Designing the Epoxy Adhesive Formulations for Manufacturing Engineered Woods

Utai Meekum, Waree Wongkheeree

Abstract


The design of an epoxy adhesive was investigated by a 2K design of experiment (DOE). All the assigned parameters showed no significant effect for both curing and mechanical properties, except for bisphenol A (BPA), which showed a significantly negative effect on the heat distortion temperature (HDT) of the cured samples. Adding dicyandiamine (DICY) into the hardener retarded cure time and also caused an incomplete curing at room temperature. Curing at 110 °C and 150 °C post curing were the optimal conditions and 20 g of DICY with 50 g of triethylenetetramine (TETA) was optimized. Adduct obtained from aliphatic epoxy (RD108, 14.63 g) and TETA (7.71 g) were selected and employed as hardener ingredients. The incomplete crosslinking reaction was the main reason for the inferior properties at high RD108 loadings. The toughening by blending with polycarbonate (PC) was explored, and 5 phr of PC was selected. Limitation of resin/fiber infusion due to high viscosity was observed. Dilution of the solvents using ethyl acetate (EA) and methyl ethyl ketone (MEK) to reduce viscosity was explored. The mechanical properties of the wood samples manufactured from the EA-diluted epoxy were superior to the MEK dilution. The lower boiling point and good solubility of EA were explained.

Keywords


Epoxy adhesives; Engineered wood; Mechanical and durability properties

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