| It is a important that behavior of polymer melt acted on shearing strength to processing and performance of produce, and change of temperature is key factor in industrial processing of polymer, and abundant heat generation of polymer melt due to viscous dissipation caused large temperature rises and inside temperature gradients. There change will influence processing of polymer. A common model of viscous dissipation in tube was upbulided, and we find a approximately solution of three boudary condiction. We measured many melt surface temperature rise in exit of nozzle by infrared pyrometer, when melt was air injected. Calculation show that fairly large temperature rises exist, we compared calculation with experimentation of commom PE, PP and filling stuff, the main conclusion were listed as followings:(1)reduced temperature 0 gradient exist in radial and axis of tube, and real distributing of 0 is relate to boundary condition.(2)Polymer characteristic (density p ,heat conducting k,heat capacity C~,etc), length of tube and velocity of folw will affect melt temperature rises, these factors are untied a reduced distance in axis. But influence of non-Newtonian index n is most. It trend is resemble, but it extent different in three boundry condition.(3) The change in temperature rises of experimentation and calculation alongIINwith shear rate, are similar with power function of index of 0梚 .but accord with experimentation and calculation is better in low shear rate than high.(4)The temperature rise in PP filled stuff is less than pure PP at same shear rate, the reason must be decrease of non-Newtonian index,because the influence of n more than viscosity ,of course there are influence of others charater.
|
PDF Full Text Request