Effects of the actual diameters and diameter ratios of barrels and dies on the elastic swell and entrance pressure drop of natural rubber in capillary die flow

Sombatsompop, Narongrit; Dangtangee, R.

doi:10.1002/app.11212

Cited by 25 publications

(15 citation statements)

References 12 publications

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“…In addition, the presence of agglomerates (due to high filler load) caused resistance against the flow and increased viscosity of composites. All the dynamic viscosity decreases showing shear thinning behavior as previously observed in other filler melts [46] [47]. This behavior can be attributed to the higher degree of polymer-filler interaction, which requires higher shear stress and longer relaxation times for the composites to flow [48].…”

Section: Rheological Behaviorsupporting

confidence: 69%

The effect of Poly-ethylene-co-glycidyl methacrylate efficiency and clay platelets on thermal and rheological properties of wood polyethylene composites.

Badji¹,

Ly²,

Ndiaye³

et al. 2016

ACES

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Global ecological concerns have resulted in an interest in renewable natural materials. Composites based on high density polyethylene (HDPE), wood fiber (Veneer) and containing coupling agents like nanoclay (NC) and poly-ethylene-co-glycidyl methacrylate (PEGMA) were made by melt compounding and then injection molding. In this study, the effects of two variable parameters namely nanoclay and coupling agent on the rheological and thermal properties of wood polyethylene composites (WPECs) were investigated. The study investigates the morphology phase, rheology behaviors and thermal properties by scanning electron microscope, capillary rheometer and thermal gravimetric analyzer. The SEM micrographs of the composites showed that the outer surfaces of the wood were coated by a section of amorphous lignin. The state of dispersion in HDPE/pine/clay composites was improved by EGMA because it could interact with pine flour in addition to clay. The interaction of reinforcement with coupling agent and HDPE matrix is strong based on the observation of the fracture surface of composites when EGMA is present. However the addition of 2.5% clay slightly lowered the initial degradation temperature (T d ) but did not improve the thermal stability. Obviously, all the composites materials exhibit viscoelastic values greater than those of neat HDPE.

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Section: Rheological Behaviorsupporting

confidence: 69%

The effect of Poly-ethylene-co-glycidyl methacrylate efficiency and clay platelets on thermal and rheological properties of wood polyethylene composites.

Badji¹,

Ly²,

Ndiaye³

et al. 2016

ACES

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“…The change in extrudate swell was found to be associated with the degree of flow complexities in the barrel, residence time, elastic characteristic and the temperature rise. They also found that the change in extrudate swell was linearly influenced by entrance pressure drop at low actual barrel/die diameters (D B /D D from 20/4 to 30/7 mm/mm), but was associated with the change in material viscosity at high actual barrel/die diameters (D B /D D from 35/ 7 to 40/8 mm/mm) [6]. For a constant barrel diameter, the smaller the die diameter the greater the extrudate swell due to the increases in the extensional deformation, shear rate, and a reduction in the melt residence time.…”

Section: Introductionmentioning

confidence: 97%

Extrudate swell behavior of PS and LLDPE melts in a dual die with mixed circular/slit flow channels in an extrusion rheometer

Sombatsompop

O-Charoen

2003

Polymers for Advanced Techs

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Extrudate swell behaviors of polystyrene (PS) and linear low-density polyethylene (LLDPE) melts in a dual channel die, having mixed circular/slit flow channels, in a constant shear rate rheometer were examined. The extrudate swell ratio for PS melt was observed to be higher than that for LLDPE melt for all cases, this being associated with the differences in molecular structures that could be described in terms of power law indexes and secondary flows near the die entrance. In single channel die, the extrudate swell of both PS and LLDPE melts in circular flow channel die was greater than that in slit flow channel, whereas, in dual channel die the slit channel exhibited a higher extrudate swell ratio, the results being explained by revealing the flow patterns of the melt in the barrel and die of the rheometer. It was found that the dimensionless size of the vortex flows near the entrance, and the extent of disentanglement of molecular chains on entering the die were the important factors for the differences in the extrudate swell ratios of the melts at the die exit influenced by the die designs used.

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“…[5,6] So, there exists a critical value of die length above which reduction of the die length would not have much effect on the die swell ratio but could dramatically reduce the extrusion pressure while the flow rate remains constant or increase the flow rate while the extrusion pressure remains constant. We suggest this critical length is the entrance length.…”

Section: Entrance Length Of Polymer Flow Through a Contraction Die 947mentioning

confidence: 99%

Entrance Length of Polymer Flow Through a Contraction Die: Comparison of Calculation from an Equation and Flow Induced Birefringence Measurements

Fan

Peng

2011

Journal of Macromolecular Science, Part B

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When a polymeric melt flows through a contraction die, it experiences a certain distance in the slit before a fully developed flow is achieved, which is defined as the entrance length. Here, an equation for calculation of the entrance length was proposed based on an assumption that the pressure drops in an exponential function way along the flow direction in the contraction die from the entrance to the fully developed flow. The entrance length could be calculated from the flow parameters, such as volumetric flow rate, the pressures at the entrance and at the defined point in the fully developed flow. The entrance lengths of a low-density polyethylene (LDPE) and a high-density polyethylene (HDPE) melt were calculated from this equation with the measured flow parameters at various flow rates. The results are quite close to those measured from flow induced birefringence and similar to that reported in a published study by Martyn et al., which suggested that the equation could be used to describe the relation between the entrance length and the flow parameters.

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Effects of the actual diameters and diameter ratios of barrels and dies on the elastic swell and entrance pressure drop of natural rubber in capillary die flow

Cited by 25 publications

References 12 publications

The effect of Poly-ethylene-co-glycidyl methacrylate efficiency and clay platelets on thermal and rheological properties of wood polyethylene composites.

The effect of Poly-ethylene-co-glycidyl methacrylate efficiency and clay platelets on thermal and rheological properties of wood polyethylene composites.

Extrudate swell behavior of PS and LLDPE melts in a dual die with mixed circular/slit flow channels in an extrusion rheometer

Entrance Length of Polymer Flow Through a Contraction Die: Comparison of Calculation from an Equation and Flow Induced Birefringence Measurements

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