Strain dependent evolution of structure and stress in propylene-based elastomer during stress relaxation

Yang, Xiao; Sun, Yingying; Liao, Tao; Men, Yongfeng

doi:10.1016/j.polymer.2020.122612

Cited by 10 publications

(9 citation statements)

References 65 publications

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“…In the literature, there are many papers which carry out mechanical stress relaxation experiments and correlate them to scattering data taken during straining, at fixed strains or fixed stresses, but we have found only a few papers that monitor the morphology relaxation of soft matter. Yang et al [4] stretch an ethylene-propylene elastomer slowly (ε < 0.003  ) to different strains (Δε between 0.2 and 1.9) and relate the stress relaxation to the morphology relaxation monitored by wide-angle X-ray diffraction. During relaxation they observe increasing crystallinity and study crystal orientation as a function of strain and time.…”

Section: Doi: 101002/mame202000386mentioning

confidence: 99%

Short‐Term Morphology Relaxation of Thermoplastic Polyurethane Elastomers after Fast Strain Steps

Stribeck

Schneider

Eling

et al. 2020

Macro Materials & Eng

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Strain steps are applied to elastomers in a pneumatic relaxometer and monitored by small‐angle X‐ray scattering (SAXS). The relaxometer provides a rise time of 13 ms for strain pulses of step height Δε = ±1 in strain. The basic character of the 2D SAXS frames is examined and corresponding invariants Q(t) are analyzed. Three thermoplastic polyurethanes (TPU) of hardness 85 Shore A with different soft segments are studied both unannealed and annealed. The first response of all materials is a fast morphology conversion which finishes within tmc =250 ms. Because it has been untraceable, it is characterized by a settling stroke Q(tmc) − Q(0). The second response is a slow morphology adjustment process which complies with logarithmic relaxation. It is characterized by a relaxation rate DQ = Q(10 t)/Q(t) − 1. Comparison indicates that the nanoscopic morphology relaxation processes appear to have little direct relation to the macroscopic stress relaxation curves. The materials differ with respect to hard‐domain morphology stability and morphology recovery. Most unstable is the morphology of the annealed polyether‐based material. It forms nanofibrillary entities when strained.

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Section: Doi: 101002/mame202000386mentioning

confidence: 99%

Short‐Term Morphology Relaxation of Thermoplastic Polyurethane Elastomers after Fast Strain Steps

Stribeck

Schneider

Eling

et al. 2020

Macro Materials & Eng

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“…To elucidate the relationship between the (002) plane orientation and global chain orientation, we introduce a parameter, mass fraction of anisotropic part ( f a ), to quantify the global orientation of polymer chains. , The f a is evaluated by separating the 2D WAXD pattern into isotropic and anisotropic parts, according to the “Halo method” (elaborated in Supporting Information). , In Figure c, f a changes in a traditional way, that is, increasing with strain and decreasing after unloading. Therefore, the enhancement of the (002) plane orientation after unloading is not originated from a more significant chain orientation.…”

Section: Results and Discussionmentioning

confidence: 92%

“…12,51 The f a is evaluated by separating the 2D WAXD pattern into isotropic and anisotropic parts, according to the "Halo method" (elaborated in Supporting Information). 52,53 In Figure 5c, f changes in a traditional way, that is, increasing with strain and decreasing after unloading. Therefore, the enhancement of the (002) plane orientation after unloading is not originated from a more significant chain orientation.…”

Section: ■ Results and Discussionmentioning

confidence: 96%

Multistage Structural Ordering and Crystallization of Poly(trimethylene terephthalate) during Sub-T_g Stretching: Synergetic Effects of Chain Orientation and Conformational Transition

Zhou

Zheng

et al. 2021

Macromolecules

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Crystallizable glassy polymers can undergo multistage structural evolutions and form multiple types of ordered phases (e.g., mesomorphic and crystalline phases) during stretching below their glass transition temperatures (T g ). However, the structural evolution of polymers during sub-T g stretching and the associated molecular mechanisms have not been well understood. In this work, we investigated the multistage structural ordering of glassy polymers and the related mechanisms during stretching below T g by studying poly(trimethylene terephthalate) (PTT) as a model system. Roles of chain orientation and conformational transition on the multistage structural evolution of melt-quenched PTT were elucidated through a loading−unloading experiment. When stretched below T g (e.g., 25 °C), the orientation of polymer chains and the stacking of phenylene rings lead to an intermolecular ordering, which induces the generation of a smectic C-like mesomorphic phase. The orientation degree of chains in such a mesomorphic phase increases with further stretching. This highly oriented mesomorphic phase transforms into a triclinic crystalline phase when the applied stress is unloaded. Stretching at a higher temperature (e.g., 40 °C) results in the formation of a more ordered mesomorphic phase and facilitates the induced crystallization due to the enhanced chain mobility. Fourier transform infrared results demonstrated that the unloading-induced crystallization of stretched PTT is originated from the trans-gauche conformational transition.

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“…22,25,26 As the higher hard domain contents, the more hard crystal skeleton (or physical cross-linking points), thus enhancing the tensile strength of TPEs but sacrifice elongation at break. 49 These results clearly revealed that PCVL soft midblock played an essentially important role in affecting the toughness of the TPEs (vide infra).…”

Section: Mechanical Properties Of Tpesmentioning

confidence: 80%

“…It is known that the occurrence of H-point indicated the strain-hardening and change of network modulus during stretching, probably attributed to the presence of strain-induced crystallization (SIC). 49,55 To verify it, we performed in-situ WAXD measurement to investigate the possible crystallization behavior of TPE3 to TPE5 with different soft block contents during stretching at RT. Prior to stretching, the initial crystallinity value of TPE3 is only 0.05 (Figure 4a).…”

Section: Toughening Mechanismmentioning

confidence: 99%

One-Pot Synthesis of Supertough, Sustainable Polyester Thermoplastic Elastomers Using Block-Like, Gradient Copolymer as Soft Midblock

Zhao

Yang

et al. 2022

CCS Chem

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It remains challenging to synthesize supertough thermoplastic elastomers (TPEs) since stretchability and tensile strength is mutually exclusive. Here we report a one-pot strategy for preparation of sustainable, triblock polyester TPEs consisting of poly(L-lactide) (PLLA) hard segments and poly(caprolactone)-co-poly(-valerolactone) (PCVL) soft segments. Without the requirement of specific functionalized groups, TPEs are successfully synthesized with high stretchability (up to 2100%) and strong tensile strength (up to 71.5 MPa), by simply adjusting microstructures of polymers, thus exhibiting toughness of the world's record (445 MJ/m 3 ). Systematic investigation reveals that the block-like, gradient microstructure of PCVL not only improves ductility by providing flexible elastic network, but also enhances tensile strength through strain-induced crystallization. The practicability of this strategy is well demonstrated by the lifting up water tank over 30000 times heavier than itself and the easy scale-up experiments.

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Strain dependent evolution of structure and stress in propylene-based elastomer during stress relaxation

Cited by 10 publications

References 65 publications

Short‐Term Morphology Relaxation of Thermoplastic Polyurethane Elastomers after Fast Strain Steps

Short‐Term Morphology Relaxation of Thermoplastic Polyurethane Elastomers after Fast Strain Steps

Multistage Structural Ordering and Crystallization of Poly(trimethylene terephthalate) during Sub-T_g Stretching: Synergetic Effects of Chain Orientation and Conformational Transition

One-Pot Synthesis of Supertough, Sustainable Polyester Thermoplastic Elastomers Using Block-Like, Gradient Copolymer as Soft Midblock

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Strain dependent evolution of structure and stress in propylene-based elastomer during stress relaxation

Cited by 10 publications

References 65 publications

Short‐Term Morphology Relaxation of Thermoplastic Polyurethane Elastomers after Fast Strain Steps

Short‐Term Morphology Relaxation of Thermoplastic Polyurethane Elastomers after Fast Strain Steps

Multistage Structural Ordering and Crystallization of Poly(trimethylene terephthalate) during Sub-Tg Stretching: Synergetic Effects of Chain Orientation and Conformational Transition

One-Pot Synthesis of Supertough, Sustainable Polyester Thermoplastic Elastomers Using Block-Like, Gradient Copolymer as Soft Midblock

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Product

Resources

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Multistage Structural Ordering and Crystallization of Poly(trimethylene terephthalate) during Sub-T_g Stretching: Synergetic Effects of Chain Orientation and Conformational Transition