TY - GEN

T1 - A Study on Material Optimization for Polypropylene Nanocomposites Based On Layered Silicates Using Elongational Flow Devices

AU - Friesenbichler, Walter

AU - Battisti, Markus

AU - Neunhäuserer, Andreas

PY - 2015/6/11

Y1 - 2015/6/11

N2 - Over the last years, the use of nano-reinforced polymers increased due to their superior mechanical, thermal andrheological properties. Polymer nanocomposites (PNCs) which are based on layered silicates feature a higherYoung’s Modulus and increased thermal conductivity.The aim of this study was to increase the material properties for polypropylene PNCs based on layered silicates byusing elongational flow generating devices with super-imposed shear- and elongational flow and optimized nozzlegeometries. The experiments were carried out at the injection molding compounder (IMC) at the Institute ofInjection Molding at the Montanuniversität Leoben. Two different materials were tested. The first material used wasa lower viscous homopolymer and the second material a higher viscous block copolymer. The formulation of thecompounds was constant at 90 wt% polypropylene, 5 % organoclay and 5 %compatibilizer. Earlier works [1]showed that there is a significant correlation between die geometries and mechanical properties of PNCs. In order togain a better understanding about the differences in influence for various nozzle geometries, five differenthyperbolical and conical nozzles were designed. The varying factors were the nozzle length, the exit diameter andthe injection speed which correlates with the elongation rate and shear rate. The influence of these parameters wastested for two different materials with a full factorial 23 design (DoE) including two center-points. Additionally theinfluence of the investigated factors on intercalation and exfoliation with SAXS-measurements was studied.The results of the tensile tests showed, that there is more room for influencing the Young’s Modulus of the lowerviscous homopolymer (FIGURE 1), therefore better results for this material were achieved. On the opposite, it wasnot possible to achieve satisfying results for the higher viscous block copolymer. This is possibly caused by aninappropriate process window or the difference in viscosity of compatibilizer and block copolymer. In FIGURE 1hLr describes a long hyperbolical nozzle with small exit diameter, and hlR describes a short hyperbolical with a bigexit diameter. The same notation was applied for conical dies which can be identified by the prefix k.As displayed in FIGURE 1, the best results wereachieved with the short hyperbolical dieaccompanied with a big exit diameter at the slowinjection flow rate. This indicates that with thissetting, the optimal level and balance betweenintercalation and exfoliation was reached. In nearfuture, further intensive research, especiallyconcerning a flexible multi nozzle system, isplanned. Furthermore, the processing temperaturesfor the block copolymer will be lowered and thePP will be additivated with a stabilizer againstthermo-oxidative degradation.

AB - Over the last years, the use of nano-reinforced polymers increased due to their superior mechanical, thermal andrheological properties. Polymer nanocomposites (PNCs) which are based on layered silicates feature a higherYoung’s Modulus and increased thermal conductivity.The aim of this study was to increase the material properties for polypropylene PNCs based on layered silicates byusing elongational flow generating devices with super-imposed shear- and elongational flow and optimized nozzlegeometries. The experiments were carried out at the injection molding compounder (IMC) at the Institute ofInjection Molding at the Montanuniversität Leoben. Two different materials were tested. The first material used wasa lower viscous homopolymer and the second material a higher viscous block copolymer. The formulation of thecompounds was constant at 90 wt% polypropylene, 5 % organoclay and 5 %compatibilizer. Earlier works [1]showed that there is a significant correlation between die geometries and mechanical properties of PNCs. In order togain a better understanding about the differences in influence for various nozzle geometries, five differenthyperbolical and conical nozzles were designed. The varying factors were the nozzle length, the exit diameter andthe injection speed which correlates with the elongation rate and shear rate. The influence of these parameters wastested for two different materials with a full factorial 23 design (DoE) including two center-points. Additionally theinfluence of the investigated factors on intercalation and exfoliation with SAXS-measurements was studied.The results of the tensile tests showed, that there is more room for influencing the Young’s Modulus of the lowerviscous homopolymer (FIGURE 1), therefore better results for this material were achieved. On the opposite, it wasnot possible to achieve satisfying results for the higher viscous block copolymer. This is possibly caused by aninappropriate process window or the difference in viscosity of compatibilizer and block copolymer. In FIGURE 1hLr describes a long hyperbolical nozzle with small exit diameter, and hlR describes a short hyperbolical with a bigexit diameter. The same notation was applied for conical dies which can be identified by the prefix k.As displayed in FIGURE 1, the best results wereachieved with the short hyperbolical dieaccompanied with a big exit diameter at the slowinjection flow rate. This indicates that with thissetting, the optimal level and balance betweenintercalation and exfoliation was reached. In nearfuture, further intensive research, especiallyconcerning a flexible multi nozzle system, isplanned. Furthermore, the processing temperaturesfor the block copolymer will be lowered and thePP will be additivated with a stabilizer againstthermo-oxidative degradation.

UR - http://www.pps-31.com/

M3 - Conference contribution

BT - Proceedings of the PPS-31

T2 - PPS-31 31st International Conference of the POLYMER PROCESSING SOCIETY

Y2 - 7 June 2015 through 11 June 2015

ER -