Preparation And Performance Study Of PET Composite Film With Anti-fog And Shading Functions

In northeast and northwest China,the winter temperature is low,the temperature difference between day and night is large,the humidity is high,the fog drops are produced much,the traditional polyethylene(PE)agricultural film has the disadvantage of poor weather resistance,poor thermal insulation,easy fog formation and so on,so it cannot be used in such areas for a long time.In addition,it’s too hot in summer,greenhouse growers usually use the shading network to cool the greenhouse,which is not only troublesome to operate but also easy to damage the greenhouse film and reduce its service life.PET film has the characteristics of good mechanical properties,good weather resistance,long service life and green recycling,which can be used as a new type of agricultural film.However,PET film has poor hydrophilicity and easy fog formation,which limits its application.In this paper,PET film was used as the base film,and the antifogging and shading performance were improved by surface coating,in order to promote the practical application of PET agricultural film.The main research results are as follows:Firstly,cellulose(Cell)was modified by homogeneous grafting,and acrylamide(AM)and acrylic acid(AA)were grafted onto cellulose skeleton.The results showed that cellulose graft copolymer Cell-g-P(AM-co-AA)was successfully prepared.Taking the water absorption rate of Cell-g-P(AM-co-AA)as the standard,the optimum process parameters of water absorption rate were obtained by changing the process conditions: when the reaction temperature was 60 ℃,the amount of initiator and crosslinker was 6 % and 3 % of cellulose mass,the total amount of monomer(AA and AM)was 10 times of cellulose mass,the mass percentage of AA and AM was 6 :1,and the grafting reaction time was 3 h,the water absorption rate of Cell-g-P(AM-co-AA)was the highest.Secondly,Cell-g-P(AM-co-AA)was prepared by using the optimum process parameters of cellulose superabsorbent graft copolymer,and the PET composite film with high water absorption and antifogging function was prepared by coating it on the surface of PET film.By characterizing the composition,structure and performance of the sample,the results show that the coating of the prepared high-efficiency water-absorbing and anti-fogging PET composite film is well combined with the PET base film,the cross section of the coating shows a layered pore structure,and the surface of the coating is uniform and the roughness is low.Superabsorbent antifogging PET composite film can rapidly spread and absorb water on its surface,has excellent anti-fogging performance,and the coating can also quickly self-repair scratches in high humidity environment.Finally,the spiropyran compound(SPEA)containing vinyl reaction group was modified with methyl methacrylate(MMA)by seed emulsion polymerization to prepare PMMA-co-PSPEA copolymer,and PMMA-co-PSPEA was coated with PET film to prepare PET shading composite film.A series of tests showed that PMMA-co-PSPEA Copolymer was successfully prepared,and PMMA-co-PSPEA Copolymer had good photochromism and fatigue resistance.The test of PET shading composite film shows that the composite film coating coated with 6 wt% and 9 wt%PMMA-co-PSPEA polymerization solution on the surface of PET film is relatively uniform,and the PET shading composite film has good discoloration and shading performance.