Effect of Different Aging Methods on the Structures and Properties of Polyethylene Mulch Films
The structures and properties of polyethylene(PE)mulch films after aging by different methods are different.In this paper,one kind of PE mulch film was prepared according to a fixed formula,and its mechanical properties and structural changes after aging by different methods were studied.The results show that the chemical structures of PE films are similar after aging for 40 days by four methods,only the C—O characteristic absorption peak appears at 1 261 cm-1 after thermo-oxidative aging.After aging,the melting temperature of the film decreases to different degrees,and the crystallinity increases obviously.The crystallinity is only 1.7%before aging,but the highest crystallinity is 13.9%after natural aging.After aging by different methods,the tensile properties of PE films have different degrees of decline.Among them,the speed of thermo-oxidative-photic aging is the fastest,and the mechanical properties of the films are lost after 20 d,the change of transverse PE film is more sensitive than that of longitudinal PE film.The number-average molecular weight of mulch film increases in different degrees after natural exposure and thermo-oxidative-photic aging,but the weight-average molecular weight of mulch film decreases and the molecular weight distribution narrows significantly.
Indoor and Outdoor AgingPolyethylene Mulch FilmTensile PropertyInfrared SpectroscopyMolecular Weight
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