【正文】 essure (MPa)5 0 % fil l e r0 % fil l e r7. Flow/No flow Test: Data obtained: Uses: Constant shear rate as temperature decreases, single die Minimum flow temperature Process design Material specification 7. Flow/No flow 8. Manual test Test: Data obtained: Uses: After initial heatup, take over manual control amp。 take data points whenever Shear / extensional data, test pressures Initial investigation Establish conditions before testing 9. Low level script Test: Data obtained: Uses: Program test yourself Whatever you want Nonstandard tests . crosslinking *need a detailed understanding of how the machine works 10. Wall slip Test: Data obtained: Uses: Steady shear using 3 dies with same L:D ratio, different diameters Slip velocity vs. shear stress Die design Process design Troubleshooting Filler effects 10. Wall slip U n f i l l e d H D PE a t 2 0 0 176。 C 。 D a t a f ro m R o s a n d O L R8010012014016018020022050 70 90 110 130 150 170 190 210 230 250Sh e a r St ra i n R a t e (/ s )Shear Stress (kPa) 8 x 0 . 5 m m1 2 x 0 . 7 5 m m1 6 x 1 m mL i n e o f c o n s t a n tSh e a r St re s s10. Wall slip W a l l Sl i p V e l o ci t y o f U n f i l l e d H D PE a t 2 0 0 176。 C 01234567100 110 120 130 140 150 160 170 180 190W a l l Sh e a r St re s s (k Pa )Wall Slip Velocity (mm/s)11. PVT / Density test Test: Data obtained: Uses: Compresses melt Special plug die amp。 piston tip Melt pressibility (versus pressure) Melt density (?5%) Flow simulation Filler amp。 additive investigation Material specification Troubleshooting 11. PVT / Density test 11. PVT / density test 11. PVT / density test results LDPE at 200176。C 051015202530351 6 . 8 1 6 . 9 17 1 7 . 1 1 7 . 2 1 7 . 3 1 7 . 4 1 7 . 5 1 7 . 6 1 7 . 7V o l u m e (c c )Pressure (MPa)12. Fibre spinning test Test: Data obtained: Uses: Special hauloff motor amp。 scales Hauloff speed ramped up Force vs hauloff speed Breaking point, tensile force Uniaxial extension Indication of biaxial extension Empirical determination of tensile strength 12. Fibre spinning test Practical measurement F, vp Uniaxial extension (Haul Off): Extensional properties at small extension rates Haul Off: Example LDPE at different temperatures ? Main interest is rupture force under nonisothermal conditions Laun, Schuch.: J. Rheol. 33 (1989), 119 13. Die Swell Test Test: Data obtained: Uses: Laser gauge diameter measurement of extrudate after exiting die Extrudate diameter vs. shear rate Indication of elasticity (high shear rates) Profile extrusion, thermoforming, shrink film etc. 13. Die Swell Test 1. DieSwell I (LaserDieSwell) Properties: ? Mono or biaxial lasersystem ? Melt amp。 Die Cutters allow measurement with defined melt tension ? Resolution ? Calculation of G and E according to Cogswell 13. Die Swell Test 2. DieSwell I (VideoDieSwell) Properties: ? higher resolution ( mm) ? two dimensional measurement ? detection of the die swell dynamics Die Swell: Example PP1 has highmolecular tail in MwD pared to PP2 ? Viscosity curves nearly identical – elastic response important for profile extrusion Laun, H. M.: Progr. Coll. Polym. Sci. 75 (1987), 111 Summary ? Standard test (shear extension) ? Other test using standard dies degradation, relaxation, wall slip, flow/no flow, melt fracture ? Specialist tests manual, lowlevel script ? Special options PVT, fibre spinning Instruments Desktop and floor standing devices RH7D amp。 RH10D RH2100/2200 Measurement Example: DesktopRH2022 RH2022 (Investigation of dental posites to find optimum geometry for pumping and surface effects) Conclusion The plete flow behaviour under processing conditions Rosand Double Capillary System with Orifice Die: ? direct measurement of the entrance pressure drop no extrapolation needed ? calculation of extensional viscosity according Cogswell method ? flow curve up to very high shear end extensional rates (107 s1) ? ability to detect wall slip by Mooney‘s method ? correlation with structural changes during processing ? additional Options for detection of elastic behaviour (DieSwell) Rheological Data for Computational Modelling Aim: describe how mercial modelling software uses rheological data Modelling software (CFD) ? Simulation of melt flow ? Extrusion and injection moulding ? Uses finite element methods divides flow up into very small pieces ? Continuum mechanics ? Principles of conservation of mass, momentum, energy etc Modelling software (CFD) ? Velocity profiles ? Temperature profiles ? Pressure drops ? Stress, shear and extension rates ? Cooling and fill time, warpage Can predict: ? Extrudate profile shape Modelling software (CFD) ? Flow data (viscosity or dynamic data) ? Temperature dependence of viscosity ? Density data (melt and solid) ? Thermal (conductivity etc.) ? Shrinkage Needs material information: ? Elastic properties 2D Results Moldflow material data Moldflow part fill time