PARTⅤ SOLVOLYSISCHARACTERIZATION OF CFRP USING RECOVEREDCARBON FIBERS FROM WASTE CFRP
Mitsutoshi NAKAGAWA*, Hiroyuki KURIYA, Katsuji SHIBATA
Hitachi Chemical Co., Ltd., Ibaraki, Japan
E-mail: mit-nakagawa@hitachi-chem.co.jp
1. Introduction
CFRP (Carbon Fiber Reinforced Plastics) is widely used in sporting goods such as golfclub, tennis racket and fishing rod, and in aerospace and industrial field because of its hightensile strength, high elastic modulus and high dimensional stability. But due to its superior
properties, it is difficult to recycle. Consequently the amount of waste CFRP is increasing andthe recycling technology is required.
We have developed the depolymerization of thermosets under ordinary pressure. We use
potassium phosphate tribasic (K3PO4) as a catalyst and benzyl alcohol (BZA) as a solvent todepolymerize cured epoxy resin (EP) and unsaturated polyester resin (UP). FRP made of EP
or UP can be dissolved in solvent and be separated into depolymerized resin andreinforcement. We have already reported that the result of application of our method to GFRP(Glass Fiber Reinforced Plastics) is useful for recycling of GFRP in Fiber Recycling 2007.
We applied our method to CFRP based EP and investigated possibility of recycling ofCFRP.

2. Experimental
2.1 Depolymerization of Cured Epoxy Resin
Epoxy resin cured with acid anhydride is mainly used for a matrix of CFRP. This isapplied to golf club, tennis racket and aerospace parts, but is difficult to recycle. We estimatethat cured epoxy resin can be depolymerized by transesterification with mono alcohols, andthen be dissolved in solvent (Fig.1).
2.2 Depolymerization of CFRPVarious CFRP products could be dissolved by the depolymerization under ordinarypressure. For example, a tennis racket was dissolved in 8 hours (Fig. 2), and an aircraft partwas dissolved in 2 hours (Fig. 3). Recovered CF (Carbon Fiber) was prepared nonwoven
fabric by a carding machine (Fig. 4).

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The 5th ISFR (October 11-14, 2009, Chengdu, China)

Fig. 1

Depolymerization of epoxy resin cured with acid anhydrideFig. 2

Dissolve of a tennis racket

Fig. 3- 242 -

Dissolve of aircraft parts

PARTⅤ SOLVOLYSIS

Fig. 4Nonwoven fabric used recovered CF

2.3 Mechanical Properties of “Recycle CFRP”
We prepared “recycle CFRP” used nonwoven fabric made from recovered CF (Tab.1).
Tensile properties compared to mass production GFRP, strength of recycle CFRP is 1.4 times
higher, modulus is equality and elongation is 1.1 times higher than GFRP (Fig.5). We expectthat “recycle CFRP” can be used as well as GFRP.
Tab. 1
Item

Mechanical properties of “recycle CFRP”
Mass production GFRP

Recycle CFRP

Glass chopped strandmatNonwovenfabricUnit

Fiber form
Matrix resin

UP

Fiber length
Fiber content

mm
vol%

Specific gravity-1.7

1.6Tensile strength
Tensile modulus

MPaGPa

63.8
5.7

89.7
5.5Tensile elongation

%

3.7

4.0

160

2516

GFRP = 100％

Relative value (%)

140
120
10080
60
40
200
Tensile strength

Fig. 5Tensile modulus

Tensile elongation

Mechanical properties of CFRP used recovered CF- 243 -The 5th ISFR (October 11-14, 2009, Chengdu, China)
2.4 Recyclate Application – Formula Car Parts
We offered Toyohashi University of Technology (TUT) nonwoven fabric using
recovered CF from tennis rackets. TUT prepared driver’s seat using this fabric by hand-lay-up
method (Fig.6). They installed the seat on the formula car, and competed at Student Formula
SAE Competition of JAPAN 2008.

Fig. 6 A driver’s seat on the formula car used nonwoven fabric made from recovered CF
3. Conclusion
Recovered CF was obtained from CFRP using the depolymerization of thermosets underordinary pressure, and “recycle CFRP” could be prepared using nonwoven fabric made fromrecovered CF. Tensile properties compared to mass production GFRP, strength of recycleCFRP is 1.4 times higher, modulus is equality and elongation is 1.1 times higher than GFRP.
“Recycle CFRP” can be used enough as FRP. We are developing applications of nonwoven
fabric of CF.

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