5-7 OCTOBERISFR2011

165

TOLEDO (SPAIN)RECYCLING OF WASTE FRP AS FILLER FOR NEW FRP PRODUCTS
S. Nakai1, Y. Tokumou2, S. Tsukawaki3, T. Okuda4, W. Nishijima4, and M. Okada5
1 Grad. School Eng., Hiroshima Univ., Higashihiroshima 739-8527, Japan
2 Tokumou Resin Ltd., 678-1 Kamiaruji, Ashida, Fukuyama, Hiroshima 103-0012, Japan
3 Hiroshima Pref. Technol. Res. Inst. Eastern Region Ind. Res. Center, Fukuyama, Hiroshima 721-0974, Japan
4 Environ. Res. Manag. Center, Hiroshima Univ., Higashihiroshima 739-8513, Japan
5 Facul. Liberal Arts, the Open Univ. Japan, Chiba 261- 8586, Japanemail:sn4247621@hiroshima-u.ac.jp

Abstract
Ground waste FRP (gwFRP) was investigated as filler for new glass fibers-based FRP. Addition of gwFRP to an
unsaturated polyester resin (UPR) at 10% resulted in 10wt% reduction in bending stress, whereas the calcium carbonate
addition did not. This reduction was possibly due to the resin fraction of gwFRP. On the other hand, irregular FRP
products manufactured in an FRP factory were ground (giFRP) and added to UPR at 10wt% to produce new FRP testpieces and products. Strength examinations using the FRP test pieces showed no weakening in bending stress, tension
strength, and impact resistance, as compared to FRP prepared using the pure and calcium carbonate-added UPR. Inaddition, the giFRP-added FRP bathtub and cover showed the same breaking load and bending stress as the no filleradded and CaCO3-added ones, indicating that giFRP can be used as the filler for UPR to produce new FRP products.

Keywords: filler, ground waste FRP, recycling, unsaturated polyester resin

1. Introduction
The annual generation of waste FRP in Japan has been
more than 40,000 t for these years [1]. Since FRP hasfibers, chemical recycling of resins requires separation offibers, hydrolysis/dissolution [2,3]. This results in limited
application of the processes for waste FRP. As for wholematerial recycling, ground waste FRP has been applied
as filler for resins and pains and as a fine aggregate formortars [4]. Since the required pretreatment is simply
grinding, these are the promising use application.
Among the material recycling purposes, we focused on
filler for resins because of the possible advantage in lessweight as compared to conventional filler, such as
calcium carbonate. Since mixing of different kinds ofplastics should be avoided from the viewpoint ofrecycling, it is preferable that waste FRP is applied forthe resin same as that used in this waste FRP. Therefore,
this study was carried out to investigate the feasibility ofusing ground FRP containing unsaturated polyester resin(UPR) as the filler of UPR of new FRP products.

2. Materials and Methods
Ground waste FRP (gwFRP) containing UPR wassupplied from Prehabu-kogyo, Hiroshima, Japan, while inthis factory irregular FRP products manufactured inTokumou Resin, Japan were ground (giFRP). In bothground FRP, grass fibers and UPR were found, and the
median size was about 25 m. gwFRP and giFRP wereused as filler for UPR, while CaCO3 was used in thecontrol experiment. In the experiment to identify thecause for weakening of UPR by addition of gwFRP,interiores libro.indd 165

ground grass fibers and UPR were respectively used asfiller.
In order to investigate the feasibility of using ground FRPas filler of UPR itself, gwFRP was added to UPR and well
mixed, followed by 30 min of degassing in vacuo. Afterhardening gwFRP-added at 20°C, the UPR test pieces
were examined for bending stress according to JIS
K6911 [5]. On the contrast, giFRP was used at 10wt% asfiller of UPR together with a glass fiber sheet to produce
new FRP board, bathtub and cover by a hand lay-up
method. The FRP test pieces were obtained by cutting
the board and examined for bending stress, tension
strength, and impact resistance at -20°C, 20°C and 60°C.
As for bathtub and cover, breaking load and bending
stress tests were carried out respectively.

3. Results and Discussion
Figure 1 compares the bending stress of UPR test pieces
to which gwFRP or CaCO3 was added as the filler. As theadded amount of gwFRP increased, the bending stressbecame weaker, whereas the calcium carbonate-added
UPR showed weakening at more than 30%. When thevirgin UPR and glass fiber sheet were respectively
ground and used as the filler, the former but not latter
showed the similar reduction in the bending stress (datanot shown). These results indicate that the resin fractionof gwFRP is the possible cause for its weakening effect.
When the giFRP was added at 10wt% as the filler to
UPR for new FRP test pieces, its weakening effect wasnot observed. A comparison of bending stress andtension strength showed no difference among the giFRP,

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6th International Symposium on Feedstock Recycling of Polymeric Materials

Breaking load [t]

2160

040

㻝

W/O filler

CaCO3gwFRP

20204060

Addition [wt%]Fig. 1 Bending stress of the UPR test pieces to which gwFRPor CaCO3 were added.
240-20䉝20䉝60䉝200a)

1.50.50Bending stress [MPa]32.5800a)160

CaCO3giFRPb)

㻜㻚㻤㻜㻚㻢㻜㻚㻠㻜㻚㻞㻜
W/O filler

CaCO3giFRP

Fig. 4 Breaking load of the FRP bathtub (a) and bending stress(b) of the FRP cover to which giFRP and CaCO3 wereadded. Bars indicates standard deviation (n=3) withexceptions for W/O filler (a & b)(n=2).

120

4. Conclusions

80
400W/O filler

120

Tension strength [MPa]weakening appears for the giFRP-added products ascompared to no filler-added and CaCO3-added ones.
This indicates that giFRP can be used as the filler for
UPR to produce new FRP products.

Bending stress㼇㼗㻺㼉

Bending stress [MPa]

CaCO3, and mixture-added test pieces, whiletemperature influenced these properties (Fig. 2). Inaddition, all samples had the same relationship between
the absorbed energy and impact angle in the impact tests(Fig. 3). On the other hand, the bending stress of thegiFRP-added FRP test piece was more than twice thanthat of the gwFRP-added UPR. The results indicated thatthe weakening effect by addition of gw/giFRP wasnegligible as compared to the strength increase by thecombinational use of glass fiber sheet in FRP production.

CaCO3

1/1 CaCO3+ giFRP-20䉝
20䉝
60䉝

100giFRPb)

80
60
40
20
0
W/O filler

CaCO3

1/1 CaCO3+ giFRP

giFRPFig. 2 Bending stress (a) and tension strength (b) of the FRP
test pieces to which giFRP, CaCO3, and their mixture(1:1) were added. Bars indicates standard deviation(n=3) with an exception for 1/1 CaCO3+giFRP (b) (n=2).
Absorbed energy [J]1412108642057

W/O filler
CaCO3
1/1 CaCO3 + giFRP
giFRP

57.5 58

58.5 59
Angle [㼻]59.5 60

Fig. 3 Relationship between the absorbed energy and impact
angle of the FRP test pieces to which giFRP, CaCO3, andtheir mixture (1:1) were added.

Addition of gwFRP to UPR at 10% resulted in 10wt%
reduction in bending stress possibly due to the resin
fraction of gwFRP; however a series of strengthexaminations using the giFRP-added FRP test pieces
showed no weakening in bending stress, tension strength,
and impact resistance. Since the giFRP-added FRP
bathtub and cover showed the same breaking load andbending stress as the no filler-added and CaCO3-added
ones, the results confirmed that giFRP can be used as
the filler for UPR to produce new FRP products.

References[1] Japan Reinforced Plastics Society (JRPS) report,
http://www.jrps.or.jp/frpcenter/st1_genjyou.html[2] K. Yamada et al. Improved preparation of recycled
polymers in chemical recycling of fiber-reinforced plastics
and molding of test product using recycled polymers. JMater Cycl Waste Manag 12 (2010) 271-274.
[3] T. Owaya et al. Recycling of fiber reinforced plastics
using depolymerization by solvothermal reaction withcatalyst. J Mater Sci 43 (2008) 2452-2456.
[4] A. Kojima & S. Furukawa. Recycling of resin matrix
composite materials. VII: future perspective of FRP
recycling. Adv Compos Mater 6 (1997) 215-225.
[5] Japanese Industrial Standards Committee; “Testingmethods for thermosetting plastic (Netsukoukaseipurasuchicc ippan shikenhou),” JIS K6911 (2006).

The breaking load of the FRP bathtub and bending stressof the FRP cover are shown in Fig. 4, where nointeriores libro.indd 166

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