Fungal deterioration of a novel scrimber composite made from industrially heat treated African highland bamboo

• Published in: Industrial crops and products 2020-05, Vol.147, p.112225, Article 112225
• Main Authors: Schmidt, G., Stute, T., Lenz, M.T., Melcher, E., Ressel, J.B.
• Format: Article
• Language: English
• Subjects: Bamboo scrimber; Durability; Heat treatment; Thermal modification; Wood-destroying fungi; Yushania alpina
• ISSN: 0926-6690; 1872-633X
• DOI: 10.1016/j.indcrop.2020.112225

•Heat treatment of African highland bamboo improved scrimber resistance against basidiomycete monocultures and soft rot (ground contact).•The minimum temperature to improve bamboo scrimber durability on industrial scale was 180 °C.•All treatments were classified as slightly durable (DC 4) when measuring stiffness loss, butDC 1 to 3 when looking at mass loss.•For basidiomycete monocultures all samples, treated and control, showed to be very durable (DC 1).•High mass losses due to abiotic factors occurred but reduced with increasing heat treatment temperature. A novel engineered scrimber was manufactured from heat treated African highland bamboo Yushania alpina (K. Schum.) W.C. Lin on an industrial scale. Scrimber are a group of engineered wood products that consist of long, slender particles resulting from a non-cutting defibration technique. Those are heat treated, impregnated with phenolic resin, highly densified and the product is believed to be resistant to biodegradation by wooddestroying fungi. The highland bamboo scrimber was tested for resistance against basidiomycete monocultures and soft rot in a soil bed test. The soft rot soil bed test caused nearly 20 % mass loss and 61 % stiffness loss for the scrimber made from untreated bamboo. Heat treatment reduced the ML to 5% for the 200 °C variant, whereas stiffness loss was only slightly reduced for heat treated variants. All treatment temperatures led to 50 % fungal stiffness loss. The notably high abiotic mass loss in sterile samples reduced with treatment temperature. The heat treatment did not affect the durability class resulting from the test against basidiomycete monocultures. Although the variability in heat treated samples was slightly lower, all variants achieved durability class 1. The soil bed test against soft rot resulted in durability classes 1, 2, 3 and 4. When based upon stiffness as parameter, the durability class was 4, whereas mass loss led to DC 1 for treatment at 200 °C, DC 2 for 180 and 160 °C and DC 3 for the untreated control, respectively. The development of substrate moisture content over time indicated that fungal growth can possibly be delayed via heat treatment, but not stopped. The minimum target treatment temperature to achieve a notable improvement in mass loss was 180 °C.