Effects of Polymer Impregnation on Properties of Bamboo
Keywords:Flattened bamboo, phenol-formaldehyde adhesive, diphenylmethane diisocyanate adhesive, polymer impregnation
This research is targeted to investigate the effects of polymer impregnation on the properties of bamboo. Polymer impregnation can improve adhesion of flattened bamboo and also improve the resistance of polymer-impregnated bamboo to fungi. During the flattening bamboo process, linseed oil was used as a processing aid. Two different kinds of solvents, methanol and ethanol, were used to extract linseed oil. Weights of samples before and after extraction were compared. Ethanol is a better solvent than methanol to extract linseed oil since weight loss is higher. The flattened bamboo samples were adhered together by phenol-formaldehyde (PF) adhesive or polymeric diphenylmethane diisocyanate (MDI) adhesive. The adhesion test was performed in shear mode. Sample extracted with ethanol and adhered by MDI gave a maximum shear stress of 5.84 MPa while samples extracted with methanol and adhered by PF gave only 2.45 MPa. A higher percentage of wood failure was observed in samples with higher adhesion strength. In durability to fungi, a polymer-wood composite was made by impregnation of methyl methacrylate in the wood under vacuum. The composite showed better resistance to fungi, especially, in nodes. Nodes have a lower densities and less effective packing of fibers than internodes. Therefore monomers can diffuse into node and then polymerize. More polymer loading gives better durability to fungi.
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