Preparation And Properties Of PET Light-converting Composite Multifunctional Agricultural Film

Sunlight is the basis for photosynthesis of crops.However,the ultraviolet light of sunlight is harmful for the growth of most crops.The light conversion agricultural film can absorb sunlight necessary for photosynthesis of crops as the energy source,and convert the ultraviolet light that has an adverse effect on the crops into the red-orange and blue-violet light required for crops photosynthesis through the light energy conversion materials,which plays an essential role in promoting the growth and production of crops.Organic light energy conversion materials show important research value and good application prospect in the research of new type agricultural film due to their high light conversion efficiency,strong compatibility with polymer film matrix structure and good structural diversityIn this paper,the polyethylene terephthalate(PET)light conversion composite multi-functional agricultural film has been successfully prepared,which shows excellent light conversion performance and can achieve the effect of multicolor fluorescence by adjusting the ratio of light energy conversion materials and excitation wavelength.At the same time,the film also shows excellent mechanical properties and light transmittance,which is of great theoretical and practical significance for promoting the research and application of the PET light conversion agricultural film.The main results are as follows:First,the PET porous film with controllable pore structure was prepared by a coating method with PEG as the pore-forming agent by adjusting the mass percentage content of PEG,extract composition,extraction time,PEG molecular weight and other technological conditions.The test results show that after 8%PEG with different molecular weights added to the PET coating liquid under 80? coating conditions,the coated film is immersed in the mixed solution of V_ethanol:V_glycerol=4:1 for more than 72 h.The surface of the PET film can form a porous structure with adjustable pore size in the range of 50-300 nm of regular shape and uniform distribution,which provides important conditions for the further preparation of multicolor PET light conversion agricultural films with excellent performance.Then,the light conversion functional layer was coated on the PET porous film through the coating method to successfully prepare the three-primary-color PET light conversion agricultural film.The test results show that the best mass percentages of the added red,green,and blue light energy conversion materials with PET are 5%,5%and 0.5%,respectively.In the excitation light range of 270-390 nm,the three-primary-color PET light conversion agricultural film can produce six kinds of color of fluorescence,showing a multicolor fluorescence of green,cyan,blue,blue-violet and purple.The mechanical properties test shows that the prepared agricultural film samples not only have good mechanical properties,but also have a strong adhesion between the coated light conversion layer and the PET porous film,which is not easy to peel off and fall off.Finally,the waterborne polyurethane suspension and emulsion were used as protective functional layer and coated on the surface of the prepared three-primary-color PET light conversion agricultural film by the coating method to obtain the PET light conversion multi-functional agricultural film.The test results show that the surface of the film sample coated with the protective functional layer of the waterborne polyurethane emulsion is more uniform,smooth and defect-free,and exhibits good fluorescence performance.The light transmittance of the film sample can reach 80%.