Creep-resistant behavior of beta-polypropylene with different crystalline morphologies

Jia, Chenfei; Liao, Xia; Zhu, J. J.; An, Zhu; Zhang, Qiongwen; Qi, Yang; Li, Guangxian

doi:10.1039/c5ra26478b

Cited by 13 publications

(13 citation statements)

References 51 publications

(55 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…After reaching a critical strain, the growth rate of strain gradually increases, which denotes the transition to the third stage (Stage III). The critical strain is determined when the second derivative of the strain crosses zero and the measured value is around 15.0% for all high stress levels, which is within the experimental range of 11.0%–17.0% . The transition time for the stress levels of 23.4, 24.7, and 28.0 MPa is 2.67, 1.18, and 0.52 ns, respectively.…”

Section: Resultssupporting

confidence: 59%

“…The critical strain is determined when the second derivative of the strain crosses zero and the measured value is around 15.0% for all high stress levels, which is within the experimental range of 11.0%-17.0%. 11,12,63 The transition time for the stress levels of 23.4, 24.7, and 28.0 MPa is 2.67, 1.18, and 0.52 ns, respectively. The time shortens with the increasing stress level, which indicates the faster deformation in the polymer.…”

Section: Creep Behavior Of Polymermentioning

confidence: 99%

See 1 more Smart Citation

Understanding Creep Behavior of Semicrystalline Polymer via Coarse‐Grained Modeling

Xia

et al. 2019

J Polym Sci B Polym Phys

View full text Add to dashboard Cite

Understanding the deformational and failure behaviors of thermoplastic semicrystalline polymers is crucial due to the practical usages in various engineering applications. Taking isotactic polypropylene (iPP) as a semicrystalline polymer model system, atomistically informed coarse‐grained (CG) molecular dynamics (MD) simulations are employed to investigate the creep behavior of iPP. The simulations reveal that there exists a threshold stress of about 20.0 MPa, above which the maximum strain of iPP within the simulation time span increases dramatically. From the strain‐time analysis, it is observed that the iPP exhibits an initial elastic deformation stage and a subsequent plastic stage at lower stress levels, while a three‐stage creep behavior including a third fracture stage is observed at higher stress levels. Specifically, at lower stress levels, the bonded energy increases continuously as the chains stretch steadily, while the nonbonded energy shows an initial increase followed by a steady decrease due to the interchain sliding. At higher stress levels, both bonded and nonbonded energies change dramatically at the third stage, resulting from accelerated chain stretching, unfolding, sliding, and breaking. This study provides physical insight into the creep behavior of iPP at a fundamental molecular level and highlights the important role of microstructural evolution of chains in the deformation of semicrystalline polymer materials. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2019 © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2019, 57, 1779–1791

show abstract

Section: Resultssupporting

confidence: 59%

Section: Creep Behavior Of Polymermentioning

confidence: 99%

Understanding Creep Behavior of Semicrystalline Polymer via Coarse‐Grained Modeling

Xia

et al. 2019

J Polym Sci B Polym Phys

View full text Add to dashboard Cite

show abstract

“…The secondary creep is a steady state, which means that the strain rate is nearly constant . The secondary creep contributes mainly to ε v ( t ,σ, T ).…”

Section: Resultsmentioning

confidence: 99%

“…The secondary creep is a steady state, which means that the strain rate is nearly constant. [7,18] The secondary creep contributes mainly to ε v (t,σ,T). Therefore, the investigation of the structural evolution during the secondary creep will help to get a better understanding of the mechanism of creep, which enables a better prediction of the lifetime of the polymer materials in use.…”

Section: Creep Test Resultsmentioning

confidence: 99%

Microstructural Evolution of Isotactic‐Polypropylene during Creep: An In Situ Study by Synchrotron Small‐Angle X‐Ray Scattering

Chang

Schneider

Heinrich

2017

Macro Materials & Eng

View full text Add to dashboard Cite

The structure evolution of isotactic‐polypropylene during creep is investigated by in situ synchrotron small‐angle X‐ray scattering. During primary creep, strain grows nonlinearly to a value less than 15%. The long period in loading direction (L∥) increases with time, whereas the long period perpendicular to the loading direction (L⊥) decreases slightly. During the secondary creep, strain increases linearly with time. L∥ and L⊥ show the same tendency with strain. The increase of the long period is caused by lamellae thickening, which is a kind of cooperative motion of polymer chains with their neighbors at the lamellae surface. Moreover, the growth rate of L∥ is larger than that of L⊥, indicating that the orientation of molecular chains along the loading direction decreases the energy barrier of the cooperative motion. During tertiary creep, strain grows dramatically in a short time. In this step, the lamellae are tilted, rotated, and then disaggregated. In addition, a fibrillar structure is formed during lamellae breaking. The length of the fibrillar structure increases from 364 to 497 nm while its width stays at 102 nm with increasing creeping time.

show abstract

“…PALS is a unique experimental technique capable of probing the size and concentration of the free volume holes in molecular material . The utility of PALS is enhanced by the fact that positrons, when injected in a polymer, are likely to annihilate with an electron directly or form a bound system, positronium (Ps), which is trapped in regions with reduced electron density.…”

Section: Methodsmentioning

confidence: 99%

Investigation of chemi‐crystallization and free volume changes of high‐density polyethylene weathered in a subtropical humid zone

Xiong

Liao

et al. 2016

Polymer International

Self Cite

View full text Add to dashboard Cite

The chemi-crystallization and free volume changes of high-density polyethylene (HDPE) exposed to subtropical humid climate of Guangzhou, China, were investigated using Fourier transform infrared spectroscopy, differential scanning calorimetry, wide-angle X-ray diffraction, dynamic mechanical analysis and positron annihilation lifetime spectroscopy. An increase in content of carbonyl groups and significant chemi-crystallization were observed to occur during natural exposure. Chain scission accounted for the chemi-crystallization and would lead to greater crystallizability of the molecules. The reheating DSC run indicated that the crystallizability of the degraded HDPE molecules increased initially with exposure time and then decreased. Positron data showed the new crystals induced by chemi-crystallization indeed had more imperfect crystal structure in comparison with the pre-existing parent crystals, and the free volume located in amorphous regions decreased involving a shrinking of the free volume holes. The shrinkage of free volume holes was correlated with the loss of mobility of HDPE molecules, which was confirmed by the increase of glass transition temperature. The formation of new imperfect crystals might increase the amount of rigid amorphous fraction of HDPE materials, as well as the occurrence of crosslinking reactions of molecules located in the interior of HDPE materials, consequently decreasing the molecular mobility.

show abstract

Creep-resistant behavior of beta-polypropylene with different crystalline morphologies

Abstract: This manuscript investigates the creep performance of β-iPP with different crystalline morphologies.

Cited by 13 publications

References 51 publications

Understanding Creep Behavior of Semicrystalline Polymer via Coarse‐Grained Modeling

Understanding Creep Behavior of Semicrystalline Polymer via Coarse‐Grained Modeling

Microstructural Evolution of Isotactic‐Polypropylene during Creep: An In Situ Study by Synchrotron Small‐Angle X‐Ray Scattering

Investigation of chemi‐crystallization and free volume changes of high‐density polyethylene weathered in a subtropical humid zone

Contact Info

Product

Resources

About