JEC COMPOSITES MAGAZINE - Issue #66 - July/August 2011 - 51

Fig. 1 FRP helmets treated by the dissolving method

Glass fiber composite material (GFRP)
GFRP is made from glass fiber (GF), unsaturated polyester resin (UP) and filler. It is necessary to separate these materials in order to recycle GFRP. Each material can be separated and recovered by the method of dissolving UP under ordinary pressure. Fig. 1 shows helmets made of GFRP treated by the method with the passage of time. GF recoverd from GFRP is 20mm or more in length.However, the recovered GF is a form of cotton, which is not applicable to GFRP, while nonwoven fabric of the recovered GF made by the dry process or the wet process can be applicable to FRP. In the dry process, a carding machine which is usually used to manufacturing futon cotton is useful. In the wet process papermaking machine can be used. The recovered GF nonwoven fabric made with dry process is shown in fig. 2. The tensile strength of recycled GFRP that uses the nonwoven fabric was lower than new one by 30% . But, it is applicable to some uses which do not require high Fig. 2 Recovered GF nonwoven fabric strength.

pressure. The results of dissolving CFRP tennis rackets and CFRP badminton rackets are shown in fig. 3 and fig. 4 respctively. As shown in the figures, CF was recoverable from the tennis racket. In the case of the badminton racket , aluminum frame , wooden grip, CF from a shaft were recovered. It is a merit of this method that aluminum and wood are recovered without degradation.

Fig.5: Recovered CF nonwoven fabric with a carding machine

Fig.4: CFRP badminton rackets treated by the dissolving method

before treatment

after 10h

recovered CF nonwoven fabric

before carding

Carbon fiber composite materials (CFRP)
The application of CFRP for the transport machines such as aircraft and cars have expanded rapidly, because it is assumed to improve fuel cost by lightening. However, since the manufacturing CF needs a large quantity of energy, exhausts a lot of amounts of the carbon dioxide, CF is no good material as the result of environmental assessment (LCA). Therefore, recycling of CFRP is indispensable to improve LCA. EP dissolves and CF is recovered from CFRP consists of CF and epoxy resin (EP) by the method to dissolve under ordinary

No66 July – August 2011 / jec composites magazine

The nonwoven fabrics were produced by the dry or wet process as same as GF from the recovered cotton-like CF ( fig. 3, fig. 4). The recovered CF nonwoven fabric currently produced using a carding machine is shown in fig. 5. This nonwoven fabric was impregnated with UP, heated in a compression molding machine, then a CFRP was molded. The recycled CFRP was about 1.4 times stronger than mass production GFRP. The tensile strength of recycled CFRP decreased sharply when the fiber was shorter than 40mm. Therefore, short CF recovered from ground CFRP cannot be used as a reinforcement.

Aramid fiber composite materials (AFRP)

Aramid fiber (AF) has two kind of chemical structures which are para-aramid and meta-aramid. Para-aramid which has high strength and high modulus is used for tire cords, conveyer belts, protective clothing, etc. While before meta-aramid which has flame treatment retardancy and heat resistance is used for filters, wire coverings, and flame retardant clothing, etc. , it is hardly used as composite materials. As for AFRP, para-aramid is chiefly used, and there are a lot of use of after 5h aircraft materials and concrete reinforcement. AFRP molded with EP is difficult to separate AF. Since AF decomposes at about 500 °C, EP cannot be removed from AFRP by after 10h pyrolysis. Supercritical fluids also degrades AF remarkably, and are Fig.3: CFRP tennis rackets not applicable for the recovering. treated by the dissolving method The method of dissolving resin

Research & development

JEC COMPOSITES MAGAZINE - Issue #66 - July/August 2011

Table of Contents for the Digital Edition of JEC COMPOSITES MAGAZINE - Issue #66 - July/August 2011