Strain‐induced crystallization of swollen, crosslinked polyethylene

McHugh, A. J.; Yung, Wai-Shing

doi:10.1002/polb.1989.090270214

Cited by 9 publications

(4 citation statements)

References 23 publications

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“…'~~~ Such stresses and the resulting strain in the precursor are, however, low otherwise one would see high birefringence before crystallization such as shown in our study of crosslinked fibers. 23 The functional dependence with flow rate of the crystallization kinetics shown in Figures 6, 7, and 8 and reproduced by eq. (8) reflects both aspects of this process.…”

Section: Flow Rate Dependencementioning

confidence: 77%

The kinetics of flow‐induced crystallization from solution

McHugh¹,

Spěváček²

1991

J Polym Sci B Polym Phys

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In situ birefringence measurements of the seeded growth in a tubular flow geometry of 0.01 wt% solution of a polyethylene fraction in xylene have been used to determine the flowinduced crystallization kinetics as a function of temperature and flow rate. In contrast to earlier reports on higher molecular weight polyethylene and polypropylene systems, orientational properties of the crystallized fibers do not show a clear correlation with growth conditions (i.e., temperature and flow rate). The combined kinetic data from these experiments and our earlier studies of higher molecular weight polyethylene—xylene and polypropylene—tetralin systems are analyzed in terms of a modified from of the Avrami equation which provides a basis for separately correlating temperature and flow rate effects. The observed temperature dependency of the crystallization process can be interpreted in terms of nucleation and growth models while the flow rate dependency can be interpreted on the basis of entanglement formation arguments. Results showing liquid phase precursor formation in an atactic polystyrene system are also presented to further document the liquidphase separation which can be induced in polymers under flow.

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Section: Flow Rate Dependencementioning

confidence: 77%

The kinetics of flow‐induced crystallization from solution

McHugh¹,

Spěváček²

1991

J Polym Sci B Polym Phys

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“…This reflects the fact that we are using a different form for the entropic contribution to the total system Hamiltonian [eq. (15)]. Strictly speaking, for quiescent crystallization, one should use the form of eq.…”

Section: +-mentioning

confidence: 99%

A continuum model for the dynamics of flow-induced crystallization

Bushman¹,

McHugh²

1996

J. Polym. Sci. B Polym. Phys.

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A model for flow‐induced crystallization is developed which is based on ideas from the theory of strain‐induced crystallization, coupled with an irreversible thermodynamic formalism based on the continuum Hamiltonian Poisson Brackets. The latter allows accounting for the changing energetics during simultaneous flow deformation and extended‐chain crystallization. Input parameters to the model include the molecular relaxation time, a crystallization parameter, and the molecular weight. Calculations of the crystallization rate, chain elongation, stress, and birefringence are presented for a variety of flow kinematics and flow histories, including transient processes following cessation of flow. Induction times based on a reasonable choice for the induction crystallinity follow experimentally observed trends reported in the literature. © 1996 John Wiley & Sons, Inc.

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“…This can be explained as follows. The movement of molecular chains could be retarded by crosslinking sites, resulting in reduction of the possibility to form extended‐chain conformation (strain‐induced crystallization) . At larger strains, the local stress can be high enough to break the crosslinking sites in the irradiated HDPE.…”

Section: Resultsmentioning

confidence: 99%

“…The movement of molecular chains could be retarded by crosslinking sites, resulting in reduction of the possibility to form extended-chain conformation (strain-induced crystallization). 36 At larger strains, the local stress can be high enough to break the crosslinking sites in the irradiated HDPE. The break of crosslinking sites consumes a part of deformation energy and results in a decrease of local stress.…”

Section: Deformation Mechanisms and Modelsmentioning

confidence: 99%

Structure evolution during uniaxial tensile deformation of high density polyethylene before and after irradiation by 1 MeV electrons

Rui

Yang

et al. 2013

J of Applied Polymer Sci

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The structural evolution of high density polyethylene (HDPE) during uniaxial tensile deformation, before and after irradiation by 1 MeV electrons, is in situ studied by synchrotron small angle X-ray scattering (SAXS) and wide angle X-ray diffraction (WAXD). Both the pristine and the irradiated HDPE exhibit three regions of deformation behavior. It is shown that the deformation in the first region is in accord with the change in long period of the lamellar structure. In the following two regions, both the straininduced melting and strain-induced crystallization could occur. The tensile stress decreases with strain in the second region due to the dominant melting effect. In the third region, the synergistic effect of the melting and crystallization results in stress leveling off first, and then the tensile stress increases again because the crystallization effect becomes dominant at higher strains. For the irradiated HDPE, the irradiation-induced crosslinking network slows down the deformation process. Compared to the pristine one, all the tensile stress is rather higher at a given strain for the irradiated HDPE.

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Strain‐induced crystallization of swollen, crosslinked polyethylene

Cited by 9 publications

References 23 publications

The kinetics of flow‐induced crystallization from solution

The kinetics of flow‐induced crystallization from solution

A continuum model for the dynamics of flow-induced crystallization

Structure evolution during uniaxial tensile deformation of high density polyethylene before and after irradiation by 1 MeV electrons

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