Self-Acceleration of Nucleation and Formation of Shish in Extension-Induced Crystallization with Strain Beyond Fracture

Cui, Kunpeng; Meng, Lingpu; Tian, Nan; Zhou, Weiqing; Liu, Yanping; Wang, Zhen; He, Jie; Li, Liangbin

doi:10.1021/ma300338c

Cited by 74 publications

(94 citation statements)

References 103 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Kuhn 0 0.65 (6) where α is a constant describing the relative magnitude of λ shish (ϕ) to λ max . ϕ 0 is an "effective" concentration of high molecular weight tail that can be stretched at current flow condition in matrix, i.e., the B0 sample.…”

Section: ■ Discussionmentioning

confidence: 99%

Kinetic Process of Shish Formation: From Stretched Network to Stabilized Nuclei

Cui

Wang

et al. 2015

Macromolecules

Self Cite

View full text Add to dashboard Cite

On the basis of the duality of the shish-kebab superstructure, coil−stretch transition (CST) is well recognized as the molecular mechanism for shish-kebab formation in polymer melts, which, however, is challenged by recent results in flow-induced crystallization (FIC). In this work, we perform a real time investigation on FIC of polyethylene bimodal blends by combing a unique homemade extensional rheometer and synchrotron radiation smallangle X-ray scattering. The results show that the critical strain for shish formation decreases with increasing long chain concentration, which contradicts the role of CST but agrees well with stretched network model (SNM). Quantitative analyses indicate that the formation of shish is determined by the degree of network deformation rather than solely by strain or long chain concentration at a specific temperature. In addition, three types of shish with different stability are observed sequentially by increasing strain. On the basis of our results, strong support is given to the idea that shish formation is a kinetic process. When stretched to a critical deformation degree, the aligned segments couple with each other to form fibrillar-like type I shish, which further transform into type II shish embedded with sporadic lamellae and type III shish embedded with welldefined periodic lamellae sequentially by increasing flow intensity. Our results and the resulting conceptual model not only demonstrates that shish formation is derived from SNM but unveils its kinetic process from initial chain configuration to final stable nuclei. ■ INTRODUCTIONThe subject of flow-induced crystallization (FIC) in polymer melts is of vital importance not only in scientific research but also in industrial application. In most common scenarios flow is inevitably involved during polymer processing, which dictates subsequent morphologies and thus end-use properties of materials. 1,2 The most dramatic change in morphology associated with flow is the transition from isotropic spherulite to highly orientated shish-kebab structure with notably increased stiffness and strength. 3−7 Shish-kebab comprises of central threadlike core, namely, shish which is encircled by disklike crystals, namely kebabs. Although has been observed for several decades, the exact molecular mechanism for shish-kebab formation still remains unclear and under open debates.Two molecular mechanisms, the coil−stretch transition (CST) 8 and stretched network model (SNM) 9 are well recognized for shish-kebab formation. The CST was first proposed by de Gennes in investigating chain dynamic of polymer solution under flow. 10 Keller provided birefringent evidence for the existence of CST and attributed it to the subsequent shish-kebab formation in polymer solution. 11 Then the CST was further extended to polymer melt as the shishkebab morphology formed in melt is analogous to that in solution. 8,12 According to CST, the longest chains can be stretched to transform into shish and the rest shorter ones stay as coil state to crystallize as kebab. Soo...

show abstract

Section: ■ Discussionmentioning

confidence: 99%

Kinetic Process of Shish Formation: From Stretched Network to Stabilized Nuclei

Cui

Wang

et al. 2015

Macromolecules

Self Cite

View full text Add to dashboard Cite

show abstract

“…Both SAXS and WAXS results indicate that the kebab crystals (lamellae) are transformed into extended‐chain crystals, which contribute to the great strength of fibers. However, few studies have focused on the structural evolution during prestretching of the gel‐spun fibers …”

Section: Introductionmentioning

confidence: 99%

Structural Evolution of UHMWPE Fibers during Prestretching Far and Near Melting Temperature: An In Situ Synchrotron Radiation Small‐ and Wide‐Angle X‐Ray Scattering Study

Cao

Chen

Lin

et al. 2017

Macro Materials & Eng

Self Cite

View full text Add to dashboard Cite

Combining a homemade extension apparatus and the in situ synchrotron radiation small‐ and wide‐angle X‐ray scattering methods for measurement, the structural evolutions of gel‐spun ultrahigh molecular weight polyethylene (UHMWPE) fibers during prestretching at temperatures of 25 and 100 °C are investigated, respectively. Lamellar rotation toward the stretching direction occurs before strain hardening, while the folded‐chain crystal destruction and extended‐chain fibril formation processes occur in the strain hardening zone at 25 °C. While at 100 °C, stretching induced crystal melting before the stress plateau region and formation of fibrous crystals at the onset of the stress plateau are observed. Further stretching results in shear displacement of crystal blocks and, finally, destruction of the folded‐chain crystals and formation of extended‐chain fibrils. Prestretching UHMWPE fibers at 100 °C within a certain strain range can produce highly oriented fibrous crystals, which may provide an ideal precursor structure for the poststretching process.

show abstract

“…[1][2][3] The mechanical properties of polymers are determined by their nal structures, as well as their evolution process. [1][2][3] The mechanical properties of polymers are determined by their nal structures, as well as their evolution process.…”

Section: Introductionmentioning

confidence: 99%

Lamellae evolution of poly(butylene succinate-co-terephthalate) copolymer induced by uniaxial stretching and subsequent heating

et al. 2014

View full text Add to dashboard Cite

The lamellar structural evolution of biodegradable poly(butylene succinate-co-terephthalate) (PBST) random copolymer was investigated under the conditions of uniaxial stretching at 50 C, and then heating from 50 to 150 C at a strain of 150% by the in situ small-angle X-ray scattering (SAXS) technique. A long period referring to the lamellae while processing PBST was calculated, and a schematic for the structural evolution was proposed. It has been found that the lamellar structure experienced a remarkable transformation accompanied by the strain-induced melting of lamellae and formation of new lamellae when the strain exceeded 84% at 50 C during the initial deformation process. After stretching by 150%, the lamellar structure remained unchanged with the perfection of lamellae in the subsequent heating process from 50 to 120 C. Only at relatively high temperatures (120-150 C), the long period of lamellae underwent a significant increase. Conclusions can be drawn that the lamellar structure of PBST is more sensitive to strain and only a relatively high temperature has a prominent impact on it, which is of great significance to provide targeted design guidance for the manufacturing and application of biodegradable PBST copolymer and also gives potential insights into other random and aliphatic-aromatic copolymers. † Electronic supplementary information (ESI) available: Thermal analysis curves of PBST copolymer (Fig. S1), the stress relaxation curve of PBST copolymer during the heating process as a function of time (Fig. S2), peak tting of XRD curve of PBST copolymer using the soware JADE 5.0 and its corresponding result for crystallinity calculated using the equation X c ¼ area of crystals peak/total area (Fig. S3). See Scheme 1 Illustration showing the chemical structure of the assynthesized PBST. 64626 | RSC Adv., 2014, 4, 64625-64633 This journal is

show abstract

Self-Acceleration of Nucleation and Formation of Shish in Extension-Induced Crystallization with Strain Beyond Fracture

Cited by 74 publications

References 103 publications

Kinetic Process of Shish Formation: From Stretched Network to Stabilized Nuclei

Kinetic Process of Shish Formation: From Stretched Network to Stabilized Nuclei

Structural Evolution of UHMWPE Fibers during Prestretching Far and Near Melting Temperature: An In Situ Synchrotron Radiation Small‐ and Wide‐Angle X‐Ray Scattering Study

Lamellae evolution of poly(butylene succinate-co-terephthalate) copolymer induced by uniaxial stretching and subsequent heating

Contact Info

Product

Resources

About