As a concrete pouring formwork, bamboo curtain plywood has a prominent feature that it can be recycled many times, which can greatly reduce the cost of concrete pouring works. However, the premise of this feature is that the plasticized layer on the surface of the bamboo plywood should have good aging resistance, otherwise it will be difficult to achieve by repeated use.
The aging of the plasticized layer on the surface of the bamboo curtain plywood is mainly characterized by darkening of the color, loss of gloss, reduction of surface flatness, peeling of the plasticized layer, and cracking on the surface. Since the bamboo curtain plywood is not used as a decorative material, the surface color becomes dark and the gloss fades is not a major problem. The surface flatness is reduced, the plasticized layer is peeled off, surface cracks and other defects directly affect the product use effect and service life. Therefore, this paper will focus on the characteristics, formation mechanism and corresponding countermeasures of these aging phenomena.
1 aging characteristics of plasticized layer
1.1 The brittleness of the plasticized layer
The plasticized layer on the surface of the bamboo plywood is made of phenolic resin or melamine formaldehyde resin as the adhesive, and the blister paper obtained by immersing and drying the base paper (generally kraft paper containing less water repellent), and the bamboo mat bamboo mat , formed by hot pressing. Since both the phenolic resin and the melamine resin have the characteristics of large brittleness, the plasticized layer on the surface of the bamboo plywood also has greater brittleness.
This brittleness is an inherent property present inside the plasticized layer. It has the potential characteristics and, in general, does not appear to be a defined extrinsic feature. However, when the plasticized layer is subjected to external forces such as impact and stretching, cracking, peeling, and internal bonding strength are likely to occur. In severe cases, even breakage occurs, and fine fragments are detached from the substrate. This kind of brittleness is not concealed because it is concealed. Under normal circumstances, it does not appear in appearance. Therefore, it is often not noticed by people.
1.2 crack of the plasticized layer
There are two kinds of cracks in the plasticized layer, one of which is cracking; the other is cracking. These two cases are not apparently different from the outside, but the internal mechanisms they form are different. This defect can see some curved, irregular fine cracks on the surface of the plasticized layer. In addition to its own role, the formation of these cracks is also one of the direct causes of cracking.
1.3 Peeling of plasticized layer and substrate
Under normal circumstances, the plasticized layer on the surface of the bamboo plywood should be firmly bonded to the substrate, but when the aging phenomenon occurs, the plasticized layer is separated from the substrate or the bonding strength of the two is significantly reduced.
1.4 Plasticized layer deformation
The plasticized layer on the surface of the bamboo plywood can make the surface of the product smooth and flat, produce a hot press molding, and create conditions for the smoothness of the surface of the product. However, after the product is used for a period of time, the plasticized layer is deformed due to the aging effect of the plasticized layer, and some parts of the cemented surface are damaged or the bonding strength is lowered, and the surface is locally raised at the surface of the surface, thereby The flatness of the entire board is reduced.
The aging of the plasticized layer on the surface of the bamboo curtain plywood is mainly characterized by darkening of the color, loss of gloss, reduction of surface flatness, peeling of the plasticized layer, and cracking on the surface. Since the bamboo curtain plywood is not used as a decorative material, the surface color becomes dark and the gloss fades is not a major problem. The surface flatness is reduced, the plasticized layer is peeled off, surface cracks and other defects directly affect the product use effect and service life. Therefore, this paper will focus on the characteristics, formation mechanism and corresponding countermeasures of these aging phenomena.
1 aging characteristics of plasticized layer
1.1 The brittleness of the plasticized layer
The plasticized layer on the surface of the bamboo plywood is made of phenolic resin or melamine formaldehyde resin as the adhesive, and the blister paper obtained by immersing and drying the base paper (generally kraft paper containing less water repellent), and the bamboo mat bamboo mat , formed by hot pressing. Since both the phenolic resin and the melamine resin have the characteristics of large brittleness, the plasticized layer on the surface of the bamboo plywood also has greater brittleness.
This brittleness is an inherent property present inside the plasticized layer. It has the potential characteristics and, in general, does not appear to be a defined extrinsic feature. However, when the plasticized layer is subjected to external forces such as impact and stretching, cracking, peeling, and internal bonding strength are likely to occur. In severe cases, even breakage occurs, and fine fragments are detached from the substrate. This kind of brittleness is not concealed because it is concealed. Under normal circumstances, it does not appear in appearance. Therefore, it is often not noticed by people.
1.2 crack of the plasticized layer
There are two kinds of cracks in the plasticized layer, one of which is cracking; the other is cracking. These two cases are not apparently different from the outside, but the internal mechanisms they form are different. This defect can see some curved, irregular fine cracks on the surface of the plasticized layer. In addition to its own role, the formation of these cracks is also one of the direct causes of cracking.
1.3 Peeling of plasticized layer and substrate
Under normal circumstances, the plasticized layer on the surface of the bamboo plywood should be firmly bonded to the substrate, but when the aging phenomenon occurs, the plasticized layer is separated from the substrate or the bonding strength of the two is significantly reduced.
1.4 Plasticized layer deformation
The plasticized layer on the surface of the bamboo plywood can make the surface of the product smooth and flat, produce a hot press molding, and create conditions for the smoothness of the surface of the product. However, after the product is used for a period of time, the plasticized layer is deformed due to the aging effect of the plasticized layer, and some parts of the cemented surface are damaged or the bonding strength is lowered, and the surface is locally raised at the surface of the surface, thereby The flatness of the entire board is reduced.
Slate is a rock with a plate-like structure and basically no re-crystallization. It is a metamorphic rock.
The original rock is argillaceous, silty or neutral tuff, which can be stripped along the direction of the slab.
The color of the slate varies with the impurities it contains.Slate is a characteristic slab-like structure.
Shallow metamorphic rocks are formed by clay stone, silty sedimentary rocks or medium-acid tuff rocks and sedimentary tuff.
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