Effects of Particle Size on Melt Viscoelastic Properties During Capillary Extrusion of Glass Bead-filled LDPE Composites

Abstract

ABSTRACT: In this study, the viscoelastic properties of a low-density polyethylene (LDPE) filled with glass beads (GBs) are measured at 150 C by means of a capillary rheometer to identify the effect of the particle size on the melt viscoelasticity. The volume fraction of the GB was 8.4%. The surface of the particles has been treated with a silane-coupling agent and the diameter range was from 4 to 180 mm. The results showed that either the entry pressure drop (P_en) or the entry elongation stress (e) is a linear function of shear stress (w) at the channel wall. The values of both P_en and e of these composite melts are close to each other. This illustrates that the influence of the bead size and its distribution on them is insignificant at low filler concentration. The die-swell ratio (B) increases nonlinearly with an addition of w. When the diameter (d) of the beads is less than 50 mm, B decreases dramatically with an increase of d, especially at low shear stress level, and then it decreases slightly under the given shear stress level.

Keywords

LDPE glass bead composite capillary extrusion melt flow property

References

Liang, J.Z. , Li, R.K.Y. and Tjong, S.C. (1997). Morphology and Tensile Properties of Glass Bead Filled Low Density Polyethylene Composites , Polymer Testing, 16: 529–548 .

Kwon, S. , Kim, K.J. , Kim, H. , Kundu, P.P , Kim, T.J. , Lee, Y.K. , Lee, B.H. and Choe, S. (2002). Tensile Property and Interfacial Dewetting in the Calcite Filled HDPE, LDPE, and LLDPE Composites , Polymer, 43: 6901–6909 .

Kozak, M. , Danch, A. , Osoba, W. , Domka, L. , Stelzer, F. and Jurga, S. (2004). Relationship between Filler Loading and Morphology of Interphase in Polyethylene-chalk Composites , Polym. Polym. Compos., 12: 409–416 .

Liang, J.Z. , Li, R.K.Y. and Tjong, S.C. (1999). Effects of Pressure and Temperature on the Melt Density and the Melt Flow Rate of LDPE and Glass Bead-filled LDPE Composite , J. Mater. Process. Technol., 91: 167–171 .

Liang, J.Z. and Li, R.K.Y. (1999). Melt Rheology of LDPE and Glass Bead Filled LDPE Composite , J. Reinf. Plast. Compos., 18: 1077–1086 .

Liang, J.Z. and Li, R.K.Y. (1999). Rheological Properties of Glass Bead-filled Low Density Polyethylene Composite Melts in Capillary Extrusion , J. Appl. Polym. Sci., 73: 1451–1456 .

Liang, J.Z. , Li, R.K.Y. , Tang, C.Y. and Cheung, S.W. (2000). Die-swell Behaviour of Glass Bead-filled Low-density Polyethylene Composite Melt at High Extrusion Rates , J. Appl. Polym. Sci., 76: 419–424 .

Gough, T. , Sparea, R. and Coates, P.D. (2005). In-process Measurements of Full Field Stress Birefringence and Velocities Inpolymer Melt Flows , Plast. Rubber Compos., 34: 393–402 .

Sentmanat, M. , Wang, B.N. and Mckinley, G.H. (2005). Measuring the Transient Extensional Rheology of Polyethylene Melts using the SER Universal Testing Platform , J. Rheol., 49: 585–606 .

10.

Liang, J.Z. and Li, R.K.Y. (2001). Measurement of Dispersion of Glass Beads in PP Matrix , J. Reinf. Plast. Compos., 20: 630–638 .

11.

Bagley, E.B. (1957). End Corrections in the Capillary Flow of Polyethylene , J. Appl. Phys., 28: 624–627 .

12.

Cogswell, F.N. (1972). Converging Flow of Polymer Melts in Extrusion Dies , Polym. Eng. Sci., 12: 64–72 .