Application Of Metallocene Polyethylene In Agricultural Film And Its Aging Performance

The problem of agricultural film residue in Xinjiang is serious,there is an urgent need to improve the mechanical properties and aging resistance of agricultural film and improve the recovery rate of agricultural film.In this paper,the differences between metallocene linear low density polyethylene(m-LLDPE),linear low density polyethylene(LLDPE)and low density polyethylene(LDPE)were compared by a series of analysis technologies such as melt flow rate,high temperature gel chromatography(GPC).It is concluded that m-LLDPE has higher melt strength,better mechanical properties and similar processing properties as LLDPE.The blending of m-LLDPE into LLDPE can improve the melt strength,mechanical strength and aging resistance of film products,and verify the feasibility of m-LLDPE as a raw material for agricultural film formulation.By comparing different brands of high density polyethylene(HDPE)products and m-LLDPE products,the types of blended raw materials were determined.Through the uniform design and regression analysis,the optimal blending formula was obtained.Compared with the original film formula samples,the formula samples have excellent mechanical properties and aging resistance,and the performances are higher than the requirements of Xinjiang local standards.The effects of light stabilizers and antioxidants on the aging resistance of m-LLDPE film products were investigated.The addition of antioxidants and light stabilizers can be increased at a certain ratio,and the thermal oxidation resistance and photo-oxidation resistance of the samples can be significantly improved.When the amount of the antioxidant added exceeds 0.2%(mass fraction),the amount of addition has a weak effect on the thermal oxidation resistance of the sample.Simultaneous addition of antioxidants and light stabilizers will produce a synergistic effect,and the sample's resistance to thermal aging will be better than that of only antioxidants.Through uniform design and regression analysis,the optimum formula of weathering agent is obtained,and the effect of improving aging resistance of film samples is the best.The effect of film thickness on the aging resistance of m-LLDPE film products is discussed.It is found that when the thickness of the film sample is the same,the aging resistance of the sample added with the light stabilizer is superior to that of the sample without the light stabilizer added.Film samples with or without the addition of light stabilizers,their aging resistance will increase with the increase of film thickness.