Influence of Thermal Annealing on the Mechanical Properties of PLLA Coiled Stents

Tré R. Welch, Robert C. Eberhart, Joan Reisch, Cheng Jen Chuong

Research output: Contribution to journalArticle

8 Citations (Scopus)

Abstract

To investigate the influence of elevated annealing temperature (70-90 °C) on the mechanical properties of coiled helical PLLA stents. PLLA 0.10 mm fibers and Ø3 mm × 12 mm stents were fabricated and annealed at 70, 80 and 90 °C for 25 min. The mechanical properties of the fibers and the functional characteristics of the stents were measured and compared to a control group processed at 21 °C. The stents were mounted, expanded and relaxed using an Ø3 mm × 2 cm balloon catheter to a maximum balloon pressure of 12 atm. Measurements of stent diameter, length, and the balloon pressure were used to determine the effective circumferential strain, incremental stiffness, elastic recoil, and lengthening of the stents. Stents exhibited progressively higher incremental stiffness with annealing temperature, higher collapse resistance and a reduction in elastic recoil vs. controls. Single fiber mechanical properties decreased as annealing temperature increased. Differential scanning calorimetry revealed crystallinity increased within thermally annealed stent fibers compared with controls. SEM examination indicated thermally annealed stents underwent less twisting than controls during balloon-induced unfurling. Thermal annealing of PLLA fibers and stents between 70 and 90 °C induced changes in crystalline structure, thereby favorably influencing fiber stress-strain behavior and stent expansion characteristics.

Original languageEnglish (US)
Pages (from-to)270-280
Number of pages11
JournalCardiovascular Engineering and Technology
Volume5
Issue number3
DOIs
StatePublished - 2014

Fingerprint

Stents
Hot Temperature
Annealing
Mechanical properties
Balloons
Fibers
Temperature
Stiffness
Pressure
Stress Fibers
Catheters
Differential Scanning Calorimetry
Differential scanning calorimetry
Crystalline materials

Keywords

  • Bioresorbable polymer
  • Crystallinity
  • PLLA stent
  • Thermal annealing

ASJC Scopus subject areas

  • Biomedical Engineering
  • Cardiology and Cardiovascular Medicine

Cite this

Influence of Thermal Annealing on the Mechanical Properties of PLLA Coiled Stents. / Welch, Tré R.; Eberhart, Robert C.; Reisch, Joan; Chuong, Cheng Jen.

In: Cardiovascular Engineering and Technology, Vol. 5, No. 3, 2014, p. 270-280.

Research output: Contribution to journalArticle

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