اثر نانو ذرات سيليكاتي بر خواص مكانيكي و عبور پذيري فيلم آلياژ LDPE/LLDPE

چكيده انگليسي :

Effect of Organo Modified Montmorillonite O MMT on Mechanical and Barrier Properties of LLDPE LDPE Blend Films Shahla Khalili s khalili@ce iut ac ir 2011 4 30 Department of Chemical Engineering Isfahan University of Technology Isfahan 84156 83111 Iran Degree M Sc Language FarsiSupervisor Roohollah Bagheri bagheri@cc iut ac ir Mahmood Masoomi mmasoomi@cc iut ac irAbstract Polyethylene films are extensively used in packaging industries Improvement in mechanical andbarrier properties of PE film will make it appropriate for advanced applications such as electronic andpharmaceutical packaging and packaging of food products which are sensitive to oxygen Since the PE blendingwith other polymers is a suitable way for it s properties improvement blend of LLDPE with LDPE is widelyused in film production An efficient way for film properties improvement is use of nanofillers Severalnanoparticles have been recognized as possible additives to improve polymer performance The packagingindustry has focused on layered inorganic solids such as silicates due to their availability low cost and relativeease of processability Three ways are suggested to synthesize polyolefin clay nanocomposites in situpolymerization solution method and melt mixing Melt mixing is the easiest and most cost effective method toproduce nanocomposites To melt mix nonpolar polyolefin with polar clay platelets clay surface must bemodified to reduce different affinity between these two components In this study organomodifiedmontmorillonite Cloisite 15A was used to improve properties of LDPE LLDPE blend films Polypropyleneand polyethylene grafted with high percent of maleic anhydride were used as compatibilizer to achieve betterinteraction between the polyethylenes blend and the organoclay The aim of this study was to investigate theeffect of organo modified MMT on mechanical and gas barrier properties of nanocomposite films ofLLDPE LDPE blends To investigate the effect of compounding method on properties nanocomposites weremelt mixed in two ways 1 materials were double extruded in a twin screw extruder 2 materials were meltcompounded in an internal mixer and then extruded in a twin screw extruder The feasibility of preparing betterexfoliated nanocomposites was studied with using two different compatibilizing agents PEgMA and PPgMA After selecting the effective way and suitable compatibilizer based on XRD and MFI results nanocompositesamples with various clay contents were prepared and film blown Mechanical properties of films were studiedin machine direction MD and transverse direction TD because blown film orients in two directions Gaspermeability of films was also investigated by the constant volume variable pressure method in a permeabilitymeasuring set up The XRD and MFI results showed that using the 2nd way and PPgMA as compatibilizerwould make a better dispersion of organoclay in nanocomposite A broad peak was observed in XRD patterns ofthe nanocomposite with 1 phr organoclay which indicates partial exfoliation state The clay diffraction peaks ofother nanocomposites shift to lower angles suggesting intercalated structures in the nanocomposite films Thepermeability results showed that addition of organoclay even at low level had significant effect on barrierproperties of the nanocomposites Oxygen permeability decreased by 38 by adding only 4 phr of nanoclay intothe blend Decrease in permeability suggests that barrier properties arise from tortuousity of nanoparticles in theblends Addition of clay also led to increase in tensile modulus in both directions without decreasing theelongation at break Nelson s model and the Halpin Tsai equation were used to calculate the number of stacksof clay in the nanocomposites using permeability and modulus results respectively These models predicted thestack number between 2 and 3 for the nanocomposites which confirms a high degree of dispersion of Cloisite15A in the nanocomposites Keywords low density polyethylene linear low densi

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اثر نانو ذرات سيليكاتي بر خواص مكانيكي و عبور پذيري فيلم آلياژ LDPE/LLDPE

پلي اتيلن سبك , نانو كامپوزيت , مونت موريلونيت , خواص عبورپذيري گازي