Effects of Roller Speed, Die Temperature, Volumetric Flow Rate, and Multiple Extrusions on Mechanical Strength of Molten and Solidified LDPE under Tensile Deformation

Harnnarongchai, Wanlop; Intawong, Naret; Sombatsompop, Narongrit

doi:10.1080/00222348.2010.497465

Cited by 8 publications

(16 citation statements)

References 24 publications

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“…For any given roller speed, the drawdown force increased with increasing volumetric flow rate in the extruder from 1.4 × 10 −7 to 4.1 × 10 −7 m 3 /s. This observation was in line with the work of Gupta and Bhattacharya [9] and our previous work [5, 29]. Higher volumetric flow rate was referred to as greater energy input or storage in the deformable polymer melts.…”

Section: Resultssupporting

confidence: 90%

“…As for the effect of volumetric flow rate from the extruder, it was found that the roller speed to failure for neat LDPE and wood/LDPE composites changed with changing volumetric flow rate. Higher volumetric flow rate contributed to greater average drawdown force and drawdown time because of the greater energy inputs given from the extruder [5, 29]. This behavior and its explanation are similar to those given for the LLDPE/LDPE blend system.…”

Section: Resultsmentioning

confidence: 71%

“…The experimental apparatus consisted of the single‐screw extruder, an adaptor (barrel rig), a capillary die, a drawdown force measuring unit (load cell), a moving roller take‐up, and control equipment. The detailed information for this experimental rig, including component design, can be obtained from our previous work [5, 29]. Our in‐house experimental rig allowed the adjustment of roller speed increasing in step‐ladder fashion for drawdown force measurement with constant acceleration.…”

Section: Methodsmentioning

confidence: 99%

“…The elongational flow properties of polymers are usually varied by weight‐average molecular weight and level of branching structure of the polymers used, additives, and processing variables (i.e., test temperature, draw ratio, roller speed) [1–3]. There have been a number of studies on the measurements of the elongational flow properties [1–11], mostly involving homopolymers, such as low‐density polyethylene (LDPE) [3, 5–7], linear low‐density polyethylene (LLDPE) [4–7], high‐density polyethylene (HDPE) [1, 3, 8], polypropylene (PP) [9], and polycarbonate [11]. Attempts to improve the melt strength of homopolymer melts have also been made especially for tension‐thinning melts, mainly by blending with a secondary polymer whose molecular structure is similar to that of the primary polymer but which contains a branching structure.…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Mechanical strengths of molten and solidified LLDPE/LDPE blends and wood/LDPE composites under tensile deformation

Harnnarongchai¹,

Sitticharoen²,

Intawong³

et al. 2011

Vinyl Additive Technology

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The mechanical strengths of neat low‐density polyethylene (LDPE), a blend of LDPE with linear low‐density polyethylene (LLDPE), and a composite of LDPE with wood flour (wood/LDPE) were investigated in molten and solidified states under tensile deformation. The results are discussed in terms of the effects of LLDPE and wood contents, roller speed, and volumetric flow rate. In LLDPE/LDPE blends, incorporating LLDPE from 0 to 30 wt% into LDPE caused a slight increase in drawdown force, a larger fluctuation in drawdown force, and a reduction of maximum roller speed to failure. The mechanical properties of the solidified LLDPE/LDPE corresponded to those of the molten LLDPE/LDPE with regard to the effect of LLDPE content. For wood/LDPE composites, increasing the wood flour content in molten LDPE caused considerable reductions in drawdown time and maximum roller speed to failure. The drawdown force increased with increasing wood flour up to 10 wt% before it decreased at the wood loading of 20 wt%. A number of voids and pores on the extrudate surfaces became obvious for the composites with 20 wt% of wood content. Increasing wood content enhanced the tensile modulus for the solidified LDPE but decreased its tensile strength. Unlike those of LLDPE/LDPE blends, the changes in tensile modulus and strength of solidified wood/LDPE composites with wood content did not correspond to those of the molten composites. In all cases, the drawdown force increased with increasing roller speed. The effect of volumetric flow rate from the extruder on the mechanical strengths of the solidified blends was more pronounced than on those of the molten ones. J. VINYL ADDIT. TECHNOL., 2011. © 2011 Society of Plastics Engineers

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Section: Resultssupporting

confidence: 90%

Section: Resultsmentioning

confidence: 71%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Mechanical strengths of molten and solidified LLDPE/LDPE blends and wood/LDPE composites under tensile deformation

Harnnarongchai¹,

Sitticharoen²,

Intawong³

et al. 2011

Vinyl Additive Technology

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“…The most widely used and important device for the melt strength and transient extensional viscosity measurements is so‐called “Rheotens” 7–9. Recently published works by Sombatsompop et al10–12 proposed an experimental device which was specially designed and constructed in a similar fashion to the Rheotens to determine the melt strength online in a single screw extruder using a wide range of polymer systems including homopolymers,10, 11 polymer blends and composites12 and processing and reprocessing conditions 10, 11. They suggested that the drawdown force of molten LDPE was dependent on volumetric flow rate, die temperature, roller speed, take‐up style, and the number of extrusion passes.…”

Section: Introductionmentioning

confidence: 99%

Rheological properties and melt strength of LDPE during coextrusion process

Keawkanoksilp

Apimonsiri

Patcharaphun

et al. 2012

J of Applied Polymer Sci

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Rheological properties and mechanical strength of coextruded low‐density polyethyelene (LDPE) were studied in this work. The influences of die temperature, shear rate at skin and core layers, and number of extrusion passes at the core layer were of interest. The experimental results suggested that the viscosity and swelling behavior of LDPE coextrudate were more dependent on the shear rate of skin layer as compared with that of core layer. Increasing die temperature resulted in decreases in viscosity and die swell ratio. The reductions in viscosity and die swell ratio of the coextrudate for the reprocessing numbers 1 and 2 at the core layer arose from the disentanglement of long chain branching of LDPE molecules, while the increase of viscosity and die swell ratio for the reprocessing numbers 3 and 4 mainly involved an occurrence of crosslinking structure. For mechanical strength results, the changes in elongational stress for different shear rates, die temperature, and number of extrusion passes were in line well with the rheological measurements. That was, the higher the stored energies in polymer melts due to higher shear rates, the greater the amount of force required to conquer the elastic resistance. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

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Melt strength, local velocity, and elongational viscosity profiles of low‐density polyethylene filaments affected by the die design and process conditions

Sitticharoen

Harnnarongchai

Intawong

et al. 2011

J of Applied Polymer Sci

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An experimental arrangement to simultaneously measure the melt strength, velocity profiles, and elongational viscosity profiles across the cross section of a molten filament that emerged from either a circular or slit die for low-density polyethylene (LDPE) under nonisothermal and isothermal conditions is proposed. The proposed experimental rig was based on a parallel coextrusion technique of colored LDPE melt layers into an uncolored melt flowing from the barrel into and out of a die to form a continuous filament before they were pulled down by mechanical rollers until the filament failed. The experimental rig was also equipped with a high-speed data-logging system and a personal computer for real-time measurements. The results suggest that the draw-down forces changed continuously with changing roller speed, and the velocity profiles of the melt were not uniform across the LDPE filament during the stretching of the melt. Greater drawdown forces and local melt velocities were obtained in the slit die or under the nonisothermal condition. The drawdown forces and velocity profiles in both dies were affected by the volumetric flow rates from the extruder and the roller speeds used, with the effect being more pronounced for the circular die. The elongational viscosity profiles of the LDPE filament were not uniform across the filament cross section and corresponded well to the obtained velocity profiles. The elongational viscosities of the LDPE filament were relatively higher when the filament was extruded and stretched in the circular die and under the nonisothermal condition. The changes in the elongational viscosity profiles were more sensitive to changes in the volumetric flow rate and roller speed in the circular die.

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Effects of Roller Speed, Die Temperature, Volumetric Flow Rate, and Multiple Extrusions on Mechanical Strength of Molten and Solidified LDPE under Tensile Deformation

Cited by 8 publications

References 24 publications

Mechanical strengths of molten and solidified LLDPE/LDPE blends and wood/LDPE composites under tensile deformation

Mechanical strengths of molten and solidified LLDPE/LDPE blends and wood/LDPE composites under tensile deformation

Rheological properties and melt strength of LDPE during coextrusion process

Melt strength, local velocity, and elongational viscosity profiles of low‐density polyethylene filaments affected by the die design and process conditions

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