Study On Preparation And Performance Analysis Of Super-hydrophobic Composite Coating On Paper Mulch

Chinese agricultural mulch is mainly plastic mulch,plastic mulch is not easy to degrade,containing ingredients have potential harm,long-term use of plastic mulch in addition to causing white pollution to the environment,serious may also cause soil loss of cultivation value.In order to better protect the cultivated land environment,the research of environmental protection mulch has become a hot spot.Environmental protection mulch can be divided into degradable plastic mulch liquid biological mulch and paper base film.Biodegradable plastic mulch is easy to produce microplastics after decomposition,while liquid biofilm has poor mechanical properties and is not easy to use on a large scale,which limits the development of these two kinds of environmental protection mulch.Paper mulch has become a substitute for traditional plastic mulch because of its environmental protection and excellent degradability.It is an inevitable trend to develop paper base mulch to reduce white pollution.Paper mulching film is often affected by rainfall,light,temperature and other external factors in the process of field mulching,resulting in moisture,aging and mechanical properties decline of paper mulching film,thus affecting crop yield under paper mulching film.Therefore,in order to obtain better environmental adaptability and mechanical properties of paper mulching film,this study prepared ZnO/SiO₂composite coated paper mulching film by self-assembly brush coating method on the basis of existing paper mulching film.Rain weather,exposure mode,and high and low temperature conditions were simulated during the use of mulching film,and relevant indexes of wettability,mechanical properties,dry heat aging properties,ultraviolet aging properties,wear resistance,permeability and low temperature properties of composite coated paper mulching film and original paper mulching film were tested,and the changing rules of the properties of composite coated paper mulching film under different environmental conditions were studied.It provides a theoretical and experimental basis for the application of ZnO/SiO₂ composite coated paper mulching film in the field.The main research results are as follows:（1）Brush coating method was used to prepare three different coating material content ZnO/SiO₂ composite coated paper mulching film（2%,4%,6%）,through infrared analysis,particle size analysis,measurement of contact Angle,rolling Angle,mechanical stability experiment,The best concentration of ZnO/SiO₂ composite coated paper mulching film is selected by scanning electron microscopy,three-dimensional morphology and roughness measuring instrument.Among them,the paper mulching film with 4%coating substance content has better mechanical durability,larger static contact Angle and smaller rolling Angle.Through acid,base and salt corrosion test and self-cleaning,it is proved that the surface of ZnO/SiO₂composite paper mulching material with coating substance content of 4%has better acid and alkaline resistance and cleaning ability,and has less adhesion to droplets.Combined with the surface morphology and surface roughness of coated paper mulching film,the distribution of ZnO/SiO₂ particles in coated paper mulching film at4%concentration is more uniform,which is conducive to the particle construction of rough structure on the surface of paper mulching film,so that paper mulching film can obtain superhydrophobic properties.（2）Through stretching and tearing experiments,mechanical properties of ZnO/SiO₂composite coated paper mulching film and original paper mulching film with 4%coating substance content were compared at different temperatures,and mechanical properties and thermal stability of original paper mulching film and ZnO/SiO₂ composite coated paper mulching film were analyzed by scanning electron microscopy and thermogratings.The results show that ZnO/SiO₂ composite coating can improve the mechanical properties and mechanical durability of paper mulching film,and the mechanical properties are more obvious at high temperature.The mechanical properties of coated paper mulch at different temperatures are improved to a certain extent compared with the original paper mulch.Combined with the phenomenon that the pores between the fibers on the surface of coated paper mulch are filled by particles,it shows that the particle coating improves the binding force between the fibers inside the paper mulch,thus enhancing the mechanical properties of the paper mulch.（3）A thermal blast drying oven and ultraviolet accelerated weathering test box were used to conduct dry-heat aging and ultraviolet aging comparison tests between the ZnO/SiO₂ composite coated paper mulching film with 4%coating substance content and the original paper mulching film.The dry heat aging test results in the shrinkage of the fibers inside the original paper mulch,resulting in the increase of pores between the fibers,which leads to the decrease of the mechanical properties and hydrophobic properties of the paper mulch.After the modification of the ZnO/SiO₂composite coating,the pores inside the paper mulch fibers are filled with particles,which leads to the enhancement of the binding force between the fibers.Thus,the effect of dry heat aging on mechanical properties and hydrophobic properties of paper mulching film can be effectively reduced.The ZnO/SiO₂ composite coating can protect the paper mulching film from ultraviolet light,so that the paper mulching film still maintains good mechanical properties after ultraviolet.In addition,the composite coated paper mulching film still maintains superhydrophobic properties,self-cleaning properties and bouncing properties after ultraviolet aging.（4）In order to verify the wear resistance of mulching film laying process,friction testing machine,scanning electron microscope and three-dimensional topography instrument were used to analyze and compare the morphologies of the original paper mulching film and the paper mulching film with ZnO/SiO₂ composite coating material content of 4%after friction and wear,as well as the hydrophobicity of the surface after wear.The results show that ZnO/SiO₂ composite coating can modify and fill the paper mulching film,reduce the surface porosity,improve the adhesion between fibers,and improve the wear resistance,hydrophobicity and durability of the paper mulching film.（5）In order to study the influence of rain on the erosion durability,hydrophobicity and mechanical stability of the paper base film,the paper film was soaked,permeated and mechanical comparison experiments.By comparing the permeability and mechanical properties of the original paper mulching film and the coating material content of 4%ZnO/SiO₂ composite coated paper mulching film under different soaking conditions,it is found that the ZnO/SiO₂ composite coated paper mulching film has better permeability resistance,and no water can penetrate the surface of the paper mulching film after soaking for 240 h.In addition,the mechanical properties of the two kinds of paper mulch decreased after soaking.The mechanical properties of ZnO/SiO₂ composite coated paper mulching film are improved compared with the original paper mulching film,and the ability to adapt to complex environment is stronger.（6）Through the study of the self-cleaning,bouncing and delay icing properties of the original paper mulching film and coating material content of 4%ZnO/SiO₂composite coated paper mulching film at low temperature,we found that:ZnO/SiO₂composite coated paper mulching film has better self-cleaning performance and bouncy performance at low temperature,and with the decrease of temperature,the horizontal bouncy and inclined bouncy performance of coated paper mulching film decrease due to the increase of surface adhesion.The ZnO/SiO₂ composite coated paper mulching film has better icing delay performance than the original paper mulching film,which makes the coated paper mulching film have better environmental adaptability at low temperature.To sum up,through the preparation of ZnO/SiO₂ composite coated paper mulching film and the comparison with the performance of the original paper mulching film,it is found that ZnO/SiO₂ composite coating can obtain better mechanical properties and hydrophobic properties by constructing micro-rough structure on the surface of the paper mulching film and filling the pores between the fibers inside the paper mulching film.In addition,the coating paper film can maintain good hydrophobic and mechanical properties under dry heat aging,ultraviolet aging,water penetration and low temperature environment.Therefore,this kind of coated paper mulch can effectively prevent the performance decline of paper mulch due to environmental and climate change problems,which will affect the yield of crops,so that paper mulch can be popularized as an environmentally friendly alternative to plastic mulch in different geographical environments.