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Molecular dynamics simulation of deformation behavior in amorphous polymer: nucleation of chain entanglements and network structure under uniaxial tension

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Yashiro, Kisaragi, Ito, Tomohiro, Tomita, Yoshihiro·2003·International Journal of Mechanical Sciences

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Crossref · 10.1016/j.ijmecsci.2003.11.001

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  • Findingown data
    § 3.3 Chain entanglements and directional orientation Figure 9 shows the snapshots of molecular chains in the tensile simulation. In the figure, a rectangular region in the center of the specimen, of which initial size is 10 nm × 10 nm × 3 nm, is drawn. The black particles indicate the flexion nodes at the initial equilibrium, as described later. The material deforms homogeneously and maintains the initial chain structure until εzz = 0.5, however, a few voids appear in contrast with the deformation of an amorphous metal [21]. The inhomogeneity in the density becomes clearer in the figure with εzz = 1.0, where splitting clusters of molecular chains with voids can be observed. Here, we can see straightened chains notably in the low-density regions, or the void regions between clusters. At the beginning of the strain hardening at εzz = 1.5, a new network structure is generated where long straightened chains connect the clusters of entangled chains. It is also observed that many chains between clusters are oriented in the tensile direction. After a strain of 1.5, some clusters dissolve but the material deforms mainly by the stretching of the oriented chains between clusters keeping the generated network structure, as recognized from the positions of clusters I and Ⅱ in the figures with εzz = 1.5 ∼ 3.0. It should be concluded from these facts that the stress increase in the present simulation, where no chain connects the top and bottom of the specimen, is caused by the nucleation of the network chain structure with the "entanglements" and the orientation and stretch of the chains bridging them. In order to clarify the characteristics of the entanglements at the initial equilibrium state, the "flexion nodes" in all molecular chains are investigated. As schematically illustrated in Fig. 10, the interior angle between two position vectors from the target particle A to the particles B and C, 10 backward and forward monomers, are evaluated. The particles, at which the angle is less than 90 deg at the initial equilibrium, are drawn in black in Fig. 9 as flexion nodes. Dense flexion nodes can be observed at the entanglements in the figure with εzz = 3.0, thus it is suggested that the flexion nodes tend to make entanglements. It is also pointed out, however, that there are many flexion nodes straightened during the deformation, since many black particles can be seen in the long straightened chains. From these remarks and the figure of εzz = 0.0, we can see that the initial arrangement of the dense flexion nodes does not correlate well with the entanglements nucleated during the yield ⇒ hardening process. The configuration or distance of the entanglements, of great interest from the viewpoint of hierarchical modelling, may not be easily characterized by the initial chain structure but depends on the history of complicated local deformations. The change in the distribution of local density during the yield ⇒ hardening process is shown in Fig. 11. In the figures with εzz = 0.5 and 1.0, the peak translates to the lower side by tension, however, the distribution maintains a broad base at the higher side because of the clusters shown in Fig. 9. It is confirmed quantitatively from the figure with εzz = 1.5 that a new structure nucleates at the beginning of the strain hardening, since another small peak appears near ρ = 0.53 g/cm³ in the density distribution. Figure 12 illustrates particles with a higher local density than the branched peak, ρhigh, at each strain of 1.5~3.0. Clusters A, B and C are indicated by ellipsoids in the figure as an example to make the relative position of the clusters clear. Many of the entanglements are observed in the center of the cross section, a few at the surface, and none at the corners. Most of the entangled chains at the corners and surfaces have disappeared during the yield ⇒ hardening process, sn ne t na s stte et etie distance between the entanglements could not be decided quantitatively, since they disperse widely as can be seen in the figure. The relationship between the distance and the average molecular weight remains to be invesitigated statistically in the next study.

    Many chains between clusters are oriented in the tensile direction.

    “It is also observed that many chains between clusters are oriented in the tensile direction.”
    Quote in the paperSubstantial claim
  • Findingown data
    § 3.1 Initial equilibrium structure and yield

    The distribution of bond length and bending angle in the initial equilibrium state shows a pulse-like sharp peak at r0 and θ0, implying almost every node is at the equilibrium length and angle.

    “The distribution of bond length and angle shows a pulse-like sharp peak at the position of ro and θ0, implying almost every node is at the equilibrium length and angle.”
    Quote in the paperNot a substantial claim
  • Findingown data
    § Abstract

    The material yields by elongating without significant stress increase up to a strain of about 1.5, where strain hardening appears.

    “Then the material “yields” by elongating without stress increase up to the strain of 1.5, where strain hardening appears.”
    • Also stated in: § 3.2 Yield ⇐ hardening behavior · plain
      “After the initial yield described in the previous section, the material elongates without significant stress increase until the strain of about 1.5, showing stress fluctuation. On the other hand, stress prominently increases after εzz = 1.5 just like the strain hardening observed in the macroscopic tension test.”
    Quote in the paperSubstantial claim
  • Findingown data
    § 3.3 Chain entanglements and directional orientation Figure 9 shows the snapshots of molecular chains in the tensile simulation. In the figure, a rectangular region in the center of the specimen, of which initial size is 10 nm × 10 nm × 3 nm, is drawn. The black particles indicate the flexion nodes at the initial equilibrium, as described later. The material deforms homogeneously and maintains the initial chain structure until εzz = 0.5, however, a few voids appear in contrast with the deformation of an amorphous metal [21]. The inhomogeneity in the density becomes clearer in the figure with εzz = 1.0, where splitting clusters of molecular chains with voids can be observed. Here, we can see straightened chains notably in the low-density regions, or the void regions between clusters. At the beginning of the strain hardening at εzz = 1.5, a new network structure is generated where long straightened chains connect the clusters of entangled chains. It is also observed that many chains between clusters are oriented in the tensile direction. After a strain of 1.5, some clusters dissolve but the material deforms mainly by the stretching of the oriented chains between clusters keeping the generated network structure, as recognized from the positions of clusters I and Ⅱ in the figures with εzz = 1.5 ∼ 3.0. It should be concluded from these facts that the stress increase in the present simulation, where no chain connects the top and bottom of the specimen, is caused by the nucleation of the network chain structure with the "entanglements" and the orientation and stretch of the chains bridging them. In order to clarify the characteristics of the entanglements at the initial equilibrium state, the "flexion nodes" in all molecular chains are investigated. As schematically illustrated in Fig. 10, the interior angle between two position vectors from the target particle A to the particles B and C, 10 backward and forward monomers, are evaluated. The particles, at which the angle is less than 90 deg at the initial equilibrium, are drawn in black in Fig. 9 as flexion nodes. Dense flexion nodes can be observed at the entanglements in the figure with εzz = 3.0, thus it is suggested that the flexion nodes tend to make entanglements. It is also pointed out, however, that there are many flexion nodes straightened during the deformation, since many black particles can be seen in the long straightened chains. From these remarks and the figure of εzz = 0.0, we can see that the initial arrangement of the dense flexion nodes does not correlate well with the entanglements nucleated during the yield ⇒ hardening process. The configuration or distance of the entanglements, of great interest from the viewpoint of hierarchical modelling, may not be easily characterized by the initial chain structure but depends on the history of complicated local deformations. The change in the distribution of local density during the yield ⇒ hardening process is shown in Fig. 11. In the figures with εzz = 0.5 and 1.0, the peak translates to the lower side by tension, however, the distribution maintains a broad base at the higher side because of the clusters shown in Fig. 9. It is confirmed quantitatively from the figure with εzz = 1.5 that a new structure nucleates at the beginning of the strain hardening, since another small peak appears near ρ = 0.53 g/cm³ in the density distribution. Figure 12 illustrates particles with a higher local density than the branched peak, ρhigh, at each strain of 1.5~3.0. Clusters A, B and C are indicated by ellipsoids in the figure as an example to make the relative position of the clusters clear. Many of the entanglements are observed in the center of the cross section, a few at the surface, and none at the corners. Most of the entangled chains at the corners and surfaces have disappeared during the yield ⇒ hardening process, sn ne t na s stte et etie distance between the entanglements could not be decided quantitatively, since they disperse widely as can be seen in the figure. The relationship between the distance and the average molecular weight remains to be invesitigated statistically in the next study.

    The initial arrangement of the dense flexion nodes does not correlate well with the entanglements nucleated during the yield ⇒ hardening process.

    “we can see that the initial arrangement of the dense flexion nodes does not correlate well with the entanglements nucleated during the yield ⇒ hardening process.”
    Quote in the paperSubstantial claim
  • Findingown data
    § 3.3 Chain entanglements and directional orientation Figure 9 shows the snapshots of molecular chains in the tensile simulation. In the figure, a rectangular region in the center of the specimen, of which initial size is 10 nm × 10 nm × 3 nm, is drawn. The black particles indicate the flexion nodes at the initial equilibrium, as described later. The material deforms homogeneously and maintains the initial chain structure until εzz = 0.5, however, a few voids appear in contrast with the deformation of an amorphous metal [21]. The inhomogeneity in the density becomes clearer in the figure with εzz = 1.0, where splitting clusters of molecular chains with voids can be observed. Here, we can see straightened chains notably in the low-density regions, or the void regions between clusters. At the beginning of the strain hardening at εzz = 1.5, a new network structure is generated where long straightened chains connect the clusters of entangled chains. It is also observed that many chains between clusters are oriented in the tensile direction. After a strain of 1.5, some clusters dissolve but the material deforms mainly by the stretching of the oriented chains between clusters keeping the generated network structure, as recognized from the positions of clusters I and Ⅱ in the figures with εzz = 1.5 ∼ 3.0. It should be concluded from these facts that the stress increase in the present simulation, where no chain connects the top and bottom of the specimen, is caused by the nucleation of the network chain structure with the "entanglements" and the orientation and stretch of the chains bridging them. In order to clarify the characteristics of the entanglements at the initial equilibrium state, the "flexion nodes" in all molecular chains are investigated. As schematically illustrated in Fig. 10, the interior angle between two position vectors from the target particle A to the particles B and C, 10 backward and forward monomers, are evaluated. The particles, at which the angle is less than 90 deg at the initial equilibrium, are drawn in black in Fig. 9 as flexion nodes. Dense flexion nodes can be observed at the entanglements in the figure with εzz = 3.0, thus it is suggested that the flexion nodes tend to make entanglements. It is also pointed out, however, that there are many flexion nodes straightened during the deformation, since many black particles can be seen in the long straightened chains. From these remarks and the figure of εzz = 0.0, we can see that the initial arrangement of the dense flexion nodes does not correlate well with the entanglements nucleated during the yield ⇒ hardening process. The configuration or distance of the entanglements, of great interest from the viewpoint of hierarchical modelling, may not be easily characterized by the initial chain structure but depends on the history of complicated local deformations. The change in the distribution of local density during the yield ⇒ hardening process is shown in Fig. 11. In the figures with εzz = 0.5 and 1.0, the peak translates to the lower side by tension, however, the distribution maintains a broad base at the higher side because of the clusters shown in Fig. 9. It is confirmed quantitatively from the figure with εzz = 1.5 that a new structure nucleates at the beginning of the strain hardening, since another small peak appears near ρ = 0.53 g/cm³ in the density distribution. Figure 12 illustrates particles with a higher local density than the branched peak, ρhigh, at each strain of 1.5~3.0. Clusters A, B and C are indicated by ellipsoids in the figure as an example to make the relative position of the clusters clear. Many of the entanglements are observed in the center of the cross section, a few at the surface, and none at the corners. Most of the entangled chains at the corners and surfaces have disappeared during the yield ⇒ hardening process, sn ne t na s stte et etie distance between the entanglements could not be decided quantitatively, since they disperse widely as can be seen in the figure. The relationship between the distance and the average molecular weight remains to be invesitigated statistically in the next study.

    Many flexion nodes are straightened during the deformation.

    “It is also pointed out, however, that there are many flexion nodes straightened during the deformation, since many black particles can be seen in the long straightened chains.”
    Quote in the paperNot a substantial claim
  • May combine two claims. 15
  • The quote only partly states this claim. 1
  • Classified as probably not a substantial claim. 2
  • May combine two claims.

    Findingown data
    § 3.1 Initial equilibrium structure and yield

    The nominal stress-nominal strain curve at the initial stage shows a linear elastic relationship up to the strain of 0.012, where the stress decreases slightly and makes a small peak (Arrow 1).

    “It shows a linear elastic relationship up to the strain of 0.012, where the stress decreases slightly and makes a small peak as indicated by Arrow ①.”
    Quote in the paperNot a substantial claim
  • May combine two claims.

    Findingown data
    § 3.1 Initial equilibrium structure and yield

    The strain of both Lines 1 and 2 coincides with the local maximum of bending potential and almost the local minimum of the bond stretch potential.

    “The strain of both Lines ① and ② coincides with the (local) maximum of bending potential and almost the local minimum of the bond stree”
    Quote in the paperSubstantial claim
  • May combine two claims.

    Findingown data
    § 3.3 Chain entanglements and directional orientation Figure 9 shows the snapshots of molecular chains in the tensile simulation. In the figure, a rectangular region in the center of the specimen, of which initial size is 10 nm × 10 nm × 3 nm, is drawn. The black particles indicate the flexion nodes at the initial equilibrium, as described later. The material deforms homogeneously and maintains the initial chain structure until εzz = 0.5, however, a few voids appear in contrast with the deformation of an amorphous metal [21]. The inhomogeneity in the density becomes clearer in the figure with εzz = 1.0, where splitting clusters of molecular chains with voids can be observed. Here, we can see straightened chains notably in the low-density regions, or the void regions between clusters. At the beginning of the strain hardening at εzz = 1.5, a new network structure is generated where long straightened chains connect the clusters of entangled chains. It is also observed that many chains between clusters are oriented in the tensile direction. After a strain of 1.5, some clusters dissolve but the material deforms mainly by the stretching of the oriented chains between clusters keeping the generated network structure, as recognized from the positions of clusters I and Ⅱ in the figures with εzz = 1.5 ∼ 3.0. It should be concluded from these facts that the stress increase in the present simulation, where no chain connects the top and bottom of the specimen, is caused by the nucleation of the network chain structure with the "entanglements" and the orientation and stretch of the chains bridging them. In order to clarify the characteristics of the entanglements at the initial equilibrium state, the "flexion nodes" in all molecular chains are investigated. As schematically illustrated in Fig. 10, the interior angle between two position vectors from the target particle A to the particles B and C, 10 backward and forward monomers, are evaluated. The particles, at which the angle is less than 90 deg at the initial equilibrium, are drawn in black in Fig. 9 as flexion nodes. Dense flexion nodes can be observed at the entanglements in the figure with εzz = 3.0, thus it is suggested that the flexion nodes tend to make entanglements. It is also pointed out, however, that there are many flexion nodes straightened during the deformation, since many black particles can be seen in the long straightened chains. From these remarks and the figure of εzz = 0.0, we can see that the initial arrangement of the dense flexion nodes does not correlate well with the entanglements nucleated during the yield ⇒ hardening process. The configuration or distance of the entanglements, of great interest from the viewpoint of hierarchical modelling, may not be easily characterized by the initial chain structure but depends on the history of complicated local deformations. The change in the distribution of local density during the yield ⇒ hardening process is shown in Fig. 11. In the figures with εzz = 0.5 and 1.0, the peak translates to the lower side by tension, however, the distribution maintains a broad base at the higher side because of the clusters shown in Fig. 9. It is confirmed quantitatively from the figure with εzz = 1.5 that a new structure nucleates at the beginning of the strain hardening, since another small peak appears near ρ = 0.53 g/cm³ in the density distribution. Figure 12 illustrates particles with a higher local density than the branched peak, ρhigh, at each strain of 1.5~3.0. Clusters A, B and C are indicated by ellipsoids in the figure as an example to make the relative position of the clusters clear. Many of the entanglements are observed in the center of the cross section, a few at the surface, and none at the corners. Most of the entangled chains at the corners and surfaces have disappeared during the yield ⇒ hardening process, sn ne t na s stte et etie distance between the entanglements could not be decided quantitatively, since they disperse widely as can be seen in the figure. The relationship between the distance and the average molecular weight remains to be invesitigated statistically in the next study.

    The material deforms homogeneously and maintains the initial chain structure until εzz = 0.5, however, a few voids appear.

    “The material deforms homogeneously and maintains the initial chain structure until εzz = 0.5, however, a few voids appear in contrast with the deformation of an amorphous metal [21].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [21] [21] Matsumoto, R., Kitagawa, H., Nakatani, K., Nakatani, A., Molecular dynamics simulation on a crack propagating in amorhous metal, Transaction of the Japan Society of Mechanical Engineers, Series A 76–653 (2001), 23–29. (in Japanese) -

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

  • The quote only partly states this claim.

    Findingown data
    § 3.1 Initial equilibrium structure and yield

    The simulated stress-strain curve shows a linear elastic relationship at the initial stage of straining up to a strain of 0.012 at a strain rate of 5.0×10^11/s.

    “It shows a linear elastic relationship up to the strain of 0.012”
    Quote in the paperNot a substantial claim
  • May combine two claims.

    Findingown data
    § 3.1 Initial equilibrium structure and yield

    After the small peak, the stress increases again and shows the maximum peak of σzz = 0.92 GPa at εzz = 0.027 (Arrow 2).

    “Then the stress increases again and shows the maximum peak of σzz = 0.92 GPa at εzz = 0.027 (Arrow ②).”
    Quote in the paperNot a substantial claim
  • May combine two claims.

    Findingown data
    § 3.1 Initial equilibrium structure and yield

    The torsion angle distribution has peaks at the stable and metastable points of trans and gauche, but many nodes are deviated from the stable or metastable angle so that the peaks have broader bases.

    “The torsion angle also has its peaks at the stable and metastable points of trans and gauche, however, there are many nodes deviated from the stable or metastable angle so that the peaks have broader bases.”
    Quote in the paperNot a substantial claim
  • May combine two claims.

    Findingown data
    § 3.3 Chain entanglements and directional orientation Figure 9 shows the snapshots of molecular chains in the tensile simulation. In the figure, a rectangular region in the center of the specimen, of which initial size is 10 nm × 10 nm × 3 nm, is drawn. The black particles indicate the flexion nodes at the initial equilibrium, as described later. The material deforms homogeneously and maintains the initial chain structure until εzz = 0.5, however, a few voids appear in contrast with the deformation of an amorphous metal [21]. The inhomogeneity in the density becomes clearer in the figure with εzz = 1.0, where splitting clusters of molecular chains with voids can be observed. Here, we can see straightened chains notably in the low-density regions, or the void regions between clusters. At the beginning of the strain hardening at εzz = 1.5, a new network structure is generated where long straightened chains connect the clusters of entangled chains. It is also observed that many chains between clusters are oriented in the tensile direction. After a strain of 1.5, some clusters dissolve but the material deforms mainly by the stretching of the oriented chains between clusters keeping the generated network structure, as recognized from the positions of clusters I and Ⅱ in the figures with εzz = 1.5 ∼ 3.0. It should be concluded from these facts that the stress increase in the present simulation, where no chain connects the top and bottom of the specimen, is caused by the nucleation of the network chain structure with the "entanglements" and the orientation and stretch of the chains bridging them. In order to clarify the characteristics of the entanglements at the initial equilibrium state, the "flexion nodes" in all molecular chains are investigated. As schematically illustrated in Fig. 10, the interior angle between two position vectors from the target particle A to the particles B and C, 10 backward and forward monomers, are evaluated. The particles, at which the angle is less than 90 deg at the initial equilibrium, are drawn in black in Fig. 9 as flexion nodes. Dense flexion nodes can be observed at the entanglements in the figure with εzz = 3.0, thus it is suggested that the flexion nodes tend to make entanglements. It is also pointed out, however, that there are many flexion nodes straightened during the deformation, since many black particles can be seen in the long straightened chains. From these remarks and the figure of εzz = 0.0, we can see that the initial arrangement of the dense flexion nodes does not correlate well with the entanglements nucleated during the yield ⇒ hardening process. The configuration or distance of the entanglements, of great interest from the viewpoint of hierarchical modelling, may not be easily characterized by the initial chain structure but depends on the history of complicated local deformations. The change in the distribution of local density during the yield ⇒ hardening process is shown in Fig. 11. In the figures with εzz = 0.5 and 1.0, the peak translates to the lower side by tension, however, the distribution maintains a broad base at the higher side because of the clusters shown in Fig. 9. It is confirmed quantitatively from the figure with εzz = 1.5 that a new structure nucleates at the beginning of the strain hardening, since another small peak appears near ρ = 0.53 g/cm³ in the density distribution. Figure 12 illustrates particles with a higher local density than the branched peak, ρhigh, at each strain of 1.5~3.0. Clusters A, B and C are indicated by ellipsoids in the figure as an example to make the relative position of the clusters clear. Many of the entanglements are observed in the center of the cross section, a few at the surface, and none at the corners. Most of the entangled chains at the corners and surfaces have disappeared during the yield ⇒ hardening process, sn ne t na s stte et etie distance between the entanglements could not be decided quantitatively, since they disperse widely as can be seen in the figure. The relationship between the distance and the average molecular weight remains to be invesitigated statistically in the next study.

    After a strain of 1.5, some clusters dissolve but the material deforms mainly by the stretching of the oriented chains between clusters, keeping the generated network structure.

    “After a strain of 1.5, some clusters dissolve but the material deforms mainly by the stretching of the oriented chains between clusters keeping the generated network structure”
    Quote in the paperSubstantial claim
  • May combine two claims.

    Findingreasoning
    § 3.2 Yield ⇐ hardening behavior

    The number of gauche nodes decreases and that of trans increases after εzz = 0.5, because both transitions decrease monotonically and the gauche ⇒ trans transition is twice as much as the other.

    “Then, the number of gauche nodes decreases and that of trans increases after εzz = 0.5, from the fact that both transitions decrease monotonically and the gauche ⇒ trans transition is twice as much as the other.”
    Quote in the paperSubstantial claim
  • May combine two claims.

    Findingown data
    § 3.2 Yield ⇐ hardening behavior

    In the yield region, only the torsion shows remarkable change at εzz = 0.5, where it turns to decrease, while the bond stretch and bending increase monotonically.

    “In the yield region, only the torsion shows remarkable change at εzz = 0.5, where it turns to decrease, while the bond stretch and bending increase monotonically.”
    Quote in the paperSubstantial claim
  • May combine two claims.

    Findingown data
    § 3.1 Initial equilibrium structure and yield

    The atomic density has its peak at the controlled density of 0.87 g/cm3 and a wide distribution in the lower side due to the surfaces.

    “The atomic density has its peak at the controlled density of 0.87g/cm³ and a wide distribution in the lower side due to the surfaces.”
    Quote in the paperNot a substantial claim
  • May combine two claims.

    Findingown data
    § 3.3 Chain entanglements and directional orientation Figure 9 shows the snapshots of molecular chains in the tensile simulation. In the figure, a rectangular region in the center of the specimen, of which initial size is 10 nm × 10 nm × 3 nm, is drawn. The black particles indicate the flexion nodes at the initial equilibrium, as described later. The material deforms homogeneously and maintains the initial chain structure until εzz = 0.5, however, a few voids appear in contrast with the deformation of an amorphous metal [21]. The inhomogeneity in the density becomes clearer in the figure with εzz = 1.0, where splitting clusters of molecular chains with voids can be observed. Here, we can see straightened chains notably in the low-density regions, or the void regions between clusters. At the beginning of the strain hardening at εzz = 1.5, a new network structure is generated where long straightened chains connect the clusters of entangled chains. It is also observed that many chains between clusters are oriented in the tensile direction. After a strain of 1.5, some clusters dissolve but the material deforms mainly by the stretching of the oriented chains between clusters keeping the generated network structure, as recognized from the positions of clusters I and Ⅱ in the figures with εzz = 1.5 ∼ 3.0. It should be concluded from these facts that the stress increase in the present simulation, where no chain connects the top and bottom of the specimen, is caused by the nucleation of the network chain structure with the "entanglements" and the orientation and stretch of the chains bridging them. In order to clarify the characteristics of the entanglements at the initial equilibrium state, the "flexion nodes" in all molecular chains are investigated. As schematically illustrated in Fig. 10, the interior angle between two position vectors from the target particle A to the particles B and C, 10 backward and forward monomers, are evaluated. The particles, at which the angle is less than 90 deg at the initial equilibrium, are drawn in black in Fig. 9 as flexion nodes. Dense flexion nodes can be observed at the entanglements in the figure with εzz = 3.0, thus it is suggested that the flexion nodes tend to make entanglements. It is also pointed out, however, that there are many flexion nodes straightened during the deformation, since many black particles can be seen in the long straightened chains. From these remarks and the figure of εzz = 0.0, we can see that the initial arrangement of the dense flexion nodes does not correlate well with the entanglements nucleated during the yield ⇒ hardening process. The configuration or distance of the entanglements, of great interest from the viewpoint of hierarchical modelling, may not be easily characterized by the initial chain structure but depends on the history of complicated local deformations. The change in the distribution of local density during the yield ⇒ hardening process is shown in Fig. 11. In the figures with εzz = 0.5 and 1.0, the peak translates to the lower side by tension, however, the distribution maintains a broad base at the higher side because of the clusters shown in Fig. 9. It is confirmed quantitatively from the figure with εzz = 1.5 that a new structure nucleates at the beginning of the strain hardening, since another small peak appears near ρ = 0.53 g/cm³ in the density distribution. Figure 12 illustrates particles with a higher local density than the branched peak, ρhigh, at each strain of 1.5~3.0. Clusters A, B and C are indicated by ellipsoids in the figure as an example to make the relative position of the clusters clear. Many of the entanglements are observed in the center of the cross section, a few at the surface, and none at the corners. Most of the entangled chains at the corners and surfaces have disappeared during the yield ⇒ hardening process, sn ne t na s stte et etie distance between the entanglements could not be decided quantitatively, since they disperse widely as can be seen in the figure. The relationship between the distance and the average molecular weight remains to be invesitigated statistically in the next study.

    In the local density distribution during yield ⇒ hardening, the peak translates to the lower side by tension, but the distribution maintains a broad base at the higher side because of the clusters.

    “In the figures with εzz = 0.5 and 1.0, the peak translates to the lower side by tension, however, the distribution maintains a broad base at the higher side because of the clusters shown in Fig. 9.”
    Quote in the paperNot a substantial claim
  • May combine two claims.

    Findingown data
    § 3.1 Initial equilibrium structure and yield

    The rotation of the dihedral angle observed during 1 and 2 is within ±30 deg while that after 2 exceeds ±60 deg, resulting in the gauche ⇔ trans transition.

    “the rotation of the dihedral angle observed during ① and ② is within ±30 deg while that after ② exceeds ±60 deg, resulting in the gauche ⇔ trans transition.”
    Quote in the paperSubstantial claim
  • May combine two claims.

    Findingown data
    § 3.3 Chain entanglements and directional orientation Figure 9 shows the snapshots of molecular chains in the tensile simulation. In the figure, a rectangular region in the center of the specimen, of which initial size is 10 nm × 10 nm × 3 nm, is drawn. The black particles indicate the flexion nodes at the initial equilibrium, as described later. The material deforms homogeneously and maintains the initial chain structure until εzz = 0.5, however, a few voids appear in contrast with the deformation of an amorphous metal [21]. The inhomogeneity in the density becomes clearer in the figure with εzz = 1.0, where splitting clusters of molecular chains with voids can be observed. Here, we can see straightened chains notably in the low-density regions, or the void regions between clusters. At the beginning of the strain hardening at εzz = 1.5, a new network structure is generated where long straightened chains connect the clusters of entangled chains. It is also observed that many chains between clusters are oriented in the tensile direction. After a strain of 1.5, some clusters dissolve but the material deforms mainly by the stretching of the oriented chains between clusters keeping the generated network structure, as recognized from the positions of clusters I and Ⅱ in the figures with εzz = 1.5 ∼ 3.0. It should be concluded from these facts that the stress increase in the present simulation, where no chain connects the top and bottom of the specimen, is caused by the nucleation of the network chain structure with the "entanglements" and the orientation and stretch of the chains bridging them. In order to clarify the characteristics of the entanglements at the initial equilibrium state, the "flexion nodes" in all molecular chains are investigated. As schematically illustrated in Fig. 10, the interior angle between two position vectors from the target particle A to the particles B and C, 10 backward and forward monomers, are evaluated. The particles, at which the angle is less than 90 deg at the initial equilibrium, are drawn in black in Fig. 9 as flexion nodes. Dense flexion nodes can be observed at the entanglements in the figure with εzz = 3.0, thus it is suggested that the flexion nodes tend to make entanglements. It is also pointed out, however, that there are many flexion nodes straightened during the deformation, since many black particles can be seen in the long straightened chains. From these remarks and the figure of εzz = 0.0, we can see that the initial arrangement of the dense flexion nodes does not correlate well with the entanglements nucleated during the yield ⇒ hardening process. The configuration or distance of the entanglements, of great interest from the viewpoint of hierarchical modelling, may not be easily characterized by the initial chain structure but depends on the history of complicated local deformations. The change in the distribution of local density during the yield ⇒ hardening process is shown in Fig. 11. In the figures with εzz = 0.5 and 1.0, the peak translates to the lower side by tension, however, the distribution maintains a broad base at the higher side because of the clusters shown in Fig. 9. It is confirmed quantitatively from the figure with εzz = 1.5 that a new structure nucleates at the beginning of the strain hardening, since another small peak appears near ρ = 0.53 g/cm³ in the density distribution. Figure 12 illustrates particles with a higher local density than the branched peak, ρhigh, at each strain of 1.5~3.0. Clusters A, B and C are indicated by ellipsoids in the figure as an example to make the relative position of the clusters clear. Many of the entanglements are observed in the center of the cross section, a few at the surface, and none at the corners. Most of the entangled chains at the corners and surfaces have disappeared during the yield ⇒ hardening process, sn ne t na s stte et etie distance between the entanglements could not be decided quantitatively, since they disperse widely as can be seen in the figure. The relationship between the distance and the average molecular weight remains to be invesitigated statistically in the next study.

    Many of the entanglements are observed in the center of the cross section, a few at the surface, and none at the corners.

    “Many of the entanglements are observed in the center of the cross section, a few at the surface, and none at the corners.”
    Quote in the paperNot a substantial claim
    • Rests on an assumption: Particles with a local density higher than the branched peak ρhigh correspond to entanglements.
  • May combine two claims.

    Interpretationown data
    § 3.2 Yield ⇐ hardening behavior

    The gauche ⇒ trans transition decreases the system energy, and is subtly balanced with the probability of the trans ⇒ gauche transition, which increases the energy.

    “that decreases the system energy, are subtly balanced with the probability of the trans ⇒ gauche transition, that increases the energy.”
    Quote in the paperSubstantial claim
  • May combine two claims.

    Interpretationown data
    § 3.1 Initial equilibrium structure and yield

    The potential energy of the whole system is minimum by the initial relaxation but some torsion angles remain at the high energy state in the intricated amorphous chain structure.

    “This implies the potential energy of the whole system is minimum by the initial relaxation but some torsion angles remain at the high energy state in the intricated amorphous chain structure.”
    Quote in the paperNot a substantial claim
  • Classified as probably not a substantial claim.

    Premisecitation
    § Simulation Procedure 2

    The potential functions and parameters adopted are proposed by Kuwajima et al. [20] for amorphous polyethylene.

    “The potential functions and parameters adopted are proposed by Kuwajima et al. [20] for amorphous polyethelene as shown in the equations below with the parameters listed in Table 1.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Kuwajima et al. [20] [20] Kuwajima, S., Noma, H., Ohsaka, T., Proceedings of the 4th symposium of the society of computer chemistry, Japan (1994), 53–56. (in Japanese) -

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

  • Probably not a substantial claim: may not pass S4 (based). May combine two claims.

    Study design and conductnone given
    § 1 Introduction

    The simulation eliminates any periodicity and the chain connecting the top and bottom of the specimen, which would undesirably determine the mechanical properties with its characteristic length.

    “By eliminating any periodicity and the chain connecting the top and bottom of the specimen, which undesirably determines the mechanical properties with its “characteristic length”, the fundamental mechanism of chain entanglements is investigated in detail.”
    Quote in the paperNot a substantial claim
17 of 17
  • The paper relies on this without support.

    The structural change of molecular chains such as chain folding requires more time in real polymeric materials.

    “The structural change of molecular chains such as chain folding requires more time in real polymetric materials.”
  • The paper relies on this without support.

    Particles with a local density higher than the branched peak ρhigh correspond to entanglements.

    “Figure 12 illustrates particles with a higher local density than the branched peak, ρhigh, at each strain of 1.5~3.0.”
  • The paper relies on this without support.

    The nanoscopic specimen with about 2 million methylene groups is large enough to capture the fundamental mechanism of chain entanglements in amorphous polymers.

    “For fundamental understanding of the deformation behavior of large, irregular and massive molecular chains in an amorphous polymer, it may still be indispensable to directly trace the motion of all chains with a huge number of molecules.”
3 of 3

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.

  • Reference 18 is attributed to the wrong authors

    Minor

    The discussion attributes reference 18 to Shibutani and colleagues, whereas the reference list identifies Ichiyanagi as its author.

  • Elastic-range limit differs between abstract and results

    Minor

    The abstract describes the response as linear elastic through a strain of 0.03, but the results say linear elasticity ends at 0.012 and describe a stress decrease before 0.03.

2 of 2

Cites

Flagged first, then by citations

1 of the 22 references couldn’t be matched to a known paper.

Research works printed but not linked: 3

  1. Furukawa, 2001, System for three-dimensional reconstruction of TEM images based on computerized tomography method, JEOL News, 36, 50
  2. Tschöp, 1998, Simulation of polymer melts. II. From coarse-grained models back to atomistic description, Acta Polymer, 49, 75, 10.1002/(SICI)1521-4044(199802)49:2/3<75::AID-APOL75>3.0.CO;2-5 · DOI
  3. Kuwajima S, Noma H, Ohsaka T. Proceedings of the Fourth Symposium of the Society of Computer Chemistry, Japan, 1994, pp. 53–6 [in Japanese].

Cited by

Sorted by citations

Authors
Yashiro, K., Ito, T., & Tomita, Y.
Affiliations
Kobe University (JP)
Corresponding author
Yashiro, Kisaragi
Venue
International Journal of Mechanical Sciences
Publisher
Elsevier BV
Published
2003-11
Volume
45
Issue
11
Pages
1863-1876
ISSN
0020-7403 (ISSN-L)
OpenAlex
W2144689690
Cited by
128
References
22
Citations by year
2026: 5 · 2025: 9 · 2024: 13 · 2023: 10 · 2022: 10 · 2021: 3 · 2020: 9 · 2019: 9 · 2018: 1 · 2017: 4 · 2016: 5 · 2015: 5 · 2014: 1 · 2013: 3 · 2012: 3
FWCI
3.59
Type
journal article
Language
en
Open access
Locations
  • International Journal of Mechanical Sciences (publishedVersion)
  • Institutional Repositories DataBase (IRDB) (submittedVersion)
  • Kobe University Repository Kernel (Kobe University) (submittedVersion, other-oa)
Funders
Ministry of Education, Culture, Sports, Science and Technology
Topics
  • Physical Sciences › Materials Science › Polymers and Plastics › Polymer crystallization and properties
  • Physical Sciences › Chemical Engineering › Fluid Flow and Transfer Processes › Rheology and Fluid Dynamics Studies
  • Physical Sciences › Chemistry › Physical and Theoretical Chemistry › Advanced Physical and Chemical Molecular Interactions
Keywords
amorphous polymers, amorphous polyethylene, uniaxial tension, chain entanglement, entanglement network, strain hardening, yielding, chain orientation, stress-strain behavior, dihedral angle

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Claims read by deepseek-v4.1-flash under definition version 3 (extract-v3) on 2026-10-10.

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