Study On Structure And Properties Evolution Of Polyethylene Film Functionalized Preparation And Mulch Film Application Verification

Polyethylene film is widely used in packaging,agriculture,electronics,new energy,and medical equipment,and is one of the most widely used film products.However,the poor physical and chemical properties of the polyethylene film after use and the many adherent impurities make it difficult to recycle the waste film,resulting in serious white pollution and waste of resources.Through the research on the structure and performance evolution of polyethylene film functional preparation process,under the condition of same raw material and thickness,based on the film manufacturing process,the strength of the film after service can be effectively maintained to increase the recovery rate,and the self-cleaning effect of the film can be improved to reduce the impurity content.Realize the high value-added recycling of waste films,provide technical support for building a high-quality green and low-carbon circular industrial chain of polyethylene films,and solve the problem of white pollution.Related research has important theoretical significance and engineering application value.This paper investigates the self-reinforcing and self-cleaning functional principles and realization methods of the preparation process of polyethylene films with different molecular chain structures.In addition,this paper studies the influence of the interlayer structure of multilayer polyethylene film on the performance of the film and its regulation method and realize the efficient preparation of high-strength and easy-to-recycle functional mulch film and the application of cotton covering planting in Xinjiang region.The main research results obtained are as follows:(1)The self-reinforcing mechanism of single-layer polyethylene film prepared by uniaxially and biaxial stretching has been investigated.The effects of different stretching ratios,stretching speeds,cooling time and stretching times on the structural properties of polyethylene films were experimentally studied: when uniaxially stretching,polyethylene grains become larger,the thickness of lamellar crystals increases,the long period of lamellar stacking is prolonged,crystallization degree of orientation and degree of orientation increase.The film prepared by biaxial stretching has refined grains,less amorphous regions,shortened lamellar stacking period,improved crystallinity,and molecular chains are oriented in two directions at the same time.The tensile strength and yield strength of the film become larger when uniaxially stretching,and the tensile strength of the film becomes larger while the yield strength is basically unchanged during biaxial stretching.The self-reinforcing effect of low molecular weight polyethylene is better,while the molecular chains of long-chain branched polyethylene are more entangled,and the lamellae of unbranched-chain polyethylene are twisted.The selfreinforcement effect of both is not as good as that of short-chain branched polyethylene.(2)The correlation model of interlayer structure on the self-reinforcement effect of multilayer polyethylene film was established.The structural changes such as orientation and crystallization of polyethylene films with different interlayer structures were studied under different stretching processes.The study found that when the inner and outer layers of the multilayer polyethylene film responded stronger than the middle layer,the inner and outer layers promoted the orientation crystallization of the middle layer,and when the inner and outer layers responded weaker than the middle layer,the inner and outer layers inhibited the orientation crystallization of the middle layer.This study provides a theoretical basis for the design of the interlayer structure and the optimization of the preparation process of highstrength and easy-recycling multilayer polyethylene films.(3)A superhydrophobic self-cleaning film resistant to acid,alkali,salt and high temperature was prepared based on physical imprinting method.The effects of different embossing pressures and screen meshes on the surface microstructure and wetting properties of polyethylene films were studied,and the film wetting angle was increased from 98±4° to154±1°,realizing the super-hydrophobic function.The microstructure of functionalized polyethylene film still has good self-cleaning performance in harsh environments such as acid,alkali,salt,high temperature and multiple pollutants.This study provides guidance for reducing the impurity content of recycled polyethylene film,improving cleaning efficiency and reducing the difficulty of reuse.(4)The effectiveness of self-reinforcing and self-cleaning functional preparation of polyethylene films was verified.For the first time,the longitudinal/transverse stretching blow molding of multi-layer polyethylene film has been realized,and a high-strength and easy-torecycle functional plastic film suitable for cotton covering planting in Xinjiang has been developed,and the covering planting experiment has been carried out.The results show that the high-strength and easy-recycling functional mulch film has good heat preservation,moisture retention,aging resistance,and production increase effects,and can greatly improve the recovery rate of the mulch film after service and reduce the impurity content of the residual film,and its one-time mechanical recovery rate has increased from 61.3%.to 92.9%,the impurity content dropped from 98% to 38%,and improved the quality and production of cotton,the yield of seed cotton increased by 9.9%,and the cotton content increased by 0.3%.This research work effectively solves the problems of soil pollution and crop yield reduction caused by mulching planting.The self-reinforcement mechanism and control method of multilayer polyethylene film based on the manufacturing process proposed in this paper can improve the service performance and recycling effect of the film with the same material and thickness,and realize the selfcleaning function under harsh conditions;the developed high-strength and easy-to-recycle functional mulch film has been successfully applied to cotton covering planting in Xinjiang,realizing full recovery of the mulch film after service and improving cotton quality and yield.The research in this thesis provides a new processing method and theoretical support for the functional preparation of multilayer polyethylene films.