| Summary: | 碩士 === 國立宜蘭大學 === 森林暨自然資源學系碩士班 === 103 === The objective of this study was to investigate the properties of three- and four-layer Moso bamboo (Phyllostachys pubescens) plywood composed of peeled veneers and carbon- fiber sheet (CFS). The bamboo plywood made from untreated veneer compared with those made from 120℃ steam-treated veneer, untreated veneer combined with carbon-fiber sheet, and untreated veneer impregnated with phenol formaldehyde resin (PF). The effects of different veneer treatments, PF contents, and hot press time on adhesive, physical, mechanical, and surface properties were investigated.
Results from type I boiling delaminating test, CNS 1349 show that plywood integrated with 60, 70 and 80 g/m2 PF spread and veneers impregnated in PF for 30 and 60 min met the standard requirement. Among them the plywood made of 60 min PF impregnated veneers indicates the best static bending and abrasion resistance properties, therefore, was chosen to compose of varied layer components into different types of plywood for the tests followed.
For plywood with CFS inner layers and adhered by PF the moisture content and moisture absorption rate are 13.79% to 33.09% and 3.41% to 32.38% lower respectively than the ones without CFS, while the densities are 0.21% to 17.66% higher. The moisture content of plywood laminated with PF impregnated veneer and CFS inner layers are 14.97% to 31.01% lower those without CFS while the density is of no significant difference. Combination with CFS in the inner layers enhanced the dimensional stability of plywood in the direction vertical to the fiber direction of board surface and the thickness direction. The three-layer PF adhered plywood passed the thermal cycling test of CNS standard.
PF adhered plywood with CFS inner layers increases the MOR vertical to the fiber direction of board surface 34% to 114% in comparison with those without CFS and the anisotropy is also reduced.
The density, MOR and MOE of plywood laminated with PF impregnated veneers increase as the number of PF impregnated veneer in the plywood increase while the moisture content is of the opposite trend. Integration of CFS into plywood laminated with PF impregnated veneers shows good dimensional stability and indicates no effects on plywood density and static bending properties.
Integration of impregnated veneer into plywood significantly increases the physical, mechanical, and surface properties while the abrasion resistance, water repellency, smoothness, and pencil hardness properties of plywood surface are also increased. The color of plywood surface is more even than that of the PF adhered plywood, however, the color and brightness of bamboo materials is altered by PF impregnation to yellowish red and dimmer which may affect the appearance of products made of it. The emission of formaldehyde content of four-layer plywood manufactured by PF adhesion or PF impregnated veneers passed the standard of “F2 grade” specified by CNS 1349.
|
|---|
