Physical and mechanical properties of polyethylene for pipes in relation to molecular architecture. I. Microstructure and crystallisation kinetics

Hubert, L.; David, Laurent; Séguéla, Roland; Vigier, G.; Degoulet, Christophe; Germain, Yves

doi:10.1016/s0032-3861(01)00351-2

Cited by 104 publications

(85 citation statements)

References 46 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…It is worth noticing that is spite of their very close M n and M w values and similar co-units contents, PE-C and PE-D have significantly different M z values. This is relevant to the presence of a small amount of very long chains in PE-D that is expected to influence the crystallization behavior [38,39]. The four polymers have been submitted to three different thermal treatments in order to modify their crystalline microstructure and chain-topology.…”

Section: Experiments 21 Materials and Sample Preparationmentioning

confidence: 99%

On the strain-induced fibrillar microstructure of polyethylene: Influence of chemical structure, initial morphology and draw temperature

Xiong¹,

Lame²,

Chenal³

et al. 2016

Express Polym. Lett.

View full text Add to dashboard Cite

A general feature of the morphogenesis of semicrystalline polymers is the regular stacking of chainfolded lamellar crystals alternating with amorphous layers. This stacking s characterized by an intercrystalline long period L p including the crystalline lamella and amorphous layer thicknesses. The stacking long period is in the range of a few nanometers to a few tens. When crystallization is performed from a quiescent melt, the resulting microstructure is isotropic with a spherulitic arrangement of the lamella stacks as a result of the radial growth of the crystals from a common multiple nucleus often designated as axialite [1]. The size scale of spherulites ranges from a few to several hundred microns. Upon plastic deformation at large strains, isotropic semicrystalline polymers transform into fibrillar materials that aroused a great interest from both academic and industrial standpoints owing to their remarkable mechanical performances [2-6] to be used as ropes, textile fibers for high performance tissues and fabrics, reinforcing fibers for polymer-based composites, etc. Abstract. The influence of crystalline microstructure and molecular topology on the strain-induced fibrillar transformation of semi-crystalline polyethylenes having various chemical structures including co-unit content and molecular weight and crystallized under various thermal treatments was studied by in situ SAXS at different draw temperatures. The long period of the nascent microfibrils, L pf , proved to be strongly dependent on the draw temperature but non-sensitive to the initial crystallization conditions. L pf was smaller than the initial long period. Both findings have been ascribed to the straininduced melting-recrystallization process as generally claimed in the literature. The microfibrils diameter, D f , was shown to depend on the draw temperature and initial microstructure in a different way as L pf . The evolution of D f was shown to correlate with the interfacial layer thickness that mainly depends on the chemical structure of the chains. It was concluded that, in contrast to L pf , the microfibril diameter should not be directly sensitive to the strain-induced melting-recrystallization. The proposed scenario is that after the generation of the protofibrils by fragmentation of the crystalline lamellae at yielding, the diameter of the microfibril during the course of their stabilization should be governed by the chain-unfolding and subsequent aggregation of the unfolded chains onto the lateral surface of the microfibrils. The morphogenesis of the microfibrils should therefore essentially depend on the chemical structure of the polymer that governs its crystallization ability, its chain topology and subsequently its fragmentation process at yielding. This scenario is summed up in a sketch.

show abstract

Section: Experiments 21 Materials and Sample Preparationmentioning

confidence: 99%

On the strain-induced fibrillar microstructure of polyethylene: Influence of chemical structure, initial morphology and draw temperature

Xiong¹,

Lame²,

Chenal³

et al. 2016

Express Polym. Lett.

View full text Add to dashboard Cite

show abstract

“…The X code parameter indicates the material rank in the decreasing density classification. According to a previous complete molecular characterization of polymer fractions from similar polymers via "Temperature Rising Elution Fractionation" [24], the following general rules can be put forward for the various polymers of the present study. The Cr1 and Cr2 polymer series are both unimodal and have the same co-unit distribution profile which decreases with increasing molar weight.…”

Section: Experimental Methodsmentioning

confidence: 99%

“…ESCR steadily increases with decreasing density, for every series. This is relevant to the increase of either co-unit content or broadening of the MWD on the high molar weight side which both promotes the occurrence of tie chain [24], due to crystallization considerations that will be discussed below. At equivalent density, i.e.…”

Section: Experimental Methodsmentioning

confidence: 99%

Structural Approaches of Polyethylene Environmental Stress-Crack Resistance

Cazenave¹,

Sixou²,

Séguéla³

2006

Oil & Gas Science and Technology - Rev. IFP

View full text Add to dashboard Cite

Résumé -Approches structurales de la fissuration sous contrainte du polyéthylène en milieu tensio-actif -Ce travail est une contribution à la compréhension et la prédiction du comportement à long terme du polyéthylène en relation avec l'architecture moléculaire. L'exploration de la microstructure semi-cristalline et de la topologie moléculaire constituée de chaînes liantes intercristallines et de boucles de repliement constitue l'objectif majeur du travail. Une cristallisation fractionnée en deux étapes a été utilisée pour la séparation des espèces pouvant facilement cristalliser par repliement régulier de celles qui ne peuvent pas. Le taux de déformation naturel qui se développe au-delà du seuil d'écoulement plastique en traction uni-axiale s'est avéré très sensible à la topologie moléculaire par le biais de la fragmentation lamellaire et du dépliement de chaîne. La diffusion des rayons X aux petits angles a fourni de précieux renseignements semi-quantitatifs sur la régularité d'empilement de la microstructure lamellaire. Les données issues des trois approches révèlent des corrélations avec l'architecture moléculaire en bonne concordance avec l'évolution de la résistance à la fissuration sous contrainte. Ces corrélations sont discutées en termes de cinétique de cristallisation et de topologie moléculaire. Un résultat pratique de ce travail est l'accès à des outils prédictifs fiables pour la résistance à la fissuration sous contrainte. Abstract -Structural Approaches of Polyethylene Environmental Stress-Crack Resistance -This work was aimed at understanding and predicting of the long-term mechanical behavior of polyethylene in relation to molecular architecture. An insight into the semi-crystalline microstructure and the chain topology consisting of intercrystalline tie chains and loose folding loops was the main objective of the

show abstract

“…Side branches also cause a disruption in crystallinity and hence lower the degree of crystallinity in the microstructure [3]. The fraction of low molecular weight chains is responsible for high stiffness and good processability while the higher molecular weight fraction with short chain branches yields increased creep resistance and mechanical properties by increasing density of inter-lamellar tie molecules [4][5][6]. Considering previous research regarding mechanical properties-microstructure relationship, strain hardening phenomenon is known to have a direct correlation with long term creep performance and resistance to slow crack growth (SCG) in polyethylene materials [7][8][9].…”

mentioning

confidence: 99%

Correlation between rheological and mechanical properties of black PE100 compounds – Effect of carbon black masterbatch

Pircheraghi¹,

Sarafpour²,

Rashedi³

et al. 2017

Express Polym. Lett.

View full text Add to dashboard Cite

Physical and mechanical properties of polyethylene for pipes in relation to molecular architecture. I. Microstructure and crystallisation kinetics

Cited by 104 publications

References 46 publications

On the strain-induced fibrillar microstructure of polyethylene: Influence of chemical structure, initial morphology and draw temperature

On the strain-induced fibrillar microstructure of polyethylene: Influence of chemical structure, initial morphology and draw temperature

Structural Approaches of Polyethylene Environmental Stress-Crack Resistance

Correlation between rheological and mechanical properties of black PE100 compounds – Effect of carbon black masterbatch

Contact Info

Product

Resources

About