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Production of particle boards from bioresources
Bioresource Technology 75 (2000) 87±89
Short communication
Production of particle boards from bioresources O. Akaranta Department of Pure and Industrial Chemistry, University of Port Harcourt, Port Harcourt, Nigeria Received 28 June 1999; received in revised form 8 February 2000; accepted 16 February 2000
Abstract Particle boards of 1.2 cm thickness were prepared from rubber seed pod, cashewnut shell, and their blends, using an adhesive resin based on cashewnut-shell liquid. Performance evaluation showed that the boards satis®ed the ASTM speci®cations for construction-grade building boards. The bending strength, water resistance and swelling ratio of the boards were better than those obtained for a commercial board. The results also showed that cashewnuts can be fully exploited by production of cashewnut-shell liquid for adhesive resins and spent shells which can be used as a source of lignocellulosic material for particle boards. Ó 2000 Elsevier Science Ltd. All rights reserved. Keywords: Particle boards; Rubber seed pod; Cashewnut shell; Adhesive resin
1. Introduction The quantities of agricultural wastes, bioresources, are increasing in developing countries due to increase in agricultural activities. Such agricultural wastes have remained largely under-utilized owing to lack of the technology for their eective utilization. The increasing demand for industrial raw materials and the realization that most natural resources, especially minerals, are non-renewable have brought agricultural wastes into focus as a potential source of raw materials. In recent years a great deal of attention has been given to the conversion of agricultural wastes into valueadded products (Coppens et al., 1980; Roy et al., 1989; Sampathrajan et al., 1991; Akaranta et al., 1996; Akaranta, 1996; Akaranta and Osuji, 1997; Akaranta and Wanksai, 1998). Of particular note is that most of such conversion processes treat each type of waste as an independent entity. As a result, amounts of many agricultural wastes generated may be deemed too small to sustain waste conversion schemes. However, if wastes from dierent agricultural sources are combined, based on their chemical composition and/or physical properties, the problem may be overcome. In this connection, Odozi et al. (1986) described the use of blends of mangrove bark, corn cob and sugarcane bagasse for the production of particle boards of considerable strength and durability. The production of particle boards using agricultural wastes is expected to increase, particularly in developing countries, due to the declining potentials of the forests in such countries.
Apart from lignocellulosic materials, adhesive or binder is another important raw material for the production of particle boards. Researches into the development of phenol±formaldehyde (PF) types of resins from bioresources have been reported (Ebwele et al., 1984; Odozi and Agiri, 1986; Akaranta and Wankasi, 1988). The research ®ndings are in favour of partial or full replacement of phenol in PF type of resin intended as wood adhesives. The use of red onion skin extract modi®ed with cashewnut-shell liquid as wood adhesive has been reported (Akaranta et al., 1996). It was the aim of the present study to investigate the potentials of cashewnut-shell liquid, red onion skin, rubber pod and spent cashewnut shells in the production of particle boards. 2. Methods 2.1. Materials The lignocellulosic wastes used for the production of the boards had the following compositions: spent cashewnut shell ± cellulose 14.1%; lignin 3.4%; rubber pod shell ± cellulose 32.2%; lignin 6.9%. The rubber pod and spent cashewnut shells were disintegrated independently using a laboratory mill and sieved through a 60 mesh screen. The particles retained were dried in the oven to a moisture content of 10±12%. Red onion skin was used as a source of natural phenols for the production of the adhesive resin.
0960-8524/00/$ - see front matter Ó 2000 Elsevier Science Ltd. All rights reserved. PII: S 0 9 6 0 - 8 5 2 4 ( 0 0 ) 0 0 0 3 5 - 3
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O. Akaranta / Bioresource Technology 75 (2000) 87±89
2.2. Extraction of cashewnut-shell liquid Cashewnut shells (500 g) were extracted with 1.251 of ether using a soxhlet extractor according to Akaranta et al. (1994). The extract solution was stripped of the solvent by distillation to give a dark brown liquid with average yield of 24.8%.
ASTM (1997) using an Avery dension universal testing machine. All board samples were tested for speci®c gravity, water absorption and bulk swelling on immersion in water. Each test value reported is an average of ®ve board samples.
3. Results and discussion
2.3. Preparation of adhesive resin The method used in the preparation of the adhesive resin has been described elsewhere (Akaranta and Wanksai, 1998). It involves reacting red onion skin extract with formaldehyde under alkaline conditions, with the resultant resin modi®ed with cashewnut-shell liquid. 2.4. Preparation of particle boards Particle boards of about 1.2-cm thick were prepared using 20% resin content. A known weight of the lignocellulosic waste was treated with the adhesive. Finally paraformaldehyde (0.5%) was added and the mixture pressed to shape in an iron mould using a hot press at 120°C for a press time of 30 min. Boards containing 100% of each lignocellulosic waste and blends of 80:20, 60:40, 50:50, 40:60 and 20:80 (rubber pod:cashewnut shell) were prepared as shown in Table 1. 2.5. Testing of particle boards The static bending strength test was carried out on dry and wet boards according to Annual Handbook of
The characteristics of particle boards prepared from the two lignocellulosic wastes independently and in blends are shown in Table 1. The boards produced had speci®c gravity in the range 1.01±1.30 and an average thickness of 1.2 cm. From Table 1, it is clear that board 1 produced using 100% rubber pod shell gave a higher bending strength than board 7 produced using 100% spent cashewnut shell. Board 3, containing rubber pod shell (60%) and cashewnut shell (40%) gave the highest dry bending strength. The ASTM requirements for boards specify a minimum bending strength of 1:65 106 N/m2 for construction-grade building board, 9:65 105 N/m2 for roo®ng board and 1:38 106 N/m2 for interior wallboard (Annual Handbook of ASTM, 1975). From Table 1, the boards satis®ed the ASTM requirements for all grades of boards. The commercial board, used as control, satis®ed only the ASTM requirement for roo®ng board. Table 1 shows the change in the bending strength of the boards on immersion in water. In all cases, the boards showed a time-dependent loss of strength. Board 7 showed the highest level of strength retention even
Table 1 Properties of particle boards from bioresourcesa Board no.
1
Rubber pod shell (100%)
2
7
Rubber pod shell (80%) Spent cashewnut shell (20%) Rubber pod shell (60%) Spent cashewnut shell (40%) Rubber pod shell (50%) Spent cashewnut shell (50%) Rubber pod shell (40%) Spent cashewnut shell (60%) Rubber pod shell (20%) Spent cashewnut shell (80%) Spent cashewnut shell (100%)
8
Commercial grade board
3 4 5 6
a b
Materials usedb
Board thickness (cm)
1.30 (0.03) 1.25 (0.02) 1.25 (0.02) 1.20 (0.03) 1.20 (0.06) 1.20 (0.05) 1.15 (0.06) 1.20 ±
Speci®c gravity
Bending strength ( 106 N/m2 ) Dry
% strength retention after 24 h immersion
Wet Immersion in water
1.10 (0.02) 1.09 (0.03) 1.08 (0.01) 1.06 (0.02) 1.05 (0.02) 1.03 (0.01) 1.01 (0.02) 1.01 (0.01)
1.84 (0.14) 1.79 (0.13) 1.86 (0.15) 1.84 (0.12) 1.79 (0.09) 1.81 (0.16) 1.82 (0.18) 1.29 (0.08)
S.D. are shown in parentheses. For boards 1±7, 20% w/w adhesive resin and 0.5% paraformaldehyde were used.
After 2 h
After 5 h
After 24 h
1.62 (0.07) 1.59 (0.08) 1.69 (0.11) 1.70 (0.09) 1.67 (0.10) 1.69 (0.11) 1.73 (0.07) 1.12 (0.06)
1.45 (0.08) 1.46 (0.09) 1.56 (0.07) 1.61 (0.08) 1.58 (0.06) 1.63 (0.07) 1.68 (0.06) 0.97 (0.05)
1.06 (0.03) 1.09 (0.03) 1.23 (0.02) 1.31 (0.04) 1.40 (0.02) 1.45 (0.03) 1.52 (0.05) 0.74 (0.03)
57.6 60.8 66.2 71.2 78.2 80.1 83.5 57.4
O. Akaranta / Bioresource Technology 75 (2000) 87±89 Table 2 Water absorption characteristics of boardsa Board no. 1 2 3 4 5 6 7 8 a
% Water absorption after immersion for:
Swelling ratio after immersion in water for:
2h
5h
24 h
2h
5h
24 h
4.6 (0.03) 3.8 (0.01) 3.2 (0.01) 2.7 (0.03) 2.1 (0.02) 2.1 (0.02) 1.8 (0.01) 4.8 (0.02)
9.1 (0.03) 8.4 (0.04) 7.6 (0.02) 6.4 (0.03) 5.8 (0.01) 5.3 (0.02) 3.5 (0.02) 9.4 (0.03)
37.8 (0.06) 36.1 (0.09) 33.2 (0.07) 28.4 (0.07) 22.1 (0.05) 20.3 (0.05) 17.2 (0.04) 38.4 (0.06)
1.10 (0.02) 1.08 (0.04) 1.07 (0.03) 1.06 (0.02) 1.05 (0.02) 1.03 (0.01) 1.02 (0.02) 1.09 (0.03)
1.12 (0.03) 1.11 (0.03) 1.09 (0.01) 1.08 (0.02) 1.07 (0.02) 1.06 (0.03) 1.05 (0.04) 1.14 (0.02)
1.27 (0.04) 1.25 (0.04) 1.21 (0.02) 1.18 (0.03) 1.12 (0.01) 1.11 (0.02) 1.09 (0.02) 1.26 (0.01)
S.D. are shown in parentheses.
after immersion in water for 24 h. As the cashewnut shell content of the boards increased, the wet strength increased. The speci®c gravity values of the boards did not show any direct relationship with the bending strengths. However, the dierences in the speci®c gravity values of the boards suggest anatomical, physical and chemical dierences in the make up of the boards. The results of the water absorption tests are shown in Table 2. Results indicated high water resistance for most of the boards, with board 7 showing the least absorption of 17.2% after 24 h of immersion in water. The commercial board showed the highest water absorption of 38.4%. Table 2 also shows that the swelling ratio of board 7 after 24 h immersion in water was less than the values obtained for other boards.
89
In general, the results in Tables 1 and 2 show that cashewnuts could be fully exploited by production of cashewnut-shell liquid for adhesive resins and spent shells which can be used as a source of lignocellulosic material for particle boards. The boards would be suitable for out-door use. References Akaranta, O., 1996. Raw materials from agricultural wastes for surface coatings. Surf. Coating Int. 79 (4), 152±154. Akaranta, O., Donbebe, W., Odozi, T.O., 1996. Plywood adhesives based on red onion skin extract modi®ed with cashewnut-shell liquid. Biores. Technol. 56, 279±280. Akaranta, O., Nwaneri, O., Nworgu, S., 1994. Oleoresinous wood varnishes from modi®ed extracts of red onion and peanut skins. J. Appl. Sci. Manufacture Technol. 1, 41±49. Akaranta, O., Osuji, L.C., 1997. Carboxymethylation of orange mesocarp cellulose and its utilization in drilling mud formulations. Cellu. Chem. Technol. 31, 193±197. Akaranta, O., Wankasi, D., 1998. Development of wood adhesives using ¯avonoid±glycosides from orange mesocarp. Pigment Resin Technol. 27 (3), 175±179. Annual Handbook of ASTM (1975). Speci®cations for construction grade building boards, ASTM C208-58. Annual Handbook of ASTM (1977). Standard Methods for establishing wood strength values, ASTM D1037-60T. Coppens, H.A., Santana, M.A.E., Pastore, F.J., 1980. Tannin± formaldehyde condensates for exterior grade plywood and particle board manufacture. For. Prod. J. 30, 38±42. Ebwele, R.O., Peters, O.A., Olayemi, J.Y., 1984. Development of wood products adhesives from mangrove bark. J. Appl. Poly. Sci. 29, 1415±1419. Odozi, T.O., Agiri, G.O., 1986. Wood adhesives from modi®ed red onion skin tannin extract. Agric. Wastes 17, 59±65. Odozi, T.O., Akaranta, O., Ejike, P.N., 1986. Particle boards from agricultural wastes. Agric. Wastes 16, 237±240. Roy, A.K., Sardar, D., Sen, S.K., 1989. Jute stick lignin-based adhesives for particles boards. Biol. Wastes 27, 63±66. Sampathrajan, A., Vijayaraghavan, N.C., Swaminathan, K.R., 1991. Acoustic aspects of farm residue-based particle boards. Biores. Technol. 35, 67±71.
Short communication
Production of particle boards from bioresources O. Akaranta Department of Pure and Industrial Chemistry, University of Port Harcourt, Port Harcourt, Nigeria Received 28 June 1999; received in revised form 8 February 2000; accepted 16 February 2000
Abstract Particle boards of 1.2 cm thickness were prepared from rubber seed pod, cashewnut shell, and their blends, using an adhesive resin based on cashewnut-shell liquid. Performance evaluation showed that the boards satis®ed the ASTM speci®cations for construction-grade building boards. The bending strength, water resistance and swelling ratio of the boards were better than those obtained for a commercial board. The results also showed that cashewnuts can be fully exploited by production of cashewnut-shell liquid for adhesive resins and spent shells which can be used as a source of lignocellulosic material for particle boards. Ó 2000 Elsevier Science Ltd. All rights reserved. Keywords: Particle boards; Rubber seed pod; Cashewnut shell; Adhesive resin
1. Introduction The quantities of agricultural wastes, bioresources, are increasing in developing countries due to increase in agricultural activities. Such agricultural wastes have remained largely under-utilized owing to lack of the technology for their eective utilization. The increasing demand for industrial raw materials and the realization that most natural resources, especially minerals, are non-renewable have brought agricultural wastes into focus as a potential source of raw materials. In recent years a great deal of attention has been given to the conversion of agricultural wastes into valueadded products (Coppens et al., 1980; Roy et al., 1989; Sampathrajan et al., 1991; Akaranta et al., 1996; Akaranta, 1996; Akaranta and Osuji, 1997; Akaranta and Wanksai, 1998). Of particular note is that most of such conversion processes treat each type of waste as an independent entity. As a result, amounts of many agricultural wastes generated may be deemed too small to sustain waste conversion schemes. However, if wastes from dierent agricultural sources are combined, based on their chemical composition and/or physical properties, the problem may be overcome. In this connection, Odozi et al. (1986) described the use of blends of mangrove bark, corn cob and sugarcane bagasse for the production of particle boards of considerable strength and durability. The production of particle boards using agricultural wastes is expected to increase, particularly in developing countries, due to the declining potentials of the forests in such countries.
Apart from lignocellulosic materials, adhesive or binder is another important raw material for the production of particle boards. Researches into the development of phenol±formaldehyde (PF) types of resins from bioresources have been reported (Ebwele et al., 1984; Odozi and Agiri, 1986; Akaranta and Wankasi, 1988). The research ®ndings are in favour of partial or full replacement of phenol in PF type of resin intended as wood adhesives. The use of red onion skin extract modi®ed with cashewnut-shell liquid as wood adhesive has been reported (Akaranta et al., 1996). It was the aim of the present study to investigate the potentials of cashewnut-shell liquid, red onion skin, rubber pod and spent cashewnut shells in the production of particle boards. 2. Methods 2.1. Materials The lignocellulosic wastes used for the production of the boards had the following compositions: spent cashewnut shell ± cellulose 14.1%; lignin 3.4%; rubber pod shell ± cellulose 32.2%; lignin 6.9%. The rubber pod and spent cashewnut shells were disintegrated independently using a laboratory mill and sieved through a 60 mesh screen. The particles retained were dried in the oven to a moisture content of 10±12%. Red onion skin was used as a source of natural phenols for the production of the adhesive resin.
0960-8524/00/$ - see front matter Ó 2000 Elsevier Science Ltd. All rights reserved. PII: S 0 9 6 0 - 8 5 2 4 ( 0 0 ) 0 0 0 3 5 - 3
88
O. Akaranta / Bioresource Technology 75 (2000) 87±89
2.2. Extraction of cashewnut-shell liquid Cashewnut shells (500 g) were extracted with 1.251 of ether using a soxhlet extractor according to Akaranta et al. (1994). The extract solution was stripped of the solvent by distillation to give a dark brown liquid with average yield of 24.8%.
ASTM (1997) using an Avery dension universal testing machine. All board samples were tested for speci®c gravity, water absorption and bulk swelling on immersion in water. Each test value reported is an average of ®ve board samples.
3. Results and discussion
2.3. Preparation of adhesive resin The method used in the preparation of the adhesive resin has been described elsewhere (Akaranta and Wanksai, 1998). It involves reacting red onion skin extract with formaldehyde under alkaline conditions, with the resultant resin modi®ed with cashewnut-shell liquid. 2.4. Preparation of particle boards Particle boards of about 1.2-cm thick were prepared using 20% resin content. A known weight of the lignocellulosic waste was treated with the adhesive. Finally paraformaldehyde (0.5%) was added and the mixture pressed to shape in an iron mould using a hot press at 120°C for a press time of 30 min. Boards containing 100% of each lignocellulosic waste and blends of 80:20, 60:40, 50:50, 40:60 and 20:80 (rubber pod:cashewnut shell) were prepared as shown in Table 1. 2.5. Testing of particle boards The static bending strength test was carried out on dry and wet boards according to Annual Handbook of
The characteristics of particle boards prepared from the two lignocellulosic wastes independently and in blends are shown in Table 1. The boards produced had speci®c gravity in the range 1.01±1.30 and an average thickness of 1.2 cm. From Table 1, it is clear that board 1 produced using 100% rubber pod shell gave a higher bending strength than board 7 produced using 100% spent cashewnut shell. Board 3, containing rubber pod shell (60%) and cashewnut shell (40%) gave the highest dry bending strength. The ASTM requirements for boards specify a minimum bending strength of 1:65 106 N/m2 for construction-grade building board, 9:65 105 N/m2 for roo®ng board and 1:38 106 N/m2 for interior wallboard (Annual Handbook of ASTM, 1975). From Table 1, the boards satis®ed the ASTM requirements for all grades of boards. The commercial board, used as control, satis®ed only the ASTM requirement for roo®ng board. Table 1 shows the change in the bending strength of the boards on immersion in water. In all cases, the boards showed a time-dependent loss of strength. Board 7 showed the highest level of strength retention even
Table 1 Properties of particle boards from bioresourcesa Board no.
1
Rubber pod shell (100%)
2
7
Rubber pod shell (80%) Spent cashewnut shell (20%) Rubber pod shell (60%) Spent cashewnut shell (40%) Rubber pod shell (50%) Spent cashewnut shell (50%) Rubber pod shell (40%) Spent cashewnut shell (60%) Rubber pod shell (20%) Spent cashewnut shell (80%) Spent cashewnut shell (100%)
8
Commercial grade board
3 4 5 6
a b
Materials usedb
Board thickness (cm)
1.30 (0.03) 1.25 (0.02) 1.25 (0.02) 1.20 (0.03) 1.20 (0.06) 1.20 (0.05) 1.15 (0.06) 1.20 ±
Speci®c gravity
Bending strength ( 106 N/m2 ) Dry
% strength retention after 24 h immersion
Wet Immersion in water
1.10 (0.02) 1.09 (0.03) 1.08 (0.01) 1.06 (0.02) 1.05 (0.02) 1.03 (0.01) 1.01 (0.02) 1.01 (0.01)
1.84 (0.14) 1.79 (0.13) 1.86 (0.15) 1.84 (0.12) 1.79 (0.09) 1.81 (0.16) 1.82 (0.18) 1.29 (0.08)
S.D. are shown in parentheses. For boards 1±7, 20% w/w adhesive resin and 0.5% paraformaldehyde were used.
After 2 h
After 5 h
After 24 h
1.62 (0.07) 1.59 (0.08) 1.69 (0.11) 1.70 (0.09) 1.67 (0.10) 1.69 (0.11) 1.73 (0.07) 1.12 (0.06)
1.45 (0.08) 1.46 (0.09) 1.56 (0.07) 1.61 (0.08) 1.58 (0.06) 1.63 (0.07) 1.68 (0.06) 0.97 (0.05)
1.06 (0.03) 1.09 (0.03) 1.23 (0.02) 1.31 (0.04) 1.40 (0.02) 1.45 (0.03) 1.52 (0.05) 0.74 (0.03)
57.6 60.8 66.2 71.2 78.2 80.1 83.5 57.4
O. Akaranta / Bioresource Technology 75 (2000) 87±89 Table 2 Water absorption characteristics of boardsa Board no. 1 2 3 4 5 6 7 8 a
% Water absorption after immersion for:
Swelling ratio after immersion in water for:
2h
5h
24 h
2h
5h
24 h
4.6 (0.03) 3.8 (0.01) 3.2 (0.01) 2.7 (0.03) 2.1 (0.02) 2.1 (0.02) 1.8 (0.01) 4.8 (0.02)
9.1 (0.03) 8.4 (0.04) 7.6 (0.02) 6.4 (0.03) 5.8 (0.01) 5.3 (0.02) 3.5 (0.02) 9.4 (0.03)
37.8 (0.06) 36.1 (0.09) 33.2 (0.07) 28.4 (0.07) 22.1 (0.05) 20.3 (0.05) 17.2 (0.04) 38.4 (0.06)
1.10 (0.02) 1.08 (0.04) 1.07 (0.03) 1.06 (0.02) 1.05 (0.02) 1.03 (0.01) 1.02 (0.02) 1.09 (0.03)
1.12 (0.03) 1.11 (0.03) 1.09 (0.01) 1.08 (0.02) 1.07 (0.02) 1.06 (0.03) 1.05 (0.04) 1.14 (0.02)
1.27 (0.04) 1.25 (0.04) 1.21 (0.02) 1.18 (0.03) 1.12 (0.01) 1.11 (0.02) 1.09 (0.02) 1.26 (0.01)
S.D. are shown in parentheses.
after immersion in water for 24 h. As the cashewnut shell content of the boards increased, the wet strength increased. The speci®c gravity values of the boards did not show any direct relationship with the bending strengths. However, the dierences in the speci®c gravity values of the boards suggest anatomical, physical and chemical dierences in the make up of the boards. The results of the water absorption tests are shown in Table 2. Results indicated high water resistance for most of the boards, with board 7 showing the least absorption of 17.2% after 24 h of immersion in water. The commercial board showed the highest water absorption of 38.4%. Table 2 also shows that the swelling ratio of board 7 after 24 h immersion in water was less than the values obtained for other boards.
89
In general, the results in Tables 1 and 2 show that cashewnuts could be fully exploited by production of cashewnut-shell liquid for adhesive resins and spent shells which can be used as a source of lignocellulosic material for particle boards. The boards would be suitable for out-door use. References Akaranta, O., 1996. Raw materials from agricultural wastes for surface coatings. Surf. Coating Int. 79 (4), 152±154. Akaranta, O., Donbebe, W., Odozi, T.O., 1996. Plywood adhesives based on red onion skin extract modi®ed with cashewnut-shell liquid. Biores. Technol. 56, 279±280. Akaranta, O., Nwaneri, O., Nworgu, S., 1994. Oleoresinous wood varnishes from modi®ed extracts of red onion and peanut skins. J. Appl. Sci. Manufacture Technol. 1, 41±49. Akaranta, O., Osuji, L.C., 1997. Carboxymethylation of orange mesocarp cellulose and its utilization in drilling mud formulations. Cellu. Chem. Technol. 31, 193±197. Akaranta, O., Wankasi, D., 1998. Development of wood adhesives using ¯avonoid±glycosides from orange mesocarp. Pigment Resin Technol. 27 (3), 175±179. Annual Handbook of ASTM (1975). Speci®cations for construction grade building boards, ASTM C208-58. Annual Handbook of ASTM (1977). Standard Methods for establishing wood strength values, ASTM D1037-60T. Coppens, H.A., Santana, M.A.E., Pastore, F.J., 1980. Tannin± formaldehyde condensates for exterior grade plywood and particle board manufacture. For. Prod. J. 30, 38±42. Ebwele, R.O., Peters, O.A., Olayemi, J.Y., 1984. Development of wood products adhesives from mangrove bark. J. Appl. Poly. Sci. 29, 1415±1419. Odozi, T.O., Agiri, G.O., 1986. Wood adhesives from modi®ed red onion skin tannin extract. Agric. Wastes 17, 59±65. Odozi, T.O., Akaranta, O., Ejike, P.N., 1986. Particle boards from agricultural wastes. Agric. Wastes 16, 237±240. Roy, A.K., Sardar, D., Sen, S.K., 1989. Jute stick lignin-based adhesives for particles boards. Biol. Wastes 27, 63±66. Sampathrajan, A., Vijayaraghavan, N.C., Swaminathan, K.R., 1991. Acoustic aspects of farm residue-based particle boards. Biores. Technol. 35, 67±71.