Cited by 76Polymer crystallization and propertiesPolymer Nanocomposites and PropertiesMaterial Dynamics and Properties

Effects of temperature and strain rate on the deformation of amorphous polyethylene: a comparison between molecular dynamics simulations and experimental results

Open access
Sahputra, I H, Echtermeyer, A T·2013·Modelling and Simulation in Materials Science and Engineering

Abstract

Molecular dynamics simulations are used to investigate the effects of temperature and strain rate on the deformation of amorphous polyethylene. The simulations predict the effects of temperature and strain rate on the stress–strain responses, Young's modulus and Poisson's ratio similar to those observed in laboratory experiments performed by other researchers. The time–temperature superposition principle is applied to the Young's modulus and Poisson's ratio to form a master curve to address the discrepancies in strain rates between the simulations and the experiments. Differences in the numbers of monomers and chains, the degree of crystallinity and molecular orientation lead to discrepancies in the Young's modulus and Poisson's ratio between simulations and experiments.

Integrity signals

Registry

Crossref · 10.1088/0965-0393/21/6/065016

Cites

42 of 42 references verified0 citation errors · 0 not checkable

Statistics

Nothing to recompute.

Claims the paper makes

8 of 51 cited sources checked · 7 supported · 0 flagged · accuracy not yet measured

  • Interpretationcitation

    The values of the constants C1 and C2 for the previous WLF equation could not be used because the samples studied by Bucknall have degrees of crystallinity between 94% and 97%.

    “The values of the constants C1 and C2 for the previous WLF equation could not be used because the samples studied by Bucknall [29] have degrees of crystallinity between 94% and 97%.”
    Quote in the paperSubstantial claim1 of 1 sources checked
    • cites [29] source

      The Materials and Moulding section identifies the polymers studied, including high-density polyethylene, but gives no crystallinity percentages. Searches for 94–97% crystallinity and WLF constants C1 and C2 found no passage addressing either the stated range or the reason the constants could not be used; page numbers were unavailable in our copy. (LLM, conf=0.76)

      Experimental — accuracy not yet measured
  • Findingcitation

    The simulated yield stress is the same order of magnitude as found in other simulations.

    “This is the same order of magnitude as found in other simulations, for instance [2][3][4].”
    Quote in the paperNot a substantial claim1 of 3 sources checked
    • cites [2] source
    • cites [3] source
    • cites [4] source
  • Premisecitation

    Equation (2) has been validated with higher strain rates than typical experimental test rates.

    “Equation ( 2) has been validated with higher strain rates than typical experimental test rates [24,25].”
    Quote in the paperSubstantial claim1 of 2 sources checked
    • cites [24] source
    • cites [25] source
  • Premisecitation

    The sigmoidal increase of Poisson's ratio with temperature is similar to experimental results reported for other polymers (PC, PS, PMMA, PVT, ST/MMA, PVC, POMS, PBT and epoxy resins).

    “This trend is similar to the experimental results of other polymers reported by Seitz [36] for PC, PS, PMMA, PVT, ST/MMA, PVC and POMS; by Mott et al [37] for PS and PMMA; by Pandini and Pegoretti [38] for PBT and by Pandini and Pegoretti [39] for epoxy resins.”
    Quote in the paperNot a substantial claim1 of 3 sources checked
    • cites [36] source
    • cites [37] source
    • cites [38] source
  • Findingreasoning

    At a higher strain, above approximately 0.2% or 20%, the stress-strain responses of the sample differ depending on the direction of elongation.

    “At a higher strain, above approximately 0.2% or 20%, the curves demonstrate that the stress-strain responses of the sample differ depending on the direction of elongation.”
    Quote in the paperSubstantial claim
  • Classified as probably not a substantial claim. 28
  • May combine two claims. 24
  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation

    The united-atom approach simplifies each CH2 monomer as a single monomer particle and has been used by several researchers.

    “This approach simplifies each CH2 monomer as a single monomer particle and has been used by several researchers [2][3][4].”
    Quote in the paperNot a substantial claim1 of 3 sources checked
    • cites [2] source
    • cites [3] source
    • cites [4] source
  • May combine two claims.

    Interpretationcitation

    MD is a useful tool to qualitatively investigate the relationship between micro-scale phenomena and macro-scale mechanical properties and, to some extent, to quantitatively determine these terms.

    “These previous results indicate that MD is a useful tool to qualitatively investigate the relationship between micro-scale phenomena and macro-scale mechanical properties and, to some extent, to quantitatively determine these terms.”
    Quote in the paperSubstantial claim1 of 3 sources checked
    • cites [2] source
    • cites [3] source
    • cites [4] source
  • Classified as probably not a substantial claim.

    Premisecitation

    In Bucknall's report, the Young's modulus was measured from HDPE samples using tensile tests over a range of strain rates and at different temperatures.

    “In his report, the Young's modulus was measured from HDPE samples using tensile tests over a range of strain rates and at different temperatures.”
    Quote in the paperSubstantial claim1 of 1 sources checked
  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Interpretationreasoning

    The experimental samples studied by Bucknall were prepared by an injection moulding process and could have had higher degree of molecular orientation compared with the simulated samples.

    “The experimental samples studied by Bucknall [29] were prepared by an injection moulding process and could have had higher degree of molecular orientation compared with the simulated samples.”
    Quote in the paperNot a substantial claim1 of 1 sources checked
  • May combine two claims.

    Findingown data

    The stiffness and yield stress increase with increasing strain rate.

    “Figure 3 indicates that the stiffness and yield stress increase with increasing strain rate.”
    Quote in the paperSubstantial claim
  • May combine two claims.

    Findingown data

    After final equilibration at 200 K, the mean bond length is 1.529 Å with a standard deviation of 0.023 Å, and the mean bond angle is 109.29° with a standard deviation of 3.393°.

    “The mean value of bond length is 1.529 Å with a standard deviation of 0.023 Å, while the mean value of bond angle is 109.29• with a standard deviation of 3.393•.”
    Quote in the paperNot a substantial claim
  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Findingown data

    The dihedral angles are distributed around trans and gauche states, centred around 66° and 180°.

    “The dihedral angles are distributed around trans and gauche states, centred around 66• and 180•.”
    Quote in the paperNot a substantial claim
  • May combine two claims.

    Findingown data

    The experimentally obtained yield stresses are between 20 and 30 MPa while in this simulation they are about 120 MPa.

    “The experimentally obtained yield stresses are between 20 and 30 MPa while in this simulation they are about 120 MPa.”
    Quote in the paperSubstantial claim
  • May combine two claims.

    Findingown data

    Decreasing temperature increases the stiffness and the yield stress.

    “Decreasing temperature increases the stiffness and the yield stress.”
    Quote in the paperSubstantial claim
  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Findingcitation

    The distributions of bond length, bond angle and dihedral angle are similar to those in other MD simulations of PE.

    “The distributions are similar to those in other MD simulations of PE [6,10].”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [6] source
    • cites [10] source
  • May combine two claims.

    Findingown data

    The Young's moduli of these simulations are lower than those of the experiments, but the master curves have similar shapes.

    “The Young's moduli of these simulations are lower than those of the experiments, but the master curves have similar shapes.”
    Quote in the paperSubstantial claim
  • May combine two claims.

    Findingown data

    In the simulations, Poisson's ratio was 0.39 at -80 degrees C and 0.48 at 50 degrees C.

    “In the simulations, Poisson's ratio was 0.39 at -80 •C (approximately 193 K) and 0.48 at 50 •C (approximately 323 K).”
    Quote in the paperNot a substantial claim
  • May combine two claims.

    Findingown data

    The Young's modulus and Poisson's ratio values calculated from the simulations show the strain rate and temperature dependences and were in reasonable agreement with the experimental measurements.

    “The Young's modulus and Poisson's ratio values were calculated from the simulations showing the strain rate and temperature dependences and were in reasonable agreement with the experimental measurements.”
    Quote in the paperSubstantial claim
  • May combine two claims.

    Findingown data

    The curve fit to the simulation at a strain rate of 10^9 s^-1 showed that Poisson's ratio was 0.464 at -6.7 degrees C and 0.481 at 49 degrees C.

    “The equation of the curve fit to the simulation at a strain rate of 109 s-1 in figure 10 showed that Poisson's ratio was 0.464 at a temperature of -6.7 •C (approximately 266 K), and 0.481 at 49 •C (approximately 322 K).”
    Quote in the paperNot a substantial claim
  • May combine two claims.

    Findingcitation

    In this simulation, the PE system is purely amorphous, while the HDPE in Bucknall's report has a degree of crystallinity between 94% and 97%.

    “In this simulation, the PE system is purely amorphous, while the HDPE in Bucknall's report has a degree of crystallinity between 94% and 97% as measured by Pranadi and Manuel [33].”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [33] source
  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductreasoning

    The use of three simulations with elongation in X, Y or Z directions is similar to the practice of using several samples in laboratory experiments to ensure that the results are statistically representative of the material properties.

    “This is similar to the practice of using several samples in laboratory experiments to ensure that the results are statistically representative of the material properties, which could vary.”
    Quote in the paperNot a substantial claim
  • May combine two claims.

    Premisecitation

    The accuracy of C is especially important for the stress-strain response after the yield stress and for the slope of the rehardening part.

    “However, the accuracy of C is especially important for the stress-strain response after the yield stress and for the slope of the rehardening part.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [6] source
  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation

    HDPE has a simple molecular structure, even though it has amorphous and crystalline phases, and is employed in a wide range of demanding industrial applications, for example in gas distribution pipes.

    “HDPE has a simple molecular structure, even though it has amorphous and crystalline phases, and this polymer is employed in a wide range of demanding industrial applications, for example in gas distribution pipes [1].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [1] ISO/TS 10839 : 2000

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • Classified as probably not a substantial claim. May combine two claims.

    Study design and conductreasoning

    For each combination of temperature and strain rate, three simulations were performed to calculate the Young's modulus and Poisson's ratio, and the obtained values were averaged.

    “For each combination of temperature and strain rate, three simulations were performed to calculate the Young's modulus and Poisson's ratio. In each of the three simulations, the system was either elongated in the X, Y or Z direction and the obtained Young's modulus and Poisson's ratio were averaged.”
    Quote in the paperSubstantial claim
  • Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based).

    Premisereasoning

    HDPE has the chemical structure closest to pure PE because it consists primarily of unbranched PE molecules compared with other types of PE such as low-density polyethylene (LDPE).

    “HDPE has the chemical structure closest to pure PE because it consists primarily of unbranched PE molecules compared with other types of PE such as low-density polyethylene (LDPE).”
    Quote in the paperNot a substantial claim
  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    This dependence of stiffness on temperature has also been observed for other polymers, for instance by Mahieux and Reifsnider and Richeton et al.

    “This dependence of stiffness on temperature has also been observed for other polymers, for instance by Mahieux and Reifsnider [19] and Richeton et al [20].”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [19] source
    • cites [20] source
  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation

    The theoretical basis to the WLF equation is Doolittle's free volume, which is based on experimental data.

    “The theoretical basis to this equation is Doolittle's free volume [23] that is based on experimental data.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [23] source
  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation

    The shift factor used to construct a master curve was experimentally determined for a large number of amorphous polymers by Williams, Landel and Ferry, who expressed the WLF equation.

    “The shift factor used to construct a master curve was experimentally determined for a large number of amorphous polymers by Williams, Landel and Ferry [22], who expressed the WLF equation”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [22] source
  • Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based).

    Premisenone given

    The linear form of the Eyring equation is similar to the Arrhenius activation energy equation.

    “The linear form of the Eyring equation is similar to the Arrhenius activation energy equation.”
    Quote in the paperNot a substantial claim
  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisenone given

    The time-temperature superposition is widely used to form a master curve using a shift factor to superimpose mechanical properties measured at different temperatures.

    “The timetemperature superposition based on this phenomenon is widely used to form a 'master curve' using a shift factor to superimpose mechanical properties measured at different temperatures.”
    Quote in the paperNot a substantial claim
  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductown data

    The standard deviations of the average Young's modulus and Poisson's ratio values for different strain rates and temperatures are reasonably low.

    “The standard deviations are reasonably low.”
    Quote in the paperNot a substantial claim
  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation

    In the freely jointed PE chain, C = 1, in the freely rotating chain, C = 2, and in the hindered rotation chain, C = 3.4.

    “In the freely jointed PE chain, C = 1, in the freely rotating chain, C = 2, and in the hindered rotation chain, C = 3.4 [14].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [14] Gedde U W, 1995, Polymer Physics

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • Classified as probably not a substantial claim.

    Premisecitation

    The yield stress of glassy polymers below Tg can be described by the Eyring theory of non-Newtonian flow.

    “Bauwens et al [27] reported that the yield stress of glassy polymers below Tg can be described by the Eyring theory of non-Newtonian flow.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [27] source
  • May combine two claims.

    Interpretationnone given

    Using the WLF equation at much higher strain rates than used in laboratory experiments is an unproven approach, but it can explain results from MD fairly well.

    “Using the WLF equation at much higher strain rates than used in laboratory experiments is an unproven approach, but as discussed later it can explain results from MD fairly well.”
    Quote in the paperSubstantial claim
  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    Equation (2) is an empirical equation found as an approximately identical shift factor-temperature relation for a wide variety of polymers, polymer solutions, organic glass-forming liquids and inorganic glasses.

    “Equation ( 2) is an empirical equation found as an approximately identical shift factor-temperature relation for a wide variety of polymers, polymer solutions, organic glass-forming liquids and inorganic glasses.”
    Quote in the paperNot a substantial claim
  • Classified as probably not a substantial claim. May combine two claims.

    Premisecitation

    The free volume is constant up to Tg and then increases linearly with increasing temperature.

    “The free volume is constant up to Tg and then increases linearly with increasing temperature.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [23] source
  • Classified as probably not a substantial claim.

    Premisecitation

    The temperature dependence of viscosity arises largely from its dependence on free volume.

    “The temperature dependence of viscosity arises largely from its dependence on free volume.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [23] source
  • May combine two claims.

    Interpretationreasoning

    Strain rates close to the vibrational frequencies may lead to errors in the molecular trajectories, with the result that the system may no longer have a normal structure.

    “Strain rates close to the vibrational frequencies may lead to errors in the molecular trajectories, with the result that the system may no longer have a normal structure.”
    Quote in the paperSubstantial claim
  • Classified as probably not a substantial claim.

    Premisecitation

    The activation energy of linear PE is 27 kJ mol-1.

    “The activation energy of linear PE is taken from [28] as 27 kJ mol-1.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [28] source
  • Classified as probably not a substantial claim.

    Premisecitation

    In more recent light scattering measurements on linear PE in diphenyl at 400 K, characteristic ratios from 8.7 to 10.5 were found.

    “In more recent light scattering measurements on linear PE in diphenyl at 400 K (= 127 •C), characteristic ratios from 8.7 to 10.5 were found [16].”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [16] source
  • Classified as probably not a substantial claim.

    Study design and conductreasoning

    The 10^11 s^-1 simulation results are excluded from the subsequent analysis and discussion.

    “Therefore, the 1011 s-1 simulation results will not be used in the subsequent analysis and discussion.”
    Quote in the paperSubstantial claim
  • Classified as probably not a substantial claim.

    Premisenone given

    The mechanical properties of polymers vary with both time and temperature.

    “It is well known that the mechanical properties of polymers vary with both time and temperature.”
    Quote in the paperSubstantial claim
  • May combine two claims.

    Premisecitation

    Equation (2) is valid above the glass transition temperature (Tg) because below this temperature, log aT increases less rapidly with decreasing temperature.

    “Equation (2) is valid above the glass transition temperature (Tg) because below this temperature, log aT increases less rapidly with decreasing temperature [22].”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [22] source
  • Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based). May combine two claims.

    Premisenone given

    HDPE has a high degree of crystallinity and a varying amount of amorphous structure.

    “HDPE has a high degree of crystallinity and a varying amount of amorphous structure.”
    Quote in the paperNot a substantial claim
  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Interpretationcitation

    Another possible reason for the discrepancy between the simulations and experimental measurements is the effect of molecular orientation.

    “Another possible reason for the discrepancy between the simulations and experimental measurements is the effect of molecular orientation.”
    Quote in the paperNot a substantial claim
  • Probably not a substantial claim: may not pass S4 (based).

    Premisenone given

    Semicrystalline PE has not only a crystalline region surrounded by a disordered (amorphous) region, but also an interfacial region that connects the two.

    “Semicrystalline PE has not only a crystalline region surrounded by a disordered (amorphous) region, but also an interfacial region that connects the two.”
    Quote in the paperNot a substantial claim
  • May combine two claims.

    Premisecitation

    In Waterman's measurements, the experimental value of Poisson's ratio was 0.35 at -80 degrees C and 0.47 at 50 degrees C.

    “At -80 •C, the experimental value of Poisson's ratio was 0.35, and at 50 •C it was 0.47.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [41] source
  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    Waterman calculated the complex Poisson's ratio of six different samples of PE by measuring the velocity and attenuation of ultrasonic longitudinal and transverse pulses at a frequency of 5 MHz and a strain rate of approximately 10^2 s^-1.

    “Waterman [41] calculated the complex Poisson's ratio of six different samples of PE by measuring the velocity and attenuation of ultrasonic longitudinal and transverse pulses at a frequency of 5 MHz and a strain rate of approximately 102 s-1.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [41] source
  • May combine two claims.

    Interpretationreasoning

    The elastic modulus will be affected both by the degree of crystallinity and by how the interfacial region connects the crystalline and amorphous regions.

    “Therefore, the elastic modulus will be affected both by the degree of crystallinity and by how the interfacial region connects the crystalline and amorphous regions.”
    Quote in the paperSubstantial claim
44 of 44
  • The paper relies on this without support.

    MD can predict material properties based on first principles, mainly using the atomistic forces between molecules.

    “Molecular dynamics (MD) can predict material properties based on first principles, mainly using the atomistic forces between molecules.”
  • The paper relies on this without support.

    Current computational power is not sufficient to model the many macromolecules in polymeric materials and describe all the interactions within a reasonable time frame.

    “Current computational power is not sufficient to model the many macromolecules in polymeric materials and describe all the interactions within a reasonable time frame.”
  • The paper relies on this without support.

    The time-temperature superposition principle is applicable to the Young's modulus and Poisson's ratio of amorphous PE to form a master curve.

    “The time-temperature superposition principle is applied to the Young's modulus and Poisson's ratio to form a master curve to address the discrepancies in strain rates between the simulations and the experiments.”
  • The paper relies on this without support.

    Polynomial smoothing does not alter the stress-strain response in the low-strain region used to calculate the Young's modulus and Poisson's ratio.

    “The heterogeneity and small size of the sample produced noisy stress-strain curves and therefore polynomial smoothing was used to reduce the fluctuation of the stress.”
4 of 4

Self-check

Percentages, sums and reported differences re-computed from the paper’s own numbers.

Each contradiction between two passages listed here was confirmed by an independent check.

  • The higher-strain threshold differs by a factor of 100

    Minor

    The two percentages presented as alternatives are not equivalent: 0.2% is one-hundredth of 20%. This makes the threshold for the reported directional differences unclear.

  • The low-strain limit is given as two different percentages

    Minor

    A strain of 0.02% is one-hundredth of 2%. Elsewhere, the paper writes the equivalent pair as 0.02 and 2%, leaving the stated strain limit ambiguous.

2 of 2

Cites

Flagged first, then by citations

Research works printed but not linked: 1

  1. Gedde U W, 1995, Polymer Physics

Cited by

Sorted by citations

Authors
Sahputra, I. H., & Echtermeyer, A. T.
Affiliations
Norwegian University of Science and Technology (NO)
Corresponding author
Sahputra, I H
Venue
Modelling and Simulation in Materials Science and Engineering
Published
2013-08-08
Volume
21
Issue
6
Pages
065016
ISSN
  • 0965-0393 (ISSN-L)
  • 1361-651X
OpenAlex
W2077237797
Cited by
76
References
41
Citations by year
2026: 5 · 2025: 5 · 2024: 8 · 2023: 6 · 2022: 9 · 2021: 12 · 2020: 12 · 2019: 5 · 2018: 4 · 2017: 1 · 2016: 3 · 2015: 1 · 2014: 4 · 2013: 1
FWCI
1.96
Type
journal article
Language
en
Open access
Locations
  • Modelling and Simulation in Materials Science and Engineering (publishedVersion)
  • UTPedia (Universiti Teknologi Petronas) (acceptedVersion)
  • Scientific Repository (Petra Christian University) (submittedVersion)
Topics
  • Physical Sciences › Materials Science › Polymers and Plastics › Polymer crystallization and properties
  • Physical Sciences › Materials Science › Polymers and Plastics › Polymer Nanocomposites and Properties
  • Physical Sciences › Materials Science › Materials Chemistry › Material Dynamics and Properties
Keywords
amorphous polyethylene, temperature dependence, strain rate sensitivity, deformation, stress-strain behavior, Young's modulus, Poisson's ratio, time-temperature superposition

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