Elastic modulus in the crystalline region of poly(p-phenylene terephthalamide)

Gaymans, R.J.; Tijssen, J.; Harkema, Sybolt; Bantjes, A.

doi:10.1016/0032-3861(76)90133-6

Cited by 37 publications

(17 citation statements)

References 9 publications

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“…However, these stiness values computed with DREIDING are actually quite comparable to ReaxFF, giving condence that ReaxFF yields a reasonable model for PPTA. Experimental measurements for the crystalline elastic modulus E zz have yielded estimates in the 200260 GPa range [19,5,80], while theoretical estimates have placed this modulus in the 180200 GPa range [74,34]. It appears that all MD potentials list in Table 3.2 yield an overestimate of E zz compared to theory and experiment.…”

Section: Calculation Of Elastic Modulimentioning

confidence: 98%

Molecular Dynamics Modeling of PPTA Crystals in Aramid Fibers

Mercer

2016

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In this work, molecular dynamics modeling is used to study the mechanical properties of PPTA crystallites, which are the fundamental microstructural building blocks of polymer aramid bers such as Kevlar. Particular focus is given to constant strain rate axial loading simulations of PPTA crystallites, which is motivated by the rate-dependent mechanical properties observed in some experiments with aramid bers. In order to accommodate the covalent bond rupture that occurs in loading a crystallite to failure, the reactive bond order force eld ReaxFF is employed to conduct the simulations.Two major topics are addressed: The rst is the general behavior of PPTA crystallites under strain rate loading. Constant strain rate loading simulations of crystalline PPTA reveal that the crystal failure strain increases with increasing strain rate, while the modulus is not aected by the strain rate. Increasing temperature lowers both the modulus and the failure strain. The simulations also identify the CN bond connecting the aromatic rings as weakest primary bond along the backbone of the PPTA chain. The eect of chain-end defects on PPTA micromechanics is explored, and it is found that the presence of a chain-end defect transfers load to the adjacent chains in the hydrogen-bonded sheet in which the defect resides, but does not inuence the behavior of any other chains in the crystal. Chain-end defects are found to lower the strength of the crystal when clustered together, inducing bond failure via stress concentrations arising from the load transfer to bonds in adjacent chains near the defect site. The second topic addressed is the nature of primary and secondary bond failure in crystalline PPTA. Failure of both types of bonds is found to be stochastic in nature and driven by thermal uctuations of the bonds within the crystal. A model is proposed which uses reliability theory to model bonds under constant strain rate loading as components with time-dependent failure rate functions. The model is shown to work well for predicting the onset of primary backbone bond failure, as well as the onset of secondary bond failure via chain slippage for the case of isolated non-interacting chain-end defects.

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Section: Calculation Of Elastic Modulimentioning

confidence: 98%

Molecular Dynamics Modeling of PPTA Crystals in Aramid Fibers

Mercer

2016

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“…[1][2][3][4] In general, polyethers such as polyoxypropylene (POP) or poly(tetramethylene ether) glycol (PTMEG) are often chosen as the soft segment, and the hard segments are nylon-6, nylon-10, nylon-12, nylon-66, nylon-6,10, nylon-4,6, and some aromatic polyamides. [5][6][7][8][9][10][11][12][13] Both types of segments are usually chemically bonded by ester linkages from a condensation of prepolymers and diacids, which serve as chain extenders. Among the TPAEs, the nylon-6-based TPAEs have high potential for industrial usage because of the low cost of caprolactam (CPL).…”

Section: Introductionmentioning

confidence: 99%

Formulation and optimization of thermoplastic polyamide elastomer properties by mixture response surface methodology

Twu¹,

Chen²,

Shieh³

2002

J of Applied Polymer Sci

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ABSTRACT:In this study, the formulation and optimization of the properties of thermoplastic polyamide elastomers (TPAEs) were evaluated by a mixture response surface methodology. The TPAEs prepared from different chain extender blends of adipic acid, terephthalic acid (TPA), and C36 dimer acid were characterized by specific gravity measurement, water absorption measurement, differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). The results indicate that the specific gravity of the polymers increased and the water absorption of the polymers decreased as the content of TPA increased. The DSC data show two major endotherms corresponding to the melt of poly(tetramethylene ether) glycol (PTMEG) and nylon-6 segments. The TGA data show that the thermal degradation temperatures of the polymers increased as the C36 dimer acid content increased.

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“…The highly oriented high-tenacity/ high-modulus para-aramide fibers of poly (p-phenylene terephthalamide) ( P P T A ) have been studied using X-ray diffraction (for examples, see Refs. [1][2][3][4][5] in bundle form and light diffraction6 while stressing a single filament. Based on X-ray diffraction, electron diffraction, sonic and polarizing microscopic techniques, as well as macroscopic mechanical measurements of PPTA fibers, Schaefgen7 wrote an informative review on the structure, properties, and applications of PPTA fibers, known as Kevlar ( a DuPont trademark) or Arenka ( a n Enka trademark) fibers.…”

Section: Introductionmentioning

confidence: 99%

Synchrotron X-ray diffraction of a single filament and a bundle of poly (p-phenylene terephthalamide) filaments

Chu

et al. 1989

J. Polym. Sci. C Polym. Lett.

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Elastic modulus in the crystalline region of poly(p-phenylene terephthalamide)

Cited by 37 publications

References 9 publications

Molecular Dynamics Modeling of PPTA Crystals in Aramid Fibers

Molecular Dynamics Modeling of PPTA Crystals in Aramid Fibers

Formulation and optimization of thermoplastic polyamide elastomer properties by mixture response surface methodology

Synchrotron X-ray diffraction of a single filament and a bundle of poly (p-phenylene terephthalamide) filaments

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