The yield and thermoelastic properties of oriented poly(methyl methacrylate)

Botto, P.; Duckett, R. A.; Ward, I. M.

doi:10.1016/0032-3861(87)90414-9

Cited by 61 publications

(58 citation statements)

References 16 publications

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“…However, it has been suggested in the literature (see e.g. Raha and Bowden, 1972;Botto et al, 1987) that physical entanglements in amorphous polymers are being pulled out during deformation.…”

Section: An Example For Polycarbonatementioning

confidence: 99%

Analysis of shear band propagation in amorphous glassy polymers

Giessen

1994

International Journal of Solids and Structures

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Abstract-Similar to the well-known neck propagation phenomenon, shearing of polymer materials often reveals the initiation and subsequent propagation of a shear band. Finite element analysis is used to numerically simulate large plane strain, simple shear tests, focussing attention on the initiation and propagation of the shear band. The mesh sensitivity and effects of initial imperfection, strain softening, orientation hardening, strain-rate as well as the edge effects are discussed in detail. It appears that the intrinsic softening is the driving force to promote initiation of the shear band and its propagation in the shear direction, while the orientation hardening is the driving force for widening of the shear band. The predicted numerical results are compared with experimental data for polycarbonate found in the literature.

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Section: An Example For Polycarbonatementioning

confidence: 99%

Analysis of shear band propagation in amorphous glassy polymers

Giessen

1994

International Journal of Solids and Structures

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“…However, this instead allows a freedom to apply the model to a wide range of yielding phenomena covering even extremes of strain rate, temperature, experimental apparatus, and also polymers studied. [3][4][5][6] This is because the Eyring's model groups all possible molecular displacements into two activation parameters, V and ÁH. 2 Let us assume that the deformation up to the yield point is affine or the deformation on the molecular level is equivalent as that on the macroscopic level.…”

Section: Resultsmentioning

confidence: 99%

“…The yield behavior of polymers has been investigated by using polymers with varying structure (copolymer structure and composition, 1,2 amorphous or crystalline, 3,4 differential orientation and crystallinity, 5,6 presence of functional linkage, 7 etc.). Strain rate and temperature have been the experimental parameters in those studies, as polymeric molecules display temperature and rate dependent phenomena.…”

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confidence: 99%

Yield Strain Behavior of Poly(ethylene terephthalate): Correlation with Yield Stress Behavior in Strain Rate, Temperature, and Structure Dependence

Lim

Kim

2004

Polym J

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Studies on the mechanical properties of polymers such as yield behavior have been the keys to successful use of polymers in various mechanically functional purposes. The yield behavior of polymers has been investigated by using polymers with varying structure (copolymer structure and composition, 1,2 amorphous or crystalline, 3,4 differential orientation and crystallinity, 5,6 presence of functional linkage, 7 etc.). Strain rate and temperature have been the experimental parameters in those studies, as polymeric molecules display temperature and rate dependent phenomena. On the nature of the yield behavior of polymers, there have been reported a variety of phenomenological descriptions and molecular interpretations. One is to correlate the yield behavior with secondary mechanical relaxation behavior. 2,[6][7][8] It is based on the general understanding that such relaxations mediate macroscopic mechanical properties. We previously observed for oriented, semicrystalline poly(ethylene terephthalate) (PET) that tan maxima of both primary and secondary relaxations are linear increasing functions of the activation volume calculated by the Eyring's yield model. 6 All the above researches have focused mainly on the yield stress with no particular interest on the yield strain. In practical cases in mechanical applications, however, an elongational limit before the onset of a plastic deformation is also critical. To our knowledge, only one article can be found in the literature focusing on the yield strain, 9 in which it was reported that there is a transition in the yield strain for polyethylene at a temperature where a change in deformation mode occurs from elastic-plastic to viscoelastic manner. In this study, we report the yield strain variation in PET as a function of stain rate, temperature, and PET structure to reveal the similarity and difference with the yield stress behavior. In addition, a novel dimensional analysis correlating the yield strain with the activation volume of the yield was proposed. EXPERIMENTALPET samples with varying orientation and crystallinity were produced by the high speed melt spinning of high molecular weight PET (intrinsic viscosity of 0.98 dL/g). PET was extruded at a constant mass flow rate and spun at a take-up velocity range of 2.5-5.5 km/min to have different degree of melt draw ratio. Details of the melt spinning process and characterization methods are reported elsewhere, 10 and the properties of PET samples are listed in Table I. Tensile tests were performed using an Instron 4303 equipped with a temperature-controlling chamber. Measurements were done at various temperatures, e.g., 20, 50, and 75 C. Filament sample was clamped under a pretension of 0.01 g/den and placed inside the chamber preset to a desired temperature. The tensile test started after the thermal force generated in the sample became equilibrium (after 300 s).11 To impose strain rate variation, the crosshead speed varied at 0.3-300 mm/min at a constant gauge length of 50 mm corresponding to seven nominal strain ra...

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“…The knowledge of merely P2 is too nonspecific. Knowledge of P4, too, gives hope that there will be a better foundation for this discussion [15]. The possible relations between P2 and Pa as expansion coefficients of an ODF were examined byBower [5] (Fig.…”

Section: Orientationa/ State and Orientation Mechanismmentioning

confidence: 99%

The orientational state of uniaxially stretched PMMA

Weeger

Pietralla

Peetz

et al. 1988

Colloid & Polymer Sci

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Uniaxially stretched samples of PMMA were investigated by Brillouin Spectroscopy (BS). From the velocity of hypersound we could determine most of the elastic constants. Using a recently developed analysis [1] it is demonstrated that the properties of this polymer can be well described by the aggregate model. This result offers the possibility of mapping the mechanical properties by birefringence measurements. The dependence of the fourth moment P4 on the second moment P1 is identical with that determined for PC [2] and follows, in the measured range, that of an affine orientational state. Nevertheless, the dependence on the stretching ratio differs for different molecular weights. Thus the partition of the deformation into an orientational and an elongational contribution, as has been proposed [3], seems to be well founded.The partition depends on the stretching conditions.

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The yield and thermoelastic properties of oriented poly(methyl methacrylate)

Cited by 61 publications

References 16 publications

Analysis of shear band propagation in amorphous glassy polymers

Analysis of shear band propagation in amorphous glassy polymers

Yield Strain Behavior of Poly(ethylene terephthalate): Correlation with Yield Stress Behavior in Strain Rate, Temperature, and Structure Dependence

The orientational state of uniaxially stretched PMMA

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