Effect Of Wax Removing On The Surface Color And Green Colour Preservation Treatment Of Moso Bamboo Culms

Bamboo surface color plays an important role in increasing the added value of its products.The surface of bamboo green is attached with wax,which has an important effect on the appearance texture and color of bamboo.Therefore,it is of great significance to investigate the effect of wax on the surface color of bamboo,so as to modify the color of moso bamboo.This paper takes moso bamboo（Phyllostachys pubescens）as the research object,using the way of sand blasting to remove the waxy bamboo green surface of the moso bamboo,the wax removal of the moso bamboo heat treatment,analyzed the effect of waxing on the surface color of the moso bamboo heat change;Water bath and microwave heating were used to protect the green of dewaxed moso bamboo,and the green preserving process of moso bamboo was optimized.The structural characteristics of the surface elements distribution,morphology,roughness,wettability and ultraviolet aging resistance of moso bamboo before and after green preserving were analyzed.The results can provide technical reference for surface color treatment and green protection of moso bamboo.The main research results are as follows:（1）In terms of the influence of dewaxing removal on the surface color of moso bamboo under heat,the following findings were found:The brightness L*,red and green axis chromaticity index a*and yellow and blue axis chromaticity index b*were significantly affected by heat treatment temperature and time.After being heated,the surface color of the dewaxed moso bamboo will be brighter,more yellow and more glossy than that of the unwaxed moso bamboo,while the unwaxed moso bamboo will become dark and gray after being heated.Therefore,the existence of waxy layer on the surface of moso bamboo will affect the color change of bamboo in subsequent use.In actual production,if you want to obtain yellow and bright wool moso bamboo,the bamboo surface can be treated by sand blasting to remove wax.（2）In the aspect of green preservation of dewaxing moso bamboo by water bath heating,compared with the traditional chemical green preservation method,the dewaxing treatment can effectively replace the surfactants used in the traditional chemical green preservation treatment,greatly reducing the use of chemical agents,thus reducing the cost of green preservation and subsequent waste water treatment.The optimal green preservation conditions for dewaxing moso bamboo by water bath heating are as follows:dewaxing combined with3%KOH,pretreatment for 40min,and then treated with 1%copper sulfate for 2.5h,the best green preservation effect can be presented,and the lowest a*value is-13.4.（3）In the aspect of green preservation of dewaxing moso bamboo by microwave heating,the speed of microwave heating is fast,which shortens the time required for green preservation and improves the efficiency of green preservation treatment.Microwave heating temperature had no obvious effect on the green preservation effect of moso bamboo,while water bath heating temperature had obvious effect on the green preservation effect of moso bamboo.Dewaxing and rapid microwave heating have double positive effects on improving the green preservation effect of moso bamboo and reducing the use of medicine.Two kinds of green preserving effects were obtained by microwave ACQ and Cu SO₄,respectively.The optimal green preservation conditions for microwave dewaxing of moso bamboo were as follows:dewaxing combined with 3%KOH,pretreatment for 25min,and then treated with 1%copper sulfate for 25min,which showed a better green preservation effect,with the lowest a*value of-5.71.（4）In the aspect of surface structural characteristics analysis of green preserving moso bamboo,dewaxing treatment can effectively remove the waxy layer on the surface of moso bamboo,thus exposing the distribution layer of silicon elements,improving the permeability of subsequent chemical treatment,and thus changing the surface properties of bamboo.The solvent type of microwave green preservation treatment has no obvious effect on the surface morphology of the moso bamboo samples,but the effect of wax removal is more obvious.On the whole,the color,surface morphology and surface hydrophobicity of the green preserved by water bath and microwave were similar to those of fresh moso bamboo.（5）In the aspect of aging resistance analysis of moso bamboo green preservation,the a*value of moso bamboo green preservation sample obtained under the optimal condition of water bath is still negative after 300 hours of ultraviolet irradiation,and the sample is still green.Compared with the green preserving moso bamboo samples prepared by traditional chemical methods,the green preserving moso bamboo samples in this study have stronger anti-UV aging ability,that is,stronger durability.Although the main agent of microwave heating ACQ and the treatment of copper sulfate can keep the green color of moso bamboo to a certain extent,from the perspective of its durability,the microwave copper sulfate to remove wax and preserve the green color of moso bamboo is more suitable for practical production and application.