مطالعه عامل هاي موثر در جهت گيري نانورس و تاثير آن بر رفتار رئولوژيكي و مقاومت در برابر عبور پذيري نانو كامپوزيت پلي پروپيلن و نانورس

چكيده انگليسي :

Evaluation of flow induced nanoclay orientation in Polypropylene PP g MAH organoclay and its effect on rheological properties and permeability Shima Akbarpoursarabi s akbarpoursarabi@ce iut ac ir 14 03 2011 department of Chemical engineering Isfahan university of technology Isfahan 84156 83111 Iran degree msc language farsi Abstract The relationship between the flow induced nanoclay orientation and the melt linear and non linear viscoelastic behavior of Polypropylene organoclay nanocomposite films was studied An attempt was also made to compare these results with the results obtained from the birefringence measurements The elongational flow rate nanoclay cloisite 15A loading and compatibilizer PP g MAH content were among affecting parameters investigated All the nanocomposites samples were prepared by the melt compounding and using compatibilizer based masterbatch feeding method In this method the samples were prepared by first compounding the nanoclay with the PP g MAH with the ratio of 3 1 to produce masterbatch with highly intercalated morphology and the produced masterbatch was then diluted with appropriate amount of Polypropylene in the second step All the blend compounding was carried out in an internal mixture Brabender together with a modular twin screw extruder The nanocomposite films were prepared at three elongation flow rate using a single screw extruder equipped with a slit die and a drawing devise The greatly increased nanoclay interlayer spacing evaluated from the XRD results together with rheological viscoelastic results showing pronounced non terminal storage modulus and viscosity upturn at low frequency range revealed a highly intercalated morphology for the compatibilized nanocomposite samples The results of similar linear viscoelastic measurements performed on the film samples showed a decrease in low frequency storage modulus plateau value whose extend was found to be reduced by increasing the draw ratio These results could be attributed to reducing the 3D network microstructure contribution in the favor of organoclay orientation as a result of imposed elongational flow However the results of linear viscoelastic measurements prepared from PP g MAH as a matrix showed an opposite effect for applying elongational flow increasing elongational rate led to films with greater contribution of 3D network evaluated in terms of the low frequency range storage modulus Moreover the WXRD results obtained for the PP g MAH based nanocomposites samples showed that in contrast to the nanocomposite samples with PP matrix increasing the elongational flow rate increases the nanocaly interlayer spacing The results of hot stage polarized microscope performed on the nanocomposites samples showed a distinct birefringence pattern at elevated temperature whose value was found to be increased with increasing drawing ratio This was considered as an indication of nanoclay orientation which could be resist recovery for relatively long time The results of stress transient tests revealed a decrease in stress overshoot with increasing elongational flow rate for the nanocomposites films Based on these results and the results of start up flow test related to organoclay reorientation the contribution of the 3 D network and nanoclay orientation in the stress overshoot values could be evaluated The thermal analysis results of the sample indicated an increase in crystalinity with increasing nanoclay content of the samples suggesting a stronger effect for nucleating action of the nanoclay in comparison with its role in constraining the PP chains All the nanocomposites samples showed lower permeability than that of pure polypropylene which could be explained in terms of increasing tortuous path Keywords Polypropylene Nanocomposites Rheological properties permeability drawing ratio

اكبرپورسرابي، شيما

مطالعه عامل هاي موثر در جهت گيري نانورس و تاثير آن بر رفتار رئولوژيكي و مقاومت در برابر عبور پذيري نانو كامپوزيت پلي پروپيلن و نانورس

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