Effect of chain topological structure on the crystallization, rheological behavior and foamability of TPEE using supercritical CO2 as a blowing agent

Jiang, Rui; Yao, Shan-Jing; Chen, Yichong; Liu, Tao; Xu, Zheng; Park, Chul; Zhao, Ling

doi:10.1016/j.supflu.2019.02.006

Cited by 46 publications

(28 citation statements)

References 47 publications

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“…Only at the high elongation rate is E χ for PTFE0 higher than 1, showing slight strain-hardening behavior. This phenomenon is due to the linear chain structure of TPEE, which was studied in detail in previous work [35], where all the samples with PTFE nanofibrils showed extremely high E χ values for all the rates employed. As discussed for the shear rheological tests, the entangled network can lead to a long relaxation process [28].…”

Section: Rheological Analysismentioning

confidence: 62%

“…TPEE pellets and PTFE powder were dried at 110 • C in a vacuum drying box overnight and were then well mixed with a given mass ratio. To increase the viscosity of commercial linear TPEE, 0.5 wt % 2,2 -BOZ was added to all the nanocomposites, as mentioned in previous studies [35,36]. Table 1 shows the compositions of the nanocomposites.…”

Section: Methodsmentioning

confidence: 99%

“…Figure 9 displays all the elongational viscosity curves of the TPEE with different PTFE contents. As shown in Figure 9a, due to the lack of branched chains and PTFE nanofibrils, sample PTFE0 shows little strain-hardening behavior [35]. Only for a higher elongation rate such as 0.1 and 0.5 s −1 , does the elongational viscosity rise with time.…”

Section: Rheological Analysismentioning

confidence: 97%

See 2 more Smart Citations

Improving the Continuous Microcellular Extrusion Foaming Ability with Supercritical CO2 of Thermoplastic Polyether Ester Elastomer through In-Situ Fibrillation of Polytetrafluoroethylene

Jiang

Liu

et al. 2019

Polymers

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In-situ fibrillated polytetrafluoroethylene (PTFE) enhanced nanocomposites were successfully prepared by mixing thermoplastic polyether ester elastomer (TPEE) and PTFE using a twin-screw extruder. Well-dispersed, long aspect ratio PTFE nanofibrils with a diameter of less than 200 nm were generated and interwoven into networks. Differential scanning calorimetry and in-situ polarized optical microscopy showed that the PTFE nanofibrils can greatly accelerate and promote crystallization of the TPEE matrix and the crystallization temperature can be increased by 6 • C. Both shearing and elongational rheometry results confirmed that the introduction of PTFE nanofibrils can significantly improve the rheological properties. The remarkable changes in the strain-hardening effect and the melt viscoelastic response, as well as the promoted crystallization, led to substantially improved foaming behavior in the continuous extrusion process using supercritical CO 2 as the blowing agent. The existing PTFE nanofibrils dramatically decreased the cell diameter and increased cell density, together with a higher expansion ratio and more uniform cell structure. The sample with 5% PTFE fibrils showed the best foaming ability, with an average diameter of 10.4-14.7 µm, an expansion ratio of 9.5-12.3 and a cell density of 6.6 × 10 7 -8.6 × 10 7 cells/cm 3 .2 of 16 has many excellent properties including thermal stability, good elasticity, chemical and oil resistance and, especially, rebound resilience at low-temperatures [3,5]. Also, TPEE has higher tear and impact strengths over a broad range of service temperatures when compared with other traditional TPEs [8]. Because of the extraordinary performance of TPEE, it has attracted increasing interest from many fields such as the sports, automotive and military industries.Although TPEE is an attractive engineering material, its application has to overcome the exorbitant price. To overcome this shortcoming, many attempts have been made to further improve the mechanical properties or to lower the weight (i.e., material consumption). Blending the matrix with micro-sized particles is an efficient method to improve the thermal or mechanical properties of TPEE [9][10][11][12][13]. Paszkiewicz et al. [12] added carbon nanotubes (CNTs) and graphene nanoplatelets (GNPs) to poly(trimethylene terephthalate) (PTT)-based TPEE to improve the electrical conductivity. They found that CNTs had greater potential to improve electrical conductivity when compared to GNPs due to the higher purity and higher aspect ratio. Qiu et al. [13] controlled the structure of mixed filler particles in TPEE to enhance the mechanical properties. The results showed that a closely packed particle structure can significantly improve the yield strength by about 40% with a decrease of about 20% in the Young's modulus, which is preferred in TPEE used as an elastomer.Foaming is a very effective way to lower the weight and expand the application of polymers. In recent decades, foamed materials have exhibited a balance between price and...

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Section: Rheological Analysismentioning

confidence: 62%

Section: Methodsmentioning

confidence: 99%

Section: Rheological Analysismentioning

confidence: 97%

See 1 more Smart Citation

Improving the Continuous Microcellular Extrusion Foaming Ability with Supercritical CO2 of Thermoplastic Polyether Ester Elastomer through In-Situ Fibrillation of Polytetrafluoroethylene

Jiang

Liu

et al. 2019

Polymers

Self Cite

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“…Polymerization in supercritical fluids is an interesting alternative to the conventional method of polymerization in organic solvents. Supercritical CO 2 is easily removed after the polymerization process and, in the case of radical polymerization negligible chain transfer, is observed compared to organic solvents [ 72 , 130 , 131 ]. Most polymers are insoluble in supercritical carbon dioxide, except for amorphous polysiloxanes and fluoropolymers.…”

Section: Other Processes Using Supercritical Fluids In the Polymermentioning

confidence: 99%

Application of Fluids in Supercritical Conditions in the Polymer Industry

et al. 2021

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This article reviews the use of fluids under supercritical conditions in processes related to the modern and innovative polymer industry. The most important processes using supercritical fluids are: extraction, particle formation, micronization, encapsulation, impregnation, polymerization and foaming. This review article briefly describes and characterizes the individual processes, with a focus on extraction, micronization, particle formation and encapsulation. The methods mentioned focus on modifications in the scope of conducting processes in a more ecological manner and showing higher quality efficiency. Nowadays, due to the growing trend of ecological solutions in the chemical industry, we see more and more advanced technological solutions. Less toxic fluids under supercritical conditions can be used as an ecological alternative to organic solvents widely used in the polymer industry. The use of supercritical conditions to conduct these processes creates new opportunities for obtaining materials and products with specialized applications, in particular in the medical, pharmacological, cosmetic and food industries, based on substances of natural sources. The considerations contained in this article are intended to increase the awareness of the need to change the existing techniques. In particular, the importance of using supercritical fluids in more industrial methods and for the development of already known processes, as well as creating new solutions with their use, should be emphasized.

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“…[17] Hence, it seems that single modifier, such as epoxy, polyol, and anhydride, could efficiently produce relatively high melt strength PET with improved foaming ability [8,10,12] ; however, chain extension may be more dominant than chain branching as has been widely reported. [8,12,18] Then, a double-end reaction has been developed to realize the long-chain branched (LCB) structure of poly(L-lactide) and thermoplastic polyester elastomer. [19][20][21] Therefore, LCB PET needs to be prepared to dramatically promote its foaming properties.…”

Section: Introductionmentioning

confidence: 99%

Good extrusion foaming performance of long‐chain branched PET induced by its enhanced crystallization property

Yao

Guo

Liu

et al. 2020

J of Applied Polymer Sci

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Poly(ethylene terephthalate) (PET) was modified by regulating different contents of branching agent epoxy‐based multifunctional oligomer and chain extender pyromellitic dianhydride in reactive extrusion process. The modified PET with better long‐chain branched (LCB) structure boosted its rheological properties, and its enhancement of melt viscoelasticity resulted in excellent foamability in molten‐state foaming process using supercritical CO2 as blowing agent. More importantly, the branched structures acted as crystal sites to accelerate the crystallization kinetic of LCB PET whether under atmospheric pressure or high‐pressure CO2. The shear and elongation flow inside die further quickly induced the crystallization of LCB PET. The rapidly generated fine crystals could both introduce heterogeneous cell nucleation and suppress CO2 escape, so the cell morphology of LCB PET in continuous extrusion foaming process exhibited a three‐fold increase in cell density and smaller uniform cell size with respect to those of other foam‐grade PET with long‐chain structure.

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Effect of chain topological structure on the crystallization, rheological behavior and foamability of TPEE using supercritical CO2 as a blowing agent

Cited by 46 publications

References 47 publications

Improving the Continuous Microcellular Extrusion Foaming Ability with Supercritical CO2 of Thermoplastic Polyether Ester Elastomer through In-Situ Fibrillation of Polytetrafluoroethylene

Improving the Continuous Microcellular Extrusion Foaming Ability with Supercritical CO2 of Thermoplastic Polyether Ester Elastomer through In-Situ Fibrillation of Polytetrafluoroethylene

Application of Fluids in Supercritical Conditions in the Polymer Industry

Good extrusion foaming performance of long‐chain branched PET induced by its enhanced crystallization property

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