa, Tsukuba-shi, Ibaraki, 305-8569,

e-mail:Japan
tohru-kamo@aist.go.jp

Abstract
Liquefaction of fiber reinforced plastics (FRP) was carried out in three solvents (cresol mixture solvent, benzyl alcohol, and 1methyl pyrrolidone) with small amount of additives at 200 °C. FRP was liquefied almost completely in the cresol mixture
solvent with 0.05 mmol/g of sulfuric acid for 240 min under atmospheric pressure. Total weight of liquefied FRP wasincreased than that of plastics in original FRP. The results indicate solvent was incorporated into products with liquefaction ofFRP. Yield of residue in thermal decomposition of the once liquefied FRP at 600 °C was almost equal as well as thermal
decomposition of original FRP. Effect of pretreatment by liquefaction was not observed in thermal decomposition of FRP.
FRP could be liquefied almost completely in the liquid products derived from thermal decomposition of the once liquefied
FRP. These experimental results suggest that recovery of glass fiber from waste FRP is feasible by using recycle solvent
derived from the once liquefied FRP.
Keywords: FRP, solubilization, reuse, recycle cresol

1.

Introduction

Fiber reinforced plastics (FRP) have been used widely ina lot of industrial products due to their distinguishedmaterial property light and strong. On the other hand,most of the waste FRP are incinerated or landfilled,because conversion from the used FRP to usefulproducts was very difficult. FRP tank for liquefied
propane (LP) is lighter and more convenient than aconventional steel tank, and we are expecting to be usedwidely in Japan as well as in EU countries. However, notonly convenience but also environmental friendliness isvery important to create a new market of the FRP-LPtank. In this work, we developed a recovering technology
of glass fiber from the FRP-LP tank by liquefaction using
recycle solvent derived from FRP itself.

2.

Materials and Methods

RIPOXY (Showa Denko K.K., Japan); photopolymerized
polyvinyl ether; was used as FRP sample. Cresol mixture(mixture of o-cresol, m-cresol, and p-cresol), benzyl
alcohol, n-methylpyrrolidone, tripotassium phosphate(K3PO4), sodium hydroxide (NaOH) and sulfuric acid
(H2SO4) were purchased from Tokyo Chemical Industry
Co., Ltd. or Wako Pure Chemical Industries Ltd.,
respectively as special grade for chemical experimental.
FRP sample (3.0 g) was liquefied in various solvents(100 g) with additives by using a glass flask (300 ml)
connected to water cooling reflux condenser.
Liquefaction was carried out at boiling point of eachsolvent for 60 – 360 min with stirring by the magnet. Afterthe reaction, glass fibers were separated from solvent,the fibers were washed by tetrahydrofuran (THF) and by
distilled water to remove solvent and additives. The
recovered glass fibers were dried at 50°C for 10 hours
under vacuum. Solubilization rate was calculated fromequation (1). Liquefied FRP was derived from of theliquid products by distillation of solvent at 220 °C.
Thermal decomposition of the liquefied FRP was carriedout in a Pyrex reactor which was heated up to 600 °C in30 min, and the temperature was kept for 30 min.
Gaseous products were collected into a gas bag, andwere analyzed by GC.
Solbilization rate [%] = (1 – (a-c)/ (b-c)) × 100 (1)a:weight of unliquefied products,
b:weight of FRP, c:weight of glass fiber in FRP

Fig.1 Procedure of liquefied FRP in this study

7th International Symposium on Feedstock Recycling of Polymeric Materials (7th ISFR 2013)
New Delhi, India, 23-26 October 20133.

Results and Discussion

Solubilization rates of FRP using three different solvents;
cresol mixture, benzyl alcohol, and 1-methyl pyrrolidone;
with/without sulfuric acid were shown in Fig.2. Without
sulfuric acid, solubilization rates of the FRP for 60 min
using cresol mixture solvent, benzyl alcohol, and Nmethylpyrrolidone were 47%, 45% and 65%,
respectively, and the liquefaction rates were increased
with reaction time. Solubilization of the FRP wasaccelerated significantly in each solvents in the presenceof sulfuric acid, in particular the solubilization rate incresol mixture solvent reached to 99% at 240 min by theaddition of sulfuric acid.
The solubilization rate of FRP increased withconcentration of sulfuric acid as shown in Fig.3. The rate
reached 99% at 0.05 mmol/g of the sulfuric acid, and it
was saturated more than 0.05 mmol/g.
Weight of the liquefied FRP which was derived fromliquid products by distillation of solvent was much larger
than that of original FRP. The increase of liquid products
indicated that the solvent was incorporated into theliquefied FRP or polymerization of solvent proceeded
during liquefaction of FRP. On thermal decomposition of
the once liquefied FRP at 600 °C, yield of residue andgas was 21% and 5%, respectively. These yields werealmost equal to the distribution of products derived fromthermal decomposition of original FRP. Effect ofpretreatment by liquefaction was not observed in thermal
decomposition of FRP.
FRP could be liquefied almost completely in the liquid
products derived from thermal decomposition of the onceliquefied FRP as shown in Fig.4. These experimental
results suggest that reusing liquid products derived fromthermal decomposition of the once liquefied FRP assolvent is feasible.

4.

Fig.2 Effects of solvents and sulfuric acid on
solubilization rate (H2SO4:0.05 mmol/g)

Conclusions

FRP was liquefied in cresol mixture solvent, benzyl
alcohol
and1-methylpyrrolidone,respectively.
Particularly, the FRP was liquefied almost completely incresol mixture solvent for 240 min by addition small
amount of sulfuric acid. On the thermal decomposition of
the once liquefied FRP, similar yields of gas or residue
were observed as well as direct decomposition of original
FRP. FRP was liquefied almost completely in liquidproducts derived from thermal decomposition of the onceliquefied FRP. These experimental results suggest thatrecover of glass fiber from waste FRP is feasible byusing recycle solvent.

Fig.3 Effect of sulfuric acid concentration in cresol
mixture solvent on solubilization rate

Fig.4 Recovered glass fiber from FRP using recycle
solvent derived from the once liquefied FRP.
H2SO4 (0.05 mmol/g) , 250°C, 240 min.
7th International Symposium on Feedstock Recycling of Polymeric Materials (7th ISFR 2013)
New Delhi, India, 23-26 October 2013