Study on the Effect of Bambusa Rigida Keng to the Physico-Mechanical Properties ……

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Research of Materials Science December 2012, Volume 1, Issue 1, PP.25‐28

Study on the Effect of Bambusa Rigida Keng to the Physico-Mechanical Properties of the Original Structure Bamboo Composite Board

Chuan He#, Jiyuan Wang

School of Materials Science and Technology, Beijing Forestry University, Beijing 10083, China

#Email: [email protected]

Abstract

With the top parts, middle parts, bottom parts of the bamboo as raw material, making the composite board. Study the effect of

Bambusa rigida keng to the physico-mechanical properties of the original structure bamboo composite board. The results show

that: from the top to the bottom of the bamboo, the physical and mechanical performance parameters has obvious trend; while

from the top to the bottom parts of the bamboo as the raw materials composite board, the physical and mechanical performance

parameters also has obvious trend. Wherein both the bending strength has the same trend, and the density, size changes rate, and

the compressive strength has the different trends.

Keywords: Bambusa Rigida Keng; Bamboo; Composite Board

I. MATERIAL AND METHOD

Material. Bambusa rigida Keng (B. rigida Keng et Keng f.), Medium Density Fiberboard (MDF), Urea formaldehyde resin adhesive. Equipment. Chopper, hand saw, planer, sliding table saws, pressing machine, roller brush, steel tape measure, steel ruler, electronic scales, sandpaper, balance, stopwatch, calipers, cistern, mechanical testing machine. Method. Production process of the original bamboo structure composite board[1]: determination of physical and mechanical properties of Bambusa rigida Keng (refer to GB/T15780–1995[8])→raw material drying (natural drying)→bamboo segment processing→ assembly→sizing (urea formaldehyde resin adhesive) →pressure (hot press)→cutting edge→determination of physical and mechanical properties of the original bamboo structure composite board(refer to LYT 1856-2009[6] and GBT 17657-1999[7]). The process is shown in figure 1.

FIG. 1 PROCESSING OF BAMBOO SEGMENT AND ASSEMBLY PATTERN

(a) bamboo segment; (b1/b2) bamboo segment processed two/four sides; (c1/c2) assembly pattern of bamboo segment processed two/four sides


II.RESULTS AND DISCUSSIONS

Tables 1 and 2, respectively, are the physical and mechanical properties of the Bambusa rigida Keng and the composite board. As can be seen from table 1, from the top to the bottom of the Bambusa rigida Keng, air-dried density, over dried density, basic density, compressive strength and bending strength gradually reduce; tangential shrinkage rate, radial shrinkage rate, volume shrinkage rate, bamboo wall thickness gradually increased. As the raw material for the production of composite board, height variation of the Bambusa rigida Keng affect the physical and mechanical properties, and the physical and mechanical properties parameters showed obvious trends. As can be seen from table 2, since the composite board use different bamboo parts as raw materials, from the top to the bottom parts of the bamboo as the raw materials composite board, density, thickness swelling rate, bending strength and elastic modulus is gradually reduced; compressive strength is gradually increased. As can be seen from table 1 and table 2, the trend with the performance parameters of the composite board and the Bambusa rigida Keng is not the same. Besides the bending strength, the other properties have opposite trends. Since the same bamboo stalk from the bottom to the top, vascular cross-sectional area is gradually reduced; vascular bundle density increases, and the catheter aperture tapers and free water content decreased, so that the mechanical properties increase correspondingly. Therefore the compressive strength and bending strength of the Bambusa rigida Keng increased. Analyzed from the structure of composite board, the bending strength mainly from the bamboo that is in the middle of the board, so that the bending strength of the composite board depends primarily on the bending strength of the bamboo. The compressive strength of the Bambusa rigida Keng is measured along parallel to the grain direction. So there is no direct impact on the compressive strength of the composite board. Since the upper and under side of the bamboo segment remove part of the bamboo, the left and right sides of the bamboo wall take the most of the press under pressure. Although the mechanical properties of bamboo itself increase from the bottom to the top, the top parts of the bamboo wall are relatively thin and lack of stability. The trend of the density and shrinkage rate of the bamboo shows a trend of bamboo material itself. The production processes of the composite board go through the sizing and hot pressing, which to a certain extent change the bamboo properties, especially in the hot pressing with high-temperature and high-pressure. After pressing, the original bamboo catheter pore organization will have a certain degree of tightening[4][5], the adhesive will enter the bamboo pores that improved dimensional stability of bamboo, which also led to the composite board’s density and thickness swelling rate trend is different from the trend that the Bambusa rigida Keng has.

TABLE 1 THE PHYSICO-MECHANICAL PROPERTIES OF BAMBUSA RIGIDA KENG[2]

Items A B C D E F G H I

Top

1 0.602 0.562 0.455 6.94% 8.18% 15.81% 4.850 65.778 180.214

2 0.0598 0.0362 0.0337 0.0085 0.0098 0.0114 0.669 14.971 26.952

3 0.0226 0.0121 0.0112 0.0032 0.0033 0.0043 0.223 4.99 8.523

4 0.099 0.064 0.074 0.122 0.12 0.072 0.138 0.228 0.15

5 7.51 4.31 4.92 9.2 8.07 5.44 9.20 15.17 9.46

Middle

1 0.593 0.55 0.446 7.62% 8.88% 18.66% 5.693 60.506 146.78

2 0.0262 0.0815 0.0785 0.0089 0.0085 0.0407 0.522 9.203 16.405

3 0.0099 0.0272 0.0262 0.0034 0.0028 0.0154 0.174 3.254 5.468

4 0.044 0.148 0.176 0.117 0.096 0.218 0.092 0.152 0.112

5 3.34 9.89 11.75 8.92 6.31 16.15 6.11 10.76 7.45

Bottom

1 0.564 0.52 0.42 8.90% 10.13% 19.04% 6.692 57.306 117.519

2 0.0607 0.0699 0.0727 0.0138 0.0171 0.0223 0.866 11.583 17.312

3 0.023 0.0233 0.0242 0.0052 0.0057 0.0084 0.289 3.861 5.475

4 0.108 0.135 0.173 0.155 0.169 0.117 0.129 0.202 0.147

5 8.16 8.96 11.52 11.69 11.25 8.82 8.62 13.48 9.32


From 1 to 5 represent average, standard deviation, standard error, coefficient of variation and precise index. From A to I represent air-dried density, oven-dried density, basic tangential shrinkage ratio, radial shrinkage ratio, volume shrinkage ratio, bamboo wall thickness, compression strength, bending strength.

TABLE 2 THE PHYSICO-MECHANICAL PROPERTIES OF COMPOSITE BOARDS[3]

III. CONCLUSIONS

(1) From the top to the bottom of the Bambusa rigida Keng, compressive strength, bending strength, air-dried density, the over-dried density and basic density gradually reduce; the bamboo wall thickness, tangential shrinkage rate, radial shrinkage rate and volume shrinkage rate is gradually increased. (2) From the top to the bottom parts of the bamboo as the raw materials composite board, sheet density and compressive strength gradually increased; thickness swelling, bending strength and elastic modulus gradually decreased. (3) The Bambusa rigida Keng and the composite board has the same trend on the bending strength, the properties of the Bambusa rigida Keng has a direct impact on the bending strength to the composite board. (4) Due to the impact of high temperature, pressure and adhesive, the properties of the bamboo occur some certain changes. While bamboo process with the production of composite board, resulting in changes in the structure of the bamboo. So the trends of density, size changes rate and the compressive strength has some differences between the Bambusa rigida Keng and the composite board.

ACKNOWLEDGMENT

The author would like to thank his teachers from and support of Beijing Forest University, School of Materials Science and Technology.

REFERENCES

[1] Leifeng Zhao. Production of Bamboo Primordial Structure Composite Board and Its Economic Benefit Analysis, China Forest

Products Industry, Vol.28, No.5, (2011): 46-49

[2] Chuan He, Yu Liu: A Study of Physical-Mechanical Properties of Bambusa rigida Keng, World Banboo and Rattan, Vol.10, No.3,

(2012): 19-21

[3] Chuan He, Yu Liu: A Study on Physico-mechanical Properties of Original Bamboo Structure Composite Boards, Wood

Processing Machinery, Vol.23, No.5, (2012): 43-45

[4] Chuan He, Jiyuan Wang: Structural Characteristics of A New Original Bamboo Structure Composite Boards, Advanced Materials

Research, Vol.476-478, (2012): 2109-211

[5] Jiulong Xie: A Study on Bamboo Physico-mechanical Properties of Neosinocalamus affinis, Journal of Bamboo Research, Vol.30,

No.4, (2011): 30-34

[6] Extruded tubular particleboard, Chinese, Standard, LYT1856-2009, (2009)

[7] Test methods of evaluating the properties of wood-based panels and surface decorated wood-based panels, Chinese, Standard,

GBT17657-1999, (1999)

Items Composite boards processed on two sides Composite boards processed on four sides

Bottom Middle Top Average Bottom Middle Top Average

Compressive strength /MPa 3.71 2.74 1.32 2.59 4.20 3.01 1.39 2.86

MOR/MPa 41.11 44.75 46.12 43.99 46.14 55.60 56.91 52.88

MOE/MPa 1013 1271 1314 1199 1074 1494 1513 1360

Thickness swelling rate/% 5.50 11.14 11.20 9.28 4.77 6.54 8.81 6.71

Length change rate/% 0.08 0.07 0.05 0.066 0.07 0.05 0.08 0.06

Density/g∙cm‐3 0.45 0.43 0.41 0.43 0.44 0.42 0.39 0.415


[8] Testing methods for physical and mechanical properties of bamboos, Chinese, Standard, GB/T15780-1995, (1997)

AUTHORS

Chuan He, born in Beijing, China, 12th

Nov, 1987. Studying in School of

Materials Science and Technology,

Beijing Forestry University, China, for

master degree. The major field of

research is wood processing equipment

and the process automation.

Jiyuan Wang, born in Beijing, China,

1th Mar, 1988. Studying in School of

Materials Science and Technology,

Beijing Forestry University, China, for

master degree. The major field of

research is furniture and interior

decoration engineering.

Study on the Effect of Bambusa Rigida Keng to the Physico-Mechanical Properties ……

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