TH 16 INTERNATIONAL CONFERENCE ON COMPOSITE MATERIALS

COMPRESSION MOLDING OF PAPER USING TWISTED PAPER YARN AS REINFORCEMENT

Yamamoto H.*,Kimura T.*,Chikamori K.* *Kyoto institute of technology

Keywords: Twisted paper yarn, Composite paper, paper.

Abstract The twisted paper yarn made of manila As one of the attempts to develop the high was used as the reinforcement of composite. The performance paper board consisted of all natural length and diameter of hemp fiber were , the bamboo pulp paper reinforced by twisted 3~12mm and 16~35m, respectively. The paper paper yarn was molded and the mechanical with 4mm width was twisted 340times/m. The behavior was discussed to obtain the finding to manila hemp has a very high strength and also create the functionality paper board. The contents of superior absorption property of carbon dioxide. twisted paper yarn in the composites paper and the Therefore, the manila hemp is characterized as an molding pressure were varied in wide ranges. The environmental-friendly material. Figure 1 shows the technique of paper making and the tensile properties aspect of twisted paper yarn. of composite paper were discussed in detail. In this study, the content of twisted paper yarn (Wf) was varied in wide range by regulating the weight of bamboo paper. 1 Introduction Figure 2 shows the typical load-displacement Recently, reinforced composites curves for twisted paper yarn and non-twisted have been focused as environmentally friendly (before twisted) paper of manila hemp used here. It material1). Usually, the plastics are used as a matrix is noted here that the maximum load and material of composites and the biodegradable and displacement of twisted paper yarn are larger than bio-base plastics are paid attention in the many those of non-twisted paper. Namely the strength of engineering fields2). paper becomes larger by twisting the paper. Meanwhile, paper is one of the necessities for Therefore the twisted paper yarn is expected as a our human life and many efforts are being turned to reinforcement of paper or paper board. the development of high performance paper now. The paper and paper board consisted of all natural fibers are also expected as environmental-friendly materials. So, we are aiming at the creation of functionality paper board by using the paper making technique.

In this paper, as one of the attempts to develop the high performance paper board consisted of all natural fibers, the bamboo pulp paper reinforced by twisted paper yarn was molded and the mechanical behavior was discussed to obtain the finding to create the functionality paper board. Fig.1 Aspect of twisted paper yarn

2 Materials Used

Base materials used were bamboo pulp with 727ml in Freeness CSF. The average fiber length and diameter are 0.43mm and 11m, respectively. The standard weight (W) of paper based on JIS P 8222 is 133g/m2. The value of weight (W) was changed from 1W to 12W through experiments. Yamamoto H., Kimura T., Chikamori K

7 6 5 ）

N 4 （ F

d 3 a o

L 2 1 0 Bamboo pa per 0 2 4 6 8 Displacement δ（mm） Fig.2 Load－displacement curve of twisted paper yarn used.

3 Paper-making Method The sheet machine used is shown in Figure 3. Twisted paper yarn The bamboo paper reinforced by manila hemp twisted paper yarn was molded as follows. Firstly, the bamboo pulp was mixed with water well by using the mixing machine and was dispersed into container of sheet machine filled with water. Secondly, the water was drained through the drainage canal installed at lower side of container after dispersing well the pulp by using the stirrer. Then, pre-molding paper can be obtained in the container. Thereafter, the container was opened and the twisted paper yarns were placed on the pre-molded paper parallel with each other (3mm pitch). After that, the container was closed and the residual bamboo pulp was put into the container with water. And then the water was drained again through the drainage canal. Here, the wet composite paper with P ress twisted paper yarns can be obtained. The neighboring fibers were bonded by the hydrogen bond mechanism for the cellulose natural Fig.4 Aspect of lamination of each material fibers. In this experiment, the hydrogen bond process was carried out by referring JIS P 8222. The mechanical properties may largely depend Figure 4 shows the aspect of lamination of on the value of molding pressure P during the dry composites. process. Therefore, the pressure was varied from 5MPa to 50MPa in this study.

4 Experimental Procedure

Tensile properties were measured by using “INSTRON model 4206” according to JIS P 8113. The cross section and the surface of molded composites were observed by using the microscope.

5 Results and Discussion

The sketch of structure and aspect of molded paper are shown in Figure 5 for Wf = 0.39. The twisted paper yarns exist inside the bamboo pulp paper. Fig.3 Sheet machine COMPRESSION MOLDING OF PAPER USING TWISTED PAPER YARN AS REINFORCEMENT

between the bamboo paper and the twisted paper yarn. Figures 7 (a)~(c) show the typical load- displacement curves for various content of twisted paper yarn Wf and molding pressure P. It is noted from these figures that the two peaks of load can be seen for larger contents such as Wf=0.66, 0.49 and 0.14 of twisted paper yarn. In these cases, the thickness of bamboo paper is very thin. Therefore the breaking paper is caused firstly, and afterwards the fracture of twisted paper yarn occurs as shown in Fig.8 (a) of fracture mode of composites. This causes the appearance of two peaks of load said above. In the case of small content of twisted paper Fig .5. Sketch of structure of molded paper and yarn, the fracture of paper and paper yarn is aspect of molded paper synchronal because of the thick bamboo paper as shown in Figure.8 (b). Therefore the fracture mode becomes brittle and then only one peak can be seen for the curves as shown in Figure.7 (c).

80 70 P (MPa) 5 60 50

N) 50 ( F

d 40 a

o L 30 20

10 (a) P=50MPa 0 0 2 4 6 8 10 12 Displacement v4（mm）

(a) Wf=0.66

80

70 P (MPa) 60 5 50 50 N)

( F 40 (b) P=5MPa d a o

Fig.6 Aspect of paper yarn in composite L 30 20 Figure 6 shows the aspect around the paper 10 yarn of composite with Wf=0.49 in detail for 0 P=5MPa and 50MPa.. It is noted that a lot of air 0 2 4 6 8 10 12 gaps were caused around the paper yarn. However, Displaceme nt v4（mm） the air gap in the top and bottom of paper yarn disappears for higher molding pressure such as P=50MPa. This may causes a good adhesion (b) Wf=0.49

3 Yamamoto H., Kimura T., Chikamori K

450 500 450 W 400 P (MPa) f 0.66 350 5 400 300 0.56

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F 0.49

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o 200 l 0.11 100 e r 150 50 u t c

0 a 100 r 0 1 2 3 4 5 6 7 F 50 Displacement δ(mm) 0 0 10 20 30 40 50 60 Pressure P（MPa） (c) Wf=0.14

Figure.7 Load-displacement curve for various Fig.9 Relation between fracture load and Wf molding pressure

Figure 10 shows the relation between the fracture load Fmax and the content of paper yarn Wf for various molding pressure P. It is clearly seen that the fracture load decreases with increasing the content of twisted paper yarn. In this report the content of paper yarn was varied by regulating the weight of bamboo paper. Therefore the thickness of

bamboo paper decreases with increasing the content (a) W =0.66 f of paper yarn. This fact caused the decrease of fracture load with increasing the content of twisted paper yarn. As for the molded composite paper, the weight is different everything. The properties of composite paper depend largely on the weight of paper. Therefore, the consideration under the constant weight of composite paper is worthy to discuss the effect of twisted paper yarn on the properties of composite paper. Then the fracture load was divided (b) Wf=0.14 by each weight. The results of relative fracture load Fig. 8 Aspect of fracture (P=50MPa) Fr are shown in Figure.11. It should be noted here that the value of Fr decreases with increasing the Figure 9 shows the relation between the content of twisted paper. Those results suggest that fracture load F and the molding pressure P for the twisted paper yarn used here doesn’t act as a max reinforcement. This may be caused by the low various Wf. It is noted from figure that the fracture load increases with increasing the molding pressure. strength of twisted paper yarn and the lack of This may be caused by the decrease of air gap and adhesion between bamboo paper and twisted paper the increase of surface contributing to the hydrogen yarn. Namely it is conclude here that more strong twisted paper yarn is needed for the reinforcement bond as shown in Figure.6. In the cases of larger Wf, namely thin bamboo paper, the fracture load is non- and the binder material such as PVA is expected to sensitive to the molding pressure. This may means improve the adhesion. These are our next themes of the lack of bamboo pulp for the composites paper. this study.

COMPRESSION MOLDING OF PAPER USING TWISTED PAPER YARN AS REINFORCEMENT

6 Conclusion 450 400 P(MPa)

） As one of the attempts to develop the high

N 350 5 （ performance paper board consisted of all natural x 20 a

m 300

F 30 fibers, the molding of the bamboo pulp paper

d 250 a 50 reinforced by twisted paper yarn was tried and the o l 200 e

r mechanical behavior of composite paper was

u 150

t c discussed to obtain the finding to create the a 100 r F functionality paper board. 50 0 The tensile strength of composite paper

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 increased with increasing the molding pressure. Content of twisted yarn Wf However, the twisted paper yarn didn’t act as a reinforcement because of the inadequate strength of paper yarn. The improvement of Fig.10 Relation between fracture load and adhesiveness became a next topix. content of twisted yarn

200 g) References / 180 P(MPa) N

( r 160 5 F 20 d 140 a [1] Kihara Y., Ben G., Nishino M. and Matsuda T.

o 30 l 120

e 50 “Development and Evaluation of Green Composites r 100 u t Composed of Yarned Fiber Bundles and c

a 80 r f Biodegradable Resin by using Pultrusion and Hot 60 e v Press Moldings”. Proceedings of JCOM-36, Kyoto, pp ti 40 a l 1-5, 2007. e 20 R 0 [2] Cao Y., Goda K. and Shibata S. “Development and 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 Flexural Properties of Bagasse Fiber-reinforced Composites”. Proceedings of IWGC-4, Tokyo, pp Content of twisted paper yarn W f 124-128, 2006. Fig.11 Relative fracture load

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