Determination of the elongational viscosity of polymer melts by melt spinning experiments. A comparison with different experimental techniques

Baldi, Francesco; Franceschini, A.; Riccò, T.

doi:10.1007/s00397-007-0181-z

Cited by 35 publications

(54 citation statements)

References 24 publications

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“…This is attributed to higher energy inputs from the extruder with higher extrusion rate, with such energy being stored elastically within the LDPE melt during the flow in the die, and thus detected by the load cell apparatus. This claim was substantiated by the works of Muke et al [5] and Baldi et al [2] The drawdown forces upon fracture of the LDPE melts at volumetric flow rates of 2.9 × 10 −7 , 5.6 × 10 −7 , and 8.3 × 10 −7 m 3 /s were 52.6, 81.7, and 100.8 cN, respectively. It was interesting to note that during the transitions of each roller speed there were overshoots of the drawdown forces.…”

Section: Mechanical Properties Of Molten Ldpementioning

confidence: 60%

“…The measured elongational flow properties are affected by the molecular weight and structure of the polymers used, as well as the draw ratio, test temperature, roller speed, and die geometry. [1][2][3] Viscoelastic behavior of the polymer melt under extensional deformation is usually expected at low draw ratios, but it may reach the viscous behavior when the stretching level or draw ratio is sufficiently high [4] A number of studies on measurements of elongational flow properties using various techniques have been given in the literature. [1][2][3][4][5][6][7][8][9][10] Therefore, they are not detailed in this work.…”

Section: Introductionmentioning

confidence: 99%

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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

Harnnarongchai

Intawong

Sombatsompop

2011

Journal of Macromolecular Science, Part B

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An experimental rig coupled with a high speed data-logging and recording system and a personal computer was specially designed and constructed for the real-time measurement of mechanical strength (in terms of drawdown force) as a function of volumetric flow rate and roller speed for virgin low-density polyethylene (LDPE) and reprocessed LDPE during a filament stretching process. The effect of the number of extrusion passes for the reprocessed LDPE was our main interest. The experimental rig was connected to the end of a single-screw extruder, which was used to melt and extrude the polymers. The LDPE filaments were then solidified and collected for studying the mechanical properties. The mechanical strength of the virgin LDPE and reprocessed LDPE were investigated in both molten and solidified states. The mechanical strengths of the virgin and reprocessed LDPEs under these two states are discussed and compared in terms of change in magnitude under a wide range of processing conditions (volumetric flow rate, die temperature, and roller speed). The results suggested that in the molten state the drawdown force for LDPE melts was dependent on volumetric flow rate, die temperature, roller speed, and the number of reprocessing passes. The drawdown force being affected by the number of reprocessing passes could be explained by molecular degradation and gelation effects when using high volumetric flow rates. In the solidified state, the tensile properties of the solidified LDPE increased with roller speed. The effect of the number of extrusion passes for the solidified LDPE was similar to that for the molten LDPE. In the case of volumetric flow rates, the mechanical properties of the solidified LDPE decreased with increasing volumetric flow rate, whereas those of the molten LDPE exhibited the opposite effect. Thus, the mechanical strength of the molten LDPE could not always be used to assess the mechanical properties of the solidified LDPE.

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Section: Mechanical Properties Of Molten Ldpementioning

confidence: 60%

Section: Introductionmentioning

confidence: 99%

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

Harnnarongchai

Intawong

Sombatsompop

2011

Journal of Macromolecular Science, Part B

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“…The melt strength is related to the elongational viscosity of the polymer, η E , that is normally measured in a tensile test using an extensional rheometer. However, the difficulties encountered in using this type of rheometer led the researches to develop alternative experimental techniques [52]. In this work, the elongational viscosity of the unprocessed PLA and the PLA/BIOS and PLA/BPMS blends was determined from the Cogswell converging flow model [38].…”

Section: Rheological Propertiesmentioning

confidence: 99%

The effect of two commercial melt strength enhancer additives on the thermal, rheological and morphological properties of polylactide

Hernández-Alamilla

Valadez-González

2015

Journal of Polymer Engineering

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Abstract The effect of two commercial melt strength enhancer additives, Paraloid BPMS-250 (BPMS) and Biostrength 700 (BIOS), on the thermal, rheological and morphological properties of polylactide (PLA) was studied. Thermal analyses showed that both the BPMS and BIOS additives decreased the ability of PLA to crystallize. The rheological tests indicated that zero-shear viscosity and storage modulus of the PLA/BPMS and PLA/BIOS blends were significantly increased with the additive content. These could be attributed to the entanglements between the PLA chains with those of the high molecular weight additive, creating a physical network which reduces the segmental mobility of PLA and improves the melt elasticity of the blend. The entanglement molecular weights (Me) of PLA/BPMS and PLA/BIOS blends were lower than those of unprocessed and processed PLA (Me≈4×104 g/mol), which suggests greater chain entanglements and a higher entanglement density (ve). The elongational viscosity (ηE) and melt strength values were estimated using a screw-extrusion capillary rheometer, where the PLA/BIOS blends presented the highest values. Finally, scanning electron microscopy on the samples was carried out to assess the blend morphology.

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“…Muke et al [11] studied the extensional rheology of two polypropylene melts from the rheotens test, and found that the viscosity determined from the Rheotens experiment can be used to estimate transient extensional viscosity. Recently, Baldi et al [12] compared with different experimental techniques and researched the determination of the elongation viscosity of two high‐density polyethylene melts by melt spinning experiments. The results showed that for high strain and strain rate levels, the melt spinning experiments provide elongation viscosity data quite close to the transient extensional viscosity values obtained from the tensile tests.…”

Section: Introductionmentioning

confidence: 99%

Elongation properties of polyethylene melts

Liang

Zhong

2011

Polymer Engineering & Sci

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The extensional rheological properties of three grades of polyethylene melts, low density polyethylene (LDPE), linear low density polyethylene (LLDPE), and high density polyethylene (HDPE) were measured using a melt spinning technique under the test conditions with temperature ranging from 150 to 210°C and extrusion rate varying from 11.25 to 22.50 mm s−1. The results showed that the melt strength decreased with a rise of temperature while increased with an increase of extensional rate. With the rise of extensional strain rate and temperature, the melt extensional viscosity decreased. The extensional stress and viscosity reduced with increasing extrusion velocity when the temperature and extensional rate were constant. Moreover, the melt strength and extensional viscosity of the LDPE resin was the highest and the LLDPE was the lowest under the same experimental conditions. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers

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Determination of the elongational viscosity of polymer melts by melt spinning experiments. A comparison with different experimental techniques

Cited by 35 publications

References 24 publications

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

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

The effect of two commercial melt strength enhancer additives on the thermal, rheological and morphological properties of polylactide

Elongation properties of polyethylene melts

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