Preparation And Properties Of Long-Lasting Anti-Fog Polyethylene Films Based On Cross-linked Poly(Styrene-alt-Maleic Anhydride) Microspheres

Fogging of greenhouse films has multiple adverse effects on the growth of crops,thus it is of great significance to develop long-lasting anti-fog polyethylene(PE)films.The addition of slow-release agents is a common method for preparing long-lasting anti-fog PE films,with inorganic nanoparticles or layered silicates commonly used as slow-release agents.In this thesis,cross-linked poly(styrene-alt-maleic anhydride)microspheres(PMSD)prepared by self-stabilized precipitation polymerization were applied to the preparation of long-lasting anti-fog PE films.PMSD was grafted with methoxy polyethylene glycol(m PEG)or fatty alcohol(FA)through esterification reaction,and their effects in prolonging the dripping duration of anti-fog PE films were evaluated.Besides,their influences on the various properties of anti-fog PE films were systematically studied.The main contents are as follows:1.Grafted microspheres PMSD-g-m PEG550,PMSD-g-m PEG1000 and PMSD-g-m PEG2000 were obtained by grafting m PEG of different chain lengths(m PEG550,m PEG1000,m PEG2000)onto PMSD.Different types of PMSD-g-m PEG,LLDPE,LDPE,antifogging agent(LY-10)and antioxidant1010 were melt blended,and the obtained blends were hot-pressed to prepare anti-fog PE films.PMSD-g-m PEG2000 had the best dispersion state in PE.Mechanical,optical and thermal properties of the films added within 2 wt% of PMSD-g-m PEG2000 were not affected obviously.Water contact angle of the films gradually increased with increasing loadings of grafted microspheres from 0 to 10 wt%.The three types of PMSD-g-m PEG can prolong the dripping duration of the film when the addition amount was appropriate,and PMSD-g-m PEG2000 had the best effect.anti-fog PE film added with 1 wt%of PMSD-g-m PEG2000 had the longest dripping duration,which was 35.7%longer than that of the control group.2.Grafted microspheres PMSD-g-LA,PMSD-g-AA and PMSD-g-MA were obtained by grafting lauryl alcohol(LA),arachidyl alcohol(AA)and myricyl alcohol(MA)onto PMSD,respectively.Grafted microspheres were melt-blended with LLDPE,LDPE,LY-10 and antioxidant 1010,and the blends were hot-pressed to prepare anti-fog PE films.PMSD-g-MA has the best compatibility with polyethylene matrix.Mechanical,optical and thermal properties of the films added within 1 wt% of PMSD-g-MA were not affected significantly.With the loadings of the grafted microspheres increasing from 0to 10 wt%,water contact angle of the films increased gradually.Dripping duration of polyethylene anti-fog films added with PMSD-g-LA and PMSD-g-AA were not prolonged.Anti-fog PE films added with 2 wt% of PMSD-g-MA had the longest dripping duration,which was 25.0% longer than that of the control group.This study has established a new method for delaying the migration of antifogging agents,which has good application prospects in the development of long-lasting anti-fog PE films.