Cavitation in strained polyvinylidene fluoride: mechanical and X-ray experimental studies

Castagnet, Sylvie; Girault, S.; Gacougnolle, J.L.; Dang, Patrick

doi:10.1016/s0032-3861(00)00077-x

Cited by 96 publications

(106 citation statements)

References 12 publications

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“…It needs to be taken into consideration for the evaluation of the actual strain state in stretched samples whose microstructure is characterized by X-ray diffraction (WAXS) and scanning electron microscopy (SEM). Although previous authors showed that extensive shrinkage was obtained after several months at room temperature [23] or several hours at temperatures higher than 120°C [24], the recovery saturates rapidly in our experiments. In particular, we verified that that ε 33 and ε v did not change significantly any more in the period between 3 hours and 24 hours after unloading the samples.…”

Section: Materials Behavior During Unloading and Recovery Stagescontrasting

confidence: 76%

Volume Variation Process of High-Density Polyethylene During Tensile and Creep Tests

Addiego¹,

Dahoun²,

G’Sell³

et al. 2006

Oil & Gas Science and Technology - Rev. IFP

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Résumé -Processus de la variation volumique du polyéthylène à haute densité au cours d'essais de traction et de fluage -Des éprouvettes de polyéthylène à haute densité ont été soumises à des essais de traction et des tests de fluage à l'aide d'un dispositif d'essais mécaniques à pilotage vidéo-métrique (VidéoTraction ® ). L'évolution du volume spécifique de ce polymère semi-cristallin est caracté-risée en fonction de la déformation vraie. Dans le stade élastique, on mesure une expansion hydrostatique puis, dans le stade plastique, on note une compétition entre un effet de compaction et un phénomène de dilatation. La compaction, sans doute surestimée dans les expériences, est toutefois un mécanisme important dû à l'orientation des chaînes amorphes au cours de l'étirage. Ce phénomène est attesté par des mesures de diffraction des rayons X qui montrent une réduction de la distance moyenne entre les chaînes amorphes. Le processus de dilatation s'explique par la diminution du taux de cristallinité et par la formation, la croissance et la coalescence de craquelures au sein et entre les sphérolites. L'observation d'échan-tillons déformés par microscopie électronique révèle ces défauts. La compétition compaction/dilatation est dictée par la mobilité de la phase amorphe influencée elle-même par la température et le temps. Abstract -Volume Variation Process of High-Density Polyethylene During Tensile and Creep Tests -Samples of high-density polyethylene have been subjected to tensile tests and creep experiments by means of a video-controlled testing system (VidéoTraction © ). The evolution of specific volume in this semi-crystalline polymer is determined versus true strain. In the elastic stage, we measure a hydrostatic expansion and then, in the plastic stage, we observe a competition between a compaction effect and a dilatation phenomenon. Although compaction is probably overestimated in the present testing technique, it represents a pertinent mechanism that is ascribed to the orientation of the amorphous chains during stretching. This phenomenon is characterized by X-ray diffraction measurements that show a reduction of average distance between amorphous chains. Dilatation process is explained by the diminution of crystallinity and by the formation, growth and coalescence of crazes inside and between spherulites.Electron microscopy reveals these defects. The competition between compaction and dilatation, controlled by the mobility of the amorphous phase, depends on temperature and time.

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Section: Materials Behavior During Unloading and Recovery Stagescontrasting

confidence: 76%

Volume Variation Process of High-Density Polyethylene During Tensile and Creep Tests

Addiego¹,

Dahoun²,

G’Sell³

et al. 2006

Oil & Gas Science and Technology - Rev. IFP

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“…Cavitation is considered as the main reason of volume increase in deformed polymer samples [19][20][21][22][23] . G'Sell et al 22 , Pawlak et al 10 and Na and Lv 19 observed that the volume of deformed polypropylene substantially increases with increasing strain.…”

Section: Introductionmentioning

confidence: 99%

Cavitation and morphological changes in polypropylene deformed at elevated temperatures

Pawlak

Gałęski

2010

J Polym Sci B Polym Phys

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“…It was shown that cavitation originates in the amorphous phase and appears at or around the yield point [1][2][3][4][5].…”

Section: Introductionmentioning

confidence: 99%

Cavitation during tensile drawing of annealed high density polyethylene

Pawlak

Gałęski

2010

Polymer

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The annealing of semicrystalline polymers usually leads to the crystal refinement and thickening. It appears that also the cavitation during tensile drawing is affected. In the uniaxially drawn high density polyethylene a massive cavitation was detected by X-ray scattering in samples previously annealed at 125 o C. The number of voids depends on the annealing time, while their size and orientation depends on the local strain. The cavitation resulted in 30% increase of volume for annealed samples, strained to 4-5. Cavitation and volume increase were not observed for small and intermediate strains if the polyethylene samples were not annealed. The decrease of drawing rate results in reducing cavitation and also the void stability: at the low strain rate voids were detected during tensile drawing but they disappeared after unloading the sample.

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Cavitation in strained polyvinylidene fluoride: mechanical and X-ray experimental studies

Cited by 96 publications

References 12 publications

Volume Variation Process of High-Density Polyethylene During Tensile and Creep Tests

Volume Variation Process of High-Density Polyethylene During Tensile and Creep Tests

Cavitation and morphological changes in polypropylene deformed at elevated temperatures

Cavitation during tensile drawing of annealed high density polyethylene

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