Research On The Effections Of Different Additives On The Application Properties Of Polyethylene (PE) Greenhouse Film

Agriculture greenhouse is one of the most important agriculturefacilities, which has changed the dependence of traditional agricultureon natural climate, improved the quality and productivity of unit fieldeffectively and decreased the producing cost. Under the support ofNational Science and Technology Support Program (Grant No:2007BAE42B04), aims at develop a new kind of greenhouse fil m whichcould satisfy people’s need, three different kind of polyethylene (PE)was choosed as raw material, added different percentage of additive sinto it and blown molded to gr eenhouse film, researched in themechanical properties, ther mal properties, anti-fogging property, etc.The results show that:(1) Three different PE was used as material, co-blended withelastomer and extrusion, blown molded to film. We researched in themechanical property, optical property, ther mal property, rheologicalproperty, etc. The results show that:1. HDPE has the biggest molecular weight and the strongestintermolecular force, so HDPE has the best me chanical property, wit hthe tensile strength of up to48MPa; LLDPE ranks the second with thetensile strength of about30MPa; on the molecular chain of LDPE,there are too many short branches which could hinder the approach ofmolecular, the intermolecular force is the weakest, so LDPE has theweakest mechanical property, with the tensile strengt h of round20MPa2. The molecular of POE is flexible, it could be blended well withLDPE, LLDPE. POE molecular in the matrix could absorb huge energyduring frcuture develops and stop the fracture from developing. POEcould increase the tensile strength of LLDPE fr om30MPa to38MPa,with the best dosage of about5-10percentage. POE could increase thetensile strength of LDPE from20MPa to24MPa, wi th the best dosage ofabout10-15percentage.3. LDPE molecular has many short branches, which have affect theregularity of the material, the arrangement of molecular is of high disorder, the degree of crystallinity is comparative low and the materialhas the same property in every direct, so its light transmittance is thebest. LLDPE is a linear molecular and regular in structure. Themolecular is easy to orient and has a high degree of crys tallinity, so thelight transmittance is lower than LDPE. HDPE is a linear mo lecular andthe degree of crystallinity could reach97%, so the light transmittanceis the worst.4. EVA, POE are all materials with better light trans mittance, wit hthe addition of them could increase the transparency of HDPE in largeextent.5. The mi ni mu m tensile strength of greenhouse fil m required inGB4455-2006is14MPa, the greenhouse film prepared in this workcould fulfill the require ment.(2) Three different PE was used as material, co-blended withantioxidants and extrusion, blown molded to film. We researched in t h ether mal property, rheological propert y, mechanical property after age dby ultraviolet light for360hours, etc. The results show that:1. By thermal gravity analysis of the material, we found thatanti-oxidant1010could improve the thermal decompos itiontemperature of LLDPE, LDPE greenhouse fil m evidently. Anti-oxidantB225could improve the thermal decomposition temperature of LDPEgreenhouse film, i mprove its capability of resisting therma l aging.2. By reology test of the material, we found that Anti-oxidants arelow molecular weight subject and has a effect of plastifying, whichcould descend the melting temperature of LDPE, LLDPE, HDPE,increase their flowing velocity, make the m easy to process.3. Anti-oxidants could decrease the development of degradationproduct so that to stop the film from aging. When the adding dosage ofanti-oxidant B225is3percentage, the parallel and vertical tensilestrength of LLDPE greenhouse film is26.097MPa,22.671MParespectively， while the parallel and vertical tensile strength of blankLLDPE greenhouse fil m is18.047MPa，19.892MPa respectively. Withthis dosage the material has the best property of ther mal resisting. But Anti-oxidant B225has no obvious effe ct of thermal resisting to LDPE,HDPE greenhouse film.4. In Ultra-Violet environment, the mechanical property of thefilm decrease in ratio with the strength and the aging time.5. In all, anti-oxidant B225has a better thermal resisting effect tothese three kind of PE than anti-oxidant1010.(3) Three different PE was used as material, co-blended with antidropping additives and extrusion, blown molded to fil m. We researchedin the mechanical property, thermal property, rheological property,surface morphology, anti dropping property, etc. The results show that:1. Anti-dropping addi tives are subjects with small molecularweight and could affect the inter-molecular force of PE, with the addingof anti-dropping additives, the mechanical property of greenhouse fil mwill decrease, so the adding dosage of anti-dropping additives isrestricted.2. Anti-dropping additives are low mo lecular weight subject andhas the effect of plastifying, which could descend the meltingtemperature of LDPE, LLDPE, HDPE, increase their flowing velocity,make them easy to process.3. Anti-dropping additive is a kind of surfactant, which couldcombine both oil and water, to make water spread. This research foundthat anti-dropping additives could decrease the contact angle of waterand greenhouse film, increase the anti-dropping time in water bathaccelerate method. Anti-dropping additives could change themorphology of greenhouse film effectively, make the surface s mootherand make droplets easy to spread.4. Modified LLDPE greenhouse film has the best anti-droppingproperty, modified LDPE ranks the second, modified HDPE is the worst.The anti-dropping time could reach783h of LLDPE with the addingdosage of anti-dropping additive AB of3pe rcentage. The modifiedLDPE greenhouse film could also reach a anti-dropping time of578h,which are all longer than240h required in GB4455-2006.This paper has choosed three different kinds of PE with different molecular structure as material, and compared different property ofthose greenhouse films. We researched in the effections of elastomer,anti-oxidants, anti-dropping additives on PE greenhouse fil m. Thispaper could offerd a reference for the preparation of high property PEgreenhouse film.