A new approach to improve the local compressive properties of PPDO self-expandable stent

Zhao, Fan; Xue, Wen; Wang, Fujun; Yu, Chenglong; Xu, Haiyan; Yi, Hao; Wang, Lu

doi:10.1016/j.jmbbm.2017.02.015

Cited by 29 publications

(19 citation statements)

References 44 publications

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“…8 For the braided stents, the process of shaping the stent by annealing can also affect the mechanical properties of stents. 9 It is essential to study the comprehensive effects of SSD and annealing on the monofilaments before the practical application.…”

Section: Introductionmentioning

confidence: 99%

Effects of annealing constraint methods on poly(L‐lactic acid) monofilaments for application in stents annealing

Tian

Zhang

et al. 2021

Polymers for Advanced Techs

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Mechanical properties of poly(L-lactic acid) (PLLA) braided stents are closely related to the performance of the weaving monofilaments. In this study, the PLLA monofilaments were prepared via solid-state drawing (SSD) method and annealed with different constraint methods. Experimental results show that mechanical properties of fabricated monofilaments have been greatly improved by SSD method. With the constrained annealing method, mechanical properties can be further improved while negative effect is shown with unconstrained annealing method. The physicochemical properties of PLLA monofilaments were further characterized, and it is found that the draw ratio of SSD and annealing method can affect the crystallinity and crystallite size, which can directly influence the mechanical properties of the monofilaments.This work tells that it is necessary to consider collectively the effects of SSD method and annealing method of the monofilaments in order to obtain optimized mechanical properties of the braided stents.

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Section: Introductionmentioning

confidence: 99%

Effects of annealing constraint methods on poly(L‐lactic acid) monofilaments for application in stents annealing

Tian

Zhang

et al. 2021

Polymers for Advanced Techs

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“…To ensure the same technical parameters of stents, both stents are designed with identical geometric structure and braided then annealed under the same process conditions. 25,26 For braided self-expanding stents, COF as the opening force acting on vessel wall during expanding to original diameter after released from delivery system, 22,23 can influence the lumen patency profoundly and is the focus of this study. As shown in Figure 2, the COF of PLLA stent (0.082-0.142 N/mm) is more than three times higher than that of PDO stent (0.023-0.042 N/mm) when indicated use diameters are between 6 and 7 mm.…”

Section: Radial Force Of Stentsmentioning

confidence: 99%

A poly(L‐lactic acid) monofilament with high mechanical properties for application in biodegradable biliary stents

Tian

Zhang

Cheng

et al. 2020

J of Applied Polymer Sci

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In this article, a poly(L‐lactic acid) (PLLA) monofilament with high mechanical properties which can be used to construct biodegradable biliary stents (BBS) is prepared. Compared with a commercial polydioxanone (PDO) suture, the PLLA monofilament has much higher Young's modulus. As a result, chronic outward force (COF) of the stent braided by PLLA monofilament is more than three times higher than that of the stent braided by PDO suture. Furthermore, by physicochemical indexes characterizations, it is acceptable that the PLLA monofilament has stable Young's modulus and higher elongation at break without brittle fracture risk during degradation in bile. In contrast, although PDO suture can also maintain Young's modulus well during degradation, its elongation at break is attenuated rapidly, which shows a high brittle fracture risk. These results indicate that PLLA monofilament is more suitable for constructing BBS with high COF, which are promising in treating more complex biliary strictures that need longer support time.

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“…The isothermal annealing of PPDO bars [13,18]: Firstly, the vacuum oven (Shanghai Shenxian Instrument Co., Ltd., Shanghai, China) was heated to the designated temperature (50 ℃, 60 ℃, 70 ℃, 80 ℃, 90 ℃, and 100 ℃). A thermometer was placed in the oven to rectify the temperature.…”

Section: Preparation and Isothermal Annealing Of Ppdo Barsmentioning

confidence: 99%

“…The reason for this may be that the material underwent thermal degradation during annealing. Zhao et al [18] investigated several thermal treatment conditions (60 °C, 80 °C, and 100 °C for 1 h) to improve the characteristics of PPDO self-expandable stents. They suggested that the 60 °C annealing stents show higher compressive stiffness, and prior viscoelasticity and shape stability are obtained at higher annealing temperatures (80 °C and 100 °C).…”

Section: Mechanical Propertiesmentioning

confidence: 99%

“…The possibility of improving the mechanical properties of PPDO via thermal treatment has been proposed in this context [16,17]. Zhao et al [18] have improved the compressive performance of PPDO self-expandable stents through thermal treatment conditions (60 ℃, 80 ℃, and 100 ℃, 1 h). At the same time, the heat treatment process might damage the mechanical properties of PPDO because of thermal degradation or thermal oxygen degradation.…”

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confidence: 99%

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Tuning the mechanical properties and degradation properties of polydioxanone isothermal annealing

et al. 2020

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Polydioxanone (PPDO) is synthesized by ring-opening polymerization of p-dioxanone, using stannous octoate as the catalyst. The polarized optical micrograph (POM) shows thes pherulite growth rate of PPDO decreases with an increase in the isothermal crystallization temperature. PPDO is compression-molded into bars, and PPDO bars are subjected to isothermal annealing at a range of temperatures (Ta = 50, 60, 70, 80, 90, and 100 °C), and correspond to three different annealing times (ta = 1h, 2h, 3h). The effect on PPDO is investigated by using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), X-ray diffraction (XRD), and scanning electron microscopy (SEM). With an increase in Ta and ta, the grain size and the degree of crystallinity also increase. Meanwhile, the tensile strength is significantly improved. The PPDO bars (90 °C, 2 h) reach the maximum crystallinity (57.21%) and the maximum tensile strength (41.1 MPa). Interestingly, the heat treatment process does not result in serious thermal degradation. It is observed that the hydrolytic degradation of the annealed PPDO is delayed to some extent. Thus, annealed PPDO might have potential applications, particularly in the fields of orthopedic fixation and tissue engineering.

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A new approach to improve the local compressive properties of PPDO self-expandable stent

Cited by 29 publications

References 44 publications

Effects of annealing constraint methods on poly(L‐lactic acid) monofilaments for application in stents annealing

Effects of annealing constraint methods on poly(L‐lactic acid) monofilaments for application in stents annealing

A poly(L‐lactic acid) monofilament with high mechanical properties for application in biodegradable biliary stents

Tuning the mechanical properties and degradation properties of polydioxanone isothermal annealing

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