Characterisation Of Selected Wood Properties Of Thermal-Modified Bambusa Vulgaris Schrad.Ex J.C.Wendl

ABSTRACT

The preservative treatment of non-durable lignocellulosic materials, such as Bambusa

vulgaris (bamboo) enhances its service life. Thermally modified lignocellulosic biomaterial

is better than chemically treated products because it is environmentally friendly. However,

there is a dearth of information on the characterisation properties of thermally modified

Bambusa vulgaris. This study was therefore conducted to characterise the properties of

thermally modified Bambusa vulgaris.

One thousand and eighty (30 cm x 2 cm x 0.5 cm) bamboo strips were thermally modified in

a heat-chamber at 100, 110, 120, 130 and 140 °C each, for 10, 20 and 30 minutes, under

constant pressure (220 N/m2) in factorial arrangement in completely randomised design with

5 replicates. Untreated strips served as control. The strips were laminated into boards using

cold press for 24 hours and Fibre Diameter (FD), Fibre Cell Wall (FCW), Fibre Lumen

Width (FLW), Fibre length (FL) were measured. The Specific Gravity (SG), Equilibrium

Moisture Content (EMC), Radial Shrinkage (RS), Water Absorption (WA), Compressive

Strength (CS┴), Modulus of Elasticity (MOE), Modulus of Rupture (MOR), Shear Strength

(SS) and Impact Bending (IB), chemical characteristics (cellulose, hemicellulose, lignin and

ash contents) were determined using standard procedures. Samples were thereafter inoculated

with Sclerotium rolfsii (Brown rot) and Pleurotus florida (White rot) using accelerated

durability test procedure for 12 weeks and assessed for Weight Loss (WL). Samples were

also assessed in Timber Grave Yard (TGY) using Weight Loss (WL) procedure. Data were

analysed using descriptive statistics, ANOVA and regression at α0.05.

The FD ranged from 11.51±2.07 μm (140°C/30 minutes) to 17.62±3.65 μm (control), FCW

ranged from 5.96±2.13 μm (140°C/30 minutes) to 12.03±3.66 μm (control), FLW ranged

from 2.64±0.12 μm (140°C/30 minutes) to 2.80±0.22 μm (control), while FL ranged from

2.05±0.28 mm (140°C/30 minutes) to 2.52±0.39 mm (control). The SG (0.6±0.1 and

0.5±0.1), EMC (10.5±1.3 and 6.8±1.2), RS (3.7±1.1and 1.6±0.6) and WA (46.6±13.5% and

32.7±2.2) were obtained in control and 140°C/30 minutes thermal-modified samples,

respectively. The RS and WA at 100, 110, 120 and 130°C/30 minutes were 0.9±0.3, 1.2±0.4,

0.6±0.1, 0.6±0.1 and 38.4±5.3, 31.1±4.7, 26.4±3.8, 29.9±4.5%, respectively. The CS┴,

MOE, MOR, SS and IB varied from 7.41±0.24, 5461.83±594.86, 18.39±2.01, 1.07±0.26

N/mm2 and 1.68±0.03 KJ/m2, respectively in 140°C/30 minutes to 36.14±0.11,

29,703.50±4192.77, 56.29±1.86, 3.88±0.50N/mm2 and 2.30±0.02 KJ/m2, respectively for

untreated samples. The cellulose (46.46±0.11% and 42.19±0.18%), hemicellulose

(35.59±0.10% and 31.80±0.01%), lignin (29.11±0.12% and 26.17±0.13%), ash (0.92±0.02%

and 0.63±0.01%) were obtained in control and 140°C/30 minutes thermal-modified samples,

respectively. The highest WL was obtained from untreated samples inoculated with

Sclerotium rolfsii (6.1±0.3%) and Pleurotus florida (5.1±0.9%), while the least WL of

1.8±0.2% and 1.1±0.2%, respectively was recorded for samples modified at 140°C/30

minutes. The WL of untreated samples in TGY was 28.2±14.1%, while the least WL

(25.1±2.9%) was observed for 140°C/30 minutes thermal-modified samples. The IB and

EMC accounted for 83.9 and 53.8% variation of chemical characteristics.

Thermal modification at 140°C for 30 minutes improved dimensional stability and durability

of Bambusa vulgaris. Increase in temperature and time of thermal modification reduced

strength properties and chemical characteristics of Bambusa vulgaris.

Keywords: Thermal modification, Wood dimensional stability, Wood durability, Bambusa

vulgaris.