Melt Elasticity Phenomenon of Multicomponent (Talc and Calcium Carbonate) Filled Polypropylene

Abstract

The compound of single-component filled polypropylene (PP) (consists of either talc or CaCO 3 ) and multicomponent filled PP (talc/CaCO 3 /PP) are prepared by melt mixing using Brabender Plasticorder internal mixer. All systems exhibit good stability and normal flow in the molten state. The multicomponent filled PP has shown an intermediate degree of die swell and flow instabilities. The defect of extrudate in the extrusion process in the form of melt fracture could only be evidenced in the semisolid state of PP melt. The result shows that composite with highest content of talc exhibits the least melt fracture.

Effects of kaolin and maleic anhydride contents on melt elasticity and flexural behaviour of polypropylene/kaolin and unplasticised poly(vinyl chloride)/kaolin composites

“…From a careful examination of the data in Figure 1, it appears that the reduction of PP/kaolin composites is continuous until a plateau level is attained at kaolin content of 25 php. This can be interpreted as a result of decreased entanglement of polymer molecules as reported by several investigators [12][13]. On loading the extruder's hopper with PP matrix, the PP starts to melt and as the mixing of matrix and filler continues, the viscosity of PP melt is reduced until it is believed to be fully melted.…”

“…Nonetheless, this fact can only be applied to UPVC/kaolin system as PP/kaolin system shows normal flow even if kaolin concentration is added up to 30 php in the PP system. In the investigations of melt elasticity of PP composites done by Ariffin et al [12] using talc and calcium carbonate as fillers, it has been concluded that filler is capable of preventing from the appearance of flow instability in PP composites. When the external force is released from the system, the presence of filler has delayed the movement/interaction of polymer molecules and decelerated the elastic recovery.…”

“…Addition of very small amounts of any filler or additive (in this case, kaolin and MAH), can deeply cause significant changes in the polymer molecules movement [12]. The molecules movement scenario in the melt is closely related to the elastic properties of the base polymer.…”

Viscosity analysis of polypropylene-kaolin composites measured using single-screw extruder

“…In conjunction, the ability of the lower viscosity melt to recover to its original position is easier than the highly viscous melt. Because the relaxation process of the highly viscous polymer melt is restricted, this will cause the melt injection pressure for the true viscosity data to generate higher shear stress .…”

Experimental study of the melt fracture behavior of filled high-density polyethylene melts

“…These materials, which at the process temperature consist of suspensions of rigid particles in a viscoelastic liquid (the polymer melt), generally exhibit a very complex rheological behavior, which has been the subject of many theoretical and experimental studies . Part of these aimed at investigating their behavior in capillary flows at high shear rates, but the attention was rarely focused on the region close to the onset of flow instabilities .…”