Abstract250 µm particle size of wood and polyethylene (PE) materials were compounded at mixing proportions of 60/40, 70/30, and 80/20 (with an increase in polymer to decrease in wood content) and extruded using a single screw extruder at a temperature range of 110–135 °C. The particles of Gmelina Arborea, Tectona grandis, Cordiamilleni, and Nauclea diderichii with recycled Polyethylene were compounded and compressed at 175 N/mm to produce biopolymer composites. The biopolymer composites were subjected to dimensional stability test at 24 h of the water soak method and the ability to withstand load-bearing capacity was investigated. The outcome of the results shows that extruded-compressive biopolymer composites had values ranging from 0.06–1.43 g/cm3, 0.38–3.41%, and 0.82–6.85% for observed density, water absorption, and thickness swelling at 24 h of a water soak test. The mechanical properties values ranged from 0.28 Nmm−2–21.35 Nmm−2 and 0.44–550.06 Nmm−2 for flexural modulus and strength; and 191.43 Nmm−2–1857.24 Nmm−2 and 0.35 Nmm−2–243.75 Nmm−2 for tensile modulus and strength respectively. It was observed that moisture uptake and strength displayed by the composites vary accordingly in values obtained for wood species at different mixing proportions. As observed that the more polyethylene content is compounded to wood, the better its dimensional stability, and flexural and tensile properties. The wood particles of Cordiamilleni compounded at a proportion of 60 to 40 (polyethylene/wood) performed best in dimensional stability and load-bearing capacity. This study confirmed the effect of methods on wood species and recycled PE for manufacturing wood polymer-based composite for both indoor and outdoor applications.

Abstract. Bola TS, Oluyege AO, Aina KS. 2020. Dimensional stability and tensile strength of biopolymer composite reinforced with hardwood fiber at varying proportions. Asian J For 4: 1-5. This study was designed to produce bio-composites made from three different wood species and at three different mixing ratio of plastic to wood on weight to weight basis. The main variables employed in this study are wood species of Triplochiton scleroxylon, Terminalia superba and Gmelina arborea; at plastic: wood of 40:60, 50:50, and 60:40 respectively. The composite samples were made through compounding and extrusion process. The properties evaluated were carried out in accordance with the American Standard Testing Methods of 570 and 790 to determine the dimensional stability and strength properties of the composites. The values obtained for the wood species range from 0.59 g/cm3 to 0.72 g/cm3, 0.59 % to 0.71 %, 0.63% to 0.7 %and 1.84 MPa to 2.07 MPa for density, water absorption, thickness swelling, and tensile strength respectively. Meanwhile, the values obtained from the mixing ratio range from 0.54 g/cm3 to 0.79 g/cm3, 0.53% to 0.79%, 0.42% to 1.00%, and 1.58 MPa to 2.37 MPa for density, water absorption, thickness swelling, and tensile strength respectively. It was observed that mixing ratio and wood species used in this study influenced the dimensional stability and strength properties of the WPCs. This study revealed that as the wood-flour content increased to plastic, the dimensional properties, and tensile strength values increases.

Particles of dried corn cobs were employed for manufacture of cement bonded particleboards. Two types of clay soil (red and white) were used as supplement with cement to manufacture cement bonded particleboards. The production of the boards was done at varying proportions of 50/50/0, 50/40/10, 50/30/20, 50/20/30, 50/10/40 and 50/0/50 for (corn/cement/clay) in weight to weight basis while the other considerable production factors like nominal density and curing agent percentage remained constant at 1.30 g/cm3 and 3%. The chemical composition of the soil such as pH, organic carbon, organic matter, total nitrogen, and exchangeable bases were determined. Its impact on physical and mechanical properties such as density, water absorption, thickness swelling, modulus of rupture and modulus of elasticity were also investigated The results of the analysis of variance shows that all considerable production factors for the cement bonded particleboards were significant at 5% level of probability except clay soil type for density. The results show that cement bonded particleboard made of red clay soil with higher content of exchangeable bases proves better outstanding performance in density, strength and dimensional properties than the white clay soil. Among the cement bonded particleboards made at varying proportions. It was discovered that boards of 50/20/30 (corn/cement/clay) had better strength properties than others. Also, the boards made at the proportions of 50/40/10, 50/10/40 and 50/30/20 (corn/cement/clay) were better dimensionally stabled in moisture exposure but weak in strength. The outcome of this study may serve as a guideline for any manufacturer who intends to use clay soil as supplement for production of particleboards. Keywords: Cement, particleboard, clay soil, corn cobs, strength, variance

Cement bonded particleboards (CBPs) were produced of wood particles of Gmelina arborea, Afzelia africana and Triplochiton scleroxylon using two brands of ordinary portland cement manufactured by two different domestic cement companies operating in Nigeria known as Dangote PLC and Lafarge Company. The admixture of wood particles and cement for production of the CBPs were done at mixing ratios of 1:1, 1:1.5 and 1:2 (weight to weight basis). The properties such as water absorption and thickness swelling at 24 hours, density, modulus of rupture (MOR), modulus of elasticity (MOE) and impact bending strength were determined. The results of the study reveal that the density ranged from 0.61 to 0.92 g/cm3. Meanwhile, water absorption and thickness swelling were found to be 30.34 to 72.44 % and 11.43 to 10.77 % at 24 hours, respectively. The bending properties obtained from the laboratory tests ranged from 115.77 to 826.55 N/mm2 and from 1157.70 to 4773.38 N/mm2 for MOR and MOE, respectively, while impact bending strength ranged from 41.70 to 238.49 N/mm2, respectively. As the cementious content increases from 50 % to 66.3 % and wood content decreases from 50 % to 33.4 %, the properties such as density, MOR, MOE and impact bending strength increased, while water absorption and thickness swelling decreases. The statistical results showed that such factors as wood species, cement type and mixing ratio had significant influence on the physical and mechanical properties of CBPs. The study reveals that CBPs made of wood particles of Triplochiton scleroxylon and Dangote cement brand at the ratio of 1:2 were more dimensionally stable, denser and stronger while CBPs of wood particles of Afzelia africana were stiffest and most rigid. As concluded, cement brand had significant importance in qualities of CBPs, which can be attributed to chemical compositions found in materials used. Keywords: cement, physical, mechanical, wood, particleboards, mixing ratio

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